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bruce
Frequent Contributor
Username: bruce
Post Number: 223
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 05:10 pm: | 
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Hi,
I realise this isnt a typical CZ thread, but you might find it interesting:
The Government ( they cant run the Country, we're broke and theres a General Election looming, but they cant stop interfering in EVERYTHING ) Now they are targetting your gas boiler.
There's now another scrappage scheme ( also known as a get-rich-quick scheme for the cowboys ); this time for old boilers. And that doesnt include Harriet Harman. Apparently, old boilers are inefficient. Hmmm.
Some woman was being profiled on the 6 o'clock News. Her boiler was only 10 years old, but regarded as obsolete. And not sufficiently efficient, which is the main thing. It's this concept of efficiency that disturbs me.
Notice that gas fires aren't included in this drive to save energy.
I always assumed gas fires were about as efficient as you could reasonably expect. Balanced flue and all that. You burn the gas and the resulting heat enters the room. Some is lost, but how much are we talking about? 5%, 10%?
Is it feasible to make them sufficiently MORE efficient to justify all the messing about. Anybody know?
Surely the same argument holds for the boiler. The gas burns and heats the water.There is some loss of heat via the exhaust gasses, but I cant see you could improve the efficiency by very much. It's just a fancy gas fire isn't it? It might not heat the water as slickly as a newer model, but the difference cant be that big and the heat isn't lost: it still heats the house.
Over to you.
Bruce |
g6osv
Frequent Contributor
Username: g6osv
Post Number: 83
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 05:22 pm: |
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New boilers are of thr condensing type,one of the products of combustion is water in the form basically of steam.
Condensing boilers recover the latent heat from the water vapor and put it in your house instead of up the(balanced) flue.
Ian |
alec_t
Frequent Contributor
Username: alec_t
Post Number: 128
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 05:49 pm: |
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Hi g6osv,
Do you know what percentage (roughly) of the total gas energy the latent heat represents? If it's only 2 or 3% then a new boiler is an expensive luxury. Like Bruce, I'm rather sceptical about these so-called efficient boilers.
Another factor to consider is the carbon footprint of a new boiler. Has anyone done the sums, I wonder, to calculate the total energy needed to mine the metal ores, smelt them, machine/mould metal and plastic parts needed in the manufacture of a boiler, heat/cool/light the factory, transport the boiler and install it? I would guess not. I wouldn't be surprised if the total energy far exceeded any supposed energy saving from 'increased efficiency'.
Regards, Alec |
g6osv
Frequent Contributor
Username: g6osv
Post Number: 85
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 06:46 pm: |
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Depends a lot on the size/age of the boiler,a bit of info here.
http://www.which.co.uk/reviews/boilers/page/condensing-boilers-explained/
Ian |
joe
:::: Super User ::::
Username: joe
Post Number: 707
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 06:50 pm: |
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A chap at work had an old Potterton oil powered boiler. Now they have a very large house to heat, and used to use around £1000 of heating oil over 8 weeks or so in winter. Since a new boiler was installed, its quieter and they are seeing a £200 saving over 8 weeks... so far.
Now of course its possible that the old boiler was just faulty or incorrectly set up, but needless to say they are very pleased they upgraded to a new one.
Since mine is 15 years old, gas isn't getting any cheaper and a new boiler must shurly be more efficient than a 15 year old one, for me it makes sense to probably upgrade.
Joe
Read my ramblings - www.techbites.com/joe-farr
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armadillo
Frequent Contributor
Username: armadillo
Post Number: 243
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 08:00 pm: |
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My gas boiler is 31 yrs old and working fine thank you. If as they say, it's only 65% efficient then 35% of the heat must be going up the flue. However, it hasn't got a balanced flue. It goes through the middle of the house and finds it's way out through the ridge of the roof.
On the way it provides the only heat for:
The main bedroom, bedroom 3, the hall, stairs and landing and helps prevent the cistern in the loft freezing. If the heat is not on in the lounge (most of the time) it also provides an element of background heating. As I type this, it's -3C outside but the unheated areas are:
Bed1 = 18C
Bed3 = 16C
Landing = 17C
Lounge = 11C
ALL of this heat comes form the 'waste' heat from our 'inefficient boiler'. If it was taken out and replaced with a new one I would have to add more radiators so it would end up costing the same to run. Changing boilers will only be done in this house when the old one is beyond repair - which I suspect will be the first time it goes wrong. However, fingers crossed, it's never gone wrong since we've had it.
BTW the extension that we spend most of the day in is at 24C ('cos most of it's spent sitting down)
In short, the boiler may be inefficient but the heating system isn't and if the boiler was replaced the system would be insufficient as it is.
£0.02 supplied.
Armadillo
There's no such thing as gravity..........
The earth sucks!
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chippie
Frequent Contributor
Username: chippie
Post Number: 266
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 06 January, 2010 - 08:10 pm: |
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The scrappage scheme incentive is worth £400....
I work for Centrica the parent company of British Gas..in fact BG is just a brand name...
My boiler too is of the inefficient type...To replace it would mean major upheaval in my house...I dont think its worth changing atm...
A few years ago, I had to replace the main gas valve, the spares parts place I went to told me that my particular boiler was one of the best on the market at the time...and was worth keeping running..Newer types were prone to failure of expensive electronic pcb assemblies...
Seems to me that this country just seems hell bent on fleecing every one of their hard earned...
2cents supplied ( coz its worth less than 2p  )
eccentric millionaire financed by 'er indoors
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zeitghost
Frequent Contributor
Username: zeitghost
Post Number: 1393
Registered: 01-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 08:29 am: |
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Condensing boiler: heatexchanger made of aluminium: expected life: 10 years if you're lucky.
Old boiler (Harriet Harman): heatexchanger made of cast iron: expected life: decades (lots). |
bruce
Frequent Contributor
Username: bruce
Post Number: 224
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 09:11 am: |
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I wasnt sure this thread would be of interest, but it seems I've hit a sore spot. Do I get a prize?
I do wonder what's actually behind this initiative. As someone pointed out, the carbon footprint of making a new boiler plus removing the old one, would probably make the whole thing pointless. They cant be unaware of this. Could they possibly have a hidden aganda and are pulling the wool over our eyes? That's never happened before in Politics.
And nobody has answered the question of gas fires. If you can recover some of the energy which is lost in the exhaust gasses for a boiler, why not the fire as well?
Some of us aren't afraid to ask the difficult questions...... |
arw
Board Administrator
Username: arw
Post Number: 815
Registered: 04-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 11:14 am: |
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Gas boilers (furnaces) are a moot point - mine is a basic but robust Myson Marathon 70,000 Btu gas burner + gas valve + thermostat with its own flue. I've just replaced the gas valve, and I've never believed that I would save money by ripping it out and installing a new condensing type.
My plumber friend is Bosch accredited and knows these things -- he installed a modern boiler for his Mum. It's full of controls, awesome PCBs and sensors. Unfortunately, the water level sensor failed, but the system started to leak. As the boiler thought the system was still full, it carried on heating until the thing dried up altogether and melted.
Hence my plumber agrees that I should keep my basic boiler until it fails altogether. There's little to go wrong.
The £400 thing is down to G. Brown & Co trying to save the world/ his neck. It's supposedly to create work for British (or Polish) plumbers.
If my experience of grant-assisted schemes is anything to go by, you can bet the seller will have inflated the price to the maximum, in the knowledge that he can claw something back from the Gov't.
The net price to customers can be roughly the same, whether they buy through an inflated grant-assisted scheme or they haggle and buy privately on their own account.
It's like the uPVC sales pitch - buy the front windows and we'll give you the back ones, free! Don't think so...
Alan Winstanley
Visit EPE Online at http://www.epemag3.com
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bruce
Frequent Contributor
Username: bruce
Post Number: 225
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 11:47 am: |
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Honestly, Alan; so cynical!
I was thinking that, although this sheme will generate lots of jobs/work, I bet most of the money will end up in Poland. It's all very well having a chuckle about this, but theres three quarters of a million Polish young men, and all they can do is freelance manual work. I dont give a toss if you think this is being racist, but I reckon, personally, that you're being pretentious or simple-minded if you believe much tax gets paid on all these transactions. That means that large amounts of money are being drained out of this country, when it's practically broke anyway. And of course they're taking our jobs. That isn't some Daily Mail scare story; it's Darwinism. Many people competing for limited resources. It's not a level playing-field, either. These guys can undercut native workers. Why on Earth do we tolerate it?
And what kind of drain is that on the NHS, which none of them have paid anything towards. I stand by this; this is not racism. We're being comprehensively stuffed. The situation is insane and I cant understand why we lack the balls to do something about it.
This may be off topic |
joe
:::: Super User ::::
Username: joe
Post Number: 708
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 01:25 pm: |
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"guys can undercut native workers. Why on Earth do we tolerate it?"
If were still talking about boilers and gas fitting, then No, they can't...
You have to be on the Gas Safe register to carry out gas related work in the UK and it's probably prison time if you do... and your not...
If you find people who are doing this work and are not registered report them, and do everybody a favour.
http://www.gassaferegister.co.uk/help/check_an_engineer.aspx
Joe
Read my ramblings - www.techbites.com/joe-farr
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zeitghost
Frequent Contributor
Username: zeitghost
Post Number: 1394
Registered: 01-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 03:46 pm: |
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It's only prison time if you get caught & some unfortunate has died.
Of course, if, in the mean time, you've buggered off somewhere abroad... |
g6osv
Frequent Contributor
Username: g6osv
Post Number: 87
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 06:03 pm: |
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If you want to check a gas engineer as above use IE it does not seem to like Firefox.
Ian gas safe no 2292756 |
johnmosborneuk
Member
Username: johnmosborneuk
Post Number: 10
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 07 January, 2010 - 09:26 pm: |
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It seems to me that this boiler "scrappage scheme" is just as pointless as the car one.
Looking at my own central heating which is around 20-25 years old; because it's a back boiler there is a huge amount of work to relocate the boiler itself, then of course the plumber will likely shake his head while telling me that all my radiators need changing too then I'm faced with the added cost of buying a new fire as the backboiler fire most likely can't be used without the boiler!
I'm just guessing here but £400 off the price will probably still leave me with a hole in my bank balance so big that I can't afford the gas to fuel my fancy new boiler  |
terry
Frequent Contributor
Username: terry
Post Number: 559
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 08:10 am: |
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Yep the car scheme has crushed many very nice cars. My wife works in a garage and most of the cars crushed are far better than the staff are driving on the road.
Terry |
alec_t
Frequent Contributor
Username: alec_t
Post Number: 130
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 10:42 am: |
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Hi all,
This thread's been illuminating, but isn't it time to introduce a little bit of electronics...if only for Alan's sake and to justify its retention in the CZ archives?!
The boiler in my daughter's house has a 'proportional' gas control, consisting of three gas injectors of different sizes, to give gas flows in the ratio 1:2:4. These have respective gas valves which are controlled by a board full of electronics, enabling heat output to be set in steps of 0 (3 valves off) to 7 (3 valves on) in response to inputs from user-selected options, water-temperature sensor etc.
The boiler in my own house, however, is older (some 30 years old) and has simple on/off gas control with a single gas valve. No electronics in sight. Water temperature can be manually set, e.g. to compensate for exceptionally cold weather, by a knob on the boiler 'stat.
The simpler boiler has a lot in its favour. The initial cost is far lower. Fewer parts mean less to go wrong, and simpler parts are much cheaper to replace. During my 20 years ownership the gas valve and 'stat have both needed replacement, but the cost was modest, whereas the control board on my daughter's boiler needed to be replaced after about 10 years and was expensive.
The question is, is there any efficiency (as distinct from convenience) difference between the two types of control, to justify all the electronics and complications of proportional control?
Regards, Alec |
hackinblack
Frequent Contributor
Username: hackinblack
Post Number: 431
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 11:09 am: |
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the difference in efficiency comes partly from tighter regulation of overshoot in heating by using smart controllers
to compute the burn time etc.and partly from more efficient boiler tubes BUT
the easiest way to get more heat into a pipe is to make it thinner;which it lasts half as long before the acidic gases eat it away
and the PCB's are not repairable by the service agents,or worth repairing by the main agent;they cost more to fix than to mass produce...
in the good old ays we changed our old coal system for a gas combi
when it failed the main service agent quoted £150+ for a new PCB;so i checked the boiler myself,being engineering maintenance as well as electronic service trained
the fault turned out to be ...
dog hairs on the fan blades,causing a 'flue blocked' signal to the PCB |
johnmosborneuk
Valued Member
Username: johnmosborneuk
Post Number: 12
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 11:38 am: |
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I know at least two people who have had a problem with their condensing boilers due to the condensate drain off pipe being run outside with no lagging, the condensate drain froze in the icy conditions so the boiler shut down.
So they have boilers which don't like working in the cold, ironic or what? |
chippie
Frequent Contributor
Username: chippie
Post Number: 267
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 12:12 pm: |
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I lifted this from our corporate site if any one is interested.........
Prime Minister Gordon Brown visited British Gas’ Dartford energy academy today to kick-start the Government’s new-for-old boiler scheme.
Also today, British Gas announced it would match-fund the Government’s £400 discount in the boiler scrappage scheme, so customers buying a new A-rated boiler from British Gas can cut the cost by £800 this winter.
Mr Brown said: “The new scrappage scheme will help to secure 250,000 jobs across the tens of thousands of small and medium businesses involved in boiler manufacture, sales and installation that form a vital component of Britain’s low carbon economy.”
British Gas has worked quickly to put match-funding in place following the Government’s unveiling of the new scheme in the Pre-Budget Report on December 9, 2009.
Centrica chief executive Sam Laidlaw and British Gas managing director Phil Bentley hosted the 45-minute visit by Mr Brown and Ed Miliband, Energy and Climate Change Secretary.
Sam said: “If the UK is to meet its tough carbon reduction targets, it is vital that old, inefficient energy technologies are replaced. The Government’s boiler scrappage scheme is, therefore, a very welcome initiative. It will assist the replacement of the country’s four million inefficient domestic boilers with new boilers, which can improve energy efficiency by up to 30 per cent - an important step towards lowering carbon emissions.”
The £50 million scheme offers 125,000 vouchers. The Energy Saving Trust will supply customers with a voucher number, as long as their existing boiler is G or X rated, with an efficiency rating of less than 70 per cent. There are 3.7 million G or X rated boilers in the UK.
British Gas’ match-funding is available from tomorrow. More information is available at www.britishgas.co.uk/yourboiler. Or customers can call British Gas on 0800 009 4450 to arrange for a free consultation with a heating advisor.
Unveiling British Gas’ match-funding, Phil Bentley said: “We want to help customers take advantage of the new boiler scrappage scheme, so we’re offering to match the Government’s £400 allowance, which means customers can cut a total of £800 from the cost of a new boiler from British Gas.
eccentric millionaire financed by 'er indoors
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mikeb
Frequent Contributor
Username: mikeb
Post Number: 233
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 01:26 pm: |
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What a load of moaners you are.
The country needs to reduce its energy demands. Its not perfect, but its a start.
You lot will be the first to say "not in my back yard" when they get to work on the 3-5 Nuclear Generators that will need to be installed in the next 10 years.
Lagging lofts, double glazing, better insulation for 10 million people is a much better use of tax money than new Nukes.
rgds
mb |
joe
:::: Super User ::::
Username: joe
Post Number: 709
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 01:50 pm: |
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@johnmosborneuk
That's like saying your petrol car is rubbish because it keeps breaking down every time you put diesel in it.
Don't blame the equipment because of poor installation technique.
Well said Mikeb!!
Read my ramblings - www.techbites.com/joe-farr
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johnmosborneuk
Valued Member
Username: johnmosborneuk
Post Number: 13
Registered: 06-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 08 January, 2010 - 08:02 pm: |
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Don't get me wrong, I'm don't blame the equipment. I was just saying how ironic it is that the latest inovation in boiler technology has been the cause of some breakdowns at the worst possible time.
I hope that the fitters have learned from the mistakes and start lagging the condensate pipes as standard. |
twintub
Frequent Contributor
Username: twintub
Post Number: 51
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, 10 January, 2010 - 12:38 am: |
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I reply to 'johnmosborneuk':
I'm sure that the installers DO NOT want to lag the condensate pipes, because breakdowns = callouts = profit.
I know someone who has just suffered from this breakdown on a boiler that is only about a year old. I think that designed-in obselescence/unreliability is not environmentally friently at all!
On another note, my (permanently lit) pilot light had been extinguishing randomly over the past couple of months, but is now behaving itself. I suspect that the quality of the gas was iffy (air in the gas?) possibly caused by gas mains repairs in my area, or maybe due to poor quality gas from Siberia!
Remember the old adage: "If it ain't broke, don't fix it". |
hackinblack
Frequent Contributor
Username: hackinblack
Post Number: 433
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, 10 January, 2010 - 10:24 pm: |
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the bit about siberian gas is a very good reason for looking for alternatives to fossil fuel
who wants to be held at gunpoint by a foreign power?
most of europe has unwittingly done just that;it cannot cope with demand from its own supplies.VERY worrying
i read with interest the developement of a hydrogen cell 'canister' system for cars;
the hydrogen is dissolved in a lining the way acetylene is,to make storage far safer then storing high pressure tanks
the developers in the US plan to release it next year as a domestic hydrogen processing unit capable of being powered by solar/wind or grid voltage
this low demand for energy input could just be what is needed to change to renewable energy
the sums for solar/battery power simply add up to nonsense,until panels are 1/10th of the price they cost now |
alec_t
Frequent Contributor
Username: alec_t
Post Number: 136
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 14 January, 2010 - 12:41 pm: |
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I've done the sums. Based on gas calorific value stated in my gas bill, and assuming the gas is mainly methane, the latent heat energy in the water vapour produced when gas burns is 8.4% of the total energy of the gas. So a condensing boiler is potentially 8.4% more efficient than a non-condensing type (but more likely only 5 or 6%, as I bet not all of the latent heat will be recovered).
OK. If my gas bill is, say, £1000 per year then I should save £84 a year by having a condensing boiler. If the boiler costs £2000 then it will take around 24 years to recover the cost! But in that time the boiler would almost certainly need replacing at least once more!
On the bright side, that 8.4% might reduce global warming by .0000000001%
Regards, Alec |
zeitghost
Frequent Contributor
Username: zeitghost
Post Number: 1405
Registered: 01-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 15 January, 2010 - 08:24 am: |
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Need replacing only once in 24 years?
With an aluminium heat exchanger?
Hollow larf.
By the way, the scheme only applies to England, those of us in the outer darkness of the Celtic fringe are exempt. |
joe
:::: Super User ::::
Username: joe
Post Number: 715
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 15 January, 2010 - 08:36 am: |
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@alec_t
Cool maths.
But, don't the old boilers keep a gas pilot light on all the time, and the new ones dont?
If so, you need to factor that gas usage into your calculations.
Also, you are assuming that over the 24 years, the price of gas stays the same. You need to factor in inflation.
Joe
Read my ramblings - www.techbites.com/joe-farr
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alanr
Regular Contributor
Username: alanr
Post Number: 23
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 15 January, 2010 - 10:46 am: |
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I live in a modern, now 25 years old, bungalow built to the then latest insulation standards. Just one problem, all the cold water piping is in the cold loft protected from the warmth by the insulation. The lagging of course merely slows down the freezing, not prevents it. In cold weather, like recently, I have to leave the loft hatch open a bit to keep the loft warm enough to prevent freezing. Some of the neighbours on the estate did not, and are now pondering the cost of new ceilings. My boiler is oil fired (no gas in the village when built) and somehow seems to have got water in the oil and shuts down when it drops a degree or two below freezing.
Why do I mistrust modern ideas? And electronics? and computer automation? Mostly because I've had to live with them and repair them.
Happy New Year
Alan |
wizard
Regular Contributor
Username: wizard
Post Number: 47
Registered: 11-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 15 January, 2010 - 05:05 pm: |
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Just to add my two pennyworth,
I had a central heating system that worked for 30 years without a problem. The system then started to fail and I decided to install a brand new British Gas system.
This modern technology system has failed 4 times in the last 5 years at a cost of around £800.
Give me the old systems anytime. |
alec_t
Frequent Contributor
Username: alec_t
Post Number: 137
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 15 January, 2010 - 11:56 pm: |
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@joe
You're right about the pilot light, but I was trying to compare new condensing with newish non-condensing, rather than new with old. Besides, (a) I haven't the faintest idea how much gas the pilot light uses, (b) the heat from the pilot light is itself useful (at least in winter!), and (c) I doubt whether the pilot light energy in an old boiler is much different from the energy needed by all the electronics in the latest boiler control board.
Regarding inflation, I was assuming (no doubt wrongly) that boiler cost went up roughly in line with gas cost so sort of cancelled out inflation if the new boiler needed replacing by yet another new boiler after only ten years or so.
Regards, Alec |
mikem2
Just joined
Username: mikem2
Post Number: 1
Registered: 10-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, 16 January, 2010 - 07:43 pm: |
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This somewhat depressing thread has confirmed my worst suspicions. I replaced my 25 year old boiler with a Worcester Condensing boiler about 18 months ago and also replaced all the thermostatic raditor valves (TRVs).
Last winter and this winter my gas usage was/is down by about 25% (good) but as Gas prices went up and my quarterly bill was/is just about the same as before !
My old cast iron boiler chugged on every winter and apart from a regular service/clean nothing went wrong. I too was told that 'if it ain't broke don't fix it' but ignored this good advice and went ahead and replaced it. As the scrap metal man took the old boiler away I new it wasn't a good idea. It was simple and understandable and there was little to go wrong.
My new boiler is full of electronics and 'whirry' fans and is almost bound to go wrong (but so far, not yet). This thread confirmed what I sort of knew which is that it will take an awful long time to get my money back
However, it has made me more conscious of my energy usage and I now regularly log my gas and electricity consumption. In addition I have been looking at more sophisticated electronic radiator valves controlled by PC.
See Conrad Electronics web site: http://www1.conrad-uk.com and search for 'FS20'
Also I have been amazed what amateurs are doing with home energy monitoring - Google for 'Navitron' and look at the 'home automation' forum.
So, gentlemen, I suggest we apply our electronic skills to this very interesting area in the hope that we can save some money and have some fun ! |
canonman
Frequent Contributor
Username: canonman
Post Number: 85
Registered: 02-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, 16 January, 2010 - 09:13 pm: |
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mikem2, you could have done a lot worse than fit a Worcester Bosch! |
twintub
Frequent Contributor
Username: twintub
Post Number: 55
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, 16 January, 2010 - 11:43 pm: |
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Canonman, in what way are Worcester Bosch boilers better than others?
If you're knowledgeable about boilers, what should we be looking for when choosing a new condensing boiler?
As a matter of interest, does anybody know what prices are being asked for installing a new condensing boiler? |
eagre
Frequent Contributor
Username: eagre
Post Number: 349
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 18 January, 2010 - 02:46 am: |
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Being from the US what I have to offer may run against custom, tradition, or law in the UK. Or I may be misunderstanding UK terminology. However, it appears many correspondents are heating their dwellings by boiling water in gas or oil fired boilers and heating rooms by condensation of the steam in convective "radiators". This is a very inefficient scheme long abandoned in the US. It is musch better to heat air directly by exchange in the furnace and distribute to living spaces as needed.
Ed |
alec_t
Frequent Contributor
Username: alec_t
Post Number: 139
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 18 January, 2010 - 09:41 am: |
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Ed,
Our UK system involves using a gas-fired "boiler" (you'd call it a furnace) which doesn't actually boil water. It heats the water in a heat exchanger to around 60C (140F). The water then is then pumped through pipes to "radiators" which warm the rooms (at nearly 100% efficiency) by a combination of convection and radiation. It is the efficiency of the heat exchanger which is being discussed in this thread. It is enhanced in condensing-type systems by capturing the latent heat of water vapour produced by gas combustion. Hot air systems of the type you're more familiar with are also used in the UK and have the same problem of overcoming inefficiencies in the heat exchanger.
Regards, Alec |
mikem2
Just joined
Username: mikem2
Post Number: 2
Registered: 10-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 18 January, 2010 - 06:54 pm: |
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My replacement boiler cost about £1600 including fitting and a system refurb. British Gas quoted £5600 for the very same job !!!! No wonder they can offer 'scrappage' !
I am 'happy' with the Bosch but concerned that it will go wrong and cost me money. |
violin
Regular Contributor
Username: violin
Post Number: 22
Registered: 11-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 18 January, 2010 - 08:55 pm: |
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(qoute) But, don't the old boilers keep a gas pilot light on all the time, and the new ones dont? (end Qoute)
Hi. No not necessary. My combination boiler is around 20 years old which includes electronic ignition and I would rather keep this in a maintained condition than to switch to the ones of today in which I have own suspicions about them. Also with mine I am more comfortable with its electronics than I would be with the ones of today. Regards |
eagre
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Username: eagre
Post Number: 350
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 19 January, 2010 - 03:02 am: |
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alec t
The efficiency of "radiators" can not be near 100%, either condensing (at about 100 C) or cooling hot water at 60 C. The radiation transfer fron thse devices is negligible - it is a fourth power driving force. The transfer is almost entirely by natural convection, which has very low heat transfer coefficients. In a system that distributes heated air their is almost no inefficiency at the dwelling room end, and the transfer at the furnace is under forced convection, although admittedly between two gas streams. Complaints of early failures of condensing furnaces have not been freuent in the US, and aluminum (aluminium?) is surely a far better material for heat transfer duties than iron.
Ed |
alexr
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Username: alexr
Post Number: 99
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 19 January, 2010 - 03:51 am: |
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I would have thought that as long as the boiler and pipes are well insulated it doesn't matter how inefficient the radiator is, any heat not given up by the radiator stays in the system to be used next time around.
In fact in a system with multiple radiators if the radiator to be too efficient you will dump all the heat out of the first one and the rest will remain cold. This is why they don't make radiators out of aluminium.
Alex
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alec_t
Frequent Contributor
Username: alec_t
Post Number: 140
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 19 January, 2010 - 11:03 am: |
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"any heat not given up by the radiator stays in the system to be used next time around"
That's precisely the point I was trying to make when I said, rather clumsily perhaps, that a radiator is 100% efficient. The only place the heat can escape to from a radiator is, eventually, into a room, be it by convection or (albeit only minimally) by radiation. The 'radiator' (perhaps we ought more accurately to call it a convector) is in reality just another heat exchanger, transferring heat from the hot water to the air in the room.
Of course, we then have to use our skin as yet another heat exchanger to get the heat from the air into our body. Anyone know what the heat transfer efficiency of air-to-skin is?
Regards, Alec |
mikem2
Just joined
Username: mikem2
Post Number: 3
Registered: 10-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 19 January, 2010 - 07:01 pm: |
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Violin - you have expressed my exact concerns ! I too was (albeit expensively) 'comfortable' with my understanding of my old boiler but fear this one greatly !! Just like cars have become - pipes, wires and electronics that nobody but the designer understands.
However there is scope for us electronic engineers to improve upon the thermo mechanical thermostatic radiator valves. I have purchased some nifty electronic radiator servos and room thermostats from Conrad Electronics and am very impressed with them. Google for 'Househeat' |
gajjer
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Username: gajjer
Post Number: 286
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 20 January, 2010 - 06:28 pm: |
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Hi all
the point about radiator efficiency is not how much heat is wasted but how quickly you can transfer that heat to the room. When the boiler comes on you want to heat the rooms as quickly as possible. That way you don't have to turn on hours before you get up.
Another point is where you measure the temperature relative to the radiator. You can not measure the 'room' temperature, only the part where the thermostat is.
Another point to consider is zoning. When I put together my own central heating system I considered spliting it into two zones. The idea being that as we were both working, why would I want to heat the lounge in the morning? I want the bedroom and bathroom and kitchen to be warm, but not the whole house. Then at night the lounge kitchen etc but not necessarily the bedroom. ( I like going to bed in a cold bedroom ).
From news reports of people having problems with condensing boilers freezing up, I am surprised that some designs haven't taken that into consideration. It wouldn't have happened in my day!!! ( I used to work for British Gas Research )
cheers
gaj |
zeitghost
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Username: zeitghost
Post Number: 1409
Registered: 01-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 21 January, 2010 - 08:38 am: |
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The freezing up bit is due to the wrong size of condensate pipe being used. 1/2" bore is not big enough.
There were some very acid comments on a plumbing site I visited before Xmas on this very point. |
gajjer
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Username: gajjer
Post Number: 288
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 21 January, 2010 - 05:41 pm: |
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Completely off topic but here goes.
When I was a lad living in a council house the cold water tank overflow developed a drip. With the sensitive ears I had in those days it kept me awake. So, not being able to get dad to fix it I attached a hose pipe to the overflow outlet. Sound of dripping gone completely - good nights sleep. Ahhh. The following morning I went down to inspect the hose and was surprised to see that there was no water coming out of it. But then there had been a frost. Not a good idea it turned out!
Got the ladder and removed the hose pipe from the overflow outlet.
WHOOOOOOOOOSh!!!!
A stream of water jetted from the overflow like an erupting volcano. How it did not cause damage I don't know.
How we laughed!!
cheers
gaj |
arw
Board Administrator
Username: arw
Post Number: 818
Registered: 04-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 21 January, 2010 - 06:19 pm: |
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The plumbing in my place was very shoddily done when it was new 30 years ago. The water tank started to overfill but the overflow pipe had been bodged, so water ran down the side of the tank onto the chipboard base, which became completely sodden. The whole lot was getting ready to collapse and fall through the ceiling. I only noticed it due to a brown stain appearing on the (newly decorated) ceiling below. I used a 3kW fan heater to dry it out.
Then I found the overflow pipe was bodged as well, with two pipes roughly pushed together, so even if the tank hadn't leaked we would have wrecked a ceiling elsewhere.
Not to mention the loo that fell off the wall due to steel mounting screws rusting through, or the thin-gauge hot water copper pipe buried in concrete that split open, destroying the kitchen entirely. Apparently we had been leaking hot water into a void in the foundations for 20 years. So we got that fixed and the same thing happened in the utility room.
Don't even get me started on gas boilers :-)
Alan Winstanley
Visit EPE Online at http://www.epemag3.com
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echase
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Username: echase
Post Number: 270
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 25 January, 2010 - 02:18 pm: |
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My 85 year old mother’s Worcester Bosch condensing boiler failed after a mere 4 years, leaving her without heating for 9 days in this recent freezing spell. Partly this was down to Worcester Bosch or their agent not supplying the spare gas valve quickly. (zeitgost, I thought it was the frozen pipe problem, after visiting similar/same site as you mention, but it was not).
I stripped down the old valve and the coil in one solenoid valve is o/c (why failed so soon?). It would be a £5 part if they had made the coil replaceable but instead it’s £120 for a whole unit.
Sadly the boiler was replaced because the servicing people sold my mother a sob story about possibly not being able to get spares any more for the old cast iron job that was very reliable, as others have noted.
My son wants to replace his genuinely ancient boiler under the scrappage scheme. He has had £3000 quotes for a combi boiler. I said he should go for non combi as has a hot water cylinder, etc. already. I worry about reliability of their extra complexity, slow feed of hot water and instability of temperature when feeding a small flow like a non power shower. Any views? |
741
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Username: 741
Post Number: 124
Registered: 08-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 25 January, 2010 - 05:57 pm: |
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Does anyone else have the combi-boiler problem that after the hot tap has begun issuing hot water it then decides to spurt out cold before returning to hot at some random later time ? |
poplar10
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Username: poplar10
Post Number: 59
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 25 January, 2010 - 09:59 pm: |
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I have the same problem.
The hot water that issues first is either hot water already in the supply pipe or hot water stored in the heat exchanger within the boiler construction.
When you turn on the sink/basin hot tap the boiler senses that hot water is required and fires up.
But unless the boiler is already running supplying central heating hot water there will be a delay while the boiler gets up to temperature.
As a consequence there will be a 'slug' of cold water in the supply chain between the hot water already in the system and the newly heated water.
Nothing's impossible, I have found ...
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echase
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Username: echase
Post Number: 273
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, 25 January, 2010 - 11:26 pm: |
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Some 20 years ago I had a Vaillant combi boiler which did have a variable flame height like modern ones. I found that it would light up OK and supply hot water to the tap. But if the tap was half open or it was a non thermostatic shower valve, this hot water would cause the tap/valve to close up a little due to the thermal expansion of the seals, etc. Thus the flow dropped past the minimum flow of the boiler and the gas shut off. After the entire pipe run had run though slowly the valve/tap opened again, as it was then receiving cold water and the boiler then relit. So it was an alternating hot/cold feed. Only opening the tap right up stopped this but that made getting hot water to the tap slower than starting at half flow to get the boiler temp high. It was a case of learning to start slow and then to open up the tap after say 10 secs.
Hence my statement before about difficulty of regulate temperature in showers. Maybe the modern combis are better. |
poplar10
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Username: poplar10
Post Number: 60
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 06:38 am: |
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@echase
The reason I replaced my 25+year old gas back boiler which was performing adequately was that I installed a new thermostatically controlled shower cabinet. This shower when full on required a flow of 16 litres per minute according to the manufacturer.
I had two options:
1. Install a pump in the present storage tank setup to increase the flow to the required rate.
2. Replace the back boiler with a combi unit supplying hot water at the required rate.
My daughters had a pumped shower unit and she found that the first one in the shower could drain the storage tank just for one shower, leaving the rest of the family to wait for their shower till the hot storage tank re-heated. She has now fitted an electric power shower.
So rather than fit a pump I replaced the boiler. Apart from the fact that if the shower flow rate is too low the water runs cold until the flow rate increases to re-ignite the boiler, I have had no problems.
My boiler is only just over a year old and so far there have been no problems. Mind you the plumber who installed it blithly told me that *it should last up to 10 years* !
Nothing's impossible, I have found ...
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alanr
Regular Contributor
Username: alanr
Post Number: 28
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 08:51 am: |
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Sounds just like the good old geyser in my caravan in Wales! It seems only the names have been changed to protect the guilty.
Happy days |
mark
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Username: mark
Post Number: 97
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 11:21 am: |
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I've now fitted 4 Vaillant combi condensing boilers for members of my family. I use a proper gas guy to make the final checks and gas connections, but do all the other stuff myself. It's not rocket science! The Vaillants store the condensate in a syphon thing, and send it out in bursts of warm water rather then a trickle so that overcomes frost problems (provided there is a continuaos 'fall' on the outlet pipe). No problems this winter anyway.
All four have been trouble free, and the hot water flow rate is plenty for showering, - and your daughter can't empty the tank 'cos there aint one! Also good because there is no need for tanks in the loft, so our lofts are copletely dry - can't freeze up, and we can keep the hatch closed and insulate to a high level.
I don't know how long the boilers will last, but so far so good. |
echase
Frequent Contributor
Username: echase
Post Number: 276
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 11:24 am: |
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popular 10 would it not be easer to replace your daughter as one who uses a whole tank for a shower is profligate. Or give her a good lecture about the environment, saving the pennies, etc. OK it won’t work!
Do maintenance contracts for combis cost more than non combis? That would be a sign that the gas companies think them more expensive to repair and/or less reliable.
(Message edited by echase on 26 January, 2010) |
poplar10
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Username: poplar10
Post Number: 61
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 01:44 pm: |
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@echase
It wasn't the daughter that was the problem. I managed to offload her many years ago, for a sum which could have kept me in pic's for the rest of my natural life, to a lad who became our son-in-law.
No, the problem is her children. Particularly the two teenage boys who regularly emptied the tank performing their ablutions. The only way she could get them out of the shower was to turn the water off, or it ran cold !
From my experience the maintenance cost for my new combi is no more than that of the old back boiler. Technique nowadays, like the motor industry, is to plug in various gizmos into the boiler when then tells the Corgi lad what actions to perform to correct any abnormalities.
Mind you the last time he serviced the new boiler he said that it was running at 99% efficiency. Do I look that gullible ? Or was this in fact true ?
John
Nothing's impossible, I have found ...
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echase
Frequent Contributor
Username: echase
Post Number: 279
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 02:30 pm: |
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99% of the as new figure? |
poplar10
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Username: poplar10
Post Number: 62
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 04:06 pm: |
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@echase
I'm looking at the printout that came from the Corgi guy's little gizmo. And it says *EFF (C) 99.3%*. There's also a raft of other figures quoting CO and CO2 percentages and ppm. I understood him to say that this was (energy out) times 100 divided by (energy in). On the face of it it does seem a bit high.
He also said that the old back boiler efficiency was around 30 percent as most of the heat produced was used to push the products of combustion up the chimney.
I must do a check comparison of gas used between the old boiler and the new, however this will be skewed because of the severe winter we are experiencing this year with consequent increased gas consumption.
Nothing's impossible, I have found ...
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kevinbrunt
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Username: kevinbrunt
Post Number: 88
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 04:42 pm: |
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Does that printout include a "CH4" figure? One possible measure of "efficiency" is whether the input fuel is being completely burned. (A high CO to CO2 ratio would imply incomplete burning, with unburnt gas passing straight through.) |
poplar10
Frequent Contributor
Username: poplar10
Post Number: 63
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 07:07 pm: |
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The total printot is:
O2% 6.2
CO2% 8.4
CO ppm 50
FLUE deg C 55.0
INLT deg C 24.4
NETT deg C 30.6
EFF (C) 99.3
LOSSES 1.4
XAIR % 42.1
CO/CO2 0.0005
PRS mbar 0.13
Fuel Natural Gas
Boiler type Baxi Platinum 40HS
Can't see a CH4 figure though.
John
Nothing's impossible, I have found ...
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g6osv
Frequent Contributor
Username: g6osv
Post Number: 89
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 07:42 pm: |
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The 99% is combustion efficiency,not boiler efficiency.
Ian |
poplar10
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Username: poplar10
Post Number: 64
Registered: 10-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 26 January, 2010 - 08:03 pm: |
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Combustion efficiency ? Well that makes a deal of sense.
I did suspect that 99% boiler efficiency was too good to be true !
Nothing's impossible, I have found ...
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arw
Board Administrator
Username: arw
Post Number: 823
Registered: 04-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 28 January, 2010 - 12:49 pm: |
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Woke up this morning to the smell of damp plaster, and water dripping from a large brown stain in the ceiling... I am NOT in a good mood!
Alan Winstanley
Visit EPE Online at http://www.epemag3.com
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twintub
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Username: twintub
Post Number: 69
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, 09 February, 2010 - 11:48 pm: |
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Today I found out a bit more on these new 'economical' condensing boilers from a colleague who did some gas training durng a bout of unemployment:
Condensing boilers are only able to extract the heat out of the exhaust gases if the water return from your hot water tank/radiators is lower than 55degC. In practice most (if not all!) current systems have a return temp of around 85degC.
The only way of achieving a return of <55degC is to have extremely large radiators in all rooms. People who have had these new condensing boilers fitted as replacements will not see the massive savings they have been led to believe, and the only time that condensing boilers actually see a return of <55degC is during the initial start-up phase until the system has reached temperature.
The only benefit I can see is for those of us with wasteful permanently lit pilot lights burning 24/7. Factor in the apparent unreliability and it is just not worth the change if you can avoid it! |
armadillo
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Username: armadillo
Post Number: 244
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 07:19 am: |
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Those temperatures sound very dubious to me. If the return temp is 85C the radiators would be hot enough to cause burns. In fact I know that the (secondary) hot water temp in my house is about 60C so the primary boiler water temp is unlikely to be much higher. In fact I've just measured the top of the radiators as 60C. If the radiator valves have been set up correctly, there should be a 20C drop across the radiators which would make the return temperature just above 40C - say 45C which is well below the 55C quoted.
Armadillo
There's no such thing as gravity..........
The earth sucks!
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echase
Frequent Contributor
Username: echase
Post Number: 296
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 11:41 am: |
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I thought they were mandatory nowadays in UK so you can’t avoid them in upgrades and new installations.
I agree that 85C is too high. |
ant
Frequent Contributor
Username: ant
Post Number: 579
Registered: 05-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 02:44 pm: |
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Hello all,
I forget the fine detail but I think that to be sure to not have Legionnaire's disease incubating in and around one's hot water system the water should be stored at 65oC.
Regards Ant |
twintub
Frequent Contributor
Username: twintub
Post Number: 70
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 09:59 pm: |
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I was quoting figures from an article given to my colleague during a gas installers course. I haven't verified the figures myself (I'll get round to measuring my system soon) but the article's explanation seemed convincing to me!
The article explained that the low return temperature is necessary in order to make the water vapour condense, otherwise the vapour's stored energy won't be recovered and transferred into the second heat exchanger! |
twintub
Frequent Contributor
Username: twintub
Post Number: 71
Registered: 02-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 10:10 pm: |
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@ant
I thought that Legionnaires wasn't a problem if the water was regularly flushed (normal houshold usage) but was a problem in low usage systems, such as offices that are not used at weekends?
My hot water tank is around +50degC (on the thermostat) and I haven't died yet!
Maybe loft installed cold water tanks are more prone to Legionnaires - nice and warm in summer? |
ant
Frequent Contributor
Username: ant
Post Number: 580
Registered: 05-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, 10 February, 2010 - 10:31 pm: |
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Hello tt,
I have no specific knowledge, this is something I picked up somewhere. The knowledge, not the affliction! Unless knowledge is an affliction but that should be in the Anything Else section perhaps.
I think it was to do with hotel taps.
"...water temperatures between 20°C and 45°C should be avoided by insulation of cold water tanks and pipes in warm spaces, and by storing hot water at 60°C and circulating at 50°C."
http://www.healthandsafety.co.uk/infolegionn.html#howcan
That's as far as I looked...
Regards Ant |
echase
Frequent Contributor
Username: echase
Post Number: 298
Registered: 07-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 11 February, 2010 - 10:22 am: |
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Legionella is a long and tortuous subject. There are theoretical risks of legionllea in most UK homes. It’s greatest in showers as water stored at less than 60C is turned into fine droplets that you breathe in. So twintub you are at risk as am I because I have yet to change mine to increase the temperature. Although very few cases are reported it is likely that there are more than reported because it’s just passed off as flu or pneumonia. Office and industrial premises are not allowed to only heat to 50C.
I had to research the subject as an occasional installer of solar heating systems as the wrong sort of installation is a risk, indeed 90% of all solar installations done by ‘professional’ installers (not my ones) do not comply with recommended practice on Legionella (HSE Approved Code of Practice (L8)). This is because they usually (expect when very sunny and water usage is low) make the bottom half of the hot water cylinder (HWC) lukewarm and an ideal Legionella breeding ground.
It’s almost impossible to fully comply with the Code but best compromise is to make sure, whether you have solar heating or not, that the top of cylinder is >60C all the time so any infected lukewarm water is sterilised by passing through this layer. Or heat the whole cylinder up to >60C once a day or at worst once a week.
Not sure what you do with a lukewarm header tank but if the water is changed regularly I guess the risk is low.
In CH systems Legionella is not an issue as you don’t come into contact with the water and I expect the inhibitor, etc. makes it hard for Legionella. But the water feeding the HWC heating coil needs to be >>60C to get >60C in HWC. |
bruce
Frequent Contributor
Username: bruce
Post Number: 247
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 11 February, 2010 - 10:29 am: |
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I never thought such an 'off topic' topic would generate so many posts.
I try to avoid infection with Legionella by never washing. It makes the infection risk low, although you can get some funny looks from people in bus queues.
bruce |
alexr
Frequent Contributor
Username: alexr
Post Number: 109
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 11 February, 2010 - 10:55 am: |
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Washing is one route of infection certainly, but a much more hazardous practice is actually ingesting the stuff. You should avoid that at all cost or at the very least make sure you disinfect any water you do ingest with a liberal does of alcohol, preferably single malt whiskey.
Alex
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ant
Frequent Contributor
Username: ant
Post Number: 581
Registered: 05-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 11 February, 2010 - 11:30 am: |
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Hello all,
I wrote this for a friend who got a mild dose from an aircon outlet:
A young lady I know who's called White
Went to London and got quite a fright -
She started to sneeze
In a way Legionnese
And everyone hopes she's alright!
She was, after a bit of worrying!
Regards Ant |
bruce
Frequent Contributor
Username: bruce
Post Number: 248
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, 11 February, 2010 - 08:29 pm: |
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Alexr, are you telling me you actually drink the stuff! Wheres that bottle of brandy...
Ant; I'm going to propose you for Poet Laureate.
Bruce |
eagre
Frequent Contributor
Username: eagre
Post Number: 355
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 12 February, 2010 - 04:13 am: |
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It appears from much of this discussion that condensing furnaces (boilers?) are best used by heating air that is circulated to the living spaces, as is usual in the US for newer installations. The heat transfer at the furnace is gas-to-gas (not a high heat transfer coefficient but as forced convection much better than natural convection coefficients at "radiators"), but there is no heat transfer limit when the heated air enters the dwelling space.
Ed |
petelobus
Frequent Contributor
Username: petelobus
Post Number: 235
Registered: 06-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 12 February, 2010 - 10:58 am: |
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I guess that part of the reason we (in UK) don't use warm air heating, is that its much harder to retrofit (big ducts etc)to our older housing stock and our houses are generally smaller anyway. There is also the tradition/experience issue - most heating engineers are very familiar with 'wet' systems, but no so with air systems. I've not had any experience of it, but a friend lived with it in Canada, and claimed it was a really efficient dust distributor!
It would be really interesting to see a total efficiency comparison between the latest air and water heating systems. Bet the information is not available! To go a step further, include servicing costs too...!
I wonder what nastinesses can lurk in air ducts. I've found some really HORRID slime in coach air-con systems!
Ian |
bruce
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Username: bruce
Post Number: 253
Registered: 04-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, 12 February, 2010 - 11:01 am: |
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I wonder what nastinesses can lurk in air ducts. I've found some really HORRID slime in coach air-con systems
Ian, I dont think it's right to talk about Piers Morgan in that way.
bruce |
eagre
Frequent Contributor
Username: eagre
Post Number: 358
Registered: 05-2005
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, 14 February, 2010 - 03:40 am: |
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petelobus -
I know the problem of retrofitting ducting as one home I owned had ductwork adequate for heating but not for air-conditioning (in an area with over 40 days above 40 C each summer). I had to install room air-conditioners. But, the the problem of "nastiness" in the ducts is non-existant in my experience. Filters in the circulation system remove dust, allergens, etc. very effectively, and give an air quality better than would exist without the air circulation.
Ed |
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