We bought our house in 2003. It had just had a new what I assume was cast iron floor mounted boiler to replace the old one because "it fitted in the same space, etc". It broke my heart to have to dump something so new in order to refit the rest of the kitchen properly.
MBQ
Lets take another example. My house has a cast-iron boiler with no=20 electronics needing maintaining. In the 27 years we've been here, the=20 only thing replaced has been the pilot light thermocouple, several=20 times, which I do myself. I now have heating controlled by a modern=20 programmable thermostat and have a separate, pumped hot water circuit,=20 controlled by a cylinder thermostat. =20
OK, so the boiler is not a top-notch efficient one, but the heat escape=20 from the case warms the kitchen, which doesn't need a radiator as a=20 result. We had a boiler maintenance contract when we let the place for=20
4 years and, discussing what was done with the technician doing the=20 work, I now do it myself with a vaccuum cleaner, a smoke bomb and a=20 permanently installed CO detector. =20As a comparison, my Sister's family house, of similar size but with a=20 more "modern" CH installation has had FOUR new boilers in a similar=20 period, the last replacement being of a condensing type with another=20 one. All these replacements were due to "irreparable" problems,=20 including one burn-through of the thin steel boiler resulting in the=20 need for a floor replacement, due to flooding, as well(!!). They have=20 also had an annual boiler contract that covered several electronics=20 parts replacement. All the major replacements were not covered, also=20 being out of the warrenty period, as usual.
So, as you say I've wasted =A36,500 in fuel cost but this has been at an=20 equivalent cost of 4 lots of =A33-4,000 boiler replacements plus a more=20 necessary annual maintenance contract if we had migrated to state-of- the-art boilers. I'm spending less, bottom line, than is my sister's=20 family. What should I do now, given that I'd also probably have the=20 replace the old, but very functional cast iron radiators and pipework? =20 I know what several gas installers have advised when I've enquired about=20 this in the past. - plus I'm not likely to be in this house for another=20
20 years...Has anyone got a source of an electronic ignition add-on for a cast-iron=20 boiler that will mean I don't have to keep the pilot light on, wasing=20 energy keeping the boiler warm and burning through the thermocouples?
--=20 John W I you really want to mail me, replace the obvious with co.uk twice
sure - the majority is lost though
You've got outdoor air blowing tandomly around the exchanger sitting with still water in it for what, maybe 10 minutes.
NT
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from snipped-for-privacy@care2.com contains these words:
Even more like Dribble than before. Moving the goalposts and falsifying what has gone before:-
"IOW its datedness is not a cause for any concern... but if cast iron then replace."
and
"The metal is very relevant. Cast iron can only be cast in relatively heavy coarse lumps,"
Which observation I have also concluded is incorrect. Cast iron can be cast with very thin sections. Whether it is wise to do so where strength is required is another matter but what strength do fins used to increase surface area require?
Dribble must be proud of his only disciple.
The message from "Dave Plowman (News)" contains these words:
That might be an unreliable guide. My non condensing boiler has a plume as the condensation occurs as the flue gases meet the outside air. The only reliable way to establish how much (or even if) condensing is taking place is by reference to the return temperature of the water. (Strictly speaking to the post heat exchanger temperature of the flue gases which will always be higher but flue gas temperature is much harder to measure accurate IMO).
The message from snipped-for-privacy@care2.com contains these words:
snip
More obfuscation. As Dave pointed out if you have pump overrun then the water is still flowing and with a horizontal flue there isn't even any tendency for the heat to go "up the flue", a flue which in any case would have to share the heat dissipation with the rest of the boiler which is normally situated in an area where this heat is useful, not wasted.
Pure bullshit.
The heat remains insignificant. Your point is otiose.
Your point is invalidated.
A very pertinent point in that it indicates you don't really have a clue about heat transfer.
More economics from the Dribble stable.
Pick a gas bill well over average, a boiler efficiency so low that SEBUK doesn't even quote a boiler with that rating, go for low end installation costs, nothing for the cost of capital and then hypothecate a life expectancy well into the realms of cloud cuckoo land
We might be getting precious little on most investments atm but 3% is relatively easily found and borrowing, if it can be found at all, is probably still in excess of 10%.
Now for a realistic calculation:
SEDBUK has the typical annual gas costs for a detached house as £470 for a 65% efficient boiler and £355 for an 88% boiler, a saving of just £115. These figures seem too low for current prices but not excessively so. My gas bill has gone up by 35% comparing the last 2 years so 50% extra should be more than necessary.
So:
Cost of installation - £3000
annual saving on gas - £175.
less cost of capital at 3% - £90 & additional maintenance - £25
Net annual saving - £60
Pay-back time 3000/60 - 50 years.
Ignore the cost of capital and on these figures you would just break even after 20 years in the unlikely event of the boiler lasting that long. If the boiler is going to last 10 years then the saving needs to be £300 pa again ignoring the cost of capital.
This calculation of course assumes a constant price for gas but gas prices are going down atm so gambling on a large increase in future gas prices is just that, a gamble.
Using a simple spreadsheet with the initial factors giving a net annual saving of £60 as above and the only variable a constant percentage increase in gas prices the increase in gas prices needs to be 4.2% pa to recover £3000 over 20 years (increase of 218% and 18.2% pa to recover it in just 10 years (increase of 450%).
FWIW my gas payments have only gone up 74% over the last 10 years.
Oh yes and finally cost of borrowed capital at 10% - £300 pa.
The message from snipped-for-privacy@care2.com contains these words:
New to science - the unbalanced balanced flue. :-)
If the boiler isn't modulating in the proper way, it's modulating by turning the flame on and off. In this situation the water is still circulating, and will carry away the residual heat in the exchanger.
Andy
Sssh. he's happy in his dreams. Leave him be.
If it has a plume it probably isn't condensing the water vapour very well. The plume is condensing water vapour and it should be doing that inside the boiler and it comes out through the condensate drain. My none condensing boiler has a plume BTW.
You reckon air from outside blows in a balanced flue, cools down the heat exchanger, and exits again? Wouldn't that cause problems with normal combustion?
My old one certainly didn't.
The message from "Dave Plowman (News)" contains these words:
May be down to the length of the flue in my case (6') giving the flue gases more chance to cool down. I can't actually remember whether mine does it all the time or just in certain circumstances. Certainly the colder it is outside the more chance there is for the outside air to precipitate condensation.
With a condensing boiler even if the flue gases aren't cool enough to give up much (or even any) of their latent heat within the boiler they will be cooled to a considerable extent and much more vulnerable to external condensation.
My old one had the common square BF terminal just the thickness of the wall - and I never saw a plume from that.
The new one is in exactly the same place with the same length flu and even on a warm and dry day you can see the plume - although it's not as obvious as on a cold damp one. The design modulates both burner and water circulation and I'd guess attempts to keep it in condensing mode always.
This man is a barking mad plantpot. Do not take any notice of him.
This man is a barking mad plantpot. Do not take any notice of him.
This man is a barking mad plantpot. Do not take any notice of him.
balanced-ness prevent bulk blow-through as happens with chimney type arrangements, but it doesnt stop the air swirling about inside as outdoor air blows across the openings.
An open ended tube where this didnt hapen would be new to science.
NT
More tripe. A cast-iron heat exchanger will dissipate its heat in to the open air via the flue.
Condensing boilers, with downwards firing burners, with very long twin flues are more efficient as the heat does not flow out into cold air only inches away. It mainly stays inside the boilers casing and the heat from the flue pipe, inside the heat envelope of the house.
Then you use a "dual temperature" boiler as the Broag, with integrated weather compensation and room temperature influence, that keeps the return temperature as low as possible at all times.
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