efficient heating

[Doctor Drivel]

The exchanger is not the big draw-back, it is boiler design overall. Old cast-iron gas boilers with balanced flues would pour heat out of the flue wasting heat, when the burner was off. So, between each frequent boiler cycle great heat loss. A thermal store attached to these old boilers eliminating cycling improves efficiency a hell of a lot, as they have one long burn.

Fan flues improved matters a lot and having extended flues, so heat doesn't easily escape when the burner is off helps again. A large water jacket in a boiler with a fanned flue and long flue lengths reduces boiler cycling.

Small capacity tubed heat exchanger boilers came in to reduce size and get them wall mounted to easily fit in small homes. Oil boilers still had large water jackets while gas boilers virtually eliminated them. These large water jackets were enlarged in oil boilers and used as thermal stores for instant water heating. Some oil combis have quite decent flowrates. The extra water mass reduced inefficient burner cycling too.

IMI introduced the Powermax. A non-condensing boiler with large water jacket (thermal store). The flue/exchanger ran up the centre of the thermal store. The heating and instant DHW ran off this store of water. Heat did escape up the flue, however long flues made it more efficient. The current Potterton Powermax is totally different to the IMI original.

ACV have now introduced a large stainless steel water jacket in the condensing HeatMaster boiler with the burner at the top and the exchanger/flue down the centre and exiting at the bottom. No heat floats out the top and through the open flue when the burner is off as did with the original Powermax. The water jacket (thermal store) supplies the heating directly and a cylinder is immersed inside the water jacket for DHW. Efficiencies and recovery rates are very high and all in one box. There are oil versions I believe by replacing the burner.

So, large water jacketed heat exchangers are not inefficient in themselves. It is the total boiler package that matters. Other one-box solution boilers have thermal stores/heat banks inside, but these are separate boilers with their own small water capacity tubed heat exchangers and a separate cylinder. The water mass in the cylinder is not the boilers water jacket.

The ACV points the way back to large water jacket heat exchanger gas boilers, with the water jacket eliminating the need for a separate water stored water vessel.

[Tony Bryer]

I'm not sure about loads, since that implies lots of programmer setting, but my place - a long narrow flat - is split into a living and bedroom zone with two CM67s and it works brilliantly - background heat only in the bedroom until late evening, earlier start in the bedroom than in the living zone. New houses larger than 150m2 (not many round here!) are required to have at least two independent zones.

[Owain]

In order of increasing initial cost/difficulty:

-1. Turn thermostat down and wear more clothes.

1. Insulating jacket on hot water cylinder (although heat lost from here contributes to warming the house).
2. Draughtproofing doors, windows, letterbox.

NB clear plastic semi-rigid sheet over windows can be effective at low cost. Interlining curtains with bubble-wrap ditto.

1. Loft insulation.
2. Lag pipes not in the heating area (these are likely to be less accessible than the loft).

Owain

[TheOldFellow]

No. The losses calculation show that I need this amount of input heat for this house now that I'm heating the Workshop as well. You can't actually say this unless you know how much hot water I use either.

No. My boiler service arrangements mean that the cylinder is inspected by a certified person when the boiler is serviced - at no extra charge.

I think I agree with you on the thermal store, by the way, especially for a DIYer. But I'm aware you bang on about it all the time.

R.

[Grow Your Own Energy]

Yes - my recommendation supplement your boiler's work heating your water using a solar thermal collector.

All the details are at

The site can tell you how much money you are likely to make. It will pay for itself and make a you profit in gas bill savings (future heating oil prices assumed)

My quick calculation is a tax free profit of =A37,105 or a 7.1% return - compare 7.1% to what you could get in bank interest!

[cynic]

Knowing which make and model and age of oil boiler you have might help in giving sensible advice. Is your hot water cylinder insulated and is it controlled or a gravity system. The solid stone walls sound dreadfully lossy as does the single glazing. Is the loft insulated?

[Owain]

Until the Chancellor decides that all homes are deemed to have a solar panel and must pay a tax on the theoretical energy obtained.

Owain

[Andy Hall]

You never eliminate cycling unless the demand exceeds the supply of heat and the latter can modulate to meet the demand.

[The Natural Philosopher]

26KW is not unreasonable for many a large, or poorly insulated, house.

My boiler and unvented cylinder are now 5 years old, and I haven't touched wither of them.

Mind you the boiler is in need..its failing to light now and a gain. Neads its photosensor wiping probably.

[Doctor Drivel]

Matt, you can elimiante cycling by using a thermals store

It will only go so low in kW then cycling.

[Doctor Drivel]

The cylinder requires an annual service. Have a leak and see if the insurance company pay out.

[Doctor Drivel]

You said 15kW

Are you a laundry as well?

They do it for nothing? Lucky man. 99% of them charge.

I bang on about them because they are a far better solution and no annual service charge either - you not paying one is not the norm. Or do they load the boiler service.

[Dave Plowman (News)]

Might be worth it if you have self closing doors everywhere and each room well insulated from the next. And don't mind a room being cold when you enter it - the idea of bedrooms never being used other than to sleep in seems strange to me - don't most use them for changing clothes etc after work? Kids as a study/playroom? So if you arrange for the general temperature of the house to be lower during the day I wonder just what savings zoning would achieve in the average house with average use? And the fact that dribble likes it is another kiss of death...

[Tony Bryer]

But if you've got CM67 type control it's not a question of hot or cold, but having the option of background heat too. It's (IMO) nice to have a warm bedroom last thing at nice and in the morning, but 16 is fine for most of the evening.

[Peter Parry]

How on earth do you come up with that figure?

[PeTe33]

Insurance companies will do all they can to get out of paying anything.

What are the chances of getting a leak in your cylinder?

Insurance companies are there BECAUSE the risk/odds of paying out is less than the cost or the premiums.

How many thousands of pounds have you pain to the insurance companies in your lifetime and what minuscule percentage of that have you received back?

How many people drive cars on insurance policies where they have forgotten to declare or failed to notify their insurance company about penalty points?

Don't drive a car, the insurance company won't pay out!

[Michael Chare]

My comments & suggestions:

Eliminate draughts and improve insulation where pratical.

Fit a modern condensing boiler if you can easily dispose of the condensate. (You dont describe your existing boiler)

Fit a programmable thermostat so that you can vary the temperature during the day, but don't fit TRVs as these try to maintain a constant temp.

Use a 'double insulated' (50mm foam) H/W tank.

My oil consumption in perhaps a similar size house is about half yours.

[The Natural Philosopher]

Well opening a door just means one zone will open up and the nextdoor one shut down..

and with a stat in every room you can turn it up or down for raping the au pair, or putting the kids to bed, whatever..;-)

I agree that fact that dribble likes it is the single worts thing to have held against it tho. Suppose he came visiting and wouldn't go?

[Colin Wilson]

Our WB 28siII we have seems to struggle keeping ours properly warm, and it's been on 24/7 since about October (rad in each bedroom, one in the hall, one in the living room, and one in the bathroom which is in the downstairs extension - all the rads are doubles)

Its a 3 bed double glazed "sort of" detached / terraced - passageways down both sides downstairs, linked on the first floor (no cavity wall insulation).

The loft is insulated, but we have a large dog-flap, which necessitates the living room door and a door to the extension (where the back door is) being open at all times.

[Doctor Drivel]

..and associated controls. Reasonable really.

Yep. Anything not 100% right and they will not pay.