Insulation - HELP!

[PurpleDragon]

We bought this house last August. It came with an external oil fired boiler. The boiler is one of those boilers that are supposed to heat the water on demand i.e you run a tap, the boiler fires up and the water flowing thru it heats up.

Well, we recently had some problems with it, so we got a bloke in, and he tells me that it keeps a whole tankful of water hot and continues to reheat it as it cools during the day. Now I know why my oil costs me so much!

So - my boiler, that is situated outside the house, is heating water 24/7 and winter is coming on. I am both gobsmacked at the stupidity of putting a hot water tank outside the flippin house, and worried to death about the cost of it as it is run on oil and the price of oil ain't cheap!

We can't afford to do anything about it this year, hopefully will be able to replace it with something sensible next year, but in the meantime - how do I stop the snow and ice leaching the heat out of my hot water?

There is a small amount of lagging around the boiler, which is housed in a little metal shed. There isn't much space between the boiler and the shed. We have talked about adding lagging, but does the boiler need to breathe? If we put a layer of the nasty yellow stuff outside the metal shed, then wrap it in a wooden shed or similar, is the thing gonna blow up?

[baldowrie]

They designed to be outside and the water held is not a vast amount, I believe around 9ltrs but I am not sure. It should be insulated inside the covering or around the water tank. If you try and add insulation you will compromise the flue etc. They are also fairly efficient. If they were not they would not pass current building regs.

[Shirley]

I've just answered this post on Neeps! Yes. I agree with Baldowrie!! We've got the same kind of thing.

[Muddypause]

It sounds like what you have is a 'storage combi', which is quite posh in terms of combination boilers.

There are a couple of variations on a theme, but as Baldowrie says, they generally have a small tank inside which keeps a small amount of water warm, so that either the flow rate of the water is not slowed down as the water heats up, or you don't get that annoying delay waiting for the burners to spring into action and heat the water up. It's a different kettle of fish to heating up a whole full-sized hot water tank, though inevitably there is going to be some waste. On the other hand, you may waste less water, because you don't need to run the tap for so long before it gets hot.

If it was installed after April 2002, then it certainly should be a more efficient condensing boiler; before that date it is less likely.

Also, it's not that unusual to have a boiler outside, though obviously it needs some sort of shelter. This may have been done so that pipe runs are kept to a minimum, and you don't lose heat by having longer pipes than necessary.

There is probably not much you can do beyond making sure it is protected from the elements, and all the pipes are lagged. I suspect that the problem you have with running costs is mostly a reflection on a) how much fuel is used to heat water; b) how much fuel is used to run central heating; c) the cost of oil.

[PurpleDragon]

Thanks for your replies - very interesting.

The water comes into the house straight thru the wall behind the tank, so it isn't running around outside at all.

I do know that we have a lot of radiators and I'm a cold morsel, so the heating is on a lot during the winter. We have just bought an electric heater for the living room, which may prove cheaper to run than using the oil

Last March, we were snowed in and we had about 3' of snow in the back garden, less than around the rest of the house of course because it is fairly sheltered from the weather by being in a dip, and also by being behind the house. Anyway - 3' of snow in the garden, and a big melted space around the boiler.