Boiler btu's

[aks_72]

Can some one tell me. What is the highest btu boiler i can buy from a plumbing merchant, DIY Store, As the house i moving to is a large old 3 storey house with attics. It's not double glazed and has old push up and down sash windows.
I have done a rough calc and i need 95,000 btu's, I have not included the bathroom or all three hallways as do not know the measurements, So I want a boiler probably of a higher btu than 95,000, as i don't want it to struggle heating the attics. The biggest i have found is 102,000 btu's, Any ideas what Btu and were i may get one

 

[Gasguru]

There are plenty of boilers providing over 100,000 Btu's. Go onto the Sedbuk database for a list of manufacturers.

 

[Slugbabydotcom]

I dont know how you came up with the figure of 95kbtu but chances are it includes a margin for error so to cover it with 7000btu's should mean it is sized adequately. The rougher the calculation the more likely it is that the boiler requirement you came up with is oversized.
You will only need the maximium output in very severe conditions anyway and will probably have unnaccounted heat inputs from appliances and supplementary heating.
To oversize a boiler is not always a good thing. An excessively oversized boiler that isnt rated down to its required btu value will wear out gas valves more quickly due to excessive cycling. A boiler with 102kbtu capacity would be likely rated down to the 95kbtu requirement by a competent installer.

You will probably find that the attic rooms heat up ok due to stratification of air and heat gains from rooms below. If attic rooms are difficult to heat it would be better IMO to insulate rather than heat the rooms up and lose most of the heat through the roof. Thats a messy job I know but I do think it would be cost effective. The problem will more likely be heating up the downstairs rooms. This can be overcome by careful rad sizing.

Fitting TRV's and taking energy saving measures as well as those in part L of the building regs further reduces the need for an oversized boiler.

To give a specific answer to your question. Larger boilers can be easily obtained but you will need to ask at a plumbers merchant eg Graham, PTS or Plumb Center.