Boiler Sizing?

Question

Hi all,
I am going to replacing my hot water system with Buderus GB142 boiler.
I have met 5 contractors. 3 of them suggest me that to get one 135,000 BTU to 140,000 BTU (input) boiler. One of them suggests me to get 84,800 BTU after performed calculations according to ACCA Manual J. One of them suggest that "Typically baseboard heat is figured on 550 BTU's per foot. 200 x 550 = 110,000 btu's needed for heat"
My house is around 2300 sq ft and has 200 ft long of hot water radiators baseboards. How much BTU should I get for the new boiler?

Thank you for your help

Kam

Answer 1

from all the problems i have seen on yahoo answers asking,
how to, fix my boiler problems, i would seriously think of putting a furnace [air heat] system,
mine has been running for 10 yrs with out problems,

Answer 2

The way to start is not going by the amount of baseboards you have. You need to start with what is called a load calculation. That takes into account all the factors that affect heat loss in a home and will tell you what size boiler you need. Then you match the radiators required to the rooms and boiler. For more info, check out the load calculation page at my source. The contractor that perfromed the manual j had the right idea.

Answer 3

Kam as a ball park figure if you have an average size home then 100,000 btus should be more than enough. dont forget the rating for your hot water either! this depends on what system your thinking of having whether you consider a combi, regular, or system set up then all must be taken into account! If you are nervous about this then get a proper heating engineer to call around with a good old mears calculator he can then work out all sorts of heat losses, u values and efficiencies arriving at your ideal system. heat loss through glass is also very important. Please also be very carefull on boiler manufacturer choose carefully. if your going to spend allot of money on this project then pay a good price for the boiler. obviously without knowing or seeing the house it is difficult but I hope this helps all the best!

Answer 4

The contractor that figured the load calculations is probably correct. Provided he has all the correct information and did not make a calculation error suggestion is the correct way to size a heating boiler. All the other answers are just educated guesses.

Please be aware that NO ONE including myself can make this determination based on information given over the Internet. There are too many factors involved to do it correctly.