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. What how much BTU should I get for the new boiler?Thank you for your help Kam
Hot Water Baseboard Heat Calculator
There isnt enough information here to answer. The answer to this question is actually in your house and is your question. 1. you are replacing an existing hotwater system. 2. The baseboard and existing heater were installed orginally based on a load calculation. 3. Unless the existing heater failed to properly heat your house (before it broke) or you are planning to add an addition to your house the answer is on the data plate of the existing unit. Both input and Output BTUH is there. And that is the btuh required for your existing baseboard to heat your house as well as the temperature that your new boiler needs to be set at for your baseboards to heat correctly by the water temperature thermostat setting. As for the contractor using manual J that is subjective to the data he used - type windows-type doors-type of house construction and a myrid of other varibles used to complete a 4 page form. 3-contractors hitting from 135k to 140k has to be asked did they check the data plate or just guess based on other houses in the area they did. Typical baseboard contractor requires the question what makes him sure your baseboard is typical. 3/4 pre 1970 was not the same wall thickness as 1970-1990 which changed again to higher efficency requiring less water temp to transfer the same btu per linear foot of finned baseboard.
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.
