Home>Discussions>INSULATION & HVAC>Final Biasi sizing question
2 posts / 0 new
Last post
bostonfan49
Final Biasi sizing question

Have settled on the Biasi boiler but have a sizing question. If I measure the total number of feet of baseboard (measuring fin to fin) which equals 115 feet X 600 btu gives a MBH of 69. This is what my boiler guy said to do! The MBH Heating capacity of the B-3 model is 67. If I go up to the B-4 the MBH is 87 to 110. (87 per the brochure, 110 at the QHT website. Is there a fudge factor? If my math is correct, I have to reduce my total fin feet by 3 feet to match the MBH. Otherwise I have to go to the much larger B-4 which doesn't seem right. Confused! Bill

JacktheShack
Re: Final Biasi sizing question

bostonfan49:

The B3 will no doubt do fine, but talk to the installer--it is the INSTALLER who is supposed to do the HLC to make sure the boiler is properly sized---if there is a subsequent problem with the heat output, it's then up to the INSTALLER to make the necessary changes.

That said, there are always minor changes in nozzle size or gas valve size that can be easily done to increase or decrease the btu output of the unit---there's no need to touch the baseboard, a few feet more or less of baseboard will have little effect on overall heating.

Sizing the boiler by using the length of baseboard in place is not as accurate as doing a proper HEAT LOSS CALCULATION--these are computer software programs that take into account numerous factors present in a particular building---an excellent free HLC by Slant/Fin is below---it may take some time to load if your system has limited storage capacity.

Two more rudimentary HLC's are included so you can get a ballpark figure for your building.

The HLC is based on the reality that each residential building is unique in its ability to hold heat on a cold day---so an attempt is made to measure how many heat units (btu's) are bleeding out of the building per hour on a cold day.

If there is little insulation in the exterior walls, or attic, the windows are very loose, there are high ceilings, or the building is located in a frigid area, more btu's will bleed out of the house, & thus, more btu's will have to be produced by the boiler to keep the building warm---all of these factors are plugged into the HLC program in the sizing process.

You can also Google "heat loss calculation" to get numerous other free calcs on the internet.

http://www.bgmsupply.com/calculateheatloss.asp
http://hearth.com/calc/roomcalc.html
http://www.slantfin.com/heat-loss-software.html

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.