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Question related to "Heating Capacity Oil/MBH

My Biasi B10-4 runs great and so far this early in the heating season I have used about 120 less gallons than last year although I am not sure about the temp difference vs last year this time. Could someone explain the part of the sticker that says "Heating Capacity Oil/MBH = 110. Is that Btu's? My house is about 2400/2500 square feet, not including an unfinished unheated basement. Because of recent major improvements the house is quite tight. My old Weil McLain had a heating capacity/MBH of 151,000 which my oil tech said was oversized given that years ago we replaced our HW Heater with a Super Stor tank, plus he said it was too large for our house. So the new Biasi has a MBH of 110,000. The hot water demand has a priority over heat which is no problem as there is just the two of us and the hot water heats up real fast. My question is if I can add some additional base board (water)...I have a total of 117' (fin to fin) some of which is pretty banged up, both the fins and the housing. From a cosmetic stand point, some new baseboard would be welcome! (I have done the fin repair and painting enough already) Some of the rooms might benefit from some extra baseboard. These rooms are on the cool side! The rooms with longer runs of baseboard are fine. I was wondering if I could replace the cooler rooms with the 700+ or 800+ btu baseboard rather than the 600+ I have now. I think I have the boiler capacity to do this, does this sound viable? Thanks, Bill

Re: Question related to "Heating Capacity Oil/MBH


Yes, the "heating capacity" refers to the heating output of the boiler---this sounds like the Dept. of Energy calculation (DOE)---the 110 means the boiler outputs heat of 110,000 btu/hr.

This should equate roughly to 40 btu/sq.ft. (arbitrary heat factor) of space needing heat in your building to keep the building warm on a very cold day: 2500 sq.ft. X 40 = 100,000 btu/hr.

You should also do a heat loss calculation for each room, comparing the heat output of the length of baseboard you have in a particular room to the square footage of the room to be heated---you probably have too little baseboard in the rooms that are not warm enough.

The setup you have there since you have a new boiler now, would be an ideal candidate for OUTDOOR RESET and lowered temp baseboard----with the idea of saving more fuel by running the system at say 140 degrees, rather than 180 degrees, which needlessly burns a lot of fuel most of the year.

As you might have noticed by now, boilers are still designed to make & pump 180 degree water thru the system all during the heating season---when in fact this high temp water is needed on only the coldest days in January & Feb.

The strategy would be to increase the # of baseboard to ~200', sizing each room for 140 degree hot water baseboard, allowing 40 btu/sq.ft. for each room.

Thus, I would recommend going with standard output baseboard.

Thus, a typical room of 15' X 15' = 150 sq.ft. X 40 (heat factor) = 9000 btu.hr to heat the room.

Standard baseboard run at 140 degrees (400 btu/ft output) X 23 feet of baseboard for this room = 9200 btu/hr.

Outdoor reset would keep the water temp at 140 degrees for mild weather, and raise it up to 180 degrees only on very cold days---thus there would be considerable savings in oil.

Why not run it by your local heating tech to see what they say.

BTW, did you solve your noise problem with the biasi b10???

Re: Question related to "Heating Capacity Oil/MBH

..thanks Nashua Tech! Actually, I have the out- door reset. You mention 140 degrees but mine is set slightly higher, it shuts off the boiler between 145-147 maybe because I'm in Vermont. Now I realize that the three upstairs bedrooms were warmer last winter because the boiler was set at 180-185. Warmer, but going through the oil!!! It would seem more expensive to tie in and put in more baseboard and piping than to replace 3 sections in 3 rooms with a larger btu rated one, or am I misunderstanding something? As far as the noise, QHT has made a double wall insulated pipe section(s) If that doesn't do the trick, I will add the 1000 degree yellow/white formed pieces on top.

Re: Question related to "Heating Capacity Oil/MBH

That sounds like a good plan, Bill.

Glad to see you did put in outdoor reset & that Biasi stepped up to solve the noise problem.

Two points on baseboard:

1) it's a drug on the market--everyone makes it--that makes it inexpensive ~$50-$60 for a 12' section---check around the plumbing supply houses in your area for the best price.

2) it's normal practice to line just about all the exterior wall of a room with baseboard (usually 2 walls), avoiding doorways, etc.

Glad to hear of your drop in oil usage, I'm envious.


Re: Question related to "Heating Capacity Oil/MBH

I only have baseboard on one exterior wall, and I agree that I probably need it on two. But...I still wonder about just upgrading my existing baseboard with a larger fin, higher output model. Wouldn't that save a bundle and produce a warmer room?

Re: Question related to "Heating Capacity Oil/MBH

I think you should definitely run this by your heating contractor to get their opinion on the matter.

You have to come up with a solid DESIGN of the baseboard so that each room is comfortable in mild weather & severe cold.

I've included a link to heating help; Dan Holohan discusses many of the ins and outs---there's a lot of engineering that goes into the install:

No 3/4" loop can exceed 67'; the input temp to the loop should drop 20 degrees at the exit point of the loop (delta T).

Too long of a loop & you'll run out of hot water at the loop's end.

Since the outdoor reset is constantly changing the water temp, this has to be taken into consideration when designing the length of the baseboard to cover mild days & very cold days.

If you don't like hot bedrooms, the hot water should first go to the living room/kitchen, where most of your leisure time is being spent.

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