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# Baseboard Heating Calculations

#1
03-20-18, 06:48 PM
Member
Join Date: Jan 2016
Location: USA
Posts: 28
Baseboard Heating Calculations

Hey Forum,

I live in Minnesota. Obviously it's cold. The third floor of my house is finished. It used to be an apartment many years ago. According to previous owner, the problem was with the heat. The house is heated with a boiler and radiators, but the third floor wasn't included. So somebody installed a natural gas heater a long time ago. Apparently it didn't work too well. It's centrally located, and some of the adjacent rooms stayed pretty cold. So I'd like to heat it appropriately and use it as additional living space.

The guidelines I found online were to take square footage, multiple by 10, and that's your required wattage. It's about 490sq ft. So according to the calculation I'd need 4900 watts of baseboard.

My question: does this calculation account for the fact that the third floor is heated somewhat from the heat in the rest of the house, beneath? The temp never drops below about 55 degrees up there. So I'd like to be able to raise the temperature by about 20 degrees.

Second question: Am I correct to assume that distributing that wattage around the unit is the best idea? For example, there are 5 rooms up there. Would it be best to have 5 smaller baseboards, one for each room, rather than three 1500 watt units?

Thanks!

#2
03-21-18, 06:07 AM
Member
Join Date: Dec 2005
Location: VA
Posts: 5,795
approximately 20x25 area is not that big of a area to heat. the 4900 watts sounds huge to me. If this house is even remotely close to modern insulation standards id guess you need half of that. Yes id get a smaller heater for each room. This will make it have more consistent temps between room. What about cooling? Ductless mini split could heat and cool the area.

#3
03-24-18, 07:29 AM
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Join Date: Jan 2016
Location: USA
Posts: 28
Thanks Airman.

I was just in Europe, and everybody had mini splits. I thought they were great. My biggest concern with them in this context is the exterior mounting. It would be difficult on this house.

I posted a rough outline of the area. As you can see its long and skinny, which was why I was a little worried about distribution.

The house is old, so the insulation is poor/nonexistent. However, we plan to insulate the entire area. The only walls that won't have insulation are the short North and South walls at each end, and the Easternmost wall of that adjoining room. Those are all exteriors. The rest of the area has knee walls and we plan to insulate.

So in your opinion, half of he wattage I mentioned should do the trick? 2500-3000 maybe?

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#4
03-26-18, 05:36 AM
Member
Join Date: Dec 2005
Location: VA
Posts: 5,795
A heat load would be wise thing to do because it will tell you exactly what you need. But I heat a 27x28 ft room in VA with a 1500 w oil filled heater. Now it is mostly below grade but I have only R4 on the walls and it does fine.

The condenser of a ductless can be wall mounted or just placed on a pad on the ground like a normal heat pump.

#5
03-31-18, 06:05 AM
Member
Join Date: Jan 2016
Location: USA
Posts: 28
Thanks Airman.

I've been picking away at the remodel. Leaning towards baseboards, because I have plenty of available electricity, and they're so affordable (to buy at least). But still interested in the ductless though, if I can make it work.

If I did mount it on the ground, is there a rough limit on the distance of the compressor/condenser to the indoor unit? If I mounted on the ground, I'm thinking the tubing would have to stretch 25' to 30'.