Heating advice for 3rd floor

Brad White

Let's assume the roof is insulated to R-19, walls to R-13 and the windows are 15 SF each with storm windows (assuming one 15 SF window per gable end and no skylights nor dormers) here. I will also assume a zero F. outside temperature and a 70 degree inside temperature design basis. Also assume 0.5 air changes per hour of infiltration loss (3,750 cubic feet/60) x 0.5 = 31.5 cfm leakage.

Whew.

(But do start with insulating so we do not just toss things out the window. Also foam fill (not just fiberglass) those portions UNDER your knee walls. Seal the attic tight, blown in cellulose on top and over the tops of the knee-wall space. you get the idea...)

I do not know where you live, but that can be adjusted. Basically I would figure about 110 BTUH per degree difference, specific to this particular space. If you are at -20 and keep it at 60 indoors, that is a delta of 80 so it would be 8,800. You get the idea.

I get about 7,700 BTUH heat loss at 0 outside and 70F inside. That is about 0.75 gallons of hot water per minute, not much. My cat <i>pees</i> more than that. :)

I would use your hot water system. You could easily extend a circuit of 1/2" copper or even better, 5/8" PEX-AL-PEX semi-flexible tubing up to the attic via a closet or chase. Maybe next to the chimney but not too close, you may have a chase?

With that heat loss, 0.75 GPM, even call it 1.0 GPM could be handled with ease. A TRV (thermostatic radiator valve) and a panel radiator at each end under the windows? Should be quite comfortable indeed.

But start with insulation and sealing first, really.

Lara

Heating advice for 3rd floor

I need advice on heating our 3rd floor, which used to be a walk-up attic. The space is about 400 SF (approx. 25x15). The roofline is slanted on both sides going from about 4' where it meets the walls to 8' at the peak.

The rest of the house is heated with hot water radiators powered by a fuel oil run boiler.

We currently have plastic over the windows, a oil filled radiant heater and run the ceiling fan on the "winter" setting to heat the space. Do you have any other recommendations or what would be a more efficient way to heat the space?

Thanks.