Situation: new superinsulated and very tight house nearing completion, with just inside work remaining. Temporary heat is being provided by a nonvented torpedo heater. With the thermostat set low, the thing doesn’t come on often, but when it does the humidity introduced overwhelms the dehumidifiers and condenses on the bottoms of the windows. That is wetting the wood around the glass, and we need to keep that dry before staining it. If we turn up the thermostat, the glass would be warmer, but the heater would come on more often and introduce more humidity. We need a heat source that doesn’t introduce humidity. The regular heating system has not been installed yet.
One option is electric heat. It would take about 3 KW to maintain a 40 degree delta T. Heating this way would cost almost $100/week. We may have to do that.
Another option is to connect the new wood stove to the chimney and air inlet duct. That would mean feeding it wood all day in order to let the place warm up enough to coast through the night. Also, we need the wood for the cottage on the site where we are living while the house is finished.
Does anyone know of a temporary heater that could be vented through the woodstove chimney?
Replies
How about
an old used furnace.
If this is a superinsulated very tight house, I cant see $100/week electric heat, unless this is as big as a mall.
I'll second Calvin's used furnace plan. Rental centers sometimes have portable, vented, contractor heaters, such as JetHeat or the Allmann units, but the rental and associated fuel cost will make the $100/week for electric heat look like a bargain.
Used to be you could get a "floor furnace" or something like that -- a unit maybe 2.5' high, 2.5' wide, and 4 feet long. Burned propane (or maybe oil) and had a flue coming out one end. Kind of a laying-down version of a wall furnace.
But I haven't seen one of these in maybe 40 years (though I don't frequent the type of house that would use one).
Might be worth it talking to some local HVAC folks and see if they have a "loaner" furnace of some sort. A high-efficiency unit that would vent through plastic pipes out an open window would be ideal.
Dick,
Connect your torpedo to your wood stove with some sheet metal and let it rip.
I always make the H&A sub hook up early to either heat or cool. They do bitch and moan.
KK
Lotsa people don't like to hook up the "real" furnace until after the drywall's sanded.
Dan,
I have heard all the excuses for why not and drywall dust is one. Double filter works fine and does not hurt the coils. I have done it many times and have checked. It dries out the structure and makes workers more efficient.
KK
Yeah, I agree that doubling up on the filters (and using good ones) should work. And probably best to not hook up the return trunk but just draw in air directly, so as not to pull dust into the ducts.
But some HVAC outfits have "loaners" (as I suggested earlier) to remove the salmon of doubt.
Uhhh....
If you do that, aren't you just blowing the hot air up the chimney? I thought the idea was that the hot air out of the torpedo stayed in the room and got recycled into the intake again.
Those things make no sense to me. Using one as temporary heat in a house under construction causes tons of problems.
Presumably if you ran the exhaust through the wood stove, the stove would serve as a radiator and save some of the heat. But still you're probably right that most would go up the chimney.
Electric
Go to the hardware store and buy a couple of 1500-watt oil-filled electric radiators. They should cost about $50 each and put plenty of heat into the house. They're silent and don't blow any air. If you run a pair of them on full for 12 hours per day each, you'll use 1080 KwH in a month. That would cost me $82, at a little over 7.5 cents per KwH. To get to $400 you'd have to be paying 30 cents.
David, 3 KW won't heat the place up fast, although it wouldn't cool down fast either. I'd have to run the heaters around the clock. Also, your power is cheap there. Here it is roughly doubled. Still, with equipment rental and fuel, it probably would be easiest and maybe not all that more expensive to go electric. It's just another construction cost, which has been bad enough. [We should have made the place a lot smaller, but that's hindsight]
By the way, I posted this question over on the "other" BT. It was taking forever for it to appear, so I came back over here to post. Replies on both forums are generally similar, but some are different. Conclusion is largely the same. Electric it is.
Edit: the torpedo heater runs diesel as a substitute for kerosene. Propane has higher hydrogen to carbon ratio, and natural gas (mostly CH4) is still higher. Any hydrocarbon fuel burns to CO2 and H2O. The unit is supposed to have a low oxygen detector that will shut down the unit.
This raises a question that I've always wondered about.
The torpedo heater is LP fired, right? Does the burning of unvented LP introduce lots of humidity into a space?
Yep, that's the source of the OP's problem.
I've always wondered about that...how LP can contain so much latent H2O.
Thanks.
Lots of hydrogen.
rethink "getting by" with 2T
rethink "getting by" with 2T
based on the info I might lobby for the woodstove...
I don't completely see all your reasons for not using the woodstove.
You need the wood for your temporary quarters but don't they sell firewood in your locale? [just asking, not trying to be a wise, uh, acre.]
Sure you will have to feed it but the dry heat can be an asset during new construction.
Otherwise I agree that the hvac guy should have set you up earlier.
Will try the woodstove
I'm going to walk over shortly and connect the woodstove, then fire it up. I'm reluctant to have a load of wood delivered, since I don't know how seasoned it would be. I like to cut, split, and stack my own so I know what condition it is in come woodstove season. With two stoves using wood, I know I'm going to run out of what's on hand before we are into the new house. Still, it could be the way to go until the heating system is in operation. This isn't the HVAC contractor's fault. I wanted to confirm the tightness of the house by blower door before ordering the heat pump, and that got done just a week ago. I did set two electric space heaters over there yesterday, and we may add a third. I'll post later when I know how the woodstove is working out. By the numbers, it ought to be able to provide more heat than the house needs all by itself.