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heater for zone 5 greenhouse

12 years ago

I am finishing up my lean-to greenhouse here in frosty Michigan. I have been perusing old threads to see what seems to be keeping people happy with their heating needs- but I haven't found anybody from colder regions saying much... I have just over 500 square feet of space, and the greenhouse calculator puts me at needing about 75000 btu's of heat in the dead of winter- when we go below zero for long spells of time with not much sun... I have electricity in there, but no natural gas hookup. I've also been keeping an eye on Craigslist for two months but nothing has turned up. So my question for other cold-region growers is this: what do you use to heat your greenhouse, and how do you like it?

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Comments (3)

orchidnick
12 years ago
I'm not from a cold area but have an unconventional method which might work for you. In principle at least. Electricity works great if you got a dedicated 50 Amp breaker for what you'll need. I faced the same problem and decided against running gas to the GH. Instead used the gas where it was, got a larger water heater, turned the temp up to max (in the winter only) then ran the hot water in insulated pipes to the GH. A recirculating pump does the work.

I found an industrial 2' x 4' copper radiator which, with 3 fans behind it distributes the heat to the GH. Other alternatives are base copper pipes with fins which do the same thing. I just happened to find the radiator. I can keep 350 sq feet of relatively non insulated, one layer of agricultural plastic only, at 60F when outside temp goes down to 28.

The weak link is the recirculating pump, 1/2" in, 1/2" out, I may run a second set of pipes to get maximum usage of the water heater. On the coldest nights the water in the water heater remains hot so the heat is not transferred enough, more circulation is probably the answer.

Nick
highjack
12 years ago
I use propane but would have preferred natural gas because it is the least expensive. It works great. Make sure you get a vented heater and a big enough propane tank so the propane guy doesn't show up very often or the neighbors will talk :>)

Brooke
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lisa_z5wmi
Original Author
12 years ago
Thanks for the suggestions. I had read about your system in previous posts, Nick- didn't think it would work for me. But now I am not sure. I have my local guy coming out this afternoon for a look (one of the benefits of living in a really small town is that you get to know your local handymen) to let me know what would actually be possible in my space. My husband is not keen on a propane tank, and I am leaning towards a Modine natural gas unit right now.
Any further comments are welcome. Weather will be mild enough for the next couple of weeks that I can think on this a bit more.

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