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Greenhouse Heater

Posted by anthantropical (My Page) on
Fri, Jan 17, 14 at 11:33

I have a 8x24 Greenhouse covered by 6mm twin wall polycarbonate. I wonder if anyone in here having a similar size greenhouse and using a 5 KWH electric heater to keep the greenhouse warm during winter. I am planning to buy this King 5 KWH electric heater (King KBP2406 5700-Watt), After using a portable propane heater for two months and many trips to refill my three 20lb tanks, I realized that it is expensive and inconvenience considering the cost of $20 per 20lb (or about $4.24/gallon), and refilled at least twice per month (3 20lb tanks), and waking up in middle of cold night to exchange tank to keep the heater running. I am thinking about getting a 100lb Tank to make it more convenient, but at the rate of $4.24/gallon of propane vs. 10 cent per kw of electricity, electric heater will be less expensive for me. My intention is to keep my greenhouse at around 60F during cold winter. Living in Fairfax, Virginia, it might be a challenge because we get many nights with temperature between 10F and 20F, but low average is about 28F. Please let me know what you think.

I appreciate all input.
Thank you so much!!!!

Follow-Up Postings:

RE: Greenhouse Heater

i just built my greenhouse, i use a cheapo wall-mart electric heater, and just on cold nights, and i actually had it set to "LOW"
I used the home depot clear polycarb stuff, its not a big greenhouse, and i have insulation 4ft + down

it was 27 degrees the other night, when i walked into the greenhouse in the morning, it was about 55-60
cool, but not enough to hurt anything

If you need a lot more than that, i would get a 220v heater, if you can get 220v into the greenhouse. thats probably the most efficient/ cheapest way

To me, the most important thing is air leaks.
if its closed in well, you dont need a lot of heat.

Here is a link that might be useful: heater 220v

This post was edited by greenman62 on Sat, Jan 18, 14 at 4:39

RE: Greenhouse Heater

Water is efficient at storing heat in the day and releasing it at night which saves on heating. I have one 55 gallon barrel in my greenhouse for that reason. It is blue but if painted black would be even better. Also a cheapo Wal Mart electric heater to protect from freezing. I also have a remote thermometer which I can monitor in the comfort of my home. Ideally maybe I get another barrel and use them on both ends to hold up shelving dual purpose style.

RE: Greenhouse Heater

You might want to consider Phase Change Materials. They are passive (like water) but store a lot more heat in much less space. You can pair PCMs with a fan to maximize gain. It is passive (without the fan) so it would work whether or not you had a power outage. With a fan system, it would be more efficient.

RE: Greenhouse Heater

i wonder if adding rock salt
to a 55 gallon drum of water would help ?

Here in New Orleans it doesnt normally get very cold. a couple of weeks ago it was abou 30 and my little cheapo heater was on LOW setting 750watts and it worked just fine.
Yesterday it was 32 and for some reason it wasnt keeping up. i think it was the humidity which was much higher

it was raining, it felt much colder in there.
maybe i will have to blow that little heater on a rock or something ?

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