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Title: Greenhouse Heating and Insulation Post by: Darkhorse on September 12, 2012, 01:47:07 PM Hi everyone,
I'm looking for advice from those experienced in heating and insulating greenhouses for winter. I just bought myself a big, nice greenhouse. Nice as it is, I will still need to heat it. I'm shopping for an electric heater, and am wondering if anyone has any tips or recommendations. My greenhouse is 8' x 20' with an R value similar to single-pane glass. From my calculations I'll need a heater that puts out about 20,000 BTU/hr. My concerns are as follows: Will I be better off with two smaller heaters instead of one large one? As in... one in each corner of the greenhouse? Or will a heater on one end with a fan be sufficient? I don't want any cold spots. I'm considering 1 King Pic-A-Watt 240v Electric Heater, or two Dayton U36 Heaters. I found them here: http://www.littlegreenhouse.com/accessory/heaters3.shtml Will too high a wattage dry my plants out? Will greenhouse humidity kill electric heaters too easily? I'm also looking into bubble insulation. Any knowledge on that topic will be appreciated as well. I'm concerned that with the insulation, enough light won't be able to pass through when it's dark and overcast here for a few months. Thank you all, as always! Title: Re: Greenhouse Heating and Insulation Post by: Aleksandr on September 12, 2012, 01:57:14 PM Hi Darkhorse,
I'm also thinking about heating of greenhouse and not to have cold spot I decided to make underfloor heating. Something like that Title: Re: Greenhouse Heating and Insulation Post by: Charlie on September 14, 2012, 07:56:14 AM Jordan, Alexandr is using a common technique for heating greenhouses. The idea is to heat from the floor so that most of the energy is used to heat the first few feet above the floor rather than the top few feet where there are usually no plants. It's a great way to go but costs more and is more complicated to install, with good savings to be had later when operating the system.
HAF (horizontal air flow) fans are well known to distribute the warm air not only front to back but also top to bottom. I use them and have been pleasantly surprised how well they do to distribute the heat to all parts of the greenhouse. Of course, the heat has to be there to start with. I've not used electric heaters so cannot say whether they will do the job and be cost effective. Good luck! Charlie Title: Re: Greenhouse Heating and Insulation Post by: Darkhorse on September 14, 2012, 02:31:40 PM Thank you Charlie and Aleksandr! I will let you know how it goes. If I can keep the air circulating with fans, then I'm sure that will help prevent cold spots. I'll look into the HAF fans and see what I can find. I don't think I'll go with the heated floor, just because my current home is just a starter home. I'm probably going to move within the next 5 years and I want something that can easily be broken down a taken with me.
Title: Re: Greenhouse Heating and Insulation Post by: LJG on October 04, 2012, 12:43:43 AM It would be recommended to go gas if you can. Much cheaper to run (at least here in California). I have a 25 x 13 greenhouse and I just use one 20,000 unit to heat to 55-60 degrees in winter. This is what I have:
http://www.4seasongreenhouse.com/non-vented-greenhouse-heater-20000-btu-p-2133.html If I were in an area that freezes many nights, I might run a backup heater to be safe. I would do so even with an electric heater. Things break or circuits trip for example. And Murphy's Law tells us it will happen on the coldest night. |