heating small greenhouse

auntielaurie98031(z6WA.USA)November 11, 2005

Just wanted to know what you think.

I have a 8' by 12' greenhouse with 4 tier metal racks. They all have 40 watt florecent lights on them. I have 32 lights with 2 40 watt bulbs each, so 64 bulbs. Anyway they are keeping my greenhouse arount 60 to almost 80 degrees warm. It's preety cold outside, 35- 45 degrees. I had a electrican do the wiring,it's grounded. I use extention cords though.I still wonder how safe it is with the moisture in the greenhouse. I try to be careful when I water. The electrican seems to think I'm ok. Any thoughts?

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weebus(Z8 Sunset 5 WA)

Shoot! didn't know this was here. I'm moving it to the other side so we can see it.

    Bookmark   November 14, 2005 at 4:22PM
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kudzu9(Zone 8a - PNW)

I'm not sure you can get a definitive answer given that you have given very little info about exactly how this is all set up. Where are all those lights plugged in and how easy is it for the receptacles to get sprayed with water? In any case, just because they're grounded doesn't mean that it can't be hazardous (fire) or worse (shock). I'm not going to tell you whether this is good or not, but I will say that at a minimum you need to have those receptacles changed to GFCI receptacles or have them all run to a GFCI breaker. I'm assuming you know what those are.

    Bookmark   November 16, 2005 at 12:29AM
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seedbandito(7 NC)

I agree with Kudzu, my DH is an electrician by trade. Most of the talk is french to me however, he was INSISTANT on GFI breakers & receptacles because of the moisture inside a GH.


    Bookmark   November 18, 2005 at 7:41AM
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weebus(Z8 Sunset 5 WA)

Well she had an electrician do the wiring, and he seems to think it's OK I would think he installed GFI breakers, don't you? My thing is, if I don't feel safe, I don't care what someone else thinks. I need to feel safe to be comfortable...

    Bookmark   November 18, 2005 at 12:58PM
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He did install GFI breakers in the greenhouse. I just want to know if the extention cords are ok. Lots of lights are pluged into extentiion cords then into the GFI breaker.
It just seems that if this is a good safe set up more people would be doing it. You get lights and a warm greenhouse in winter.

    Bookmark   November 20, 2005 at 11:04AM
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weebus(Z8 Sunset 5 WA)

The lights are warming the GH, only becuase they are inefficientusers of energy. My grow light is hung about 8 feet high in my greenhouse, so the plants aren't growing 2-3 inches from the light source.

It also depends on the size of your GH...

    Bookmark   November 20, 2005 at 12:41PM
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byron(4a/5b NH)

It's warm inside while the lights are on, but how cold is it at 2 AM ?

    Bookmark   November 23, 2005 at 12:24PM
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kudzu9(Zone 8a - PNW)

I'm relieved to know that you have GFCI protection. However, I'll still ask if the receptacles are in a protected enough location that they're not going to be accidentally hit by water from a hose or a big spill.

    Bookmark   November 24, 2005 at 1:12AM
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The outlets are covered with water proof outlet covers, but the multipal outlet extention cords are not protected so I do have to be careful.They are up high though so I don't get them wet.

    Bookmark   November 27, 2005 at 8:32PM
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weebus(Z8 Sunset 5 WA)

You are probably just fine...

    Bookmark   November 27, 2005 at 9:52PM
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virgo91967(z6 KY)

Webus is right, AuntieLaurie... your electricals should be fine... And I would estimate that your lights would be putting out something like 1500 watts of heat.. Should keep your greenhouse from freezing solid down to an outside temperature of 20F.

You may want to consider using a 1500W oil-filled electric heaters as your primary heat source and use the incandescent lights as emergency backup heat. I like using that sort of electric heater because there are no exposed heating elements, they handle damp well (not that there should be much humidity in a winter greenhouse) and they provide nice gentle convective heat.

Just be careful to put them on seperate circuits from each other or you will be tripping breakers on a regular basis

    Bookmark   December 4, 2005 at 8:14PM
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I live in Northern Elko County, Nevada and it gets down below freezing (can be wayyyy down) I am pretty new to the area and have a greenhouse attached to the south side of my house, about 8x20 feet in size. I am trying to figure out if its going to be worth the cost, or even possible, to keep things growing in there during the winter, and how early I should try to get things going in there in the spring. its about 30 degrees today, and the temp in the greenhouse is almost 70 degrees. I do have one of those oil filled heaters..was wondering how that might work. I guess I need to track the temps in their better through the nights..but any suggestions from you would help. This is the first time I have had a greenhouse, am an avid gardener, but am new to this cold climate and could use some help. Thanks in advance.

    Bookmark   February 5, 2006 at 2:40PM
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