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Can you recommend what to use under heatmat in GH for insulation?

Posted by bonechickchris 7A/6B NJ 08731 (My Page) on
Mon, Jan 27, 14 at 11:46

Hi there,

I currently have a couple of 48" X 20" heat mats that I want to use in my Solexx greenhouse to keep the roots warm of my citrus trees during these extreme cold nights we have been having here in NJ.

I want to use something under the mats to help retain the heat. But I want to use something that is heat/fire resistant in some way.

I was originally thinking of Tekfoil that you can get from Farmtek/Growersupply but was hoping to be able to get something similar from a Home Depot or similar store.

If you have any suggestions, please let me know. Thank you! Christy

Follow-Up Postings:

RE: Can you recommend what to use under heatmat in GH for insulat

You don't say, but I assume your citrus trees are in pots in the GH, not rooted in the ground out there. If so, a few thoughts:

I would be tempted to use some foil covered foam insulation board. Even a 1/2" thick one would greatly limit the heat loss down, and I suspect it would be quite a bit more firm than the bubbly type of insulation for placing pots on. Home Depot has 1/2" urethane foil covered boards which are quite a bit harder than the styrofoam ones and better insulation too, but does give off toxic fumes if they burn.

The foam (all types) can and will burn if exposed to flame. The real risk is probably from a short in the heat mats, which may present a real fire danger on foam. If so, then perhaps a piece of sheet metal over the foam but under the heat mat would solve this (should be safe if all this is on a GFI and the metal was grounded, but I am not that familiar with the failure modes of the heat mats).

Quite a few citrus growers use Xmas lights, wrapped around the pots to provide soil level heat. That might be an alternative.

Also, depending upon how long this is going to be used, heating the ground underneath may be a good thing in the long run.

RE: Can you recommend what to use under heatmat in GH for insulat

Thanks Steve for the reply! Actually, after having a heat mat failure recently after all these years, I am a little freaked now using them. I had a larger cheaper version (dirtgenius) instead of the actual Hydro Farm brand, and not sure if that was the reason for failure or not.

I was lucky enough to be in the GH when it happened, I saw a small stream of smoke coming from the mat, and I quickly unplugged it. Not sure if it would of caught fire or not. I have used other mats for years without any issues. I am hoping it was just a fluke.

I do have a Hydrofarm 48"X20" mat now to use that is UL listed, and made for greenhouse extremes, so I am trying to get the courage to use one again. But that is why I am so worried about using something heatproof. I was even thinking maybe a silicone mat if I could find one.

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