The best thing you can do is insulate the north side wall and north roof glazing, Kenny. Go to HD or Ace and get the sheathing insulation with the reflective material, and put that material to the inside. If you have greenhouse film make another layer for dead air space too.

Then the 1000 W heater has a known BTU output, and there are scores of calculators out there on The Interwebs that will figure the BTU requirement for your GH at a given temperature level. You'll then find you probably want some water in there as well to help moderate the temp, I'd say 50 gal should make a decent difference, 75+ better yet, put it at the front and paint container black, make sure gets lots of sun. There's a couple threads on the other forum with the 5gal container pix, use those as the water doesn't stratify & stack.

I'm hardening off my babies inside with the fan right now, in prep for the WOWs maybe next weekend, depending.

Dan

I'm trying to slow the tomatoes down, Kenny. They are stretching from lack of sunlight. So, I took them out of the heated greenhouse and put them in the unheated, plastic tunnel.

It turned out to be a big mistake that first night, 26°. What was I thinking?!?

It was 38° in the middle of the tunnel but too cold (whatever it was) near the plastic. Got some seriously wilted tomatoes in a couple of flats.

sunshine & warmth, sunshine & warmth, sunshine & . . .

Steve

Thanks Dan. I am glad to hear that even 50 gal of water can make a difference. After all the reading I have done, I had my doubts. I am not trying to keep it warm. Just keep from freezing on those one or two frost nights that we always get here In Colorado. About 350 or 400 cu. feet. I like things simple and two barrel of water with a plank across for a bench sound easy to me. That much heat sink for what ever it is worth.
Digit, I have problems with 2 or 3 tomatoes in my laundry room. They are wilted like a wet dishrag and leaves and stems fall off. Looks like frost but no way..got to be the a water deal.
Kenny