Tent Greenhouse Heating.

[amh]

I have an 11X11, tent style greenhouse that I would like to keep above 20^oF.  I plan on keeping my cold hardy plants inside for frost and rain protection, but I would like to prevent the inside temperature from getting below 20^oF. I currently plan on keeping a 100 gallon stock tank full of water inside, but will this hold enough heat? Any recommendations on heaters? The green house is protected by deciduous canopy.  I'm in a warm zone 8A with low humidity and no cloud cover.

Half full of cycads:

[ZPalms]

20 hours ago, amh said:

I have an 11X11, tent style greenhouse that I would like to keep above 20^oF.  I plan on keeping my cold hardy plants inside for frost and rain protection, but I would like to prevent the inside temperature from getting below 20^oF. I currently plan on keeping a 100 gallon stock tank full of water inside, but will this hold enough heat? Any recommendations on heaters? The green house is protected by deciduous canopy.  I'm in a warm zone 8A with low humidity and no cloud cover.

Half full of cycads:

I got one of these types of greenhouse ordered, I think you should buy some plastic from lowes and double it up to help retain heat because that material that comes with it just won't do anything for insulation. outdoor and interior air in the greenhouse will level off quicker than you can keep it above 20 I think.

Edited November 14, 2022 by ZPalms

[BeyondTheGarden]

My greenhouse is clear acrylic paneling, it's fairly similar to what you've got going.  It only stays a degree or two above ambient air temp, depending on duration.   A single layer of thin plastic is a poor insulator.  It's better than nothing and will help keep frost off, but can you run an extension cord and a portable heater or a heat lamp?  That would make a big difference. 

Edit, just saw you were looking for a heater recommendation.  I should have read the whole thing!  

IR heaters are supposed to be the most efficient, but they're not as cheap as a few old-fashioned heat lamps.  The kind you use for chickens.  If you're going to run more than one (of any kind of heater), you'll need to pull power from more than one outlet circuit as a normal heater will be about the max that a 15 or 20 amp circuit can sustain.  You don't want to load a circuit past 80% of its rated capacity for long durations.  Also, pulling from more than one circuit, provides you with a backup, incase one breaker trips.  "Two is one, one is none".  

I'll be out of town for awhile later this season, I'm going to run an IR heater on once circuit, and several grow lights on another circuit.  High power grow lights also produce a good amount of heat.  I'll leave them on 24/7. 

Edited November 14, 2022 by Jesse PNW

[amh]

19 hours ago, ZPalms said:

I got one of these types of greenhouse ordered, I think you should buy some plastic from lowes and double it up to help retain heat because that material that comes with it just won't do anything for insulation. outdoor and interior air in the greenhouse will level off quicker than you can keep it above 20 I think.

 

17 hours ago, Jesse PNW said:

My greenhouse is clear acrylic paneling, it's fairly similar to what you've got going.  It only stays a degree or two above ambient air temp, depending on duration.   A single layer of thin plastic is a poor insulator.  It's better than nothing and will help keep frost off, but can you run an extension cord and a portable heater or a heat lamp?  That would make a big difference. 

Edit, just saw you were looking for a heater recommendation.  I should have read the whole thing!  

IR heaters are supposed to be the most efficient, but they're not as cheap as a few old-fashioned heat lamps.  The kind you use for chickens.  If you're going to run more than one (of any kind of heater), you'll need to pull power from more than one outlet circuit as a normal heater will be about the max that a 15 or 20 amp circuit can sustain.  You don't want to load a circuit past 80% of its rated capacity for long durations.  Also, pulling from more than one circuit, provides you with a backup, incase one breaker trips.  "Two is one, one is none".  

I'll be out of town for awhile later this season, I'm going to run an IR heater on once circuit, and several grow lights on another circuit.  High power grow lights also produce a good amount of heat.  I'll leave them on 24/7. 

Thank you both for the input. I've been thinking of adding a second layer of plastic for when temperatures get really cold. My absolute lows usually only get down to 13F or 14F, but most nights will stay above 17F. The plants are usually kept on my porch under the overhang, but I ran out of room. I can run power to the area and was thinking of using heat lamp(s); I use tarps and regular incandescent light bulbs for my citrus, but that is for a much smaller volume of air. I am considering a small outdoor heater, but I don't want it to run all night. Any experience with the small propane types?

BTW, I do have a heater for the stock tank, but I worry that I could create frost if the water is too warm.

[BeyondTheGarden]

I have a simple single/double burner propane heater, it is AWESOME.  It was cheap and will keep the greenhouse (or barn) comfortable.  But, it's not automated and you have to manually turn it on/off.  

There are propane heaters with thermostats, I need to do some more research on them.  I would be wary of leaving them unattended, however.  I wouldn't sleep for fear I'd wake up to a giant fireball where the greenhouse used to be.