small greenhouse day/night temp control

[Anne Pfaff]

I live in a Zone 5 area and just built a 100sf polycarbonate greenhouse. An elec. heater blower is being installed, but don't know if the Peco "Nema 4X Raintight" thermostat I bought can create a 15 degree temp differential. Found a few multiple setting greenhouse thermostats online, but they don't appear to be waterproof. Any advice from greenhouse growers in cold climates on this?
Thanks -Anne

[Orchidking]

Why does the thermostat need to be waterproof in en enclosed greenhouse? Do you have sprinklers or something?

My instinct would be to have 2 thermostats with a weaker night time heater, both set 15 degrees apart.

There are of course thermostats that can control both day+night but I haven't actualy come across a good one, 2 seperate ones works better for me

[Ray]

You'll be fine setting a minimum temperature only.

If the day is sunny, the interior temperature will rise naturally. If it is a gray day, it will not.

Artificially boosting the temperature when there is not a commensurate increase in light level can lead to weak, leggy growth.

[Anne Pfaff]

Orchidking, I had the same thought about using 2 heaters, but Ray makes good points.

I've always grown under lights with timers (basement) and kept day lengths longer than outside in winter. Since it got quite warm during the day under lights, my orchids lived in luxury!

I guess I don't want to mess with mother nature. Will possibly add bubble wrap for more R value, but one thing at a time...

Thanks, both!

[Fairorchids]

Anne,

Even when the sun is not out, the day time temperature will rise in the greenhouse on most days. Only when it is really cold outside, AND overcast, will the temp remain near the min set on the thermostat.

Having said that, if you want to use a 2 setting indoor thermostat, install it under a cover (shelf), which should be painted white to avoid unintentional temperature rise around the thermostat.

Best rgds,
Kim

[Roberta]

Originally Posted by Orchidking

Why does the thermostat need to be waterproof in en enclosed greenhouse? Do you have sprinklers or something?

My instinct would be to have 2 thermostats with a weaker night time heater, both set 15 degrees apart.

There are of course thermostats that can control both day+night but I haven't actualy come across a good one, 2 seperate ones works better for me

Greenhouse, even without sprinklers, is a very damp environment. Not friendly for electrical connections - or electronics. Anything electrical needs to be waterproof or protected from dampness. This learned from experience. In fact, I found that wireless remote thermometer sensors lasted about 6 months in the greenhouse, due to the humidity. I have gone to a thermocouple on a long wire (with the base unit in the house) to monitor temperatures from inside the house, and it has worked nicely for about 8 years.

Thermostats that actually control heater (and fogger in the summer) are waterproof types. The GH heats naturally during the day, so I have no problem with day-night differential. I agree with Ray, just set a minimum temperature.

[richardb]

Ray and Roberta have hit the spot precisely. Keep things as simple as possible....nature does.

[Anne Pfaff]

Kim, I should have asked you in the first place given your beautifully grown plants!

All my installations are going to be waterproof. I even bought an ambient weather station, which should hold up in dampness. It has an alarm so I can remotely monitor temps and humidity.

Thanks all!