From Connecticut USA so a heater is a must. Was given a heater with a basic thermostat and set it to 50 degrees, but noticed a couple of the more tender plants were starting to show signs of cold exposure (this was in early November) I checked the thermostat and it appeared to be set correctly, checked the cords and power source etc. and could not find anything wrong. The heater turned on/off when I manually dialed it on the unit. I also went back out at some random times and it had turned on. Decided to purchase a digital thermometer (the heater didn’t have one) with Bluetooth so I could be alerted if it dropped below 50. When the temps started going below freezing, not only did the heater not maintain the 50 degrees, but all the plants had been frost bitten. I brought inside a few tropicals that were important to me ( my Dad grew them but is now deceased).
The photo is a 24 hour reading from the Bluetooth thermometer. I cannot figure out why it gets up to temperature during the day but goes below freezing at night…
Any advice greatly appreciated!!
by chowchowchow4321
7 Comments
Can you share the wattage of your current heater and the size of your greenhouse?
What type of heater? How many watts and btu? Size of greenhouse? It sounds like your heater is undersized
I’m guessing your heater isn’t big enough and the sun is doing all the work during the day.
I just sucked it up and had a gas heater installed, electric just wasn’t keeping up and gas is supposed to be much more efficient. Your heater isn’t enough at night.
Solar gain during the day adds heat. You need more insulation to hold the heat in at night. What type of structure do you have? Glass or poly? Try bubble wrap or thermal blankets. Ditch the thermostat at night and just run it constantly if it’s getting that cold.
Most greenhouses have an insulation rating of about R0.5 or R1 at absolute best.
Your house is somewhere between R10 if older and R30 if newer or updated. (Note that R-value is not linear, either.)
Now compare the size of the heater in your home to the heater in your greenhouse. This is why it can’t keep up overnight.
Try adding 2″ R13 foam board to your north wall, and portions of your east and west that don’t see much sun. Study your sun angles at this time of year and insulate accordingly.
A 1500 watt heater is not nearly enough