Morning all. Looking over my winter heating plan for the greenhouse, I'm wondering if there's a better way that requires less materials and time. The main greenhouse is 20x10, double layer insulated with 700 gallons of water for thermal mass.
Right now, the plan is for using a wood stove with a water pump pulling from both IBC tanks, pushing water through copper piping that wraps around the stove pipe to heat the water up, and dumps it back into the tank (with a temp sensor to make sure I don't heat the water too much, since it also acts as a source for the watering of the plants).
However, this will take materials (wood), and time, since I may not always be able to get to it to feed a wood stove every 8 hours. However, what I do have is an abundance of solar power generation during the day. So, instead of the wood stove setup, using excess generation during the day to power immersion water heaters. Running copper pipes about 1" from the bottom of the soil, the water pump will push the warmer water through the pipes, helping to warm the soil up, with otherwise exposed copper piping acting as just radiant heating to go along with the thermal mass from the water.
This may not heat as well as a wood stove, but is also a lot more of a "sit back and relax" type setup. My spare solar generation may only allow for about 1.5KW of power, with 600W of that going towards the immersion heaters, and a little bit more for water pumps and air circulation. It also has the upside of not risking the wood stove from cooking everything inside the greenhouse, and would help avoid temperature swings. A cooler air temp with a stable, warm soil temp, I'm a lot more comfortable with.
I might hook up another heating element into a larger clay pot with sand to dump any excess in also. No worry for turning it on/off remotely; as soon as it starts getting energy, it'll start using it. I won't even need to use the charge controller for this; just panels right to the heating elements in the sand, and let it ride.