Self powered heated greenhouse

If your greenhouse can top 80F on sunny winter days and you get plenty of sunny days, you can store the heat in the ground for use at night. I have an indoor setup but i only use it to get an early start on the season.

 

If one was able to build/dig a heat sink you're correct but I don't have that option. Mine sit on a deck. I did try adding troughs of water which were heated by a solar water heater but because our winter temps are so severe, it wasn't a feasible mode of moderation beyond the end of November and through to March. Very little gain in lengthening the season. The heater was quite dandy though as it would output the water at 55c on a sunny day.

 

I'm sorry I can't remember it cost an arm and a leg and was useless. We have 100w solo panel stuck on top of the caravan that cover ms a free view box, data lite and TV, all the lights and we have been down over Christmas and a to had plenty of power

 

The deck wouldnt work too well as a thermal mass I made use of the heavy clay soil under mine, digging a load of 4ft deep trenches and a 6ft sump keeps you fit (to drop) lol

 

I had the troughs of water running along the inside edges of the greenhouse and this was my home made water heater - the water circulated via thermosiphon- I had dyed the intake at one end the trough with red food dye and then timed how long it took to complete the circuit which was about an hour. I also used the sun to dry things in my solar dehydrator complete with fans run from small panels... love to tinker! to circulate the water.

 

You cant beat a bit of tinkering Your heater looks good, unique even.
I would be a little concerned about having open troughs of warm water in the greenhouse as they are likely to raise the greenhouse humidity levels a fair amount, especially at night.

In case you are wondering why it not a good thing here`s the technical guff
The sensible heat that initially warmed up the water is converted into latent (hidden) heat as the water evaporates (aka changes phase from a liquid into a gas). The latent heat is locked up in the water vapour so it doesnt raise the greenhouse air temperature, only the RH% When the moist air hits the cold glazing, the water vapour condenses back into liquid water releasing the sensible heat (which would heat the air) directly onto the glazing and its off into the yard

I use the same principle to cool the greenhouse, except the sensible heat is released underground in the form of warm rain. The heat is stored in the soilmass, the roots get the water back and you dont have to water as often.

 

Oh, I forgot to mention that the troughs had tile "lids" so the moisture level didn't seem to be raised ...

 

The victorians figured it, enabling them to grow pineapples in the UK.

Their method has already been hinted at in this thread.

They had raised beds inside the greenhouse. The raised beds would be filled with fresh manure. Soil filled crates would be placed on top. Pineapples were planted in them. The manure had the perfect conditions to rot, being well insulated and with water draining through the soil crate lids. Perfect rotting conditions meant a steady source of heat. Heat rises, into the soil crate lids. The heat is regular, being generated by microbes it's not hot enough to damage anything by the time it reaches to your plants. Perfect eco heating, dating way back to before the term eco.

 

The victorians were great innovators, most of the farm work and transportation of goods involved horses so they had an abundance of manure which they put to good use.