[westglenn]

First time I have posted on the forum.

I am looking to use thermosiphoning to raise/maintain the temperature and extend the greenhouse growing season. Has anyone tried this before?

Some history first.

I have had an allotment for two years now and am lucky to have a greenhouse.

I have installed temperature controlled roof vent lifter which works birlliantly.  Two (2) litre pop bottles were put around the inside base to collect heat during the day and slowly release it over the night.

A thermosiphon works by heating water within a panel and transferring the hot water into a container. The transfer is conducted the cooling of the water and gravity. Supposedly cooling water is heavy than hot water.

I am looking for advice or experience.

[joyfull]

hello and welcome. Sorry I have no idea about thermosiphon (never heard of it before  ) however hopefully somebody will be along shortly to chat with you 

[Aidy]

Like the idea but I can see one possible major flaw, no thinking about it two possible flaws.

1st: you will need a constant supply of sun in winter 
2nd: daylight hours are so low I dont think to plants other than those which are generally grown in winter would be too happy.
Just what sort of crops do you plan to try and grow?
Just thought of another possible problem, I like to clear and steralise the greenhouse at the end of the growing season ready for next years seedling etc, if you plan to grow pretty much all year round are you not risking problems?

However I would love it to be proved wrong and if you manage it, please let us know.

[smud6ie]

If you want some heat at night have you thought about using the bricks out of old storage heaters,there are plenty being thrown away and I would think they should work well if painted black?well I hope they do because I picked up a load last weekend to try
smud6ie

[arugula]

I'd still be more inclined to install something like Dick Strawbridge's heat sink.

 

[Aidy]

I am still not convinced, the air will be a lot more moist/ damp in the winter, I reckon because of this most things will suffer from mould/ rotting issues as you wouldn't be able to get the correct air flow as in commercial greenhouses.
Also as I mentioned its a lot of hassle for the limited crops you could grow due to short daylight hours.

[kiltferret]

I ran tube from solar panel (black painted radiator behind double glazing and in a box made from 100mm kingspan) around and cast  inside fairly massive concrete block. Hoping this will at least keep greenhouse above freezing.
Hope we both have some success.

[lfcevans]

We have a serious lack of sun and usually an abundance of wind in winter, so, to me, it would make sense to use this form of green energy. I`m not sure what size blades are needed or what size generator, but surely not to big to be unsiightly, and can be run at night aswell...because wind doesnt stop at night.

just putting it out there