Thermal mass as temperature control

[Jwood0123]

When you've done it, post a picture.
Always exciting to see, especially if there's a compost thermometer in there giving a warm reading

Will do, I'll probably have it finished in spring, takes a while to save up scrap materials from work

[MyWifesBrassicas]

Il look into it in further detail once I get around to building the storage space in my GH. Even if it doesn't help heat the GH, you can never have too much compost. Thanks again for your help.

When you've done it, post a picture.
Always exciting to see, especially if there's a compost thermometer in there giving a warm reading

[Jwood0123]

Il look into it in further detail once I get around to building the storage space in my GH. Even if it doesn't help heat the GH, you can never have too much compost. Thanks again for your help.

[MyWifesBrassicas]

I just had a little bit of a look into the hotbed system. I might give it a go as i have the materials to make a sort of "coffin" below the walkway inside the greenhouse. while it wouldn't be directly below any growing space, it will be in the centre so it may still work. Other than that, I personally wouldn't be keen on doing it directly under grow space - i imagine it being too much hassle and one of the main crops im growing are strawberries (which i hope will survive winter) so they would get in the way.

Thanks for the suggestion, do you think the system i have mentioned would work? it would be 2 layers of approx. 20mm thick fibreglass plywood floor. hopefully insulating it so that the heat gets slightly dispersed towards the grow spaces that surround it. the "coffin" itself would probably be around 1.5mtrs long and 1/2 a mtr deep and wide. My main concern with this method would be the smell from anaerobic activity.

Give it a go, it's worth a shot.
Not sure how much heat it'll produce and for how long, anaerobic activity is colder than aerobic.
I think the french hotbeds were about 1-2 ft underground, but built up so that it was above ground by another ft or so, making it about 3ft deep, they were very successful

[Jwood0123]

There's nothing wrong with trying, loads of gardeners provide extra heat early in the growing season.
There's a fellow in yorkshire call Jack First, google him, he runs courses in hotbeds and has a fantastic hotbed setup, he's even written a book.
Good luck, keep it posted what you do, it's really interesting

I just had a little bit of a look into the hotbed system. I might give it a go as i have the materials to make a sort of "coffin" below the walkway inside the greenhouse. while it wouldn't be directly below any growing space, it will be in the centre so it may still work. Other than that, I personally wouldn't be keen on doing it directly under grow space - i imagine it being too much hassle and one of the main crops im growing are strawberries (which i hope will survive winter) so they would get in the way.

Thanks for the suggestion, do you think the system i have mentioned would work? it would be 2 layers of approx. 20mm thick fibreglass plywood floor. hopefully insulating it so that the heat gets slightly dispersed towards the grow spaces that surround it. the "coffin" itself would probably be around 1.5mtrs long and 1/2 a mtr deep and wide. My main concern with this method would be the smell from anaerobic activity.

[MyWifesBrassicas]

There's nothing wrong with trying, loads of gardeners provide extra heat early in the growing season.
There's a fellow in yorkshire call Jack First, google him, he runs courses in hotbeds and has a fantastic hotbed setup, he's even written a book.
Good luck, keep it posted what you do, it's really interesting

[Jwood0123]

Seems like the general consensus is that there is little benefit to GH heating, especially based on the poll veggiechicken linked. I'll probably still make the ground a dark colour to help heat absorption, but just not bother with anything complicated.

I'll look into what winter crops i want to grow once im set up.

Thanks guys

[veggiechicken]

Some more old threads...............https://www.growfruitandveg.co.uk/gr...eat_94028.html
https://www.growfruitandveg.co.uk/gr...ink_92709.html
https://www.growfruitandveg.co.uk/gr...ink_43191.html

[MyWifesBrassicas]

there's loads of winter crops that don't need heat, though. And it's far easier than creating elaborate warming devices

[MyWifesBrassicas]

I think I probably will. But while I'm still designing my greenhouse layout, if I can figure out a way to stabilise temperature without sacrificing too much grow space, I'm hoping it'll help even with winter crops anyway.

I'm not overly convinced there's much to gain extending the growing season at the end of the year as there's a reduction in light, however I think it's more beneficial feb onwards as the light levels are increasing.
Maybe others here may have differing thoughts?
I did play with the idea of using the composting system outside the green house to heat a "propagator mat" as opposed to heating the whole greenhouse. I've assumed it's easier to heat a propagator than the whole greenhouse

[veggiechicken]

Line it with bubblewrap - doesn't take up any growing space. I used to do it when I first had a GH and thought I should try to keep the temperature up if possible.................Now I have 5 GHs and just grow whatever I can with whatever the temperature may be.

[Jwood0123]

To be honest with you, I think you'd do better to concentrate on growing winter hardy crops in your GH than giving up valuable space to water containers that may not make much difference to the temperature.

I think I probably will. But while I'm still designing my greenhouse layout, if I can figure out a way to stabilise temperature without sacrificing too much grow space, I'm hoping it'll help even with winter crops anyway.

[MyWifesBrassicas]

This may actually be a possibility for me, I have my compost bin directly behind the greenhouse. Once I have managed to sustain a decent compost temp, I may be able to feed a pipe from the bin into the greenhouse. even if it doesn't last all the way into winter, I imagine it could still extend the growing period.

I've been composting a large pile of wood chips since Dec 18 and it's only just started to cool down.
Stayed at around 60C for the majority of that time, it's now 40C, that's 9 months of heat.
However, if what i use to store the heat, say water barrels in the greenhouse, then loosing space for valuable winter growing is a little counter productive just as VC say's.

[veggiechicken]

To be honest with you, I think you'd do better to concentrate on growing winter hardy crops in your GH than giving up valuable space to water containers that may not make much difference to the temperature.

[Jwood0123]

Hi,

Back in the 50's and 60's, Jean Pain did this through composting wood chips.
He create a complete heating system of self sufficiency, this heated his home and all the hot water he needed to 60C
Of course he used tons of woodchips, but this can be down scaled to heat a greenhouse, thinking of trying this very principal to slightly raise the temp of my greenhouse over winter.
The woodchip build is outside my greenhouse with a piping system providing heat to the greenhouse, just not too sure which system to use to pump the heat (no power supply at the allotment)
This also gives me a great supply of compost.

This may actually be a possibility for me, I have my compost bin directly behind the greenhouse. Once I have managed to sustain a decent compost temp, I may be able to feed a pipe from the bin into the greenhouse. even if it doesn't last all the way into winter, I imagine it could still extend the growing period.