Stored heat for tunnel.

Polytunnels, cold frames, greenhouses, propagators & more. How to get the best out of yours...

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Westi
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The tunnel is not heated but I know a lot of people use buckets of water & stuff to offer stored warmth transference in their tunnel. Anyone do this & recommendations for what containers are best ie: buckets or bottles, how many needed, do you put them in with the plants or along the path?

Basically anything you can offer as I'm a bit confused as you can get some great sunny days which warms the tunnel, but you can also get days & days of cloud as well so it would be pretty useless in these conditions I would think even though it is still warmer in there than outside.

Cheers in advance! Mind thanks to the mice I haven't got too much in there but noted the late sows of salad stuff & some fennel is up & moved a couple of brassica plants in there as well that were too small to do anything outside. (Another cheeky late sow).
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oldherbaceous
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I was interested in this too, Westi…but seems we might have to wait for answers…. :)
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Geoff
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I have a concrete path the length of my tunnel and wonder if that helps.
Westi
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I suspect the concrete path would certainly help. I might look around for some bricks actually now you say that Geoff. I think I can safely take the netting off the brassica's as we had a few light frost so the cabbage whites will be gone, then I can collect all of the bricks & broken pavers & put them in there as divisions between the rows & along the edges. That should make a bit of a difference until someone comes along that can explain about the water element.
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Looking at Charles Dowding video comparing greenhouse and poly tunnel which seemed to imply not a lot of heat is retained in polytunnel. I know he does hot bed composting in the greenhouse not sure if in poly tunnel, perhaps you could give it a try.
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tracie
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This is my system. Milk cartons filled with water all around the edge of the polly, I leave them in situ all year. Between the cartons and plastic polly wall I have radiator foil. I then double fleece tucking into the edges of the frame, and hold back with canes. Also have a black bin filled with water too.

Sounds a lot of work but does not take long to set up/ take down.

Certainly makes a difference.
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Westi
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Thank you Tracie,

Well I better start getting some plastic bottles then, but I'm sure the neighbours will contribute if I ask. I have a milkman still so only rarely have a plastic milk bottle if I run out. I had thought about the foil but I was thinking light rather than heat & dismissed it as I have a bubble cover on my tunnel which refracts the light so you get little rainbows in there on a sunny day. What I do have though is loads of polystyrene sheets from online deliveries so I might use them with the foil attached as that would be extra insulation.

It will be a bit at a time project but I could start on the beds with the more delicate crops & will also try the bricks as little paths between the crops. I normally don't have a problem as by this time of the year the crops are fairly established but I had several sowing fails this year. I think this was related to the temp min & max which were well extreme due to the erratic weather we had.

Thanks again! x
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My late dad used to fill a metal jerry can with boiling water every night in winter to leave in his greenhouse but that was for a completely different purpose - i.e. to place next to a straw filled box which was the nightly sleeping place of an elderly feral stray cat who he looked after. He always gave him dish of catfood and this hot water bottle in return for him keeping the mice at bay !
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tracie
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One of my older children (23) used to drink 4 pints in one sitting, and we used to have over 40 pints of milk a week, so we quickly collected the bottles. Better for him that alcohol, and his preference was skimmed.
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Primrose
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Maybe Westi you should contact your local Sixth Form grammar school science students and ask them to come up with a practical solution as a science project ???? Who knows, you might help find the next Einstein although I think what the world needs right now is a actually Cooling project, not a Heating one !!
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Compo
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Has anyone set up solar power to provide eithervhest for growing places or for electric popagators?
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Westi
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I can report no discernible difference with the bricks the tunnel, they remained cold, (well cool) to the touch so were either not emitting heat or what little they had was used up. They are now out of the tunnel stacked up ready for their role of netting security.

On the subject of solar which I am interested in more so now I haven't got the greenhouse and want to do some sowings in tunnel but unsure how they will fare with the fluctuations between high & low temp. It was 31.3C max on a proper sunny day last week but 2.8C min. Compo I have a friend who set up 2 small solar panels on his camper & he says it would be suitable for my tunnel & I would only need one to just provide some timed night heating. Maybe rather than a general search you could look at these as might be the right voltage & they are sold as the full set up. His heats the shower, lights & microwave in the van so not using too much gas as he says it is well expensive now.
Westi
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