greenhouse heating

[oldjerry]

Most of us wouldn't probably bother heating the whole GH(maybe hotbed,or propagator only) due to cost,carbon footprint etc..But when I was an innocent,impressionable young man,it was common to have water pipes and a solid fuel stove either inside the GH,against the outside wall,or in an adjacent potting shed.

There's loads you can do with a heated GH,that we don't seem to bother with much these days,raising bedding(lucrative at boot sales etc) forcing seakale,rhubarb,mushrooms,etc....but not worth the fuel today...but....

Well S\H woodburners are cheap,some come with backboilers,they're also pretty easy to make (once made one from asmall digger bucket with a flat hinged piece of steel welded n the back)You'd have to load it last thing at night,But the new garden I'm planning will have the whole potting shed\heated GH set up as it's centrepiece(not least as there will be a nice warm retreat which only I will have a key to.)

Not much good to any of you in warmer climes (sigh),but for you guys in the frozen North, Any thoughts? suggestions? have I lost the plot while still designing it?

[Green Aura]

Nothing so elaborate OJ but we have a heat sink in our polytunnel.

It's a big polystyrene box filled with gravel and buried to its full height. Heat from the top of the tunnel is fed down to the gravel by a solar-powered fan.

All a bit Heath Robinson but last winter, despite the horrendous weather, it never got below freezing in what is essentially a large plastic bag

[Odsox]

I too remember my grandfather's greenhouse with a solid fuel fire set into the end wall next to the door, feeding 2 huge 6" pipes that ran around the walls inside on a gravity system. Not actually HIS greenhouse I have to admit, he was head gardener at a Victorian type estate.
What I intended to do this autumn, but didn't find the time, was to set up my wind turbine to heat water to warm my greenhouse and potting shed cum propagating room. As it happens it would probably have worked very well considering all the wind we've had just about every day for the last couple of months.
It would be easy to do, wind turbine feeds a DC immersion heater in a hot water cylinder, connected to gravity fed radiators ... no electronics needed and I have all the bits.
Maybe next autumn.

[oldjerry]

Maggie,shows what a dinosaur I am,cos I've never heard of this set up,but it seems so simple you'd have thought all tunnels would have one.

Tony,how large a turbine d'ya need to power this system,and how warm would you get a 16' by 6' GH?

[Odsox]

Tony,how large a turbine d'ya need to power this system,and how warm would you get a 16' by 6' GH?

That's part of the problem OJ, how long is a piece of string ?
My turbine is rated at a kilowatt, but that is maximum output at gale force winds.
At sensible of wind speeds of say 8 m/s it would generate about 500 watts, so comparable with a 500 watt electric fire in your greenhouse I suppose ... but only when the wind blows, no good on a calm frosty night.

[oldjerry]

Hmm,bearing in mind I got thrown out of Physics at 13 for getting 12% in an exam( I was copying off the wrong kid),could you not devise something of an amalgamation between yours and Maggie's set up, ie generate heat to a heat sink that would function on a still frosty night?

[boboff]

Heating any poorly insulated space in this day and age has got to be wrong.

Window sills and covering with newspaper on frosty nights seems the way to go.

Use your time on a lean too conservatory that would double up as a plant area? at least you would get the "shed" idea, but the solar gain would heat the house as a heat sump and give it back at night to the conservatory and the house? If you had your log burner on the other wall in the house, then at least you would be burning wood you could use to cook on, dry washing over etc????

The heat sink idea is a good one though, apparently glass wine bottles filled with water and stacked are good, as they hold and give heat freely due to uniform gaps!

[Odsox]

Yes, of course you could. Probably best bet would be to lag the hot water cylinder and bury copper pipes in the beds. Once you have warmed the soil it would stay warm for extended periods, but you would maybe need a thermostatic valve to stop cooking the roots of your plants.
Also if you're serious about it and bought some deep cycle batteries, you could have electric soil warming cables that would work over calm periods (provided you have enough battery capacity).
There are many ways if you have the time to play.

I don't see why heating a poorly insulated green house is wrong Boboff if you do it with wind power, it would cost me nothing and if I didn't use the wind and thereby slow it down a fraction, it would be that much windier when it got to Cornwall.

[boboff]

Well wrong is not really quite what I meant, it's just that to spend effort and energy digging out a sump, rigging it all up etc etc, would it not be better to share that with a domestic arrangement?

To me it seems odd to spend money on heating "greenly" green houses when you then put your own central heating on??

Oh I don't know, do what you like, it's got nothing to do with me, I am just thinking about that I would like to do something like this, but then I think I should spend the money/effort on reducing home bills first, thats all.

Oh and the thought of Jerry with his dodgey legs walking up an icey path at 10pm to fill the logs up, after a glass of Nettle Beer?

[grahamhobbs]

A couple of thoughts, if you just want to keep the tunnel from freezing another alternative is to share it with animals or poultry. But if you want real heat, the disadvantage of just a wood burning stove is that it losses heat quickly if not regularly attended to. What you need is a large thermal mass, like green Aura's, but you can make what is often referred to these days as a masonry rocket stove but similar to ceramic stoves, popular in places like Switzerland. These can be built of bricks or clay, basically a fire but the gasses then passes through passages in the clay structure before exiting out the chimney, bit like the Romans did. The 'rocket' bit is because the idea is that the fire burns intensively and therefore only needs to be once a day as the heat is then absorbed by the masonry and released slowly. You could build a hot bed on top of the masonry.
We have a very crude version of this on our allotment for brewing tea, basically the 'rocket' bit, not the thermal mass. It's really just a pile of bricks but it means we can boil tea quicker than with a gas canister and it costs us nothing.

[oldjerry]

Boboff,I'll have you know that only 1 leg is dodgy the other is strangely attractive(in a manly sort of way ),in fact I'm thinking of going into modelling with it,now the Tarzan role is out.

Graham,that sounds good(or it did till you mentioned the Sw. word) any links,piccies forsomeone of poor magination?

Besides your'e all missing the vital point.... comfy WARM shed AWAY from house,yale lock,1 key,bottle of Talisker..............

[Odsox]

Besides your'e all missing the vital point.... comfy WARM shed AWAY from house,yale lock,1 key,bottle of Talisker..............

Ah now, I DO have one of those.
I have an old caravan that had started to leak, so I built a shed around it.
Now I have a double insulated, double glazed shed with all mod cons (including flush loo) running water,cooker and kettle, with a yale lock (as it's full of amateur radio gear), but strangely no plants .. not even a tomato plant.
Oh, and the bottle would be Remy Martin but I wouldn't dare take it out there.

[boboff]

Would it not be cheaper just to walk to the Pub?

Liking the modelling idea! I hear the Chimps dead as well, Maybe I could get a part!

" You have one leg too few"

[The Riff-Raff Element]

Would it not be cheaper just to walk to the Pub?

Not when my nearest actual pub is in Portsmouth, about 300 miles from here. And the bar / café in the village is a bit pants. I like the shed idea very much.

[Big Al]

I'm going to have a wood fired oven built in the garden around March as an alternative cooking source. My design for this will include pipes in the build that will fill an indirect copper boiler in the garage [ the greenhouse is against the end wall of the garage] The pipes will Run through the greenhouse and probably through a small radiator for cold times. During the summer months I will need to bypass the greenhouse in order to use the WFO so there will be a couple of Rads in the garage to act as a heat sink / remover.

You are certainly not mad or away with the fairies, well not this time as old heaters are all used up here in the dark North East and they are also fuelled still with seacoal if you go around the allotments.

If you have made one out of the bucket before why not have a go at a gas bottle heater. For the water side of it you can wrap 8 mm copper pipe around the gas bottle as a sort of heat exchanger idea. You can then cover the heating coil with fibre glass loft insulation to retain some heat. You will need to make sure it is an open system and not sealed cue to pressure and all that.

HTH

BA