Central heating in green house.

Why do you want to heat the greenhouse?

Thats a good question, the first thing i want to heat would be me Then I was just thinking in terms of keeping it just above freezing to protect all the cuttings and non hardy plants i will be bringing in such as fuschias. Also i have a lot of potatoes intended for Christmas/ new year.

In Torquay I don't think you would need to worry too much about frost Bill.

I would think a paraffin or bottled gas heater would be enough. How close to the house is your greenhouse?

I didnt think about extending the central heating, but the boiler flue releases boiling hot vapour and I was thinking about how wasteful that is. If you could direct a pipe it to the greenhouse and leave an exposed part of the pipe inside the GH you could provide heat in there. Then have it exist the greenhouse to release the vapour.
Of course I'm nowhere near competent enough to pull it off but it was the only useful 'free' waste product I could think of utilising for the greenhouse.

Its pretty close, 3 metres or so, we do have a conservatory which i have my eye on, it already has a radiator in it and would be ideal but my wife has insisted we using it for living in!! Is'nt growing plants the epitome of living?

As for frost, I am sure most gardeners would cut off their right arm to have my micro climate, last winter, no snow and my fish pond had one day when I noticed a hint of ice on it. Having said that i felt cold from last November through to April of this year (old age creeping on).

I was really asking about using the central heating out of interest, I dont fancy digging up my patio just to keep a few fuschias warm. But where people do heat their greenhouses I would think gas central heating could be cheaper than electric.

Yes i look at my gas boiler exhaust sometimes and think what a waste, but that stuff is highly toxic carbon monoxide and would kill everything. It would need to be an indirect heat source, maybe heating a large water butt and then cirulating that water through the green house.

That's true. I did a bit of research and commercially hot water or steam is sometimes used and the pipes just warm the air around them through convection. You would want to have the whole thing sealed tight as a drum with those fumes alright but I'd say there's someone out there who'll pop up on youtube some day having done it
I think the central heating idea is great for you, being so close to the greenhouse. SHouldn'd be difficult for a plumber to install a small secondhand rad. Couldn't they run the pipes out above ground along the bottom of a wall with appropriate insulation?

As it's so near to the house, I'd be tempted to run an electricity cable into the greenhouse and then have a thermostatic radiator in there instead of your central heating..
Obviously you'd need it to be professionally installed with armoured cabling etc!
That way it'd come on when the temperature drops to whatever you consider is the lowest you'd be happy with.
We did exactly that for our bunnies which lived in our summerhouse over winter...(with our overwintering plants).
During the day we opened the doors to allow ventilation so we didn't encourage fungal spores on the plants.

Extending your central heating wouldn't be that difficult as you just need to add a radiator or two to the chain of pipes, keep your heating going all night on the cold nights in winter, and take out the mortgage extension to pay the bill! It depends entirely on what sort of greenhouse you have, as most are very leaky of heat and have gaps between the glass panes and the bars or wood. If you really want to heat a greenhouse all winter it is a far better approach to build a lean-to extension on the house wall, which is south facing, if it gets winter sun. Not everyone can do that of course. Polycarbonate is also much warmer than glass and easier to fit more snugly.
I wouldn't heat with paraffin any more as the stuff is more expensive than just about any other fuel, certainly here it is, and you have so much maintenance to do with refuelling, cleaning wicks and so on. Often they give off fumes which are damaging to plants. The easiest way to heat is to have a small electric fan heater with a thermostat that can be set to avoid frost, which will serve most small greenhouses, but you need to line the greenhouse with bubble wrap to avoid losing too much heat even with that.

Bertie beat me to it but I was going to suggest bubblewrapping the greenhouse and putting Tea-Lights under terracotta pots on a night.

Bertie good sound common sense.

I suffer from the cold too. Last winter I got one of these, it's brilliant. I just want them to bring out a cordless version, but if I attach it to the extension cable I can wear it in the gh

Hate to say this but lots and lots of tosh being bandied about with reference to the use of boiler flues, flue gasses being poisonous, central heating etc.

(1) As a Gas Safe registered engineer if I came and found you had disturbed the flue pipe/termination in anyway I would be asking to shut down your boiler. If you refused I would telephone the National Gas Emergency service who would on my say so disconnect the gas supply to your home. So forget messing with flues it is extremely dangerous and can lead to the production of large amounts of CO. Apart from anything else on a modern high efficiency boiler there is very little heat left in the flue gas.

(2) Central heating is my business and there are several things to think about if you consider putting a radiator in your GH. First is expense of installation to insure the pipework does not freeze you would need 25mm wall thickness top grade insulation at approx £5 per mtr it is more expensive than the pipe that goes in it. Then due to the massive heat loss in a GH you would need a fair sized radiator. Next is running costs to insure the radiator does not freeze and burst you would have to install a frost stat in the GH and wire it back to your boiler controls. As the outdoor temperature drops the frost stat would automatically produce a demand and fire the boiler any time of night or day. It may just be fiesable if you win tonight's triple roll over.

I have all to tools and skills to hand and I heat my GH with a 2Kw thermostatically controlled electric wall heater. As the advantage of being removable for extra space in the summer too.

Potty

Thanks Pots - I was working out how to say 'don't be so flippin daft' without ending up in a PM fight.

And on that note I'm going to close this thread.