Heating greenhouse?

[Alison]

Redser, I may be wrong but the word "banned" appears under Brengirl's name so she may not be able to answer you.

Blimey, I missed that one, unusual for somebody who had been so much of a regular to get banned so must have been something quite bad!

[biggreenfingers]

A work colleague had trialled a sawdust heater in my previous job. I helped out with a view to building one for my greenhouse. It worked quite well but we couldn't get it entirely smoke free so didn't build one for home.

It was constructed using a small metal drum that was used to store cooking oil. The lid was removed and a hole about 2" in diameter was cut in the bottom of the drum. We had used a bit of pvc pipe as a template for the hole. The drum was then raised up on bricks, the pvc pipe placed in the hole so that it stood up vertically and sawdust was packed tightly into the drum around the pvc pipe until it was about an inch from the top of the top. At this point a layer of moist sand was placed on top of the sawdust and then the pvc pipe removed carefully. This left a "chimney" through the sawdust. The sawdust was ignited by placing a bit of newspaper at the bottom of the hole in the drum and lighting it. The one we had build smoked a fair bit at the start but then was smokless for most of the burning time and then started to smoke at the end of the burn as well. It could have been the fact that the sawdust may have not been entirely dry ??? One fill lasted about 4-6 hours approximately depending on the wind where it was being trialled. There are instructions somewhere on the net, will have a look later and see if I can find them.

Might try it again sometime in preparation again for winter.

[redser]

A work colleague had trialled a sawdust heater in my previous job. I helped out with a view to building one for my greenhouse. It worked quite well but we couldn't get it entirely smoke free so didn't build one for home.

It was constructed using a small metal drum that was used to store cooking oil. The lid was removed and a hole about 2" in diameter was cut in the bottom of the drum. We had used a bit of pvc pipe as a template for the hole. The drum was then raised up on bricks, the pvc pipe placed in the hole so that it stood up vertically and sawdust was packed tightly into the drum around the pvc pipe until it was about an inch from the top of the top. At this point a layer of moist sand was placed on top of the sawdust and then the pvc pipe removed carefully. This left a "chimney" through the sawdust. The sawdust was ignited by placing a bit of newspaper at the bottom of the hole in the drum and lighting it. The one we had build smoked a fair bit at the start but then was smokless for most of the burning time and then started to smoke at the end of the burn as well. It could have been the fact that the sawdust may have not been entirely dry ??? One fill lasted about 4-6 hours approximately depending on the wind where it was being trialled. There are instructions somewhere on the net, will have a look later and see if I can find them.

Might try it again sometime in preparation again for winter.

Thanks, sounds very interesting. Been doing some research and there's lots of great ideas out there, like penny stoves and hobo stoves. I have a small rigid plastic coldframe (looks like a mini-greenhouse with a pitched roof, 1 square meter in size). Dug it out this evening and put it together in the back garden. Put two tin cans inside, each one sitting slightly above a tealight. Temp outside is about 2 degrees and inside the coldframe is about 11 degrees! Chuffed. The tealights are only 4 hour burners but the local 2 euro shop sell bags of 50 8 hours burners for 6 euro. I reckon that would be enough for a month. Probably won't get much use of it this year but for next year it could be a winner. Hope to develop it and put an end to the indoor/outldoor shuffle agony