mojocain wrote:
I've built a lean-to greenhouse 1.80metre long, 1.0 metre wide, about
3 metre high. In the floor I want to put a heat sink using an old
polypropylene water butt (100 litre), one of those slim ones for
narrow spaces. It's split at the bottom a bit so is now useless for
water. Does anyone think, given the size of the greenhouse that it
will be worthwhile or not using this size butt? Plan to fill it with
broken glass. Been saving beer and wine bottles. There's no room for
a bigger container for the glass. Thanks.



100 litres of bottles isn't going to do much. Water has a much greater
thermal capacity than glass, especially glass and a lot of air. Could you
patch it up and fill it with water?

D