London (change)
8 messages
21/09/2013 at 16:58

We have made provision in our new greenhouse to accommodate a heat sink - but so far have been unable to find a source of glass cullet in Scotland.  Has anyone out there been luckier than us?  Would be grateful for any info.  Thanks

21/09/2013 at 18:26

Hi Sue, what is glass cullet and how does the heat sink work?

21/09/2013 at 21:44

Hi Sue, my OH used to work for Pilkingtons Glass, I've just asked him about it and he said that all glass cullet is is broken glass, so find some glass - bottles, greenhouse panes and break them up.  It's basically just waste glass.

21/09/2013 at 22:22

Water has one of the highest specific heat capacities (the ability to absorb, store and release heat energy) and is higher than glass so perhaps using glass containers filled with water would be the most efficient.  I use 2l plastic pop bottles filled with weak comfrey solution as the brown colour helps to trap the sun's energy.  It also means I always have plant food handy within the greenhouse, too.   If anyone is interested in this (which is something the Victorians used to do I believe), there is information in the link below (even if they do seem to be calling it a 'new' idea!)


22/09/2013 at 02:26

read that, Bob. now. I really fancy a go at a 'hot bed', but am having difficulty in my small garden in having enough materials at one go to build a big enough 'hot' compost heap, even tho I rush to collect all of my neighbours' 'leavings' when they are gardening. It shrinks to nothing before I can add more. Would a hot bed in the gh help to keep out the frost?

22/09/2013 at 07:15

Glass cullett is the ground down glass that goes for recycling.

Dick Strawbridge used glass cullett when making a heat sink for a greenhouse on his tv programme.  Most of the info about the heat sink is here, except for stuff about the glass cullett or anything else that could be used to hold the heat.


There is stuff on the internet about using bottles of water to hold the heat.


23/09/2013 at 10:27

Thanks for replies, folks ... food for thought there!

23/09/2013 at 23:25

Lots of food for thought! Now GH empty for cleaning and repair, can I take time from other jobs for tis, I wonder?

Thanks, Sue, for the idea in the first place, and everyone else for the replies!

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