"David Hill" wrote in message
...
I have this idea to draw the heat from the top of my Large poly tunnel
and
to duct it through a channel of concrete blocks and gravel to form a
heat
sink.
The problem is I am wondering if I can get some form of thermostat that
will
switch ON when the Temp rises and OFF when it falls.
My local Electrical wholesaler doesn't know of anything to do the job.
Any ideas?

I can only say your electrical wholesaler is an idiot, there are any
number of manufacturers who make thermostats that can turn on or off on
temp rise or fall or even with a two way or two pole switch do both.
Honeywell would spring to mind but there are many others.
--

Chris Thomas
West Cork
Ireland