Hi Keith
I heat my greenhouse to 60F. Gas 10000 btu (came with the greenhouse)
right now but I'll be switching to hot water later as the greenhouse
needs 15000 btu at 0F maybe less when I get the aluminum frame
insulated. The original design had the greenhouse sitting on the ground
but I have too many critters for that (possums, raccoons, squirrels,
rats and cats) not to mention the kids next door with their soccer
ball.. So I built a lower wall 3 feet high of 2 X 6's and filled the
empty space between with foam insulation. On top I put an aluminum sheet
with an overhang so critters cant get a grip. The outside I covered with
plywood siding and the inside with James Hardie cement fiber siding
painted, no worries about rot with this stuff.
Filled to the rafters? thanks for the warning but it's a bit late as
it's already a jungle in there.

Grow well and bloom magnificently
dusty

"Keith Kent" wrote in
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"Dusty" wrote in message
. 17.102...
"jtill" wrote in news:1171828780.521208.66700
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Mcmaster.com.

Thanks a lot. I'm going to try that if the weather ever warms up
again.



Grow well and bloom magnificently

Hi Dusty, i think no matter how well insulated a greenhouse is
,unheated you will always get a touch of frost inside.Especially when
there are long periods of cold weather ,the same would apply to any
dwelling if left unheated.All you can do is reduce the heatloss so the
extremes are not so great so you can maintain the min temp you
require.In my ali greenhouse i used 6ft by 3ft by 1 inch thick
polystyrene insulation panels for the lower half to just above bench
height,the rest of the glass is insulated with greenhouse bubble wrap
which is thicker than the normal stuff and the air bubbles are bigger
giving better insulation.You can get fixings for doing this for a ali
greenhouse.I can keep the min temp i require which is around 60f
,without this it was impossible and costly.(it is still costly
however)!Also on the outside lower 4ft i used wooden fence panels to
clad ,mainly to protect damage from the glass.I would advise anyone IF
growing orchids not to use a aluminium greenhouse,mine will soon be
used for general use not orchids.But growing orchids is a progression
which does grab you and from talking to other orchid growers no matter
what size/type of greenhouse they have are not fully happy and will
soon fill to the rafters! Thanks Keith