"Pam Moore" wrote in message
...
On Thu, 9 Jun 2005 13:41:55 -0400, "Harold Walker"
wrote:

Is the pit style greenhouse in use in England?.........H

Do you mean that you dig a pit, plant in the bottom, then cover the
top with polythene?
I did that one year on my allotment, ages ago, haviing read it in a
book. It can't have been very successful, as I didn't do it again.
Trouble is, digging a pit on my allotment is difficult as there are
great slabs of limestone as little as a foot down in some places.
'twould depend on the water table too!


Pam in Bristol

If you have the patience to read I will give a fairly brief description of
the total "system".. a pit 8 feet X 12 feet and five feet deep.....at each
corner stacked up concrete blocks and filled with concrete...these were to
hold 2inch x 8inch pressure treated timber for the base of the
greenhouse....the blocks were connected with 2 x 6 wall plates and the
greenhouse built on top of that....the north wall was built out of 2 x 4's
and boarded in solid with insulation between the 2 x 4's(16 inch on
centre).the north wall was 4 feet above ground.......the northerly roof
section was about 4 feet with double glazed 8mm poly material(2x4's 16 inch
on centre)....from the peak the front of the greenhouse dropped down at an
angle favorable to the winter sun for maxim heat.....again the glazing was
double 8mm polycarbon....both ends constructed with same
mateerials....window openers on the north roof and at both ends were auto
operated....total height of the greenhouse from max height to floor was 9
feet.....at the rear side and inside the greenhouse made a 300 gallon tank
(not a waste of space as I grew potted seedlings there)..the 300 gallon tank
was my heat sink....at the top of the greenhouse was a four inch plastic
pipe with holes in it...one end of the pipe was lead into the water tank
which was then connected to a copper pipe in the tank...at the output end
was a fan....the fan pulled the upper air in the greenhouse down thru the
tank to warm up the water and from there back into the greenhouse.....at
night time the warmish air from the tank gave me a frost free greenhouse
even in the dead of winter....even when the outside temperature dropped down
to minus 17 degree C the greenhouse remained frost free.....the tank gained
its heat not only from the upper air but also from the earth as at a depth
of 5 feet the soil remains at a fairly constant temperature well above the
freeze level....in my particular case the water table was of no problem...at
the wettest of times it was about 15 feet below the surface level...when I
had a well drilled to cut down on the water bill they had to do down 20 feet
for a good supply.....hope this is understandable..........if I was to do
another one I would locate the water tank right down the middle of the
greenhouse with a board on top to walk on.......H