Is anyone using this method? Sounds intriguing. Knowing the length of the
trench to be effective would be helpful. And what about ducting the hot air
from the greenhouse down through the trench? I can see this method working
on a small hobby greenhouse.


"Ray B" wrote in message
news:6ajZi.1890$cD.932@trndny08...
About the least expensive heating method (it's good for cooling, too) I've
ever heard of was published in the AOS Bulletin in the late '70's or
'80's.

A guy had an extended trench dug 6' into the ground (or some depth
well-below his frost line), and made a long duct of large, unglazed clay
sewer pipe. One end came up through the floor of the greenhouse, and the
other end was enclosed in a structure above ground. The inlet end was
covered with a mesh and filter to prevent all but air from entering.

A thermostatically-controlled fan in the GH drew air through the submerged
pipe, where the natural subsurface temperature was in the low-'60's F year
round, which is certainly plenty warm for nighttime, with solar heating
boosting the daytime temp. In the summer, he would switch to a cooling
thermostat, drawing that same cool air. That's certainly less maintenance
than a swamp cooler!

The article also discussed how the unglazed clay absorbed the condensed
humidity in the summer, and moistened the air in the winter, but I don't
recall details.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"alpickrel" wrote in message
oups.com...
You were smart.

My old hoophouse frame is still standing right next to the
greenhouse. It is 15 x 30 (or so). Just the metal frame right now.
It has grapes growing on it. I have had the idea in the back of my
head to cover it with insualtion and black plastic water circulating
tubes and turn it into a giant solar hot water collector/storage unit
of some kind that I can then use at night to pump the heat into the
greenhouse next to it. The heat sink can't be IN the greenhouse
because to be of any real use, whatever goes in there...a pool or
whatever..., it has to be able to get hot enough to be of use long
after the sun gets off it, so plants won't be able to be grown in
there with it. (now I get K Barrett's joke about lying to herself
about her barrel of water.)

I was staring at my electrical subpanel for the greenhouse this
afternoon and wondering what it would take to run a line large enough
to power an electric heater that would make me feel like I was not
lying to myself when I plugged it in.

I still think a good option is to find a way to drag a big warm
blanket over the greenhouse every night.

I also wondered when somebody with the know how will get the bright
idea of turning clear 6 mil greenhouse plastic film into a giant solar
electric collector sheet. I mean I spend all summer trying to REMOVE
light and heat. It would be nice to be doing something useful with
it. There is talk of a spray-on solar panel.

On Nov 9, 8:05 pm, "Pat Brennan" wrote:
When I put up my last greenhouse I needed a new power service. I had
the
power company run an extra 200 amps of service and used it for my backup
heating system. The thought that oil now costs the same as that backup
system is as you said scary stuff.

This greenhouse is one third the size of my others. As we started to
get
into heating season I was able to empty it and turn it off. As oil
continues to rise I am wondering if between the store (which closes at
the
end of the month) and the little greenhouse if I can close a big
greenhouse.
And if I do not need the greenhouse, I am also wondering how I turn it
into
a solar collector. I think I need to do some reading on heat pump and
transfer systems and swimming pools.

Pat