Following my posting re reverse thermostat, I have been wondering just what
ideas the collective brains on this group could come up with for
Greenhouse/poly tunnel heating.
We get a lot of questions re Gas , electric or paraffin heating, but surely
we can come up with something free/cheep and useable.

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50 then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from the
top of the house in the day and heating the tanks.........


--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"David Hill" wrote in message
...

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50
then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from
the
top of the house in the day and heating the tanks.........

It's called solar heating with heat storage. Or if not using heat from the
sun heat pump systems can take it from the environment directly.

--

Chris Thomas
West Cork
Ireland

"David Hill" wrote in message
...

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50
then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from
the
top of the house in the day and heating the tanks.........

It's called solar heating with heat storage. Or if not using heat from the
sun heat pump systems can take it from the environment directly.

--

Chris Thomas
West Cork
Ireland

"David Hill" wrote in message
...
Following my posting re reverse thermostat, I have been wondering just
what
ideas the collective brains on this group could come up with for
Greenhouse/poly tunnel heating.
We get a lot of questions re Gas , electric or paraffin heating, but
surely
we can come up with something free/cheep and useable.

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50
then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from
the
top of the house in the day and heating the tanks.........

I see no thermodynamic advantage in that, compared with any massive black
material in the tunnel to absorb heat during the day and release it during
the night. But you are likely to find that the amount of heat you can trap
in this way is nowhere near enough to keep your greenhouse warm over night.
Let's face it, winter is winter because there is not much heat sculling
around.

Franz




--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"Cerumen" wrote in message
...

"David Hill" wrote in message
...

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50
then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from
the
top of the house in the day and heating the tanks.........

It's called solar heating with heat storage. Or if not using heat from the
sun heat pump systems can take it from the environment directly.

But unfortunately the price of a heat pump is so high that the money spent
in amortising it might as well be spent buying electricity ot paraffin.

Franz

On Mon, 8 Mar 2004 22:58:07 -0000, David Hill wrote:

Following my posting re reverse thermostat, I have been wondering just what
ideas the collective brains on this group could come up with for
Greenhouse/poly tunnel heating.
We get a lot of questions re Gas , electric or paraffin heating, but surely
we can come up with something free/cheep and useable.

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50 then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from the
top of the house in the day and heating the tanks.........

I saw a report on Austrian telly a while ago about a chap who uses flexible
rubber/polythene pipes of water to heat the soil under his cold-frames
during the winter. The water was heated by the sun in a normal
central-heating radiator painted black and the water pumped round slowly by
a small, cheap solar-powered pump. He didn't heat the cold frames directly,
just the earth underneath, and this acted as enopugh of a heat sink to
allow him to grow many vegetables in the winter when the ground is normally
frozen solid for months.
Extrapolate that to the milder British winters and it might keep a green
house warm enough. You might be surprised how much heat you can collect
even in the winter.

--
Tim.

If the human brain were simple enough that we could understand it, we would
be so simple that we couldn't.

The message
from "Franz Heymann" contains these words:

It's called solar heating with heat storage. Or if not using heat from the
sun heat pump systems can take it from the environment directly.

But unfortunately the price of a heat pump is so high that the money spent
in amortising it might as well be spent buying electricity ot paraffin.

You can make a heat pump for no cost at all, or very little - assuming
you can find someone with an old freezer they don't want.

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/

The message
from "Franz Heymann" contains these words:

It's called solar heating with heat storage. Or if not using heat from the
sun heat pump systems can take it from the environment directly.

But unfortunately the price of a heat pump is so high that the money spent
in amortising it might as well be spent buying electricity ot paraffin.

You can make a heat pump for no cost at all, or very little - assuming
you can find someone with an old freezer they don't want.

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

In message , Franz Heymann
writes

"David Hill" wrote in message
...
Following my posting re reverse thermostat, I have been wondering just
what
ideas the collective brains on this group could come up with for
Greenhouse/poly tunnel heating.
We get a lot of questions re Gas , electric or paraffin heating, but
surely
we can come up with something free/cheep and useable.

Such things are generally mutually exclusive. The closest is wind power
where you can buy reasonable 500W wind turbines for around £600. Or make
them from old alternators and scrap for somewhat less.

Your next best bet is a water wheel - provide you have a stream in the
garden.

I seem to remember talk of having bottles of water with washing soda in
solution in them, the idea being that when the temp dropped to below 50
then
the soda would crystallize giving off heat, and when the water was over
about 60 then the soda would absorb heat as it went back into solution.
Now have this in tanks with some sort of heat exchanger taking heat from
the
top of the house in the day and heating the tanks.........

I see no thermodynamic advantage in that, compared with any massive black
material in the tunnel to absorb heat during the day and release it during
the night. But you are likely to find that the amount of heat you can trap

There is some advantage in that the latent heat of crystallisation is
moderately large so the stuff manages to store more heat than plain
water can. And in theory it provides some weak thermostat action - the
bad news is that it can supercool and then bounce. And sometimes the
containers rupture due to volume change on crystallisation.

in this way is nowhere near enough to keep your greenhouse warm over night.
Let's face it, winter is winter because there is not much heat sculling
around.

At UK latitudes that is true, with short days and very low sun but at
latitude 45 or lower there is still real power available in the winter
sun.

Regards,
--
Martin Brown