There was such a hard frost last night that the frost-stat on the ch boiler
came on for a short time. There was thick ice on all the open water in the
garden and all roofs were white.

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

Mary

Mary Fisher wrote:
There was such a hard frost last night that the frost-stat on the ch boiler
came on for a short time. There was thick ice on all the open water in the
garden and all roofs were white.

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

What sort of panels?
I'm contemplating doing something with the old radiators, bus windows,
and polystyrene sheet that I've got lying around.
Currently I'm wondering how hot you could get with silly (say 5 panes)
amounts of glazing, with a system to suck air through the panes.
So that light absorbed in the panes is not lost.

Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

"Ian Stirling" wrote in message
...

What sort of panels?

A commercial product but self-installed.

Mary

Mary Fisher wrote:
"Ian Stirling" wrote in message
...

What sort of panels?

A commercial product but self-installed.

Mary

elaborate :-)

Ian Stirling wrote:
Mary Fisher wrote:
There was such a hard frost last night that the frost-stat on the ch boiler
came on for a short time. There was thick ice on all the open water in the
garden and all roofs were white.

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

What sort of panels?
I'm contemplating doing something with the old radiators, bus windows,
and polystyrene sheet that I've got lying around.
Currently I'm wondering how hot you could get with silly (say 5 panes)
amounts of glazing, with a system to suck air through the panes.
So that light absorbed in the panes is not lost.

Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

Hmm sounds overkill to me. A one metre square panel that I made myself
works well enough to give 200 litres plus of water at 80C from around
five hours in the sun. Traditional construction of a single panel steel
radiator with an aluminium frame, polyurethane insulation, single glazed
in 4mm glass.

Did anyone see the Dick Strawbridge thing? His solar panel design was
utter pants, a double panel radiator using corrugated PVC glazing.

On Mon, 10 Apr 2006 17:50:54 +0100 someone who may be "Mary Fisher"
wrote this:-

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Excellent. Now the days are longer you should get a fair amount of
hot water.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

Perhaps you should sell hot water to the neighbours in the summer:-)


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
news
On Mon, 10 Apr 2006 17:50:54 +0100 someone who may be "Mary Fisher"
wrote this:-

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Excellent. Now the days are longer you should get a fair amount of
hot water.

More than we use, I suspect.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

Perhaps you should sell hot water to the neighbours in the summer:-)

Can't be bothered!

They can jolly well get their own systems!!

Mary

Steve Firth wrote:
Ian Stirling wrote:
snip
Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

Hmm sounds overkill to me. A one metre square panel that I made myself
works well enough to give 200 litres plus of water at 80C from around
five hours in the sun. Traditional construction of a single panel steel
radiator with an aluminium frame, polyurethane insulation, single glazed
in 4mm glass.

That does seem rather unlikely, unless you're starting from something
quite warm.

5 hours * 1.3Kw/m^2 (sunlight falling on top of atmosphere) = 23.4MJ

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.
23.4/0.88 = 26.6K temperature rise.

I'd be astonished if you got a real 20C rise out of it.

Your numbers do however work out perfectly for a panel of reasonable
construction on mercury

"Mary Fisher" wrote


A commercial product but self-installed.

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to self
installing the rest next year.

So as we are trying to find out about other peoples experiences a few
questions please.

What brand/type/supplier/cost please? Did you buy a complete kit or did you
self source mix and match? And did you find it easy to fit?

TIA

Jake

HI Jake

On Mon, 10 Apr 2006 22:47:39 +0100, "Jake"
wrote:


"Mary Fisher" wrote


A commercial product but self-installed.

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to self
installing the rest next year.

That's what we did when we moved here 5 years ago.


So as we are trying to find out about other peoples experiences a few
questions please.

What brand/type/supplier/cost please? Did you buy a complete kit or did you
self source mix and match? And did you find it easy to fit?

My local installer sold me a complete kit (less the copper pipe !) -
which came with a pretty comprehensive diagram, and the offer of
'hand-holding' if necessary.

It consists of an array of Thermomax evacuated collectors and their
header assembly (got the installer to fit that lot on the roof for me
and provide pipe stubs through into the loft space). He also supplied
the controller and all the necessary brasswork, pump etc.

After I'd done the necessary plumbing and wiring for the controller -
he came back and commissioned the system for me - took about an hour.
Been running fine ever since - with the occasional slight topping-up
of the circulating water.

Don't really know how much money I saved by doing the plumbing myself
- but ISTR that the total kit cost just over £2k. Plumbing wasn't
particularly complicated, and the (3) sensors for the controller
fitted into metal sleeves (supplied) and the wiring was pre-terminated
with plugs - so that was easy.

In terms of performance, I've never formally recorded it - but I know
that from about May to September we're not needing much input from the
immersion heater to get the DHW up to temperature. Becomes more
complicated to assess in winter because the woodburing stove gives
priority to the DHW .....

I'd say go for it !
Have tried a complete 'home-brew' system in the past - old radiators,
glazed collector etc - but the Thermomax-type tubes are reckoned to
capture more heat for a given illumination....

Hope this helps
Adrian
Suffolk UK
fwiw there's a picture of the collector at
http://www.inspired-glass.co.uk/bungalow.htm
- 4th photo down....

======return email munged=================
take out the papers and the trash to reply

On Mon, 10 Apr 2006 22:47:39 +0100 someone who may be "Jake"
wrote this:-

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to self
installing the rest next year.

Mary used a Solartwin panel, for which you wouldn't need a new
cylinder, though the existing one must have proper insulation. For
DIY this has the advantage of minimum installation time and effort.

For a more involved DIY project Navitron are one source of useful
bits.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

Ian Stirling wrote:
Mary Fisher wrote:

There was such a hard frost last night that the frost-stat on the ch boiler
came on for a short time. There was thick ice on all the open water in the
garden and all roofs were white.

But it's been sunny today (although cold) and I did three machine loads of
washing and we still have a cylinder full of water at just short of 60C.

Scoffers can scoff away but we're very happy -it's just a foretaste of
what's to come :-)

that it works was established long ago.


What sort of panels?
I'm contemplating doing something with the old radiators, bus windows,
and polystyrene sheet that I've got lying around.

Rads are limited by their high water capacity, making for slow
response. So solar pv as a control mechanism is out with these.
Concentration improves this a lot, and is easy to do with all metal
radiators, eg with greased silvered mylar film. Even ali foil works for
a while. Concentration improves heat availability in poor weather,
financial efficiency or ROI, and system reliability (less plumbing
failure points).

Greeenhouse poly could be used under the glass to provide cheap double
glazing. Glass absorbs uv which helps the poly last longer, plus it
protects it from mechanical stresses. How long its life would extend
like that I dont know, but its easy to replace if your panels are
ground or wall mounted rather than roof.


Currently I'm wondering how hot you could get with silly (say 5 panes)
amounts of glazing, with a system to suck air through the panes.
So that light absorbed in the panes is not lost.

I think you'll find its counterproductive. ISTR double glazing gaving
the best temp rise for one scenario I calculated. But the real point is
output per pound in, not per square metre, or in your case per material
use.

If you have a lot of glass, how about a hot air collector with one
sheet of glass and one poly?


Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

I still cant see what you mean there


NT

"Jake" wrote in message
...

"Mary Fisher" wrote


A commercial product but self-installed.

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to
self installing the rest next year.

So as we are trying to find out about other peoples experiences a few
questions please.

What brand/type/supplier/cost please? Did you buy a complete kit or did
you self source mix and match? And did you find it easy to fit?

We're in UK.

www.solartwin.com All information is there.

It's just for domestic hot water - not house heating.

We bought the kit, including a pv panel which powers the pump and all the
silicone piping necessary.

It was easy to fit, I can send pictures. If the company had done it it would
have been quicker for a straightforward connection to an existing tank but
we didn't have one so it was more complicated. And Spouse hates having
anyone doing things in the house :-)

The company was friendly, professional and helpful from start to finish,
even when we were just thinking about it for six months. The paperwork they
provided was excellent.

It's the way to go, I think the capital costs will reduce too but I wish
we'd done it years ago when we'd have had more time to enjoy the benefits.

Mary

Ian Stirling wrote:
Steve Firth wrote:
Ian Stirling wrote:
snip

Hmm sounds overkill to me. A one metre square panel that I made myself
works well enough to give 200 litres plus of water at 80C from around
five hours in the sun. Traditional construction of a single panel steel
radiator with an aluminium frame, polyurethane insulation, single glazed
in 4mm glass.

That does seem rather unlikely, unless you're starting from something
quite warm.

5 hours * 1.3Kw/m^2 (sunlight falling on top of atmosphere) = 23.4MJ

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.
23.4/0.88 = 26.6K temperature rise.

I'd be astonished if you got a real 20C rise out of it.

Your numbers do however work out perfectly for a panel of reasonable
construction on mercury

it does seem optimistic, I wonder if Steve meant the panel was only
1m^2 but had a large external concentrator of some sort?


NT

Ian Stirling wrote:
Steve Firth wrote:
Ian Stirling wrote:
snip
Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.
Hmm sounds overkill to me. A one metre square panel that I made myself
works well enough to give 200 litres plus of water at 80C from around
five hours in the sun. Traditional construction of a single panel steel
radiator with an aluminium frame, polyurethane insulation, single glazed
in 4mm glass.

That does seem rather unlikely, unless you're starting from something
quite warm.

5 hours * 1.3Kw/m^2 (sunlight falling on top of atmosphere) = 23.4MJ

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.
23.4/0.88 = 26.6K temperature rise.

I'd be astonished if you got a real 20C rise out of it.

Your numbers do however work out perfectly for a panel of reasonable
construction on mercury

Gee thanks. I'd suggest that the water in the cylinder is stratified.
Your figure of 23.4 MJ on the atmosphere is higher than the actual
insolation with is about 24MJ/8H according to the local Uni.

I estimate that we should get about 95 litres of water at 80C from this
over the day, as I say in practice after 5h water delivered is at 80C.

I presume it's possible that the cylinder remains hot over night, it's
difficult to eyeball a cylinder and know how much heat is in it.

Steve Firth wrote:
Ian Stirling wrote:
Steve Firth wrote:
Ian Stirling wrote:
snip
Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.
Hmm sounds overkill to me. A one metre square panel that I made myself
works well enough to give 200 litres plus of water at 80C from around
five hours in the sun. Traditional construction of a single panel steel
radiator with an aluminium frame, polyurethane insulation, single glazed
in 4mm glass.

That does seem rather unlikely, unless you're starting from something
quite warm.

5 hours * 1.3Kw/m^2 (sunlight falling on top of atmosphere) = 23.4MJ

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.
23.4/0.88 = 26.6K temperature rise.

I'd be astonished if you got a real 20C rise out of it.

Your numbers do however work out perfectly for a panel of reasonable
construction on mercury

Gee thanks. I'd suggest that the water in the cylinder is stratified.
Your figure of 23.4 MJ on the atmosphere is higher than the actual
insolation with is about 24MJ/8H according to the local Uni.

snip

Yeah - I was mainly doing the numbers as they seemed surprisingly good,
and diddn't accord with what I remembered.


I presume it's possible that the cylinder remains hot over night, it's
difficult to eyeball a cylinder and know how much heat is in it.

But, if in practice it gives you enough hot water

wrote:
Ian Stirling wrote:
Mary Fisher wrote:

There was such a hard frost last night that the frost-stat on the ch boiler
came on for a short time. There was thick ice on all the open water in the
garden and all roofs were white.
snip
I'm contemplating doing something with the old radiators, bus windows,
and polystyrene sheet that I've got lying around.

Rads are limited by their high water capacity, making for slow
response. So solar pv as a control mechanism is out with these.

Control systems aren't a problem.
Concentration improves this a lot, and is easy to do with all metal
radiators, eg with greased silvered mylar film. Even ali foil works for
a while. Concentration improves heat availability in poor weather,
financial efficiency or ROI, and system reliability (less plumbing
failure points).

But of course, concentration works best with direct sun.

Greeenhouse poly could be used under the glass to provide cheap double
glazing. Glass absorbs uv which helps the poly last longer, plus it
protects it from mechanical stresses. How long its life would extend
like that I dont know, but its easy to replace if your panels are
ground or wall mounted rather than roof.

Yeah - I'll have to do some sums/testing.

Currently I'm wondering how hot you could get with silly (say 5 panes)
amounts of glazing, with a system to suck air through the panes.
So that light absorbed in the panes is not lost.

I think you'll find its counterproductive. ISTR double glazing gaving
the best temp rise for one scenario I calculated. But the real point is
output per pound in, not per square metre, or in your case per material
use.

I was actually wondering about a scheme which was an air heater alone,
for that one.
You have a stack of n (where n is a large number of panes, which absorbs
say 80% of incoming light before it hits the bottom.
The air is drawn past these from the outside in, in a serpentine
fashion, so that the inner panels are hottest, and hopefully essentially
all IR radiation is trapped.
I wouldn't be surprised if 2-300C was possible.
But, it'd use a hell of a lot of glass, and probably take a long time to
start up, due to thermal inertia.


If you have a lot of glass, how about a hot air collector with one
sheet of glass and one poly?

Possibly - there is an obvious tradeoff (for non evacuated panels)
between power output, and maximum temperature.
Obviously, adding another layer of glazing will always increase the
maximum steady-state temperature, but due to absorbing some light, will
decrease the power output.
I suspect a 'low temperature' panel, and a high temperature one may be
worthwhile.
Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

I still cant see what you mean there

2m^2 panel, 1m^2 radiator and a fan.
Or 0.5m^2 radiator, ...

Helps with the thermal inertia thing as well as to some extent the cost.

"Adrian Brentnall" adrian-the papers and the wrote
in message ...
HI Jake

On Mon, 10 Apr 2006 22:47:39 +0100, "Jake"
wrote:


"Mary Fisher" wrote


A commercial product but self-installed.

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to
self
installing the rest next year.

That's what we did when we moved here 5 years ago.


So as we are trying to find out about other peoples experiences a few
questions please.

What brand/type/supplier/cost please? Did you buy a complete kit or did
you
self source mix and match? And did you find it easy to fit?

My local installer sold me a complete kit (less the copper pipe !) -
which came with a pretty comprehensive diagram, and the offer of
'hand-holding' if necessary.

It consists of an array of Thermomax evacuated collectors and their
header assembly (got the installer to fit that lot on the roof for me
and provide pipe stubs through into the loft space). He also supplied
the controller and all the necessary brasswork, pump etc.

After I'd done the necessary plumbing and wiring for the controller -
he came back and commissioned the system for me - took about an hour.
Been running fine ever since - with the occasional slight topping-up
of the circulating water.

Don't really know how much money I saved by doing the plumbing myself
- but ISTR that the total kit cost just over £2k. Plumbing wasn't
particularly complicated, and the (3) sensors for the controller
fitted into metal sleeves (supplied) and the wiring was pre-terminated
with plugs - so that was easy.

In terms of performance, I've never formally recorded it - but I know
that from about May to September we're not needing much input from the
immersion heater to get the DHW up to temperature. Becomes more
complicated to assess in winter because the woodburing stove gives
priority to the DHW .....

I'd say go for it !
Have tried a complete 'home-brew' system in the past - old radiators,
glazed collector etc - but the Thermomax-type tubes are reckoned to
capture more heat for a given illumination....

Hope this helps
Adrian
Suffolk UK
fwiw there's a picture of the collector at
http://www.inspired-glass.co.uk/bungalow.htm
- 4th photo down....

======return email munged=================


Thanks for the info, very informative. Nice house by the way, bit out of our
price range though. Lovely area down there and somewhere I wouldn't mind
living even if such an idea is blasphemy for a Norfolk boy :-)

Jake

"David Hansen" wrote in message
...
On Mon, 10 Apr 2006 22:47:39 +0100 someone who may be "Jake"
wrote this:-



Mary used a Solartwin panel, for which you wouldn't need a new
cylinder, though the existing one must have proper insulation. For
DIY this has the advantage of minimum installation time and effort.

For a more involved DIY project Navitron are one source of useful
bits.


Thanks for the info. My parents did a while back briefly consider the
Solartwin system but didn't go ahead in the end. Think because they had a
combi fitted and this made the system impossible or less practical. It's a
good idea but we are going for the indirect style system.

Jake

"Mary Fisher" wrote


We're in UK.

www.solartwin.com All information is there.

It's just for domestic hot water - not house heating.

We bought the kit, including a pv panel which powers the pump and all the
silicone piping necessary.

It was easy to fit, I can send pictures. If the company had done it it
would have been quicker for a straightforward connection to an existing
tank but we didn't have one so it was more complicated. And Spouse hates
having anyone doing things in the house :-)

The company was friendly, professional and helpful from start to finish,
even when we were just thinking about it for six months. The paperwork
they provided was excellent.

It's the way to go, I think the capital costs will reduce too but I wish
we'd done it years ago when we'd have had more time to enjoy the benefits.

Mary
Thanks for the info Mary, it's much appreciated.

Regards

Jake

"Jake" wrote in message
...



Thanks for the info. My parents did a while back briefly consider the
Solartwin system but didn't go ahead in the end. Think because they had a
combi fitted and this made the system impossible or less practical. It's a
good idea but we are going for the indirect style system.

Hang on - why is it impractical to use when you have a combi system?

We have a combi boiler too, the two systems work well together. Remember
that you can't guarantee all the hot water you want every day of the year
from solar, at those times the 'boost' on the combi boiler controller can
heat the water in the cylinder for as long as you like up to an hour, or on
'over-ride' for as long as you want - through the indirect system.

It's a wonderfully versatile arrangement!

Mary

Jake

HI Jake

On Tue, 11 Apr 2006 15:56:03 +0100, "Jake"
wrote:


"Adrian Brentnall" adrian-the papers and the wrote
in message ...
HI Jake

On Mon, 10 Apr 2006 22:47:39 +0100, "Jake"
wrote:


"Mary Fisher" wrote


A commercial product but self-installed.

More info please. We are having a new boiler system put in and though we
can't afford a whole solar system, can't quite stretch to Jupiter ;-) this
year we are specifying a solar compatible dual coil tank with a view to
self
installing the rest next year.

That's what we did when we moved here 5 years ago.


So as we are trying to find out about other peoples experiences a few
questions please.

What brand/type/supplier/cost please? Did you buy a complete kit or did
you
self source mix and match? And did you find it easy to fit?

My local installer sold me a complete kit (less the copper pipe !) -
which came with a pretty comprehensive diagram, and the offer of
'hand-holding' if necessary.

It consists of an array of Thermomax evacuated collectors and their
header assembly (got the installer to fit that lot on the roof for me
and provide pipe stubs through into the loft space). He also supplied
the controller and all the necessary brasswork, pump etc.

After I'd done the necessary plumbing and wiring for the controller -
he came back and commissioned the system for me - took about an hour.
Been running fine ever since - with the occasional slight topping-up
of the circulating water.

Don't really know how much money I saved by doing the plumbing myself
- but ISTR that the total kit cost just over £2k. Plumbing wasn't
particularly complicated, and the (3) sensors for the controller
fitted into metal sleeves (supplied) and the wiring was pre-terminated
with plugs - so that was easy.

In terms of performance, I've never formally recorded it - but I know
that from about May to September we're not needing much input from the
immersion heater to get the DHW up to temperature. Becomes more
complicated to assess in winter because the woodburing stove gives
priority to the DHW .....

I'd say go for it !
Have tried a complete 'home-brew' system in the past - old radiators,
glazed collector etc - but the Thermomax-type tubes are reckoned to
capture more heat for a given illumination....

Hope this helps
Adrian
Suffolk UK
fwiw there's a picture of the collector at
http://www.inspired-glass.co.uk/bungalow.htm
- 4th photo down....

======return email munged=================


Thanks for the info, very informative.

No problem!

Nice house by the way, bit out of our
price range though. Lovely area down there and somewhere I wouldn't mind
living even if such an idea is blasphemy for a Norfolk boy :-)

You're right - it's a very nice area g

Don't worry about being from Norfolk - they're very broad-minded down
here and let all sorts of people 'in' GG

I had a stand at an exhibition last Sunday - big notice on it saying
'Cheques welcome - also Hungarians, Australians and people from
Norfolk'

Corny, I know - but it raised a few smiles.... !

Good luck with your solar
Adrian
Suffolk UK
======return email munged=================
take out the papers and the trash to reply

"Mary Fisher" wrote in message
t...

"Jake" wrote in message
...




Hang on - why is it impractical to use when you have a combi system?

We have a combi boiler too, the two systems work well together.

Interesting, how does the system heat the water if there isn't a storage
cylinder? I'm puzzled.

Jake

Jake wrote:
"Adrian Brentnall" adrian-the papers and the wrote
in message ...
HI Jake

On Mon, 10 Apr 2006 22:47:39 +0100, "Jake"
wrote:


"Mary Fisher" wrote


A commercial product but self-installed.




Thanks for the info, very informative. Nice house by the way, bit out of our
price range though. Lovely area down there and somewhere I wouldn't mind
living even if such an idea is blasphemy for a Norfolk boy :-)

You could still support the Caneries, just don't shout to loud.
Brian (another old Norfolk boy)

"Jake" wrote in message
...

"Mary Fisher" wrote in message
t...

"Jake" wrote in message
...




Hang on - why is it impractical to use when you have a combi system?

We have a combi boiler too, the two systems work well together.

Interesting, how does the system heat the water if there isn't a storage
cylinder? I'm puzzled.

You getastoragecylinder.

They're not expensive :-)

Mary

Jake

"Mary Fisher" wrote in

You getastoragecylinder.

They're not expensive :-)

They are if you haven't got the space ;-) I think there was also problems,
amongst others, with access to a suitable roof. Instead they went for
massive amounts of insulation well above current regulation standards.

Jake

"Mary Fisher" wrote


who?

They

HTH

Jake

Jake wrote:

Interesting, how does the system heat the water if there isn't a storage
cylinder? I'm puzzled.

I think the clue was in the bit where she said "heat the water in the
cylinder for as long as you like"

i.e. they *do* have a cylinder. (just because you have a combi, it does
not mean you can't also have a cylinder)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Ian Stirling wrote:

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.

4200J/K/kg shirly?


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Jake" wrote in message
...

"Mary Fisher" wrote


who?

They

HTH

No

Jake

John Rumm wrote:
Ian Stirling wrote:

200l of water has 4400J/K/Kg * 200Kg = 880KJ/K.

4200J/K/kg shirly?

Oh, you mean he's not using the standard 1:3 normal - heavy water ratio?

Ian Stirling wrote:
wrote:
Ian Stirling wrote:
Mary Fisher wrote:

Concentration improves this a lot, and is easy to do with all metal
radiators, eg with greased silvered mylar film. Even ali foil works for
a while. Concentration improves heat availability in poor weather,
financial efficiency or ROI, and system reliability (less plumbing
failure points).

But of course, concentration works best with direct sun.

well, it does improve capture with diffuse light, but not by anywhere
near as much as with direct sun. Poor real world performance of
concentrator systems in winter is down to their typically small
collector areas.

There are times a concentrator will deliver heat when flat panels wont.


I was actually wondering about a scheme which was an air heater alone,
for that one.
You have a stack of n (where n is a large number of panes, which absorbs
say 80% of incoming light before it hits the bottom.
The air is drawn past these from the outside in, in a serpentine
fashion, so that the inner panels are hottest, and hopefully essentially
all IR radiation is trapped.
I wouldn't be surprised if 2-300C was possible.
But, it'd use a hell of a lot of glass, and probably take a long time to
start up, due to thermal inertia.

ok theres a proven system a bit like this using shade cloth. 2 or more
layers of shade cloth, just one of glass. The air flow is from near the
outer glass towards the inside, through the cloth, and efficiency is
very high, far above any black or selective absorber system. And the
cloth is cheap, unlike glass.


If you have a lot of glass, how about a hot air collector with one
sheet of glass and one poly?

Possibly - there is an obvious tradeoff (for non evacuated panels)
between power output, and maximum temperature.
Obviously, adding another layer of glazing will always increase the
maximum steady-state temperature, but due to absorbing some light, will
decrease the power output.

only above a point. Double glazing will give more power out than
single, as conduction losses are less. Triple may not. Extending the dg
layer below the first glazing layer also provides reduced heat loss.

: ___
: |___|
: | | |
: | | |
: | | |
: | | |
: | | |
: | | |
: |_| |
: | |
: | |
: |___|
:
:

in order from left to right:
dots for text formatting
roof/base of panel
single glazing layer
double glazing layer

The area below the panel captures heat that flows over the single
glazing layer, reducing panel heat loss further.


I suspect a 'low temperature' panel, and a high temperature one may be
worthwhile.

this is what I've been thinking about for some time now. Each panel
type performs best in different parts of the system. Eg vac tubes for
the top of the tank, as theyre the only thing that performs sensibly at
high temp, rads as a simple minimum cost inlet prewarmer, and flat
panel for the bulk of tank heating.


Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

I still cant see what you mean there

2m^2 panel, 1m^2 radiator and a fan.
Or 0.5m^2 radiator, ...

Helps with the thermal inertia thing as well as to some extent the cost.

still just as puzzled


NT

wrote:
Ian Stirling wrote:
wrote:
Ian Stirling wrote:
Mary Fisher wrote:
snip
You have a stack of n (where n is a large number of panes, which absorbs
say 80% of incoming light before it hits the bottom.
The air is drawn past these from the outside in, in a serpentine
fashion, so that the inner panels are hottest, and hopefully essentially
all IR radiation is trapped.
I wouldn't be surprised if 2-300C was possible.
But, it'd use a hell of a lot of glass, and probably take a long time to
start up, due to thermal inertia.

ok theres a proven system a bit like this using shade cloth. 2 or more
layers of shade cloth, just one of glass. The air flow is from near the
outer glass towards the inside, through the cloth, and efficiency is
very high, far above any black or selective absorber system. And the
cloth is cheap, unlike glass.

Interesting.

If you have a lot of glass, how about a hot air collector with one
sheet of glass and one poly?

Possibly - there is an obvious tradeoff (for non evacuated panels)
between power output, and maximum temperature.
Obviously, adding another layer of glazing will always increase the
maximum steady-state temperature, but due to absorbing some light, will
decrease the power output.

only above a point. Double glazing will give more power out than
single, as conduction losses are less. Triple may not. Extending the dg
layer below the first glazing layer also provides reduced heat loss.

To restate.
Adding another level of glazing will increase the maximum temperature it
will reach at 0 flow.
It will reduce the maximum power output at a reasonable flow to below
the temperature without an extra pane, due to the lower power due to the
losses from the first pane.

snip
I suspect a 'low temperature' panel, and a high temperature one may be
worthwhile.

this is what I've been thinking about for some time now. Each panel
type performs best in different parts of the system. Eg vac tubes for
the top of the tank, as theyre the only thing that performs sensibly at
high temp, rads as a simple minimum cost inlet prewarmer, and flat
panel for the bulk of tank heating.

Also wondering what the possible ratio of a fan assisted panels
radiator/panel size is.

I still cant see what you mean there

2m^2 panel, 1m^2 radiator and a fan.
Or 0.5m^2 radiator, ...

Helps with the thermal inertia thing as well as to some extent the cost.

still just as puzzled

Ok, in more words

Instead of having a 1m^2 radiator, in a 1m^2 panel, you have a 0.5m^2
radiator in a 1m^2 panel, and a fan, to circulate the air to the
radiator.

Ian Stirling wrote:
wrote:

ok theres a proven system a bit like this using shade cloth. 2 or more
layers of shade cloth, just one of glass. The air flow is from near the
outer glass towards the inside, through the cloth, and efficiency is
very high, far above any black or selective absorber system. And the
cloth is cheap, unlike glass.

Interesting.

IIRC The solar barn uses it at
http://builditsolar.com/Projects/Spa...rn_project.htm


Possibly - there is an obvious tradeoff (for non evacuated panels)
between power output, and maximum temperature.
Obviously, adding another layer of glazing will always increase the
maximum steady-state temperature, but due to absorbing some light, will
decrease the power output.

only above a point. Double glazing will give more power out than
single, as conduction losses are less. Triple may not. Extending the dg
layer below the first glazing layer also provides reduced heat loss.

To restate.
Adding another level of glazing will increase the maximum temperature it
will reach at 0 flow.

yes

It will reduce the maximum power output at a reasonable flow to below
the temperature without an extra pane, due to the lower power due to the
losses from the first pane.

I still am not seeing how you can conclude that, since an extra layer
of glazing has 2 opposite effects, not just one. First there is 5% or
so absorption reducing the power output, then there is the double
glazing effect reducing convention losses, which increases power out.



Instead of having a 1m^2 radiator, in a 1m^2 panel, you have a 0.5m^2
radiator in a 1m^2 panel, and a fan, to circulate the air to the
radiator.

ahh I dont think youd need a fan. Why dont you run this past
alt.solar.thermal? Lots of expertise there. When I calculated something
similar, small collector plus plenty of space yielded more than the
small colelctor in small box but less than the bigger in the bigger
box. I think small rads in bigger boxes would make good sense, long as
youre not short on glass.


NT