Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for the
tubes said that they were more efficient, less susceptable to dirt (i.e.
bird **** was more likely to splat between them rather than all over them)
and any damage was more likely to mean the replacement of a tube or two
rather than then whole panel (he obviously had a thing against birds as he
cited an example of a bird dropping a stone or some such)

The next guy was all for the flat panels reckoning that the difference in
efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive with
no real gain.

I would be extremely interested in other people's experiences and comments
to try and sort the wood from the trees.

Cheers

Fredrick Skoog wrote:
Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for
the tubes said that they were more efficient, less susceptable to dirt
(i.e. bird **** was more likely to splat between them rather than all
over them) and any damage was more likely to mean the replacement of a
tube or two rather than then whole panel (he obviously had a thing
against birds as he cited an example of a bird dropping a stone or some
such)

The next guy was all for the flat panels reckoning that the difference
in efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive
with no real gain.

I would be extremely interested in other people's experiences and
comments to try and sort the wood from the trees.

I read somewhere on a site that supplies both tubes and panels that in Germany
panels make up 75% (?) of all units installed.They are less "ugly" and although
they take up a little more space the difference is marginal.

I personally think a larger (modern) flat panel is much more visually appealing
than a big array of tubes.

Pete

--
http://gymratz.co.uk - Fitness & Gym Equipment/nutrition specialists.
http://www.trade-price-supplements.co.uk - Bulk buy for up to 33% off.
http://www.BBE-Boxing-Equipment.co.uk - New Boxing Equipment site.
http://www.commercial-gym-equipment.co.uk - Commercial Gym Equipment.

"Fredrick Skoog" wrote:

Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for the
tubes said that they were more efficient, less susceptable to dirt (i.e.
bird **** was more likely to splat between them rather than all over them)
and any damage was more likely to mean the replacement of a tube or two
rather than then whole panel (he obviously had a thing against birds as he
cited an example of a bird dropping a stone or some such)

The next guy was all for the flat panels reckoning that the difference in
efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive with
no real gain.

I would be extremely interested in other people's experiences and comments
to try and sort the wood from the trees.


I don't know the answer, but I had colleagues who were facing a
similar choice and went to the Centre for Alternative Technology for
advice:

http://www.cat.org.uk/

There is an excellent free information service at:

http://www.cat.org.uk/information/info_content.tmpl

Fredrick Skoog wrote:
Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for
the tubes said that they were more efficient, less susceptable to dirt
(i.e. bird **** was more likely to splat between them rather than all
over them) and any damage was more likely to mean the replacement of a
tube or two rather than then whole panel (he obviously had a thing
against birds as he cited an example of a bird dropping a stone or some
such)

The next guy was all for the flat panels reckoning that the difference
in efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive
with no real gain.

I would be extremely interested in other people's experiences and
comments to try and sort the wood from the trees.

Cheers

I would say that with efficiencies down around the zero mark in our
benighted climate , it probably makes little difference.

Anyway as long as the bird**** goes black eventually..


Did you read hat article in one of the weeklies where the blokes panels
sludged up after a year. He got them serviced. The annual service cost
twice as much as the estimated fuel bill saving ;-)

Fredrick Skoog wrote:
Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for the
tubes said that they were more efficient, less susceptable to dirt (i.e.
bird **** was more likely to splat between them rather than all over them)
and any damage was more likely to mean the replacement of a tube or two
rather than then whole panel (he obviously had a thing against birds as he
cited an example of a bird dropping a stone or some such)

The next guy was all for the flat panels reckoning that the difference in
efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive with
no real gain.

I would be extremely interested in other people's experiences and comments
to try and sort the wood from the trees.

Cheers

This page
http://www.wiki.diyfaq.org.uk/index....=Solar_Thermal
has a graph that explains the difference between them.

On the face of it, tubes have significant advantages, but things are
never as simple as they first seem. Fact is tubes cost way more
than flat plates, hence for the same money you get far more flat
plate than tube, and can thus achieve much better payback with
flat plate.

So pros and cons on both sides. The article also explains how to
improve panel performance. Dont forget that what counts in the end
is total power output per cost in, and in no way are tubes 'the
winner' in this. No simple answer, sorry!


NT

On Thu, 29 May 2008 21:35:34 +0100, Fredrick Skoog wrote:

Hi All,

I am considering getting a solar heated hot water system

May I ask why? Given that domestic hot water is a small proportion of a
typical house's energy consumption then unless your house is already
insulated and draught-proofed to Scandanavian standards and has the most
efficient heating controls, condensing boiler and appliances and you're
not on mains gas I'd question the economic/ecological case for solar DHW.

--
John Stumbles

Pessimists are never disappointed

wrote:

Fact is tubes cost way more than flat plates, hence for the same money you
get far more flat plate than tube, and can thus achieve much better
payback with flat plate.

Hmm, not my experience. I have 2x20tube panels which cost less than I
was quoted for flat panels (£600 for the tubes, £750 for the equivalent
panels). A lot depends on where you buy the collectors. I got mine from
someone who was honest and imported them from China, I've seent he same
untis sold as "German" which seems to mean "Made in China, exported to
Germany, sold on again to the UK" the price for those units was £3000
for two arrays of 20 tubes, but on inspection, the units were identical.

For a hot water supply in a barn I used a panel I made myself for £50.
It's not as efficient as the tubes and weighs a lot more. OTOH for that
price it's possible to make a very big array of flat panels.

John Stumbles wrote:

On Thu, 29 May 2008 21:35:34 +0100, Fredrick Skoog wrote:

Hi All,

I am considering getting a solar heated hot water system

May I ask why? Given that domestic hot water is a small proportion of a
typical house's energy consumption then unless your house is already
insulated and draught-proofed to Scandanavian standards and has the most
efficient heating controls, condensing boiler and appliances and you're
not on mains gas I'd question the economic/ecological case for solar DHW.

It seems pointless using solar just for DHW. However using it to feed a
large thermal store seems a very good idea, and IME it is a very good
idea. OTOH the farm doesn't have mains gas, and oil for water heating is
currently the same price as diesel and propane isn't that much cheaper.

The main headache with solar is educating family and guests to fit their
use of hot water into the cycle of when hot water is available, that is
shower, bath, wash and do the laundry in the late afternoon. Also
finding a washing machine with hot water fill is a PITA.

Steve Firth wrote:
wrote:

Fact is tubes cost way more than flat plates, hence for the same money you
get far more flat plate than tube, and can thus achieve much better
payback with flat plate.

Hmm, not my experience. I have 2x20tube panels which cost less than I
was quoted for flat panels (�600 for the tubes, �750 for the equivalent
panels). A lot depends on where you buy the collectors.

You can always find someone charging silly prices. Panels are
very DIYable.

For a hot water supply in a barn I used a panel I made myself for �50.
It's not as efficient as the tubes and weighs a lot more. OTOH for that
price it's possible to make a very big array of flat panels.

quite so - and thats where they win. Efficiency may be inconsistent
but when they perform, a large area can output a whole lot at very
low cost.

2 sets of panels is always an option, flats feeding the bottom
section of the tank, and a small tube array feeding the top.


NT

Steve Firth wrote:
wrote:

Fact is tubes cost way more than flat plates, hence for the same money you
get far more flat plate than tube, and can thus achieve much better
payback with flat plate.

Hmm, not my experience. I have 2x20tube panels which cost less than I
was quoted for flat panels (�600 for the tubes, �750 for the equivalent
panels). A lot depends on where you buy the collectors.

You can always find someone charging silly prices. Panels are
very DIYable.

For a hot water supply in a barn I used a panel I made myself for �50.
It's not as efficient as the tubes and weighs a lot more. OTOH for that
price it's possible to make a very big array of flat panels.

quite so - and thats where they win. Efficiency may be inconsistent
but when they perform, a large area can output a whole lot at very
low cost.

2 sets of panels is always an option, flats feeding the bottom
section of the tank, and a small tube array feeding the top.


NT

"Fredrick Skoog" wrote in message
...
Hi All,

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes. The guy who quoted for the
tubes said that they were more efficient, less susceptable to dirt (i.e.
bird **** was more likely to splat between them rather than all over them)
and any damage was more likely to mean the replacement of a tube or two
rather than then whole panel (he obviously had a thing against birds as he
cited an example of a bird dropping a stone or some such)

The next guy was all for the flat panels reckoning that the difference in
efficiency was marginal, that the tubes had some inherent issue with
overheating the heat-transfer fluid and that they were more expensive with
no real gain.

I would be extremely interested in other people's experiences and comments
to try and sort the wood from the trees.

Cheers

We chose a flat panel and installed it ourselves more than two years ago.
Any dirt washes off in the rain. The glass is very tough and unlikely to be
broken.

Ours is a direct system, rather than transferring heat from a fluid to
water, the water in silicone piping is heated. It's pumped round the system
by an integrated pv panel so no mains power is used and when the sun isn't
shining - i.e. when water doesn't need to be moved - it doesn't run.

We've been very satisfied with ours, it heats water even in winter. Our gas
bills plummeted after we installed it. Even if the water is only 20C (that's
unusually low by the way) we know that the boiler doesn't need to heat mains
water more than necessary.

Remember, too, that experience does count more than opinion :-) If you want
to know more please mail me.

Mary

On Fri, 30 May 2008 12:28:53 +0100, Mary Fisher wrote:

We've been very satisfied with ours, it heats water even in winter. Our
gas bills plummeted after we installed it.

Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly, and
(2) that your boiler and hot water cylinder are pretty ancient and
prodigiously chuck heat into the house and out the flue for ages while
heating the water in the cylinder. If so then your water heating costs
would be a relatively high proportion of your total heating costs. If
you'd spent the money you spent on your solartwin on a condensing boiler
instead you might have found that your gas bills plummeted even further.


--
John Stumbles

I forgot to take my amnesia medecine again

John Stumbles wrote:

Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly, and
(2) that your boiler and hot water cylinder are pretty ancient and
prodigiously chuck heat into the house and out the flue for ages while
heating the water in the cylinder.


Quite presumptuous, aren't you!

On Thu, 29 May 2008 21:35:34 +0100, "Fredrick Skoog"
wrote:

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes.

Good tubes always beat panels, on everything except cost. However that's
enough to make or break installation actually taking place, so it's a
hard choice. All you can really say is that you need to run the numbers
for your site, your system and your budget. Anything else, even someone
else's first-hand experience, is just hand-waving in comparison. It's a
pretty exact science, or ought to be if you do it right.

http://www.t4sustainability.co.uk includes John "Wookie" Beardmore who
used to post hereabouts.

In message , Bruce
writes
John Stumbles wrote:

Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly, and
(2) that your boiler and hot water cylinder are pretty ancient and
prodigiously chuck heat into the house and out the flue for ages while
heating the water in the cylinder.


Quite presumptuous, aren't you!

Well, she did claim to save more than a normal person actually spends on
heating water

.... but then you're new and wouldn't know these things


--
geoff

On Fri, 30 May 2008 20:43:56 GMT, John Stumbles
wrote:


Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly,

Nothing wrong with that.

--
Frank Erskine

On Fri, 30 May 2008 20:43:56 GMT, John Stumbles
wrote:

On Fri, 30 May 2008 12:28:53 +0100, Mary Fisher wrote:

We've been very satisfied with ours, it heats water even in winter. Our
gas bills plummeted after we installed it.

Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly, and

Not necessarily, her circulation is probably buggered and she doesn't
feel the cold, my old mum got to be like that. However my dad kept
stumm (for a quiet life) sadly he died 20 years before she did of
Cardio Respiratory failure. :-((

(2) that your boiler and hot water cylinder are pretty ancient and
prodigiously chuck heat into the house and out the flue for ages while
heating the water in the cylinder. If so then your water heating costs
would be a relatively high proportion of your total heating costs. If
you'd spent the money you spent on your solartwin on a condensing boiler
instead you might have found that your gas bills plummeted even further.

H2O Duck's Back to a "Classicist" like MF.

Don't you try confusing her with facts.

Derek

On Fri, 30 May 2008 22:13:04 +0100, Bruce wrote:

Quite presumptuous, aren't you!

I have a photograph of Mary and Spouse. Chavs, they ain't :-)

--
John Stumbles

Men are from Mars, Women are from Venus
and Pop Psychologists are from Uranus

On Sat, 31 May 2008 00:05:59 +0100, Derek Geldard wrote:

Not necessarily, her circulation is probably buggered and she doesn't
feel the cold, my old mum got to be like that.

I wouldn't stand within reach of her and say that ;-)

--
John Stumbles

Question Authority

On Fri, 30 May 2008 23:29:50 +0100, Andy Dingley wrote:

http://www.t4sustainability.co.uk includes John "Wookie" Beardmore who
used to post hereabouts.

It would have been a bit of a shock if he'd been clean-shavem, wouldn't it? ;-)
In fact it was mildly disppointing that he isn't more facially hirsute.

--
John Stumbles
(Throwing stones, surname-wise, from his glasshouse :-))

On Fri, 30 May 2008 23:12:06 GMT, John Stumbles
wrote:

On Sat, 31 May 2008 00:05:59 +0100, Derek Geldard wrote:

Not necessarily, her circulation is probably buggered and she doesn't
feel the cold, my old mum got to be like that.

I wouldn't stand within reach of her and say that ;-)

It wouldn't be the first time. In the end I had to say it to my old
mum too :-((

*She* took no notice (as was her wont) but then *I* started getting
the "Hard Word" from social services.

All very sad.

Derek.

"John Stumbles" wrote in message
...
On Fri, 30 May 2008 12:28:53 +0100, Mary Fisher wrote:

We've been very satisfied with ours, it heats water even in winter. Our
gas bills plummeted after we installed it.

Let me stick my neck out here Mary and hazard a couple of guesses:
(1) that you're the sort of people who put on a jumper rather
than the central heating when it gets chilly,

Of course - it makes a lot of sense. Don't you? Do you go out on a cold day
with no coat? Or perhaps you sit in your car in **** sleeves with the heater
full on ...

and
(2) that your boiler and hot water cylinder are pretty ancient

They were both installed in January 2006. I don't think that's pretty
ancient :-)

and
prodigiously chuck heat into the house and out the flue for ages while
heating the water in the cylinder.

Not at all.

If so then your water heating costs
would be a relatively high proportion of your total heating costs. If
you'd spent the money you spent on your solartwin on a condensing boiler
instead you might have found that your gas bills plummeted even further.

I think they couldn't be any lower but We don't want a condensing boiler for
all sorts of reasons.

So you're wrong.

"John Stumbles" wrote in message
...
On Sat, 31 May 2008 00:05:59 +0100, Derek Geldard wrote:

Not necessarily, her circulation is probably buggered and she doesn't
feel the cold, my old mum got to be like that.

I wouldn't stand within reach of her and say that ;-)

I don't use physical punishment, ever.

But my circulation isn't buggered either. I'm probably more active than the
old mum was.

Today is warm, I've been gardening wearing shorts and a shirt and sandals.
Yesterday was cold, I wore jeans, shirt, sweatshirt and sandals and I was
indoors most of the time. There's a reason for the sandals which has nothing
to do with temperature. In the winter I wear knee length sheepskin boots.

"Andy Dingley" wrote in message
...
On Thu, 29 May 2008 21:35:34 +0100, "Fredrick Skoog"
wrote:

I am considering getting a solar heated hot water system and have been
quoted for either the flat panels or the tubes.

Good tubes always beat panels, on everything except cost. However that's
enough to make or break installation actually taking place, so it's a
hard choice. All you can really say is that you need to run the numbers
for your site, your system and your budget. Anything else, even someone
else's first-hand experience, is just hand-waving in comparison. It's a
pretty exact science, or ought to be if you do it right.

I'm not sure about that because different weather patterns, geographical
locations and the needs/desires of households are different.

Mary

On Sat, 31 May 2008 10:58:43 +0100, "Mary Fisher"
wrote:

It's a pretty exact science, or ought to be if you do it right.

I'm not sure about that because different weather patterns, geographical
locations and the needs/desires of households are different.

That's why you have to do it right. The data to support an accurate
model, down to a narrow geographical location, is obtainable.

Nor are the needs of different households all that different - there are
only so many ways to arrange a small number of people. The Jukes and the
Kallikaks might be different, but all of those Jukes living on the same
orientation in that same small town are going to have much the same
needs.

"Mary Fisher" wrote in message
t...

"John Stumbles" wrote in message
...
On Sat, 31 May 2008 00:05:59 +0100, Derek Geldard wrote:

Not necessarily, her circulation is probably buggered and she doesn't
feel the cold, my old mum got to be like that.

I wouldn't stand within reach of her and say that ;-)

I don't use physical punishment, ever.

But my circulation isn't buggered either. I'm probably more active than
the old mum was.

Today is warm, I've been gardening wearing shorts and a shirt and sandals.
Yesterday was cold, I wore jeans, shirt, sweatshirt and sandals and I was
indoors most of the time. There's a reason for the sandals which has
nothing to do with temperature. In the winter I wear knee length sheepskin
boots.


So you do feel the cold.
I was in shorts and short sleeved shirt last week, this week I will have to
get the AC out.

"Andy Dingley" wrote in message
...
On Sat, 31 May 2008 10:58:43 +0100, "Mary Fisher"
wrote:

It's a pretty exact science, or ought to be if you do it right.

I'm not sure about that because different weather patterns, geographical
locations and the needs/desires of households are different.

That's why you have to do it right. The data to support an accurate
model, down to a narrow geographical location, is obtainable.

Nor are the needs of different households all that different - there are
only so many ways to arrange a small number of people. The Jukes and the
Kallikaks might be different, but all of those Jukes living on the same
orientation in that same small town are going to have much the same
needs.

I'm not convinced about that. Our use of all water and fuel is considered,
others aren't so tight :-)

Mary

On Sat, 31 May 2008 10:54:01 +0100, Mary Fisher wrote:

Of course - it makes a lot of sense. Don't you? Do you go out on a cold
day with no coat?

No, but in my job (plumbing and heating) I'm frequently in people's houses
which would make Nordic saunas seem chilly :-)

Or perhaps you sit in your car in **** sleeves

Only when I've been clearing out sewers ;-)

(Reminds me of one of our teachers at tech who used to describe a loose fit
between components as being "like a turd in a shirt sleeve")

They were both installed in January 2006. I don't think that's pretty
ancient :-)

OK, should be 80% SEDBUK on the boiler & reasonable re-heat time on the HW
cylinder.

So you're wrong.

sigh! again :-)



I think they couldn't be any lower but We don't want a condensing boiler for
all sorts of reasons.

Well it wouldn't make economic or ecological sense if your boiler's
reasonably modern and efficient anyway, but go on ... I'm curious what
your objections would be otherwise.




--
John Stumbles

Things don't like being anthropomorphised.

On Sat, 31 May 2008 11:48:48 +0100, Andy Dingley wrote:

That's why you have to do it right. The data to support an accurate
model, down to a narrow geographical location, is obtainable.

Where? I've scoured various meteorological websites for baseline data and
all I can find is variations on the baseline - which presumably is so well
known within the met industry nobody bothers to publish it.

I think it would be neat to be able to make a calculator - like a
heat-loss calculator for boiler or radiator sizing - which people could
use to run their own what-if calculations, e.g. what if I got cavity wall
insulation/double glazed my windows/installed solar water heating/took X
showers instead of baths/turned down my thermostat Y degrees ... etc. -
and would show how much energy and money difference it would make over a
year.


--
John Stumbles

Life is nature's way of keeping meat fresh

On Sat, 31 May 2008 12:46:29 GMT someone who may be John Stumbles
wrote this:-

I think it would be neat to be able to make a calculator - like a
heat-loss calculator for boiler or radiator sizing - which people could
use to run their own what-if calculations, e.g. what if I got cavity wall
insulation/double glazed my windows/installed solar water heating/took X
showers instead of baths/turned down my thermostat Y degrees ... etc. -
and would show how much energy and money difference it would make over a
year.

SAP allows people to do this, in theory. However, its results should
always be taken with a pinch of salt as there is only so much a
method can do to allow for humans.


--
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

On Thu, 29 May 2008 21:35:34 +0100 someone who may be "Fredrick
Skoog" wrote this:-

The guy who quoted for the
tubes said that they were more efficient,

True, though one has to compare like with like. If an old radiator
is being used as a flat panel then it is going to be rather less
efficient than a well designed, low water volume, flat panel.

Vacuum tubes will still have an advantage over flat panels,
especially in cloudy weather, but it is not as marked as some imply.

less susceptable to dirt (i.e.
bird **** was more likely to splat between them rather than all over them)

Random bird **** is a little more likely to hit the tubes than the
gap, the gap typically being a little narrower than the tubes.
However, the gap should be filled by reflectors so both types of
panel should be a large unbroken area. A flat panel of equivalent
output will be larger, so there is a larger target.

and any damage was more likely to mean the replacement of a tube or two
rather than then whole panel (he obviously had a thing against birds as he
cited an example of a bird dropping a stone or some such)

Or someone throwing stones. However, it is true that an individual
tube can be replaced to deal with damage, as opposed to the whole
panel or the whole panel cover.

In a DIY context the advantage is with vacuum tubes. The header,
frame and tubes are all individual items which can be lifted onto a
roof individually. Lifting a flat panel, especially one made from an
old radiator, means lifting the whole thing, with size and weight to
deal with. Not insurmountable problems, but ones to bear in mind.



--
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