We have just had a modified bitumen roof laid over our 45 square metre
south facing extension, and it's a good thickness of bitumen that now
thinking about it could have had water pipes buried for solar water
heating purposes.

:-(

Would that even have been a sensible idea? Should I get the Tardis time
machine out and see if I can get the pipes laid? Console me.

Todays sunshine certainly warmed the roof up a bit!

--
Adrian C

Adrian C wrote:

We have just had a modified bitumen roof laid over our 45 square metre
south facing extension, and it's a good thickness of bitumen that now
thinking about it could have had water pipes buried for solar water
heating purposes.

:-(

Would that even have been a sensible idea? Should I get the Tardis time
machine out and see if I can get the pipes laid? Console me.

Todays sunshine certainly warmed the roof up a bit!

It could provide a preheated supply for the hot tank in summer, but
annual HW spend usually isnt very high, so the saving potential's
limited.


NT

On Wed, 18 Mar 2009 18:03:17 +0000, Adrian C wrote:

We have just had a modified bitumen roof laid over our 45 square metre
south facing extension, and it's a good thickness of bitumen that now
thinking about it could have had water pipes buried for solar water
heating purposes.

On a related note, what happens with such heating during the colder months
or on cold nights? Is there some automatic set of valves which shut the
roof pipework off below set temperatures, or is this a manual process, or
do people not bother and just run water through the pipework year-round
(latter sounds like a freezing nightmare!)

Console me.

PS3, Wii, or Xbox? (it's been one of those days)

"Jules" wrote in message
news

On a related note, what happens with such heating during the colder months
or on cold nights? Is there some automatic set of valves which shut the
roof pipework off below set temperatures, or is this a manual process, or
do people not bother and just run water through the pipework year-round
(latter sounds like a freezing nightmare!)

You arrange the pipes to drain when the pump isn't running and it doesn't
run when the panels are cold.
You fill it with antifreeze.

Jules wrote:
On Wed, 18 Mar 2009 18:03:17 +0000, Adrian C wrote:

We have just had a modified bitumen roof laid over our 45 square metre
south facing extension, and it's a good thickness of bitumen that now
thinking about it could have had water pipes buried for solar water
heating purposes.

On a related note, what happens with such heating during the colder months
or on cold nights? Is there some automatic set of valves which shut the
roof pipework off below set temperatures, or is this a manual process, or
do people not bother and just run water through the pipework year-round
(latter sounds like a freezing nightmare!)

3 methods: Antifreeze & exchanger, drainback or draindown.

http://www.wiki.diyfaq.org.uk/index....=Solar_Thermal


NT

On Wed, 18 Mar 2009 18:21:10 -0500 someone who may be Jules
wrote this:-

On a related note, what happens with such heating during the colder months
or on cold nights?

Depends on the design. Properly designed and installed solar panels
don't lose a great deal of heat to the air and so the outside
temperature is irrelevant to their operation. They work in the
Antarctic for example, they also produce useful heat during the
winter months in the UK though obviously not as much as in summer.
They don't need direct sunlight to do this by the way, indirect
sunlight is enough.

If the system is not fitted with antifreeze, freezing tolerant, or
draining then most controllers can be set to pump water to the panel
when the panel temperature (not the same thing as the air
temperature) is near freezing. Obviously this removes heat from the
cylinder, but the pump runs for very little time in this mode (a
minute or two every hour typically) and so the heat losses are not
as severe as some imply/think.

Burying pipes in a flat roof is not a particularly good design due
to winter considerations, that sort of system should either have
antifreeze to allow it to work in winter without freezing (or use
freezing tolerant pipes) or have one of the draining schemes under
automatic control (it is generally far better to fit a purpose
designed panel, though there may be specific reasons for adopting a
low engineering approach).




--
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