A couple of years ago, I couldn't find DIY solar water heating kits (you
could build your own manky system Blue Peter style, giving the satisfaction
of true DIY but little else, I fancy, or pay someone a huge amount to
install one).

Having revisited the scene I find kits are now available eg:

http://www.solartwin.com/

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv panel to
drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) giving a payback
time of 10+years.

Does anyone have experience of such kits, with regard to savings, and this
kit in particular, with regard to its quality?

--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

"Bob Mannix" wrote in message
...
A couple of years ago, I couldn't find DIY solar water heating kits (you
could build your own manky system Blue Peter style, giving the
satisfaction
of true DIY but little else, I fancy, or pay someone a huge amount to
install one).

Having revisited the scene I find kits are now available eg:

http://www.solartwin.com/

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv panel to
drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) giving a
payback
time of 10+years.

Does anyone have experience of such kits, with regard to savings, and this
kit in particular, with regard to its quality?

I haven't experience of it myself as I'm building my own "Blue Peter" one
:-) I certainly liked the pv panel for the pump and have copied this.

A while ago somebody on the www.periodproperty.co.uk forum gave the
Solartwin one the tumbs up over others. Try having a search on google for
the thread.

.."Bob Mannix" wrote in message
...

Having revisited the scene I find kits are now available eg:

http://www.solartwin.com/

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv panel to
drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) giving a payback
time of 10+years.

http://www.solartwin.com/payback_calculator.htm
suggests about 1000 kWhr a year, which is reasonable.
They only suggest £100 a year saving in exceptional circumstances.

Bob Mannix typed:

A couple of years ago, I couldn't find DIY solar water heating kits
(you could build your own manky system Blue Peter style, giving the
satisfaction of true DIY but little else,

Er
But that costs £1.9k, my Blue Peter DIY one cost £25 its been working for
over 15 years and tonight mid January ive got water at 26.4c in the
collector tank, from water at 8.5c.
sense people ingenuity money some lacking. ;-(

--
Mark

Bob Mannix wrote:
A couple of years ago, I couldn't find DIY solar water heating kits (you
could build your own manky system Blue Peter style, giving the satisfaction
of true DIY but little else, I fancy, or pay someone a huge amount to
install one).

Having revisited the scene I find kits are now available eg:

http://www.solartwin.com/

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv panel to
drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) ...

I doubt you'd save that much: we're paying c. £40 a month i.e. £480 pa
on gas for our 3-bed semi, of which most is likely to be space heating.
If 1/4 of that is water heating of which perhpas half could be supplied
by solar then we'd save £60 pa.

... giving a payback time of 10+years.

Only at 0% interest rates :-)

If you borrowed at 5% interest to install it you'd be paying £95 on the
loan in the 1st year (decreasing as the loan is paid off) so taking into
acount the lifetime of the solar system you'd quite lilely never make
anything back on it. (And if you had the money to hand already you'd
have to compare with what you could get investing it in a long-term
savings account.)

Technically, the solartwin system also constrains you to an open vented
system with a hot water cylinder (or more expense putting in heat stores
etc) so when you come to replace your CH boiler (with a shiny new
condensing one) you can't easily go for a combi.

"Mark" wrote in message
...
Bob Mannix typed:

A couple of years ago, I couldn't find DIY solar water heating kits
(you could build your own manky system Blue Peter style, giving the
satisfaction of true DIY but little else,

Er
But that costs £1.9k, my Blue Peter DIY one cost £25 its been working for
over 15 years and tonight mid January ive got water at 26.4c in the
collector tank, from water at 8.5c.
sense people ingenuity money some lacking. ;-(

It was time rather than money/ingenuity but I guess a "manky system Blue
Peter" comment deserved a snotty response from someone who had built one
that works ). I had already decided it was too expensive but wanted others
comments. At least I was asking the question!

Could you furnish any diagrams on your system? The commercial one referred
to did have the advantage of being (almost) entirely non-invasive to the
existing system.

Cheers,


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

--
Mark

"John Stumbles" wrote in message
...
Bob Mannix wrote:
snip
I doubt you'd save that much: we're paying c. £40 a month i.e. £480 pa
on gas for our 3-bed semi, of which most is likely to be space heating.
If 1/4 of that is water heating of which perhpas half could be supplied
by solar then we'd save £60 pa.

... giving a payback time of 10+years.

Only at 0% interest rates :-)

This is very true.

snip

Technically, the solartwin system also constrains you to an open vented
system with a hot water cylinder (or more expense putting in heat stores
etc) so when you come to replace your CH boiler (with a shiny new
condensing one) you can't easily go for a combi.

/duck
hooray!
duck/

I guess it's Blue Peter route (see other response) or nothing then.

Cheers,


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv
panel to
drive the pump, is =A31900.

Excessively expensive. Doesnt have a hope in hell of paying back.

Solar heating can payback very well indeed, but only if you design it
right. I have never seen a commerical system that I would describe as
desgiedn right.

For some odd reason, most solar engineers live in a world where cost
and payback are complete non issues. This problem has dogged solar
energy all along.

There is a good ng for this, alt.solar thermal.

Solar HW is quite tough to make pay; it can be done, but most systems
dont achieve it.

Solar flat panel space heating OTOH captures vastly more heat, costs
less to install, is simple to blue peter, and has excellant payback
figures as long as you design it sensibly, which is easy compared to
DHW heating.

Theres another good payer: a crossflow heat exchanger on the shower.
Warm water going down the drain heats the cold supply to the shower,
result is you use much less hot water. Payback can be under a year,
depends on level of use.


NT

On Thu, 20 Jan 2005 09:31:00 -0000, "Bob Mannix"
wrote:

A couple of years ago, I couldn't find DIY solar water heating kits (you
could build your own manky system Blue Peter style, giving the satisfaction
of true DIY but little else, I fancy, or pay someone a huge amount to
install one).

Having revisited the scene I find kits are now available eg:

http://www.solartwin.com/

Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv panel to
drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) giving a payback
time of 10+years.

Does anyone have experience of such kits, with regard to savings, and this
kit in particular, with regard to its quality?

Hi,

Vacuum tube collectors are available at fairly reasonable prices:

http://search.ebay.co.uk/solar-heater_W0QQsofocusZbsQQsbrftogZ1QQfromZR10QQcatref ZC6QQsoloctogZ9QQsotrtypeZ1QQsotrvalueZ1QQsadistan ceZ200QQsopostalZKT89AXQQsosortpropertyZ1QQcoactio nZcompareQQcopagenumZ1QQcoentrypageZsearch

There's plenty of info on the WWW about making a solar water heating
system, at a guess the rest of the parts to complete a system would
cost £50-100, given a water cylinder with an indirect coil is already
available.

cheers,
Pete.

In message , Mark
writes
Bob Mannix typed:

A couple of years ago, I couldn't find DIY solar water heating kits
(you could build your own manky system Blue Peter style, giving the
satisfaction of true DIY but little else,

Er
But that costs £1.9k, my Blue Peter DIY one cost £25 its been working for
over 15 years and tonight mid January ive got water at 26.4c in the
collector tank, from water at 8.5c.
sense people ingenuity money some lacking. ;-(

You'd better post some details then

--
geoff

wrote:
Just taking this as an example, a DIY kit, with a simple plumbing
arrangement (for those of us with tanks!), with an additional pv

panel to

drive the pump, is £1900.


Excessively expensive. Doesnt have a hope in hell of paying back.

Solar heating can payback very well indeed, but only if you design it
right. I have never seen a commerical system that I would describe as
desgiedn right.

For some odd reason, most solar engineers live in a world where cost
and payback are complete non issues. This problem has dogged solar
energy all along.

There is a good ng for this, alt.solar thermal.

Solar HW is quite tough to make pay; it can be done, but most systems
dont achieve it.

Solar flat panel space heating OTOH captures vastly more heat, costs
less to install, is simple to blue peter, and has excellant payback
figures as long as you design it sensibly, which is easy compared to
DHW heating.

And passive solar design of newbuild (or occasionally retrofit) can be
even better vfm. (When we went to Ladakh one little beacon of optimism
against the rather depressing tide of inappropriate 1st-world model
'development' of that delightful 'subsistence economy' was Helena
Norberg-Hodge's version of our CAT who were promoting such small-scale
appropriate technologies as trombe wall solar heating which could
achieve remarkable increases in comfort in buildings for the price of a
modest amount of glass and wood. (See about halfway down:
http://www.context.org/ICLIB/IC17/NHodge.htm)

And passive solar design of newbuild (or occasionally retrofit) can
be
even better vfm.

The Victorians put a lot more thought into this area of building design
- sometimes. Trouble with this sort of thing is its not a universal
plug in, it requires understadning and design skills to work out how to
do it and when. And today competition on basis of cost is pretty harsh,
and rules out such unnecessary skilled input in nearly all new builds.

The publishing of a set of standard proven designs, along with
checklists for each to see when you can use them, plus payback figures
etc, could change this. But I've not seen such a thing anywhere.

Regrettably solar seems to be the domain of those with insufficient
awareness of real world finances.

The fact is that among the sea of unlikelies, there are some solar
designs that pay back excellantly. It seems only a matter of time
before more widespread awareness occurs - though it doesnt seem to have
got anywhere yet.


NT

wrote in message
ups.com...
Theres another good payer: a crossflow heat exchanger on the shower.
Warm water going down the drain heats the cold supply to the shower,
result is you use much less hot water. Payback can be under a year,
depends on level of use.

Totally agree but big problem here is most BCOs throw a wobbly at such an
installation as it is beyond their experience. They 'understand' drainage
and don't like thinks out of the ordinary.

wrote in message
oups.com...
And passive solar design of newbuild (or occasionally retrofit) can
be
even better vfm.

The Victorians put a lot more thought into this area of building design
- sometimes.

Yep - the foyer of the Alexander palace is a fine example of when they got
it right.

Pity about some other parts of the building :-)

In message . com,
writes
Theres another good payer: a crossflow heat exchanger on the shower.
Warm water going down the drain heats the cold supply to the shower,
result is you use much less hot water. Payback can be under a year,
depends on level of use.

Are such crossflow heat exchangers easily available? I've searched via
Google but could only find air-venting ones.

--
dave @ stejonda

Bob Mannix typed:

Could you furnish any diagrams on your system? The commercial one
referred to did have the advantage of being (almost) entirely
non-invasive to the existing system.

Well ive got a few things going in my favour, I live on the south coast and
in a very sheltered valley the house having had many alterations over the
years has a roof ideally suited being a u shaped /\_/\
Theirs nothing special about the design, it's the same as the conventional
example shown on http://www.solartwin.com/ but all the parts were obtained
from boot sales or farm auctions, Its got 4x 6ft radiators in a wooden frame
with Perspex covers sited in the V of the roof facing S-SW.
Pump is 12v and powered by elec solar panel 1x1m, the only mod I had to do
was the pump motor stalled when Volts dropped below 5v,
(which also meant that there wasn't sufficient heat/light either)
fixed with 2 Zener's and relay.
We use a LOT of hot water during the summer (three B+B rooms) and hot water
is by oil boiler so every 1degree saved is worth while IF the initial outlay
is modest.
Winter I don't care as we have a HUGE wood burning stove.
HTH

--
Mark

wrote in message
oups.com...
And passive solar design of newbuild (or occasionally retrofit) can
be
even better vfm.

The Victorians put a lot more thought into this area of building design
- sometimes. Trouble with this sort of thing is its not a universal
plug in, it requires understadning and design skills to work out how to
do it and when. And today competition on basis of cost is pretty harsh,
and rules out such unnecessary skilled input in nearly all new builds.

The publishing of a set of standard proven designs, along with
checklists for each to see when you can use them, plus payback figures
etc, could change this. But I've not seen such a thing anywhere.

Regrettably solar seems to be the domain of those with insufficient
awareness of real world finances.

The fact is that among the sea of unlikelies, there are some solar
designs that pay back excellantly. It seems only a matter of time
before more widespread awareness occurs - though it doesnt seem to have
got anywhere yet.

The US government were on the verge of introducing large scale solar
research. A report stated most of the US energy needs could come from
solar....in 1952. It was dropped for the Atoms for Peace garbage. Again a
major report indicated the same in 1980. In the final days of Carter he
stared the ball rolling. Regan scrapped it and even took the solar panels
off the White House roof. Bush has suppressed any notion of large scale
solar research.

So in the USA vote Democrat not oil company lackeys Republican. Similar
here, but on a smaller scale. The Tories pander to big oil, while Labour
have an effective wind power generation project under way and increased home
insulation levels, and are still increasing them, to levels we though only
Sweden would do.

Are such crossflow heat exchangers easily available? I've searched
via
Google but could only find air-venting ones.

I'm not familiar with anyone selling them yet, it would likely be a diy
job. But its not very difficult.

You'd need 2-3 ft of copper drain sized pipe, some microbore, and
solder. Wrap microbore round the big copper pipe, but rather than one
piece, use 4 in parallel. Solder them in place. Use a 4 way manifold at
each end of the microbores, so the cold water flow goes thru the 4 in
parallel.

The cold supply for the shower goes into the microbores at the drain
end of the thing, and comes out at the plughole end, going to the
shower.

It cuts right back on energy use, and makes your tank of HW last
substantialy longer. Payback varies according to use, but maybe a year
or so, that sort of region.


NT

wrote in message
oups.com...
Are such crossflow heat exchangers easily available? I've searched
via
Google but could only find air-venting ones.

I'm not familiar with anyone selling them yet, it would likely be a diy
job. But its not very difficult.

Wouldn't the ones that both Andy and IMM recommended above a heat bank work
?

Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.


NT

wrote in message
ups.com...
Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.

Why does shower waste need to be roddable ?

"Mike" wrote in message
...

wrote in message
ups.com...
Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.

Why does shower waste need to be roddable ?

Look at:
http://gfxtechnology.com

In message , IMM
writes
"Mike" wrote in message
...

wrote in message
ups.com...
Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.

Why does shower waste need to be roddable ?

Look at:
http://gfxtechnology.com


Nice pictures to give me an idea about what I'd be attempting to make -
but that's a US site and USD300 + shipping etc. sounds like it would
take an awful long time to pay for itself!

--
dave @ stejonda

re drain heat exchanger:

Look at:
http://gfxtechnology.com

good one from IMM there, thats the beast.

Now what's $390CDN in pounds?

Ouch, =A3170. Time to diy then!

4 parallel microbores would be way easier to make than one half inch
pipe, and would give better thermal contact as well.


NT

"dave @ stejonda" wrote in message
...
In message , IMM
writes
"Mike" wrote in message
...

wrote in message
ups.com...
Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to
be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.

Why does shower waste need to be roddable ?

Look at:
http://gfxtechnology.com


Nice pictures to give me an idea about what I'd be attempting to make -
but that's a US site and USD300 + shipping etc. sounds like it would
take an awful long time to pay for itself!

The figures are there. The £ is higher than the $ at the mo, so it is a
matter of the shipping cost to add on.

You can make your own using two large bore copper pipes. One inside the
other. The mains water is in the gap between the two. Using two reducing
elbows and filing out the pipe stops inside the the fittings so the inner
pipe can slip you can easily make one yourself. Once filed out you solder
it up with a powerful blowtorch and wrap with insulation.

wrote in message
ups.com...
re drain heat exchanger:

Look at:
http://gfxtechnology.com

good one from IMM there, thats the beast.

Now what's $390CDN in pounds?

Ouch, £170. Time to diy then!

4 parallel microbores would be way easier to make than one half inch
pipe, and would give better thermal contact as well.

See my other post on a DIY. Which also has better thermal contact as there
is no spiral piping.

In message , IMM
writes

"dave @ stejonda" wrote in message
...
In message , IMM
writes
"Mike" wrote in message
...

wrote in message
ups.com...
Wouldn't the ones that both Andy and IMM recommended above a heat
bank work
?

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to
be
conducive to free flow, roddable, not pool, and be fittable to the
shower waste piping. ie a bit of pipe would be ideal.

Why does shower waste need to be roddable ?

Look at:
http://gfxtechnology.com


Nice pictures to give me an idea about what I'd be attempting to make -
but that's a US site and USD300 + shipping etc. sounds like it would
take an awful long time to pay for itself!

The figures are there. The £ is higher than the $ at the mo,

It has been for as long as I can remember


--
geoff

"IMM" wrote in message
...


snip


You can make your own using two large bore copper pipes. One inside the
other.

....................that bit I understand ...

The mains water is in the gap between the two.

....................................I can even grasp this idea ....

Using two reducing
elbows and filing out the pipe stops inside the the fittings so the inner
pipe can slip you can easily make one yourself. Once filed out you solder
it up with a powerful blowtorch and wrap with insulation.

...... I'm afraid that I get lost about here ....
Can you provide a pointer to a sketch ?

--

Brian

IMM typed:


Bear in mind the shower waste goes through it, so the shape needs
snip
You can make your own using two large bore copper pipes. One inside
the other. The mains water is in the gap between the two.

FFS how many showers do you people have a day.
Has anyone given the slightest thought to how efficient this will be, and
the likely rise in temperature achievable.
Even I cant be bothered to build one of these.

--
Mark

On Sun, 23 Jan 2005 16:31:13 +0000, Mark wrote:

IMM typed:


Bear in mind the shower waste goes through it, so the shape needs
snip
You can make your own using two large bore copper pipes. One inside
the other. The mains water is in the gap between the two.

FFS how many showers do you people have a day.
Has anyone given the slightest thought to how efficient this will be, and
the likely rise in temperature achievable.
Even I cant be bothered to build one of these.

There are only two ways this will save energy.
1) You can set the shower to half heat (assuming it has such a setting).
2) The greater flow of water permits you to have a shorter shower.

I'd guess that it would take a few minutes before there was much benefit
from the heat recovery (the shower tray has to be warmed up and the trap
water and the waste pipe itself.)

The benefits would likely be taken mostly in improved luxury rather than
reduced consumption.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

Ed Sirett typed:

On Sun, 23 Jan 2005 16:31:13 +0000, Mark wrote:

IMM typed:


Bear in mind the shower waste goes through it, so the shape
needs
snip
You can make your own using two large bore copper pipes. One inside
the other. The mains water is in the gap between the two.

FFS how many showers do you people have a day.
Has anyone given the slightest thought to how efficient this will
be, and the likely rise in temperature achievable.
Even I cant be bothered to build one of these.

There are only two ways this will save energy.
1) You can set the shower to half heat (assuming it has such a
setting). 2) The greater flow of water permits you to have a shorter
shower.



And somewhere to fit the thing, did you note the size!
http://gfxtechnology.com/bobvilahbb.html
"GFX can cut one of the largest peak water heater loads, the shower, by
50%."
Rollocks, did Dimm invent this
You would save more energy per year by shooting the cat and boarding up the
cat flap.
Or trying to recover more of the lost heat going up the chimney/flue.

--
Mark

"Brian Sharrock" wrote in message
...

You can make your own using two
large bore copper pipes. One inside the
other.

...................that bit I understand ...

The mains water is in the gap between the two.

....................................I can even grasp this idea ....

Using two reducing
elbows

Sorry should have been tee.

...... I'm afraid that I get lost about here ....
Can you provide a pointer to a sketch ?

Start again.. Lets have 15mm and 22mm pipe for understanding.

Parts:
- 1 three metre lengty of 22mm pipe
- 1 three metre lengty of 15 mm pipe
- 2 solder ring capilary 22mm x 22mm x 15mm tess. (that is a 22mm in the
centre of the tee)

- File out the the 15mm stops of each tee to make then slip 15mm pipe. Easy
enough, just elbow grease. Or drill it out if you have the right sized
drill.
- Cut the 22mm pipe to 2.5 metres in length
- Insert the tee on the 22mm pipe at one on each end.
- Run the 15mm pipe though one tee anmd push it until it reaches the other
end and run it through the slip of the other tee.
- Have the tees 180 dregrees to each other
- Solder up.
- Cover with insulation.

You then have cold water running through the 22mm tee and out the other tee
warmed up. The hot waste runs down the 15mm. This is now an effective heat
exhanger. The longer the better. I have done these over 20 foot in length
ona solar water heater and it was very effective and very cheap.

You size up the copper pipe to suit eithe a shower or a full 110mm waste.

"Mark" wrote in message
...

FFS how many showers do you people have a day.
Has anyone given the slightest thought to how efficient this will be, and
the likely rise in temperature achievable.
Even I cant be bothered to build one of these.

Another know-it-all. Do a Google on groups and type in gfx. If you did
that first you wouldn't nake such an idiot of yourself. There are some
Americans who have these installed and reported figures on them. The average
temp rise is 17C. In effect it makes your cylinder bigger too. When
showering they are effective because you are heating the incoming cold water
with waste water simultaneously.

Domestic applications have a far loger payback than commercial. Heavy use
of waste water would make it feasible, in places sucj as hotels. Make your
own, as in solar panels, and the payback is quite quick. See my post on
making one.

IMM wrote:

You can make your own using two large bore copper pipes. One inside
the
other. The mains water is in the gap between the two. Using two
reducing
elbows and filing out the pipe stops inside the the fittings so the
inner
pipe can slip you can easily make one yourself. Once filed out you
solder
it up with a powerful blowtorch and wrap with insulation.
Is that parallel or counter flow?

"IMM" wrote in message
...
Start again.. Lets have 15mm and 22mm pipe for understanding.

Parts:
- 1 three metre lengty of 22mm pipe
- 1 three metre lengty of 15 mm pipe
- 2 solder ring capilary 22mm x 22mm x 15mm tess. (that is a 22mm in
the
centre of the tee)

- File out the the 15mm stops of each tee to make then slip 15mm pipe.
Easy
enough, just elbow grease. Or drill it out if you have the right sized
drill.
- Cut the 22mm pipe to 2.5 metres in length
- Insert the tee on the 22mm pipe at one on each end.
- Run the 15mm pipe though one tee anmd push it until it reaches the other
end and run it through the slip of the other tee.
- Have the tees 180 dregrees to each other
- Solder up.
- Cover with insulation.

You then have cold water running through the 22mm tee and out the other
tee
warmed up. The hot waste runs down the 15mm. This is now an effective
heat
exhanger. The longer the better. I have done these over 20 foot in
length
ona solar water heater and it was very effective and very cheap.

Sounds okay but surely for a long run the inner pipe - which appears to be
unsupported except at the ends - will touch the outer in various random
places and cause turbulence and resistance to flow. I don't know if this
will be a problem or not so could you let me know what sort of peak flow did
you get through the 20 foot long one ?

"Aidan" wrote in message
oups.com...

IMM wrote:

You can make your own using two large bore copper pipes. One inside
the
other. The mains water is in the gap between the two. Using two
reducing
elbows and filing out the pipe stops inside the the fittings so the
inner
pipe can slip you can easily make one yourself. Once filed out you
solder
it up with a powerful blowtorch and wrap with insulation.
Is that parallel or counter flow?

Counterflow.

"IMM" wrote in message
...

There are some Americans who have these
installed and reported figures on them. The average
temp rise is 17C. In effect it makes your cylinder bigger too.
When showering they are effective because you are
heating the incoming cold water with waste water simultaneously.

So if you have a combi that gives 11 litres/min @:35C temp rise, then having
one of these pre-heating the mains water to the combi will give and extra
50% temperature rise. In effect making that 11 l/min to approx 17 litres/min

IMM typed:

FFS how many showers do you people have a day.
Has anyone given the slightest thought to how efficient this will
be, and the likely rise in temperature achievable.
Even I cant be bothered to build one of these.

Another know-it-all. Do a Google on groups and type in gfx. If you
did that first you wouldn't nake such an idiot of yourself. There
are some Americans who have these installed and reported figures on
them. The average temp rise is 17C.

Must be distant Dimm relatives of yours, theirs absolutely no way you are
going to get a 17c rise in the normal length of time it takes most people to
shower.

Make your own, as in solar panels,

I have, see my original reply in this thread

and the payback is quite
quick. See my post on making one.

I have that's even more crap and useless
(22mm pipe LOL) then the Yanks 6ft thing.

HTH :-)

--
Mark

"IMM" wrote in message
...

"Brian Sharrock" wrote in message
...

You can make your own using two
large bore copper pipes. One inside the
other.

...................that bit I understand ...

The mains water is in the gap between the two.

....................................I can even grasp this idea ....

Using two reducing
elbows

Sorry should have been tee.

...... I'm afraid that I get lost about here ....
Can you provide a pointer to a sketch ?

Start again.. Lets have 15mm and 22mm pipe for understanding.

Parts:
- 1 three metre lengty of 22mm pipe
- 1 three metre lengty of 15 mm pipe
- 2 solder ring capilary 22mm x 22mm x 15mm tess. (that is a 22mm in
the
centre of the tee)


AIUI, that's using Screwfix catalogue as an example
part code D90193 ?


- File out the the 15mm stops of each tee to make then slip 15mm pipe.
Easy
enough, just elbow grease. Or drill it out if you have the right sized
drill.
- Cut the 22mm pipe to 2.5 metres in length
- Insert the tee on the 22mm pipe at one on each end.
- Run the 15mm pipe though one tee anmd push it until it reaches the other
end and run it through the slip of the other tee.
- Have the tees 180 dregrees to each other
- Solder up.
- Cover with insulation.


that's be (?)
Hot(!) Cold out ^ Cold(!) Cold in
22 ------/ /----------------------- 22
Waste -Hot 15 ------------/ /------------------------15 Waste
(cooled)
---------/ /-----------------------------

You then have cold water running through the 22mm tee and out the other
tee
warmed up. The hot waste runs down the 15mm. This is now an effective
heat
exhanger. The longer the better. I have done these over 20 foot in
length
ona solar water heater and it was very effective and very cheap.

You size up the copper pipe to suit eithe a shower or a full 110mm waste.


Out of interest; - how do you get from a 40mm plastic waste pipe
onto a 15mm copper 'waste'? Isn't the 15mm waste outlet a
trifle slow? BTW, a 'new' bathroom is on the list once I've
got the correct tuits - I've indicated to my wife that I've only got
square tuits left from the last big-job - So I'm genuinely interested
in heat-recovery devices as I'm always annoyed when joules of
decent heat-energy goes down the plug-hole after each bath.
I'd also be interested in where-abouts the tepid (cold) water
could be introduced into the domestic-hot-water system.

--

Brian

"Brian Sharrock" wrote in message
...


"IMM" wrote in message
...

"Brian Sharrock" wrote in message
...

You can make your own using two
large bore copper pipes. One inside the
other.

...................that bit I understand ...

The mains water is in the gap between the two.

....................................I can even grasp this idea ....

Using two reducing
elbows

Sorry should have been tee.

...... I'm afraid that I get lost about here ....
Can you provide a pointer to a sketch ?

Start again.. Lets have 15mm and 22mm pipe for understanding.

Parts:
- 1 three metre lengty of 22mm pipe
- 1 three metre lengty of 15 mm pipe
- 2 solder ring capilary 22mm x 22mm x 15mm tess. (that is a 22mm in
the
centre of the tee)


AIUI, that's using Screwfix catalogue as an example
part code D90193 ?



Yep. Could be compression too.


- File out the the 15mm stops of each tee to make then slip 15mm pipe.
Easy
enough, just elbow grease. Or drill it out if you have the right sized
drill.
- Cut the 22mm pipe to 2.5 metres in length
- Insert the tee on the 22mm pipe at one on each end.
- Run the 15mm pipe though one tee anmd push it until it reaches the
other
end and run it through the slip of the other tee.
- Have the tees 180 dregrees to each other
- Solder up.
- Cover with insulation.


that's be (?)
Hot(!) Cold out ^ Cold(!) Cold in
22 ------/ /----------------------- 22
Waste -Hot 15 ------------/ /------------------------15 Waste
(cooled)
---------/ /-----------------------------



I can't understand the drawing, but I think you have it.


You then have cold water running through the 22mm tee and out the other
tee
warmed up. The hot waste runs down the 15mm. This is now an effective
heat
exhanger. The longer the better. I have done these over 20 foot in
length
ona solar water heater and it was very effective and very cheap.

You size up the copper pipe to suit either a shower or a full 110mm
waste.


Out of interest; - how do you get from a 40mm plastic waste pipe
onto a 15mm copper 'waste'? Isn't the 15mm waste outlet a
trifle slow?



I gave 15mm and 22mm for an easy to understand example. I did say size the
pipes up to suit the shower application. It makes a heat exchanger like
this once in 15mm and 22mm pipe. These days plate heat exchangers can do
the job as well or better. But using 15mm and 2mm is cheap, very cheap, as
long as you have the space to run it. You can spiral it around a loft or
basement, or under a floor.



BTW, a 'new' bathroom is on the list once I've
got the correct tuits - I've indicated to my wife that I've only got
square tuits left from the last big-job - So I'm genuinely interested
in heat-recovery devices as I'm always annoyed when joules of
decent heat-energy goes down the plug-hole after each bath.
I'd also be interested in where-abouts the tepid (cold) water
could be introduced into the domestic-hot-water system.



See the web site I gave for gfx. They give e.g's. of how and where to
connect. Using large bore copper pipe this should be easy enough to make and
far cheaper than what gfx charge. It has to be fixed in a vertical
position. When water goes down the drain it spirals around the outside of a
pipe making this form of heat recovery possible.