On Jun 22, 2:43*pm, MM wrote:
On Sun, 22 Jun 2008 13:18:11 +0100, Rod
wrote:
MM wrote:

I just need * a tank * ! I don't care what it's made from,or what its
original use may have been. All it needs to do is hold hot water at a
temperature of around hand-hot for a decent shower or for washing
dishes.

a low performance collector means your water's in the bacteria growth
zone, not hot enough, so one thing you dont want to do is shower with
it.


NT

On Jun 22, 8:44*pm, MM wrote:
On Sun, 22 Jun 2008 16:21:26 +0100, (Steve Firth)
wrote:
MM wrote:

I'd better just shoot myself then!

How about just getting a clue?

What might you suppose I am trying to do here?

MM

then why not use a proven design such as a hosepipe pancake. Lower
cost, higher perfornance, simpler, and no lethal bacteria.


NT

On Jun 22, 2:49*pm, MM wrote:
On Sun, 22 Jun 2008 13:26:19 +0100, "George \(dicegeorge\)"
wrote:

why ae you using copper pipe?
why not black plastic pipe?

Indeed. There are several YouTube videos that do exactly this.

I'd put a lot on my roof
except the weight of the water
micht collapse the roof

It doesn't *have* to be the roof (mine is too steeply pitched anyway).
A slanted south-facing collector-cum-frame in the garden is more than
adequate. Just a garden hose left on the lawn for a few hours in the
hot sun produces incredibly hot water, though not enough of it. That's
the reason for the tank. The thermo-syphon principle will keep
circulating the water throughout the late morning and early afternoon.
Hot water should be available after only a few hours.

MM

a tankless hose will all be steaming hot in half an hour, and that
makes it a lot more useful.


NT

On Jun 22, 2:49*pm, MM wrote:
On Sun, 22 Jun 2008 13:26:19 +0100, "George \(dicegeorge\)"
wrote:

why ae you using copper pipe?
why not black plastic pipe?

Indeed. There are several YouTube videos that do exactly this.

I'd put a lot on my roof
except the weight of the water
micht collapse the roof

It doesn't *have* to be the roof (mine is too steeply pitched anyway).
A slanted south-facing collector-cum-frame in the garden is more than
adequate. Just a garden hose left on the lawn for a few hours in the
hot sun produces incredibly hot water, though not enough of it. That's
the reason for the tank. The thermo-syphon principle will keep
circulating the water throughout the late morning and early afternoon.
Hot water should be available after only a few hours.

MM

If you must go with bare copper, at least put a reflector behind it or
a poly cover over it.


NT

"Steve Firth" wrote in message
.. .
MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

The biggest thing to worry about is that the tank will, if the water
gets hot enough, collapse and release hot water. You really need
something that can take near-boiling water, and the tank needs to be
insulated for best effect and closed (but vented) to prevent heat loss
by evaporation.

I believe such tanks are designed to withstand boiling water, for the very
good reason that they may be subjected to it from a faulty immersion,
although they will soften. The recent tragic accident resulting in the death
of a baby was because the tank was not properly supported on its base and
the tank *deformed* and split. The specification for withstanding boiling
water requires adequate support.

As the tank is outside and will *probably* never reach boiling point
(especially with 3m of copper pipe!), if it were adequately supported and
not over a sitting area or door or something, I would say the risk was very
low.


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

On Sun, 22 Jun 2008 22:52:45 +0100, (Steve Firth)
wrote:

MM wrote:

On Sun, 22 Jun 2008 16:21:26 +0100, (Steve Firth)
wrote:

MM wrote:

I'd better just shoot myself then!

How about just getting a clue?

What might you suppose I am trying to do here?

At the moment demonstrating absence of same.

Look, I can tell by now that you are a professional nitpicker, who so
far has only been very negative, bombastic or patronising. If you have
nothing to add except belligerent rudeness, then please, withdraw from
this thread and offer your advice to others, okay?

MM

On Mon, 23 Jun 2008 07:50:57 +0100, "Bob Mannix"
wrote:


"Steve Firth" wrote in message
. ..
MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

The biggest thing to worry about is that the tank will, if the water
gets hot enough, collapse and release hot water. You really need
something that can take near-boiling water, and the tank needs to be
insulated for best effect and closed (but vented) to prevent heat loss
by evaporation.

I believe such tanks are designed to withstand boiling water, for the very
good reason that they may be subjected to it from a faulty immersion,
although they will soften. The recent tragic accident resulting in the death
of a baby was because the tank was not properly supported on its base and
the tank *deformed* and split. The specification for withstanding boiling
water requires adequate support.

As the tank is outside and will *probably* never reach boiling point
(especially with 3m of copper pipe!), if it were adequately supported and
not over a sitting area or door or something, I would say the risk was very
low.

Thank you, God! Sorry, I mean, Bob! At last a voice of reason in a
tsunami of panic-mongering. If the darned water ever got anywhere near
boiling, then obviously I would not want either myself or others
scalded. I took that as a given. Also, while there have been continual
warnings of superheated steam to the pressure of 7000 psi bursting out
of every join (I exaggerate a tad), others or the same people have
pooh-poohed the idea as a waste of time and money that will generate
only lukewarm water! Some people seem to want to make it their life's
work to be critical before being constructive, a very irritatating
trait of us British, who seem to see it as a personal challenge to
find fault. Maybe that's why we have such a terrible trade deficit,
why manufacturing has been ruined, and why we whinge constantly about
"Brussels".

MM

On Sun, 22 Jun 2008 15:03:14 -0700 (PDT), wrote:

On Jun 22, 3:21*pm, MM wrote:
On Sun, 22 Jun 2008 06:07:57 -0700 (PDT), wrote:
On Jun 22, 8:37*am, MM wrote:
On Sat, 21 Jun 2008 13:38:22 -0700 (PDT), wrote:
On Jun 21, 5:47*pm, MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

NB: The tank will be mounted initially on outside wall, above the
copper tube "snake".

Or maybe you have suggestions for alternative tank suitable for hot
water?

The cold water tank I'm looking at (on the B&Q web site) is the Titan
Wizard 25/15 Rectangular Water Tank KM15 Black.

MM

Such tanks are unsuitable for hot water, they soften and collapse,
possibly inflicting nasty burns. People have even died this way

I hope your description of your solar system is quite inaccurate, as
its not going to achieve much as described.

What kind of (metal? plastic?) tank would you therefore recommend?

As long as my thermo-syphon domestic solar water heater can produce 15
litres hand-hot water for washing up and 5 litres for my daily
ablutions, that's all I'll want from it! I know I can get half a
bucketful of really hot water just from a garden hose in the sun. And
even if I only got a kettleful for shaving from my contraption, that's
one kettle for which I don't need to use electricity or burn oil to
heat.

MM

Right - 3m copper pipe in the sun isnt going to get you much though.

I will have to see. If it isn't adequate, I'll add another 3m. Only
£6.74 from B & Q and I take my pipe cutter with me so that the bus
driver lets me on the bus with it.

If you spent your £13.48 on garden hosepipe you'd get way more heat.
Cover it with polythene to give reasonable stagnation temp, lengthen
the season and make it heat faster.

3m of copper tube and a holding tank are far neater and more compact
than 30 metres of garden hose. And I don't relish the thought of 30
metres of hose with polythene over it practially hiding the entire
lawn.

Add it to a tank of colder water with no circulation and forget it.

The circulation is automatic, on the thermo-syphon principle, like a
car radiator. Many old cars had no water pump.

Yes, but it never circulates as well as pumped.

It circulated well enough for the systems which relied on the
thermo-syphon principle. An oft-demonstrated example of the KISS
principle.


Sounds like you'd be better off with a hosepipe pancake collector.
Make it a decent size and you wont need a tank at all. The hose can
store several litres, and since you need lower temp you can dilute the
hot at point of use, thus will require less than 15 litres in the
collector.

The pancake collector would get hot enough to self sterilise, and will
be flushed regularly. Your tank approach would be right in the
bacterial breeding zone, and never get flushed out.

Surely it gets flushed each time I empty it to use the hot water and
it is replenished with cold?

MM

yes, but only if you empty both tank and pipe fully. I'm not sure how
you're going to achieve that.

Why "fully"? Surely if you have a bowl of hot water and you pour cold
into it, excess water spills over, then the temperature of the water -
ALL the water - falls? Else, why did pouring cold water into
overheated car radiators stop them from boiling over and allowing the
journey to proceed? My "spill over" will be achieved by the simple
expediency of turning on a tap and waiting for a few moments...

Freecycle might get you free hose. Almost any colour works, green,
yellow etc. Using copper wont help.

Green! Yellow! It HAS to be black this year! (I have to think of the
garden's feng shui, too.)

MM

On Sun, 22 Jun 2008 15:06:35 -0700 (PDT), wrote:

On Jun 22, 2:43*pm, MM wrote:
On Sun, 22 Jun 2008 13:18:11 +0100, Rod
wrote:
MM wrote:

I just need * a tank * ! I don't care what it's made from,or what its
original use may have been. All it needs to do is hold hot water at a
temperature of around hand-hot for a decent shower or for washing
dishes.

a low performance collector means your water's in the bacteria growth
zone, not hot enough, so one thing you dont want to do is shower with
it.

Right. So all those tens of thousands of people around the world who
use solar-powered showers like this
http://www.firebox.com/pic/p1774h.jpg will be dead in a week, yes?

MM

On Sun, 22 Jun 2008 15:10:59 -0700 (PDT), wrote:

On Jun 22, 8:44*pm, MM wrote:
On Sun, 22 Jun 2008 16:21:26 +0100, (Steve Firth)
wrote:
MM wrote:

I'd better just shoot myself then!

How about just getting a clue?

What might you suppose I am trying to do here?

MM

then why not use a proven design such as a hosepipe pancake. Lower
cost, higher perfornance, simpler, and no lethal bacteria.

Because I think it's far neater to construct a system like this:
http://www.motherearthnews.com/uploa...-070-01pic.jpg

MM

On Sun, 22 Jun 2008 15:14:09 -0700 (PDT), wrote:

On Jun 22, 2:49*pm, MM wrote:
On Sun, 22 Jun 2008 13:26:19 +0100, "George \(dicegeorge\)"
wrote:

why ae you using copper pipe?
why not black plastic pipe?

Indeed. There are several YouTube videos that do exactly this.

I'd put a lot on my roof
except the weight of the water
micht collapse the roof

It doesn't *have* to be the roof (mine is too steeply pitched anyway).
A slanted south-facing collector-cum-frame in the garden is more than
adequate. Just a garden hose left on the lawn for a few hours in the
hot sun produces incredibly hot water, though not enough of it. That's
the reason for the tank. The thermo-syphon principle will keep
circulating the water throughout the late morning and early afternoon.
Hot water should be available after only a few hours.

MM

If you must go with bare copper, at least put a reflector behind it or
a poly cover over it.

I intend to paint the copper pipe matt black, then fit the matrix into
a box lined with loft insulation and thick black plastic like DPC
plastic. The box will be covered with either glass (if I can find a
pane for free - our local window replacement supplier often has old
customer windows stacked outside waiting to be collected) or a
polycarbonate sheet.

MM

wrote:

On 23 Jun,
"Bob Mannix" wrote:

As the tank is outside and will *probably* never reach boiling point
(especially with 3m of copper pipe!), if it were adequately supported and
not over a sitting area or door or something, I would say the risk was very
low.

If the tank is outside there will be more solar gain from the tank itself
than the measly 3m of pipe (unless it's 3m diameter!).


In the Caribbean, black plastic water tanks are sold specifically to
be used as solar water heaters. You see them on flat roofs or on top
of a steel frame.

"MM" wrote in message
...
On Mon, 23 Jun 2008 07:50:57 +0100, "Bob Mannix"
wrote:


"Steve Firth" wrote in message
...
MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

The biggest thing to worry about is that the tank will, if the water
gets hot enough, collapse and release hot water. You really need
something that can take near-boiling water, and the tank needs to be
insulated for best effect and closed (but vented) to prevent heat loss
by evaporation.

I believe such tanks are designed to withstand boiling water, for the very
good reason that they may be subjected to it from a faulty immersion,
although they will soften. The recent tragic accident resulting in the
death
of a baby was because the tank was not properly supported on its base and
the tank *deformed* and split. The specification for withstanding boiling
water requires adequate support.

As the tank is outside and will *probably* never reach boiling point
(especially with 3m of copper pipe!), if it were adequately supported and
not over a sitting area or door or something, I would say the risk was
very
low.

Thank you, God! Sorry, I mean, Bob! At last a voice of reason in a
tsunami of panic-mongering. If the darned water ever got anywhere near
boiling, then obviously I would not want either myself or others
scalded. I took that as a given. Also, while there have been continual
warnings of superheated steam to the pressure of 7000 psi bursting out
of every join (I exaggerate a tad), others or the same people have
pooh-poohed the idea as a waste of time and money that will generate
only lukewarm water! Some people seem to want to make it their life's
work to be critical before being constructive, a very irritatating
trait of us British, who seem to see it as a personal challenge to
find fault. Maybe that's why we have such a terrible trade deficit,
why manufacturing has been ruined, and why we whinge constantly about
"Brussels".


Possibly but I suspect history has a part to play (I thoroughly recommend
the 3rd book (1776-2000 - The Fate of Empire) of Simon Schama's excellent
history tv programme, what I have just re-read).

I should point out that the term "withstand boiling water" for these tanks
represents a one off occurrence that they are deemed to withstand. It would
be recommended that such a tank were replaced after exposure to boiling
water. Like you I would be happy with the fact that boiling was exceedingly
unlikely.


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

MM wrote:

On Sun, 22 Jun 2008 22:52:45 +0100, (Steve Firth)
wrote:

MM wrote:

On Sun, 22 Jun 2008 16:21:26 +0100, (Steve Firth)
wrote:

MM wrote:

I'd better just shoot myself then!

How about just getting a clue?

What might you suppose I am trying to do here?

At the moment demonstrating absence of same.

Look, I can tell by now that you are a professional nitpicker, who so
far has only been very negative, bombastic or patronising. If you have
nothing to add except belligerent rudeness, then please, withdraw from
this thread and offer your advice to others, okay?

Oh dear, refer to comment about lack of clue. You don't own any
particular thread and you don't get to decide who may or may not
contribute.

Bob Mannix wrote:

I believe such tanks are designed to withstand boiling water,

You can beleive what you like. However the case of the mother scalded by
boiling water when the cold water tank above the bed collapsed after
being filled with overflow hot water from a faulty cylinder suggests
that your beliefs are incorrect. It's not a unique case, a baby was
killed in a separate incident by exactly the same sequence of events.

http://findarticles.com/p/articles/m...5/ai_n12699473
http://www.guardian.co.uk/uk/2008/ja...s4.mainsection

Although some newspapers referred to "a hot water tank exploding" the
cause was the same in both cases. Hot water overflow from the DHW
cylinder was vented into the plastic cold water tank. The heat of the
overflow was sufficient to cause the tanks to deform.

You may think this is unlikely in a properly supported tank, but two
incidents suggest that the potential for the tank to collapse is there
and that the water does not have to be boiling for the tank to collapse.


Why design something that has a known, inherent flaw?

MM wrote:

Thank you, God! Sorry, I mean, Bob! At last a voice of reason in a
tsunami of panic-mongering.

It's a mistake to cling to the news that you want to hear because it is
the news that you want to hear.

"Steve Firth" wrote in message
. ..
Bob Mannix wrote:

I believe such tanks are designed to withstand boiling water,

You can beleive what you like. However the case of the mother scalded by
boiling water when the cold water tank above the bed collapsed after
being filled with overflow hot water from a faulty cylinder suggests
that your beliefs are incorrect. It's not a unique case, a baby was
killed in a separate incident by exactly the same sequence of events.

http://findarticles.com/p/articles/m...5/ai_n12699473
http://www.guardian.co.uk/uk/2008/ja...s4.mainsection

Although some newspapers referred to "a hot water tank exploding" the
cause was the same in both cases. Hot water overflow from the DHW
cylinder was vented into the plastic cold water tank. The heat of the
overflow was sufficient to cause the tanks to deform.

You may think this is unlikely in a properly supported tank, but two
incidents suggest that the potential for the tank to collapse is there
and that the water does not have to be boiling for the tank to collapse.

It is unlikely in a supported tank as their specification demands that they
withstand the temperature, for the very good reason that they act as the
receptacle for the vent pipe and the issuing of boiling water from this pipe
is possible and therefore the standards demand it. I believe it was the
result of the inquest on the baby that stated this and that this
specification was only met if the tank were properly supported. In that case
it was resting only on two joists, which caused the collapse.

As I reported to the OP, however, the fact that the tank had been subjected
to boiling water would be reason to replace it and (by implication) it could
not be regarded as "normal operation" but a failure. Were his system
intended or likely to contain boiling water it would not be an appropriate
soution. As it is extremely unlikely to ever boil, it's a non-issue.

Of more concern, if mounted outside, would be the effect of uv on the
plastic of the tank. This might cause a drop in the tank's specification and
might be grounds for changing it yearly or bi-yearly before it cracked. In
terms of hazard and risk, I would say the risk here is the greater. Given
that, I would keep such a tank in the shade myself and, of course, on a flat
shelf.

One might choose to use a galvanised metal tank for longevity, sure, but I
don't thing the risk of tank collapse from boiling is significant if you
don't do this and use a plastic one. I probably would as I couldn't be *rs*d
having to change it/move it and would leave it there permanently!


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


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

Bob Mannix wrote:

As it is extremely unlikely to ever boil, it's a non-issue.

Would you care to state what the critical temperature is for such use,
because I'm as sure as hell that the water doesn't need to be boiling.

The maximum safe working temperature recommended for HDPE tanks is 37°C,
that means that in almost any conceivable use of an HDPE cold water tank
for hot water it will be used above its maximum rated oeprating
temperature.

On Sun, 22 Jun 2008 20:53:39 +0100, MM wrote:

On Sun, 22 Jun 2008 18:12:07 +0000 (UTC), Ed Sirett
wrote:

On Sat, 21 Jun 2008 17:47:37 +0100, MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

NB: The tank will be mounted initially on outside wall, above the
copper tube "snake".

Or maybe you have suggestions for alternative tank suitable for hot
water?

The cold water tank I'm looking at (on the B&Q web site) is the Titan
Wizard 25/15 Rectangular Water Tank KM15 Black.

MM

If you are going to build a solar assisted HW system use a plausible
design readily obtainable from C.A.T. and others.

This is not going to be anything other than a standalone solar water
heater. It will not be hooked into the house water system (apart from a
connector on the garden tap). It will be dismantled in the autumn and
only brought out again in the spring. The design I am following is a
hybrid of many on the internet. Simple, straightforward, built largely
of discarded stuff, thus dirt cheap. Many people would probably be able
to make one for free with the contents of their rummage bin.

MM

OK.
A properly supported and correctly lidded cold water storage cistern will
probably be able to take hot water up to around 65C. Given the trouble
that some people have had with boiling water great care should be take to
minimise the risk. - Can't you find a metal tank from somewhere, at least
to use as a bund?



--
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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Mon, 23 Jun 2008 16:16:37 +0000 (UTC), Ed Sirett
wrote:

On Sun, 22 Jun 2008 20:53:39 +0100, MM wrote:

On Sun, 22 Jun 2008 18:12:07 +0000 (UTC), Ed Sirett
wrote:

On Sat, 21 Jun 2008 17:47:37 +0100, MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

NB: The tank will be mounted initially on outside wall, above the
copper tube "snake".

Or maybe you have suggestions for alternative tank suitable for hot
water?

The cold water tank I'm looking at (on the B&Q web site) is the Titan
Wizard 25/15 Rectangular Water Tank KM15 Black.

MM

If you are going to build a solar assisted HW system use a plausible
design readily obtainable from C.A.T. and others.

This is not going to be anything other than a standalone solar water
heater. It will not be hooked into the house water system (apart from a
connector on the garden tap). It will be dismantled in the autumn and
only brought out again in the spring. The design I am following is a
hybrid of many on the internet. Simple, straightforward, built largely
of discarded stuff, thus dirt cheap. Many people would probably be able
to make one for free with the contents of their rummage bin.

MM

OK.
A properly supported and correctly lidded cold water storage cistern will
probably be able to take hot water up to around 65C. Given the trouble
that some people have had with boiling water great care should be take to
minimise the risk. - Can't you find a metal tank from somewhere, at least
to use as a bund?

I'm currently looking for a galvanised tank. A galvanised dustbin
might be a suitable alternative, although I don't like the round
shape. Such a container, new, is probably watertight, but if not,
could be made so. In the interim I'm going to give it a go with a B&Q
Titan overflow tank (approx 4 gallons capacity). Let's see how hot
that gets!

MM

On Mon, 23 Jun 2008 15:48:44 +0100, "Bob Mannix"
wrote:

"Steve Firth" wrote in message
...
Bob Mannix wrote:

I believe such tanks are designed to withstand boiling water,

You can beleive what you like. However the case of the mother scalded by
boiling water when the cold water tank above the bed collapsed after
being filled with overflow hot water from a faulty cylinder suggests
that your beliefs are incorrect. It's not a unique case, a baby was
killed in a separate incident by exactly the same sequence of events.

http://findarticles.com/p/articles/m...5/ai_n12699473
http://www.guardian.co.uk/uk/2008/ja...s4.mainsection

Although some newspapers referred to "a hot water tank exploding" the
cause was the same in both cases. Hot water overflow from the DHW
cylinder was vented into the plastic cold water tank. The heat of the
overflow was sufficient to cause the tanks to deform.

You may think this is unlikely in a properly supported tank, but two
incidents suggest that the potential for the tank to collapse is there
and that the water does not have to be boiling for the tank to collapse.

It is unlikely in a supported tank as their specification demands that they
withstand the temperature, for the very good reason that they act as the
receptacle for the vent pipe and the issuing of boiling water from this pipe
is possible and therefore the standards demand it. I believe it was the
result of the inquest on the baby that stated this and that this
specification was only met if the tank were properly supported. In that case
it was resting only on two joists, which caused the collapse.

As I reported to the OP, however, the fact that the tank had been subjected
to boiling water would be reason to replace it and (by implication) it could
not be regarded as "normal operation" but a failure. Were his system
intended or likely to contain boiling water it would not be an appropriate
soution. As it is extremely unlikely to ever boil, it's a non-issue.

Of more concern, if mounted outside, would be the effect of uv on the
plastic of the tank. This might cause a drop in the tank's specification and
might be grounds for changing it yearly or bi-yearly before it cracked. In
terms of hazard and risk, I would say the risk here is the greater. Given
that, I would keep such a tank in the shade myself and, of course, on a flat
shelf.

One might choose to use a galvanised metal tank for longevity, sure, but I
don't thing the risk of tank collapse from boiling is significant if you
don't do this and use a plastic one. I probably would as I couldn't be *rs*d
having to change it/move it and would leave it there permanently!


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

Thanks for the advice, Bob. Gratefully received.

MM

MM wrote:

I'm currently looking for a galvanised tank. A galvanised dustbin
might be a suitable alternative, although I don't like the round
shape. Such a container, new, is probably watertight, but if not,
could be made so. In the interim I'm going to give it a go with a B&Q
Titan overflow tank (approx 4 gallons capacity). Let's see how hot
that gets!

Just as a suggestion, why not make a plywood box with some holes around the
bottom. (providing you have some off-cuts) for the overflow tank to fit inside.

That way, you give the plastic tank more than abundant support even if it
deforms to the state of a pond liner.
The "telltale" holes would let you know if there was (not likely) a leak
without showering somone with scalding water... ;¬)

You would also get the benefit of it being a 100% UV block so no tank
deterioration... what else....

You could make the box even bigger (4 or 5" clearance all round?) then fill the
gap with expanding foam for significant thermal insulation and yet more tank
support...and... thinking um... well, why not cut out a snug fitting
"floating" lid that would.. well... float on the surface of the water hugely
reducing surface heat escape yet providing a very free release of all that
steam ;¬))

Most expensive addition to that lot would be a large can of expanding foam for
a few £'s make sure you fill the gap in layers rather than all at once.

Just a few more ideas to throw into your experiment pot.

Cheers
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.

MM wrote:

I'm currently looking for a galvanised tank. A galvanised dustbin
might be a suitable alternative, although I don't like the round
shape. Such a container, new, is probably watertight, but if not,
could be made so. In the interim I'm going to give it a go with a B&Q
Titan overflow tank (approx 4 gallons capacity). Let's see how hot
that gets!

Just as a suggestion, why not make a plywood box with some holes around the
bottom. (providing you have some off-cuts) for the overflow tank to fit inside.

That way, you give the plastic tank more than abundant support even if it
deforms to the state of a pond liner.
The "telltale" holes would let you know if there was (not likely) a leak
without showering somone with scalding water... ;¬)

You would also get the benefit of it being a 100% UV block so no tank
deterioration... what else....

You could make the box even bigger (4 or 5" clearance all round?) then fill the
gap with expanding foam for significant thermal insulation and yet more tank
support...and... thinking um... well, why not cut out a snug fitting
"floating" lid that would.. well... float on the surface of the water hugely
reducing surface heat escape yet providing a very free release of all that
steam ;¬))

Most expensive addition to that lot would be a large can of expanding foam for
a few £'s make sure you fill the gap in layers rather than all at once.

Just a few more ideas to throw into your experiment pot.

Cheers
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.

On Mon, 23 Jun 2008 21:16:08 +0100, "Pet - www.GymRatZ.co.uk"
wrote:

MM wrote:

I'm currently looking for a galvanised tank. A galvanised dustbin
might be a suitable alternative, although I don't like the round
shape. Such a container, new, is probably watertight, but if not,
could be made so. In the interim I'm going to give it a go with a B&Q
Titan overflow tank (approx 4 gallons capacity). Let's see how hot
that gets!

Just as a suggestion, why not make a plywood box with some holes around the
bottom. (providing you have some off-cuts) for the overflow tank to fit inside.

That way, you give the plastic tank more than abundant support even if it
deforms to the state of a pond liner.
The "telltale" holes would let you know if there was (not likely) a leak
without showering somone with scalding water... ;¬)

You would also get the benefit of it being a 100% UV block so no tank
deterioration... what else....

You could make the box even bigger (4 or 5" clearance all round?) then fill the
gap with expanding foam for significant thermal insulation and yet more tank
support...and... thinking um... well, why not cut out a snug fitting
"floating" lid that would.. well... float on the surface of the water hugely
reducing surface heat escape yet providing a very free release of all that
steam ;¬))

Most expensive addition to that lot would be a large can of expanding foam for
a few £'s make sure you fill the gap in layers rather than all at once.

Just a few more ideas to throw into your experiment pot.

Cheers
Pete

Many thanks for the suggestions. All sound good. I bought the wood for
the box today at B&Q (not too expensive for 144mm wide planks, I
thought, plus exterior grade 12mm plywood). I also bought another 3m
of pipe, since several have said that 3m is not enough. So tomorrow
morning it's all systems go again in my garage!

MM

On Jun 23, 9:22*am, MM wrote:
On Sun, 22 Jun 2008 15:03:14 -0700 (PDT), wrote:
On Jun 22, 3:21*pm, MM wrote:
On Sun, 22 Jun 2008 06:07:57 -0700 (PDT), wrote:
On Jun 22, 8:37*am, MM wrote:
On Sat, 21 Jun 2008 13:38:22 -0700 (PDT), wrote:
On Jun 21, 5:47*pm, MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

NB: The tank will be mounted initially on outside wall, above the
copper tube "snake".

Or maybe you have suggestions for alternative tank suitable for hot
water?

The cold water tank I'm looking at (on the B&Q web site) is the Titan
Wizard 25/15 Rectangular Water Tank KM15 Black.

MM

Such tanks are unsuitable for hot water, they soften and collapse,
possibly inflicting nasty burns. People have even died this way

I hope your description of your solar system is quite inaccurate, as
its not going to achieve much as described.

What kind of (metal? plastic?) tank would you therefore recommend?

As long as my thermo-syphon domestic solar water heater can produce 15
litres hand-hot water for washing up and 5 litres for my daily
ablutions, that's all I'll want from it! I know I can get half a
bucketful of really hot water just from a garden hose in the sun. And
even if I only got a kettleful for shaving from my contraption, that's
one kettle for which I don't need to use electricity or burn oil to
heat.

MM

Right - 3m copper pipe in the sun isnt going to get you much though.

I will have to see. If it isn't adequate, I'll add another 3m. Only
£6.74 from B & Q and I take my pipe cutter with me so that the bus
driver lets me on the bus with it.

If you spent your £13.48 on garden hosepipe you'd get way more heat.
Cover it with polythene to give reasonable stagnation temp, lengthen
the season and make it heat faster.

3m of copper tube and a holding tank are far neater and more compact
than 30 metres of garden hose. And I don't relish the thought of 30
metres of hose with polythene over it practially hiding the entire
lawn.

Add it to a tank of colder water with no circulation and forget it.

The circulation is automatic, on the thermo-syphon principle, like a
car radiator. Many old cars had no water pump.

Yes, but it never circulates as well as pumped.

It circulated well enough for the systems which relied on the
thermo-syphon principle. An oft-demonstrated example of the KISS
principle.





Sounds like you'd be better off with a hosepipe pancake collector.
Make it a decent size and you wont need a tank at all. The hose can
store several litres, and since you need lower temp you can dilute the
hot at point of use, thus will require less than 15 litres in the
collector.

The pancake collector would get hot enough to self sterilise, and will
be flushed regularly. Your tank approach would be right in the
bacterial breeding zone, and never get flushed out.

Surely it gets flushed each time I empty it to use the hot water and
it is replenished with cold?

MM

yes, but only if you empty both tank and pipe fully. I'm not sure how
you're going to achieve that.

Why "fully"? Surely if you have a bowl of hot water and you pour cold
into it, excess water spills over, then the temperature of the water -
ALL the water - falls? Else, why did pouring cold water into
overheated car radiators stop them from boiling over and allowing the
journey to proceed? My "spill over" will be achieved by the simple
expediency of turning on a tap and waiting for a few moments...

Freecycle might get you free hose. Almost any colour works, green,
yellow etc. Using copper wont help.

Green! Yellow! It HAS to be black this year! (I have to think of the
garden's feng shui, too.)

MM


Since youre determined not to learn anything, lets hope something else
gets you before the bugs in the water.


NT

On Jun 23, 9:33*am, MM wrote:
On Sun, 22 Jun 2008 15:14:09 -0700 (PDT), wrote:
On Jun 22, 2:49*pm, MM wrote:
On Sun, 22 Jun 2008 13:26:19 +0100, "George \(dicegeorge\)"
wrote:

why ae you using copper pipe?
why not black plastic pipe?

Indeed. There are several YouTube videos that do exactly this.

I'd put a lot on my roof
except the weight of the water
micht collapse the roof

It doesn't *have* to be the roof (mine is too steeply pitched anyway).
A slanted south-facing collector-cum-frame in the garden is more than
adequate. Just a garden hose left on the lawn for a few hours in the
hot sun produces incredibly hot water, though not enough of it. That's
the reason for the tank. The thermo-syphon principle will keep
circulating the water throughout the late morning and early afternoon.
Hot water should be available after only a few hours.

MM

If you must go with bare copper, at least put a reflector behind it or
a poly cover over it.

I intend to paint the copper pipe matt black, then fit the matrix into
a box lined with loft insulation and thick black plastic like DPC
plastic. The box will be covered with either glass (if I can find a
pane for free - our local window replacement supplier often has old
customer windows stacked outside waiting to be collected) or a
polycarbonate sheet.

MM


and you expect people to help when you misdescribe what youre
building?

"Steve Firth" wrote in message
. ..
Bob Mannix wrote:

As it is extremely unlikely to ever boil, it's a non-issue.

Would you care to state what the critical temperature is for such use,
because I'm as sure as hell that the water doesn't need to be boiling.

I agree! I suspect it will spend most of its time hand hot or below, which
is what the OP wanted.

The maximum safe working temperature recommended for HDPE tanks is 37°C,
that means that in almost any conceivable use of an HDPE cold water tank
for hot water it will be used above its maximum rated oeprating
temperature.

Possibly true. The part of the thread I was responding to was that from the
disaster freaks which implied that, as soon as the water reached boiling
point, which they say it would (I disagree), the user would be maimed in an
inferno of boiling water as the tank collapsed (which it wouldn't if
properly supported). I made no claims as to whether it would be in the
recommended operating range. As such I stand by all I said. When posters
weren't saying he would be boiled to death they were saying the water
wouldn't even get hot! If the OP wants to bodge up a cheap system, support
it well and keep an eye on it, I don't see any reason why he shouldn't. If
he starts with 3m of copper tube it may get warm enough for a wash. If it
doesn't get hot enough he can add some more pipe. Were it ever to reach
boiling point, or near, he would take appropriate action. It's for his use
only on a seasonal basis. As I said in another post, *I* (were I to build
such a thing) would probably use a galvanized tank (if I could find one) for
longevity, or box in /shade the plastic tank to keep it out of the uv. This
sort of project is the true nature of D-I-Y.


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

Bob Mannix wrote:


Possibly true. The part of the thread I was responding to was that from the
disaster freaks which implied that, as soon as the water reached boiling
point, which they say it would (I disagree), the user would be maimed in an
inferno of boiling water as the tank collapsed (which it wouldn't if
properly supported).

I don't think that was being said. I think what was being said is that
collapse is a possibility, so why not obviate the possibility from
square one? And I think you're incorrect about the possibility of the
tank collapsing if the water gets hot (it doesn't need to be boiling).

MM wrote:
On Sun, 22 Jun 2008 15:06:35 -0700 (PDT), wrote:

On Jun 22, 2:43 pm, MM wrote:
On Sun, 22 Jun 2008 13:18:11 +0100, Rod
wrote:
MM wrote:
I just need * a tank * ! I don't care what it's made from,or what its
original use may have been. All it needs to do is hold hot water at a
temperature of around hand-hot for a decent shower or for washing
dishes.
a low performance collector means your water's in the bacteria growth
zone, not hot enough, so one thing you dont want to do is shower with
it.

Right. So all those tens of thousands of people around the world who
use solar-powered showers like this
http://www.firebox.com/pic/p1774h.jpg will be dead in a week, yes?

MM

Mostly, these will be used and drained completely. Considering the
market that it's aimed at, it may have a few days partial use and then
be packed away until next year.

What you are proposing will just be continuously diluting what's inside
your warm water tank.

On Tue, 24 Jun 2008 10:23:28 +0100, Dan Smithers
wrote:

MM wrote:
On Sun, 22 Jun 2008 15:06:35 -0700 (PDT), wrote:

On Jun 22, 2:43 pm, MM wrote:
On Sun, 22 Jun 2008 13:18:11 +0100, Rod
wrote:
MM wrote:
I just need * a tank * ! I don't care what it's made from,or what its
original use may have been. All it needs to do is hold hot water at a
temperature of around hand-hot for a decent shower or for washing
dishes.
a low performance collector means your water's in the bacteria growth
zone, not hot enough, so one thing you dont want to do is shower with
it.

Right. So all those tens of thousands of people around the world who
use solar-powered showers like this
http://www.firebox.com/pic/p1774h.jpg will be dead in a week, yes?

MM

Mostly, these will be used and drained completely. Considering the
market that it's aimed at, it may have a few days partial use and then
be packed away until next year.

What you are proposing will just be continuously diluting what's inside
your warm water tank.

Hardly. You will know that I am initially using a 4 gallon plastic
header tank from B&Q (until I lay my hands on a galvanised tank). 4
gallons will be all used up to wash dishes, mop the floor, get me a
shave, that kind of thing. I'm not planning a Chinese laundry here!

MM

On Mon, 23 Jun 2008 17:40:29 -0700 (PDT), wrote:

On Jun 23, 9:22*am, MM wrote:
On Sun, 22 Jun 2008 15:03:14 -0700 (PDT), wrote:
On Jun 22, 3:21*pm, MM wrote:
On Sun, 22 Jun 2008 06:07:57 -0700 (PDT), wrote:
On Jun 22, 8:37*am, MM wrote:
On Sat, 21 Jun 2008 13:38:22 -0700 (PDT), wrote:
On Jun 21, 5:47*pm, MM wrote:

I've made the first stage, i.e. the copper tube, about 3 metres of it
in a "snake" pattern. This will be mounted on a south-facing wall. Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft? Or will this plastic release
toxins when containing hot water?

NB: The tank will be mounted initially on outside wall, above the
copper tube "snake".

Or maybe you have suggestions for alternative tank suitable for hot
water?

The cold water tank I'm looking at (on the B&Q web site) is the Titan
Wizard 25/15 Rectangular Water Tank KM15 Black.

MM

Such tanks are unsuitable for hot water, they soften and collapse,
possibly inflicting nasty burns. People have even died this way

I hope your description of your solar system is quite inaccurate, as
its not going to achieve much as described.

What kind of (metal? plastic?) tank would you therefore recommend?

As long as my thermo-syphon domestic solar water heater can produce 15
litres hand-hot water for washing up and 5 litres for my daily
ablutions, that's all I'll want from it! I know I can get half a
bucketful of really hot water just from a garden hose in the sun. And
even if I only got a kettleful for shaving from my contraption, that's
one kettle for which I don't need to use electricity or burn oil to
heat.

MM

Right - 3m copper pipe in the sun isnt going to get you much though.

I will have to see. If it isn't adequate, I'll add another 3m. Only
£6.74 from B & Q and I take my pipe cutter with me so that the bus
driver lets me on the bus with it.

If you spent your £13.48 on garden hosepipe you'd get way more heat.
Cover it with polythene to give reasonable stagnation temp, lengthen
the season and make it heat faster.

3m of copper tube and a holding tank are far neater and more compact
than 30 metres of garden hose. And I don't relish the thought of 30
metres of hose with polythene over it practially hiding the entire
lawn.

Add it to a tank of colder water with no circulation and forget it.

The circulation is automatic, on the thermo-syphon principle, like a
car radiator. Many old cars had no water pump.

Yes, but it never circulates as well as pumped.

It circulated well enough for the systems which relied on the
thermo-syphon principle. An oft-demonstrated example of the KISS
principle.





Sounds like you'd be better off with a hosepipe pancake collector.
Make it a decent size and you wont need a tank at all. The hose can
store several litres, and since you need lower temp you can dilute the
hot at point of use, thus will require less than 15 litres in the
collector.

The pancake collector would get hot enough to self sterilise, and will
be flushed regularly. Your tank approach would be right in the
bacterial breeding zone, and never get flushed out.

Surely it gets flushed each time I empty it to use the hot water and
it is replenished with cold?

MM

yes, but only if you empty both tank and pipe fully. I'm not sure how
you're going to achieve that.

Why "fully"? Surely if you have a bowl of hot water and you pour cold
into it, excess water spills over, then the temperature of the water -
ALL the water - falls? Else, why did pouring cold water into
overheated car radiators stop them from boiling over and allowing the
journey to proceed? My "spill over" will be achieved by the simple
expediency of turning on a tap and waiting for a few moments...

Freecycle might get you free hose. Almost any colour works, green,
yellow etc. Using copper wont help.

Green! Yellow! It HAS to be black this year! (I have to think of the
garden's feng shui, too.)

MM


Since youre determined not to learn anything, lets hope something else
gets you before the bugs in the water.

No wonder you call yourself meow!

MM

On Mon, 23 Jun 2008 17:44:05 -0700 (PDT), wrote:

On Jun 23, 9:33*am, MM wrote:
On Sun, 22 Jun 2008 15:14:09 -0700 (PDT), wrote:
On Jun 22, 2:49*pm, MM wrote:
On Sun, 22 Jun 2008 13:26:19 +0100, "George \(dicegeorge\)"
wrote:

why ae you using copper pipe?
why not black plastic pipe?

Indeed. There are several YouTube videos that do exactly this.

I'd put a lot on my roof
except the weight of the water
micht collapse the roof

It doesn't *have* to be the roof (mine is too steeply pitched anyway).
A slanted south-facing collector-cum-frame in the garden is more than
adequate. Just a garden hose left on the lawn for a few hours in the
hot sun produces incredibly hot water, though not enough of it. That's
the reason for the tank. The thermo-syphon principle will keep
circulating the water throughout the late morning and early afternoon.
Hot water should be available after only a few hours.

MM

If you must go with bare copper, at least put a reflector behind it or
a poly cover over it.

I intend to paint the copper pipe matt black, then fit the matrix into
a box lined with loft insulation and thick black plastic like DPC
plastic. The box will be covered with either glass (if I can find a
pane for free - our local window replacement supplier often has old
customer windows stacked outside waiting to be collected) or a
polycarbonate sheet.

MM


and you expect people to help when you misdescribe what youre
building?

In your case I don't expect very much, which is why it is such a
pleasant surprise to be proved correct.

MM

MM wrote:
On Tue, 24 Jun 2008 10:23:28 +0100, Dan Smithers


MM
Mostly, these will be used and drained completely. Considering the
market that it's aimed at, it may have a few days partial use and then
be packed away until next year.

What you are proposing will just be continuously diluting what's inside
your warm water tank.

Hardly. You will know that I am initially using a 4 gallon plastic
header tank from B&Q (until I lay my hands on a galvanised tank). 4
gallons will be all used up to wash dishes, mop the floor, get me a
shave, that kind of thing. I'm not planning a Chinese laundry here!

The impression I got is that you were planning some sort of continuous
top-up.

the B and Q website lists Titan Wizard 25/15 Rectangular Water Tank KM15
Black as having a 68 l capacity (approx. 15 imp. gal.)

dan

On Tue, 24 Jun 2008 10:42:19 +0100 someone who may be MM
wrote this:-

Hardly. You will know that I am initially using a 4 gallon plastic
header tank from B&Q (until I lay my hands on a galvanised tank). 4
gallons will be all used up to wash dishes, mop the floor, get me a
shave, that kind of thing. I'm not planning a Chinese laundry here!

I suspect that, without proper insulation, the heat losses from the
tank will mean that the collector does not heat the contents of the
tank very much.

It is very easy to raise the temperature of a small volume of water.
That is what any solar collector does. What is more difficult is to
transfer and retain that heat, so that it raises the temperature of
the much larger volume of water in the store by a useful amount.


--
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 Tue, 24 Jun 2008 11:25:52 +0100, David Hansen
wrote:

On Tue, 24 Jun 2008 10:42:19 +0100 someone who may be MM
wrote this:-

Hardly. You will know that I am initially using a 4 gallon plastic
header tank from B&Q (until I lay my hands on a galvanised tank). 4
gallons will be all used up to wash dishes, mop the floor, get me a
shave, that kind of thing. I'm not planning a Chinese laundry here!

I suspect that, without proper insulation, the heat losses from the
tank will mean that the collector does not heat the contents of the
tank very much.

It is very easy to raise the temperature of a small volume of water.
That is what any solar collector does. What is more difficult is to
transfer and retain that heat, so that it raises the temperature of
the much larger volume of water in the store by a useful amount.

My understanding, from reading up on various similar projects on the
internet, is that the thermosyphon effect causes the water to
self-circulate through the system, causing the water at the highest
point to get hotter and hotter.

As for insulating the tank, surely it's a toss up between painting it
black to attract maximum effect from the sun, or the insulation
alternative? Anyway, it will be easy to add an insulation jacket
around the tank as an experiment. At the moment it's all rather
academic anyway, since our summer so far has been a washout. My
relative in Hamburg told me yesterday they enjoyed in May-June six
weeks of constant hot, fine weather.

MM

On Wed, 25 Jun 2008 08:39:44 +0100, MM wrote:

As for insulating the tank, surely it's a toss up between painting it
black to attract maximum effect from the sun, or the insulation
alternative?

Black is also a good radiator of heat. What is the relative total surface
areas of your collector and tank? The surface area of your 15 gallon tank
probably is close to that of your collector, you could just shift heat
from the collector to tank and loose it rather than store it...

At the moment it's all rather academic anyway, since our summer so far
has been a washout.

Bright sunshine has the highest energy input but only because the incident
radiation is higher. A solar thermal collector will still produce a heat
output on dull overcast days.

--
Cheers
Dave.

On Wed, 25 Jun 2008 08:39:44 +0100 someone who may be MM
wrote this:-

It is very easy to raise the temperature of a small volume of water.
That is what any solar collector does. What is more difficult is to
transfer and retain that heat, so that it raises the temperature of
the much larger volume of water in the store by a useful amount.

My understanding, from reading up on various similar projects on the
internet, is that the thermosyphon effect causes the water to
self-circulate through the system, causing the water at the highest
point to get hotter and hotter.

Indeed. However, the average temperature the water reaches depends
on its volume. Put another way the smaller the volume of water the
deeper the "high temperature" zone is.

As for insulating the tank, surely it's a toss up between painting it
black to attract maximum effect from the sun, or the insulation
alternative?

The problem comes when the sun is not shining directly.


--
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

MM wrote:
On Tue, 24 Jun 2008 11:25:52 +0100, David Hansen
wrote:

On Tue, 24 Jun 2008 10:42:19 +0100 someone who may be MM
wrote this:-

Hardly. You will know that I am initially using a 4 gallon plastic
header tank from B&Q (until I lay my hands on a galvanised tank). 4
gallons will be all used up to wash dishes, mop the floor, get me a
shave, that kind of thing. I'm not planning a Chinese laundry here!
I suspect that, without proper insulation, the heat losses from the
tank will mean that the collector does not heat the contents of the
tank very much.

It is very easy to raise the temperature of a small volume of water.
That is what any solar collector does. What is more difficult is to
transfer and retain that heat, so that it raises the temperature of
the much larger volume of water in the store by a useful amount.

My understanding, from reading up on various similar projects on the
internet, is that the thermosyphon effect causes the water to
self-circulate through the system, causing the water at the highest
point to get hotter and hotter.

As for insulating the tank, surely it's a toss up between painting it
black to attract maximum effect from the sun, or the insulation
alternative? Anyway, it will be easy to add an insulation jacket
around the tank as an experiment. At the moment it's all rather
academic anyway, since our summer so far has been a washout. My
relative in Hamburg told me yesterday they enjoyed in May-June six
weeks of constant hot, fine weather.

It's not been that bad really - my solar heating (not DIY) has been
producing 200l of 40-50 degree water for the last few weeks. You can get
quite a lot of energy even through the clouds.

If you have a an insulated tank, then it will keep the heat in better
when the sun goes in, or if it starts raining. Additionally, it will
still be warm in the morning if there is any water left in it so the
sun doesn't need to provide so much energy. The surface area of the tank
is small compared to that of your pipework.

BTW Have you considered using an old radiator as a collector?

On Wed, 25 Jun 2008 10:53:38 +0100, Dan Smithers
wrote:

BTW Have you considered using an old radiator as a collector?

Yes, I have seen that being used in some projects. Also the matrix
from the back of an old fridge. This experiment will an on-going
project and I can easily modify the system or enlarge it. If I could
afford £5,000 I could get a professional system installed on the roof
and piped into the house waterworks. Maybe the price will come down if
the government encourages solar energy utilisation as is done in
Germany. At the moment I believe companies see green energy provision
as a licence to print money - for themselves.

MM

On 22 Jun, 15:21, Rod wrote:
MM wrote:
On Sun, 22 Jun 2008 13:18:11 +0100, Rod
wrote:

MM wrote:

So this must exclude plastic (i.e. non-metal) as a material, yes? I've
now stuck an advert in Freecycle for an old loft galvanised tank. (My
old one in Bucks would have been ideal.)

You might not need it to boil - but what are you doing to prevent it
boiling?

Add cold water.

Why are you persisting with trying to use a cold water tank?

I just need * a tank * ! I don't care what it's made from,or what its
original use may have been. All it needs to do is hold hot water at a
temperature of around hand-hot for a decent shower or for washing
dishes.

(I have
never seen a loft galvanised HOT water tank.) Galvanised tanks are
rather unusual these days - given that most new loft tanks are plastic.
So you are likely to be offered a heap of junk.

But I might be offered a perfectly usable one! My old tank in Bucks
wasn't leaking when I replaced it with a black plastic one. I only
replaced it because it *may* have started leaking (it was 47 years
old). So even if I get hold of a tank with a minor leak that I can
easily repair, the tank will be good for years at what I want to use
it for.

Having a hot open tank in your loft (or pretty much anywhere else) is a
bad idea as there will be lots and lots of water vapour leading to
condensation and consequent problems.

It's not going to be mounted inside the house. The tank will be
painted black and mounted outside, against the house wall, above the
collector. (This is only for summer use.)

The obvious thing to try would be a hot water cylinder.

Yes, I might put another advert in Freecycle.

But the point both Dave and I were making is that a tank (whatever sort)
not suitable for boiling water must not be allowed to boil. Which you
could do manually - but what if you just happen to miss the temperature
going past the critical point?

Designed systems have mechanisms to avoid accidental scalding. Take care.

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org- Hide quoted text -

- Show quoted text -


This guy is either trolling or simply does not want to know how to do
it right. OK if he knows what he wants then why are we wasting our
time trying to put him right?