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

On 21 Jun, 17:47, 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


For 3 metres of copper tube (15/22mm?) you are wasting your money and
time

On Sat, 21 Jun 2008 12:42:34 -0700 (PDT), cynic
wrote:

On 21 Jun, 17:47, 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


For 3 metres of copper tube (15/22mm?) you are wasting your money and
time

How about double the length?

MM

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.


NT

wrote in message
...
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.


NT

Agreed. You might pick up more heat direct into the tank than from the coil.
The tank won't release toxins, but it will become brittle because of the UV.

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

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


NT

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.

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.

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

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.


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.


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.

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


NT

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.

Not long enough unless soldered along all its length (not spots here and
there) to some other form of collector plate a couple of square metres in
area, even then the spacing would be to high to have effcient transfer of
collected energy into the water.

Or will this plastic release toxins when containing hot water?

With your very poor collector it's not likely to get hot enough to deform,
that would be the major risk. Deformation resulting in a split or collapse
of the tank.

I can't find that Titan Wizard KM15 tank anywhere other than on the B&Q
site. It's not a Titan Tanks product as far as I can tell. You need to
find out its specified temperature range.

--
Cheers
Dave.

On Jun 21, 10:03*pm, "Dave Liquorice"
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.

Not long enough unless soldered along all its length (not spots here and
there) to some other form of collector plate a couple of square metres in
area, even then the spacing would be to high to have effcient transfer of
collected energy into the water.

Or will this plastic release toxins when containing hot water?

With your very poor collector it's not likely to get hot enough to deform,

yes This might be a start:

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


NT

On Sat, 21 Jun 2008 22:03:57 +0100 (BST), "Dave Liquorice"
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.

Not long enough unless soldered along all its length (not spots here and
there) to some other form of collector plate a couple of square metres in
area, even then the spacing would be to high to have effcient transfer of
collected energy into the water.

Or will this plastic release toxins when containing hot water?

With your very poor collector it's not likely to get hot enough to deform,
that would be the major risk. Deformation resulting in a split or collapse
of the tank.

As an experiment I took one black plastic builder's bucket (3 gall
size) and filled it with 12 litres of cold water from the tap. I stuck
in my (German) Tauchsieder (1200W) and switched it on for 15 minutes.
I measured the amount of electricity consumed with my Tschibo meter at
£0.035 (3½ pence) and the temperature of the water had increased to
*beyond* hand-hot. That is, I could just about dip my fingers in, but
not for more than a second. The bucket did not deform at all. I doubt
whether another 15 minutes (when the water would be VERY hot) would
make any difference. Now I appreciate that a builder's bucket is not
the same as a loft tank, and is probably far sturdier, especially in
the rim. So what I'm looking for is either an even larger builder's
bucket, or a tank made from the same kind of material. I could, of
course, just use two (or three) builder's buckets connected together.

MM

On Sun, 22 Jun 2008 10:45:43 +0100, MM wrote:

the temperature of the water had increased to *beyond* hand-hot. That
is, I could just about dip my fingers in, but not for more than a
second. The bucket did not deform at all.

So probably not much above 60C or 70C a decent solar collector is
perfectly capable of boil it's circulating water. Plastics do not soften
in a linear manner.

http://news.bbc.co.uk/1/hi/england/cornwall/3035606.stm
http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

Cold water storage tanks are not designed to hold hot water.

--
Cheers
Dave.

On Sun, 22 Jun 2008 11:26:40 +0100 (BST), "Dave Liquorice"
wrote:

On Sun, 22 Jun 2008 10:45:43 +0100, MM wrote:

the temperature of the water had increased to *beyond* hand-hot. That
is, I could just about dip my fingers in, but not for more than a
second. The bucket did not deform at all.

So probably not much above 60C or 70C a decent solar collector is
perfectly capable of boil it's circulating water. Plastics do not soften
in a linear manner.

I don't need it to boil. Just to get hot. I've just popped out the
back and run the tap after 2 hours in the (today, not very hot) sun
(no collector tank yet!) and the water is already warm, despite
today's strong winds. This is even before I construct the insulated
box and paint the pipes black.

http://news.bbc.co.uk/1/hi/england/cornwall/3035606.stm
http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

Cold water storage tanks are not designed to hold hot water.

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.)

MM

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?

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

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.

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

--
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

On Sun, 22 Jun 2008 13:11:06 +0100, MM wrote:

I don't need it to boil. Just to get hot.

You may not need or even want it to boil but if you have a decent
collector how are you going to stop it on bright day?

So this must exclude plastic (i.e. non-metal) as a material, yes?

Depends a cold water storage tank is for that, cold water. I'm sure there
will be plastic tanks out there that can cope with 100C without trouble
but I doubt you'll find them ina DIY shed or builders merchant.

--
Cheers
Dave.

MM wrote:

I've
now stuck an advert in Freecycle for an old loft galvanised tank. (My
old one in Bucks would have been ideal.)

FFS, why not use a hot water cylinder?

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

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

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

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

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

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?

On Sat, 21 Jun 2008 17:47:37 +0100 someone who may be MM
wrote this:-

Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft?

You can. Whether this is advisable is another matter. One question
is what happens if the collector manages to make the water very hot,
perhaps creates steam. Even a small collector can do this if it is
only heating a small volume of water. Control of excessive
temperatures is an integral part of good solar design.

There are some thermal stores made out of plastic. A (very
expensive) range is at
http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.
The difference is that the plastic vessel is designed for this use.

The other important factor in solar heating is insulation of the
cylinder/store to maintain temperature. As a minimum double
thickness sprayed on foam is desirable, triple insulation is better.
If I was making a small system for a few basins then I would
consider having a special cylinder made by McDonald Engineers
http://www.mcdonald-engineers.com/products/cylinders.htm or one of
their competitors.

For a home made collector plenty of designs are available and I
would study several before deciding on a design.


--
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 Sun, 22 Jun 2008 14:22:56 +0100, David Hansen
wrote:

On Sat, 21 Jun 2008 17:47:37 +0100 someone who may be MM
wrote this:-

Can
I feed the hot water (on thermo-syphon principle) into a black plastic
cold water tank as used in the loft?

You can. Whether this is advisable is another matter. One question
is what happens if the collector manages to make the water very hot,
perhaps creates steam. Even a small collector can do this if it is
only heating a small volume of water. Control of excessive
temperatures is an integral part of good solar design.

There are some thermal stores made out of plastic. A (very
expensive) range is at
http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.
The difference is that the plastic vessel is designed for this use.

Just had a look - I'll bet they are expensive!! (No prices stated is a
dead giveaway.) With all new technologies one has to find the
"Ryanair" version, as too many suppliers will be jumping on the
bandwagon and ripping people off, especially those with no DIY skills
who have to trust tradespeople entirely. I tend not to, in principle,
although, rarely, I am pleasantly surprised, like receiving a
Christmas present one actually wants. I always start from the basis
that a company is trying to sell me something that I could get
elsewhere in a similar design for much less. My watchword is: IKEA!


The other important factor in solar heating is insulation of the
cylinder/store to maintain temperature. As a minimum double
thickness sprayed on foam is desirable, triple insulation is better.
If I was making a small system for a few basins then I would
consider having a special cylinder made by McDonald Engineers
http://www.mcdonald-engineers.com/products/cylinders.htm or one of
their competitors.

For a home made collector plenty of designs are available and I
would study several before deciding on a design.

Yes, I have studied numerous designs and watched some YouTube vids.
Now is the time for hands-on experimentation, which is where I'm at.

Re your comment about steam, this system will be open, therefore there
won't be any pressure build up. Also, the whole device is mounted
outside the house, with the collector on a slant against the
south-facing wall and the tank mounted above it, probably on 4" x 4"
fence posts. Maybe I'm lucky in my back garden being a real sun trap.
It does get incredibly hot during the summer (not today because it's
so windy right now).

MM

On Sun, 22 Jun 2008 15:12:43 +0100 someone who may be MM
wrote this:-

http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.

Just had a look - I'll bet they are expensive!!

Four figures I believe. However, they do claim to reduce a number of
disadvantages of normal thermal stores. Whether the price is worth
the result is a matter of personal prejudice.

I always start from the basis
that a company is trying to sell me something that I could get
elsewhere in a similar design for much less.

http://www.navitron.org.uk/page.php?19

"Navitron Ltd is committed to providing low cost alternative energy
solutions to the consumer and small business. For far too long,
some companies have made huge profits from solar energy scams,
ridiculously over-priced double-glazing units and funny magnets you
stick in your hot water tank to ward off evil spirits! Don't get us
wrong: We're a profit-making organisation; just not a profiteering
one."

Re your comment about steam, this system will be open, therefore there
won't be any pressure build up. Also, the whole device is mounted
outside the house, with the collector on a slant against the
south-facing wall and the tank mounted above it, probably on 4" x 4"
fence posts.

In essence you are building an "african" water heater, of which an
example is http://www.navitron.org.uk/page.php?55. The steam vent
on the right hand side of the cylinder is necessary and steam comes
out of it even in the UK.

One of the disadvantages of a thermo-syphon design is that if the
collector overheats more water will flow to the collector, to be
turned into steam. The steam then bubbles up to the vent and more
water flows to the collector. One of the advantages of pumped
designs is that if the collector overheats the limited amount of
water in the collector is turned into steam. This forms a steam
bubble which goes a little way along the pipes and then stops. When
the sun goes down water flows into the collector again and, provided
the collector is robust enough, operation then continues as normal.

If you do this put the vent through the roof so that you don't
introduce dampness into the loft.






--
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 Sun, 22 Jun 2008 18:09:56 +0100, David Hansen
wrote:

On Sun, 22 Jun 2008 15:12:43 +0100 someone who may be MM
wrote this:-

http://www.consolar.co.uk/index.php?option=com_content&task=view&id=6&Itemid =15.

Just had a look - I'll bet they are expensive!!

Four figures I believe. However, they do claim to reduce a number of
disadvantages of normal thermal stores. Whether the price is worth
the result is a matter of personal prejudice.

I reckon solar heating is still seen, in Britain at least, as quirky,
expensive, "designer" -- and there will be much exploitation going
on, no doubt. As ever, no guidance from the Brown mob. Germany is far
and away ahead, AGAIN!

I always start from the basis
that a company is trying to sell me something that I could get
elsewhere in a similar design for much less.

http://www.navitron.org.uk/page.php?19

"Navitron Ltd is committed to providing low cost alternative energy
solutions to the consumer and small business. For far too long,
some companies have made huge profits from solar energy scams,
ridiculously over-priced double-glazing units and funny magnets you
stick in your hot water tank to ward off evil spirits! Don't get us
wrong: We're a profit-making organisation; just not a profiteering
one."

Hey! They can be my friend!

Re your comment about steam, this system will be open, therefore there
won't be any pressure build up. Also, the whole device is mounted
outside the house, with the collector on a slant against the
south-facing wall and the tank mounted above it, probably on 4" x 4"
fence posts.

In essence you are building an "african" water heater, of which an
example is http://www.navitron.org.uk/page.php?55. The steam vent
on the right hand side of the cylinder is necessary and steam comes
out of it even in the UK.

One of the disadvantages of a thermo-syphon design is that if the
collector overheats more water will flow to the collector, to be
turned into steam. The steam then bubbles up to the vent and more
water flows to the collector. One of the advantages of pumped
designs is that if the collector overheats the limited amount of
water in the collector is turned into steam. This forms a steam
bubble which goes a little way along the pipes and then stops. When
the sun goes down water flows into the collector again and, provided
the collector is robust enough, operation then continues as normal.

If you do this put the vent through the roof so that you don't
introduce dampness into the loft.

The tank is going to be mounted outside on the wall next to my small
annexe, where I have sink facilities. Nothing is going to be installed
in the house. I even take the cold water from the garden tap.

MM

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.

My concern here is that you've shown a slight lack of clue from the
outset and now it sounds like you're building up to kill someone,
possibly yourself.

On Sun, 22 Jun 2008 14:44:16 +0100, (Steve Firth)
wrote:

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.

So a galvanised tank such as used in lofts should be ideal? Or must I
worry about chemical reaction between hot water and zinc?

My concern here is that you've shown a slight lack of clue from the
outset and now it sounds like you're building up to kill someone,
possibly yourself.

I expect many more people are killed or badly scalded in ordinary
domestic baths than are ever hurt during solar hot water experiments.
Mind you, getting up on a roof carrying acres of garden hose might
mean a few broken arms and legs when they fall off.

MM

MM wrote:

So a galvanised tank such as used in lofts should be ideal?

Other than it being neither enclosed not insulated you mean?

Or must I worry about chemical reaction between hot water and zinc?

I'd be more worried about the reaction betweeen oxygen and steel.

"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 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

"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:

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.

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?

"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 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

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.

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.




--
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