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 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

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.

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 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 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 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 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

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 13:11:06 +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.

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 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 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.

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.

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?

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 Sun, 22 Jun 2008 13:41:02 +0100 (BST), "Dave Liquorice"
wrote:

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?

If it is really a problem I'll just run some cold water into the tank.
Or cover the collector with a shiny reflector to shield it.


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.

Since my last post I've thought of another brilliant wheeze: A
galvanised dustbin. These are available from Wilko and elsewhere and
are dirt cheap. If it's too tall, then I can cut it down to size with
tin snips. The lid will still fit.

MM

On Sun, 22 Jun 2008 14:58:23 +0100 someone who may be MM
wrote this:-

If it is really a problem I'll just run some cold water into the tank.
Or cover the collector with a shiny reflector to shield it.

Are you around all the time during daylight to do this?



--
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 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

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

On Sun, 22 Jun 2008 15:01:19 +0100, David Hansen
wrote:

On Sun, 22 Jun 2008 14:58:23 +0100 someone who may be MM
wrote this:-

If it is really a problem I'll just run some cold water into the tank.
Or cover the collector with a shiny reflector to shield it.

Are you around all the time during daylight to do this?

Yes. I'm retired. If I go off somewhere on a very hot day, I'll just
shield the collector so that the temperature is reduced. I won't need
the hot water anyway if I'm away. Actually, I have designed the whole
system to be unclipped easily for putting away during winter.

MM

On Sun, 22 Jun 2008 14:44:17 +0100, (Steve Firth)
wrote:

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?

"FFS"? Is this really necessary?

MM

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:

On Sun, 22 Jun 2008 14:44:17 +0100, (Steve Firth)
wrote:

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?

"FFS"? Is this really necessary?

It makes more sense than using something that is not designed for the
job. I don't understand your approach to making a solar collector and
hot water store.

FWIW, my first experiment was with a 1 metre square single-panel
radiator. I painted the radiator with matt black using a high
temperature paint, and built an enclosure using aluminium extrusions and
aluminium sheet. I insulated the rear of the panel using urethane foam
and fitted a glass sheet to the front of the panel. Connections to the
top and bottom of the panel were done using hose tails.

This used as a thermal syphon or in conjunction with a 12V pump and 20W
solar panel set up to recirculate water provided enough hot water for
three people to shower and wash dishes/clothes. One a clear sunny day
the temperature of the water got high enough to soften the hose used and
to deform the first container I used. I changed to using a polypropylene
container which is the sort of "plastic" container referred to by
Hansen, which melts at 130°C and is therefore safeish to use with solar
hot water. Polypropylene is an expensive material and if I had to pay
for the container it would have been a silly price. The container had a
screw lid wich I fitted with a vent and I insulted the body of the
container.

If you don't have a tank with a lid, you will lose heat almost as fast
as you collect it by evaporation from the surface of the water. If you
don't have insulation the tank will cool rapidly. Your "serpent" is
woefully undersized and IMO you have done little or no research before
starting your project.

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.

On Sun, 22 Jun 2008 15:40:51 +0100, (Steve Firth)
wrote:

MM wrote:

On Sun, 22 Jun 2008 14:44:17 +0100, (Steve Firth)
wrote:

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?

"FFS"? Is this really necessary?

It makes more sense than using something that is not designed for the
job. I don't understand your approach to making a solar collector and
hot water store.

FWIW, my first experiment was with a 1 metre square single-panel
radiator. I painted the radiator with matt black using a high
temperature paint, and built an enclosure using aluminium extrusions and
aluminium sheet. I insulated the rear of the panel using urethane foam
and fitted a glass sheet to the front of the panel. Connections to the
top and bottom of the panel were done using hose tails.

This used as a thermal syphon or in conjunction with a 12V pump and 20W
solar panel set up to recirculate water provided enough hot water for
three people to shower and wash dishes/clothes. One a clear sunny day
the temperature of the water got high enough to soften the hose used and
to deform the first container I used. I changed to using a polypropylene
container which is the sort of "plastic" container referred to by
Hansen, which melts at 130°C and is therefore safeish to use with solar
hot water. Polypropylene is an expensive material and if I had to pay
for the container it would have been a silly price. The container had a
screw lid wich I fitted with a vent and I insulted the body of the
container.

If you don't have a tank with a lid, you will lose heat almost as fast
as you collect it by evaporation from the surface of the water. If you
don't have insulation the tank will cool rapidly. Your "serpent" is
woefully undersized and IMO you have done little or no research before
starting your project.

I'd better just shoot myself then!

MM

MM wrote:

I'd better just shoot myself then!

How about just getting a clue?

On Sun, 22 Jun 2008 15:25:06 +0100 someone who may be MM
wrote this:-

Yes. I'm retired.

Lucky you.

If you are interested in solar projects and have the time then the
It's Not Easy Being Green forums have a thread on building a clone
of the Solartwin.



--
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 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 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

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

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

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

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.

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