Non-metallic hot water cylinders

[Doctor Drivel]

Please eff off as you are a total idiot.

[Edward W. Thompson]

snip

[Mary Fisher]

?

'Commonplace' wasn't specified :-)

Mary

[Matty F]

The hot water tank was in a little box on top of the roof of a mountain hut miles from any other residents. Now that the tank is gone, there is steam coming out of the solar panel, which is made from copper with a glass top. I don't know why they didn't steal the panel as well, although it's rather heavy to carry for 500 yards to the thieves truck.

If we decide we want to have hot showers again we will certainly wire the hot water box up to the Screamer alarm on the roof which can be heard for about a mile. Hopefully there will be a very deaf thief who breaks his leg falling off the roof.

[Matty F]

Yes I have a plastic kettle that has lasted well for 15 years. I could just buy 50 plastic kettles! :) My car radiator is plastic and that is pressurised, so would exceed

100 degrees. The tank is above a roof, so no problem if it leaks. The water probably does not reach boiling point except when the tank is stolen, but it's hot enough that we had to have a temperature limiting mixing valve. The water is only used for a shower.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Plowman (News)" saying something like:

" most easily/cheaply available plastics"

"I was looking at HDPE primarily"

[John Stumbles]

If it's a one-off DIY job I'd look for a pre-loved GRP CW storage tank, build a stout box around it and pack a load of skip-grade Kingspan and glass/rockwool fibre or PU foam between the tank and the box (to partially support, as well as insulate, the tank - I'm sure even GRP is weaker when it's hot). And a lid, natch, insulated natch squared.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Matty F saying something like:

I was looking at easily available plastic tanks, barrels and drums of

60~200L in HDPE (think blue plastic) and IBC containers of 1000L (again, white HDPE or similar). Anything else will cost you or not be easily available or identifiable. As for kettle or radiator plastic - for f*ck's sake read what I wrote, not what you think I wrote.

[Matty F]

Yes I think that or Grimly's HDPE should do the trick thanks. We already have the box and glass fibre insulation.

[Andy Champ]

Seems to me that if you foamed the void between tank and container fully (expanding foam foamed in place, not bits) the outer, cold, container would take the strain, not the hot inner.

ISTR this being used in the Haber process - the vessel is double walled, the weak inner vessel protects the strong outer vessel from the reactants, an inert gas being used between them to transfer the load.

Andy

[Matty F]

OK, so I'll look out for two containers, and use that expanding foam stuff between them. Perhaps I don't need a lot of insulation, and then the water won't reach boiling point. It would be better to have a large tank at a lower temperature. We've never run out of hot water anyway. It costs nothing to heat it, and the water is collected on the roof, going into a tank that holds about 30 cubic metres.

[Doctor Drivel]

30 cubic metres? Do you need that much hot water?

[Matty F]

That's just the cold water tank. Goodness knows why they got such a large tank. However it was useful for the fire brigade when someone burnt the original building down. At least it didn't set fire to the trees as well. The existing box on the roof would accommodate a 100 litre hot tank, but we could rebuild it for a 200 litre tank. Or tell people to have shorter showers. To hell with it, 20 minutes of shower is enough for a hutload of people, 100 litres it is.

[Andy Dingley]

Expanding foam isn't a good insulator - different mechanical structure to the factory-foamed stuff, much lower performance.

My solution to this (solar thermal store) is to switch from a round to a rectangular plastic tank, then use a constructed box of yellow foam PIR boards on the sides of it.

[Mary Fisher]

And difficult to get into a restricted space.

A solution suggested to me by someone high up in such things is to build the box round it and fill it with expanded polystyrene beads. It wouldn't be perfect but it would be cheap and easy to do.

Nothing's perfect :-)

Mary

[Matty F]

Here's the box after the thieves wrecked it:

it's square I guess a square tank would be sensible :) There's about 360 litres of room there excluding insulation.

[Bruce]

Does he need that much weight?

30 tonnes of water! I hope the foundations are built to take it.

[Andy Dingley]

Sorry, Solar twin, not Thermal twin.

If you had a heatpipe system instead, even compared to a vacuum tube system with a water loop like the Solartwin, then you'd see much higher output temperatures.

[Mary Fisher]

You need to brush up, Andy :-)

Mary

[Matty F]

The large cold water tank is on the ground uphill from the building. There's a small cold water tank on the ground below the building fed by rainwater from the roof. Water is automatically pumped to the large tank when the level drops.