I have been following this thread. I looked at the DPS Pandora hea bank, which looks appealling. It is filled by a hose pipe and seale with a screwed plug. If the water boils inside what happens? There i no overflow pipe. How do they get around the explosion
-- Hands On
An overheated cylinder would burst explosively from the steam pressure. The explosive force in an overheated cylinder was reckoned to be (when they were legalized, in about 1987) equivalent to about 4oz of HE.
A colleague saw the result of a coal-fired domestic boiler having burst the hot water cylinder in the 1940s. All the cold feed and open vent pipes were frozen. It demolished part of the side of the house.
I forgot to mention that a thermostatic mixing valve on the output is de rigeur. The cost should still be around the 200 quid mark.
Christian.
Especially if the boiler's overheat stat has blown (or is not existent). The boiler itself can be pumping pressurised steam through the cylinder's coil.
Obviously, an electric immersion has a much more common failure mode to do so, though.
Christian.
A boiler has many levels of safety, whereas an immersion usually has one. A boiler: usually two electrical and one mechanical (blow-off) on the boiler. There is also the cylinder and room stats which are the first safety level. So usually 4 in all on a sealed system.
Christian.
Probably expansion vessels for a pressurization unit or a twin-impeller negative head pump. See the information on neagtive head shower pumps on the Stuart Turner site. Maybe necessitated by a shower in the loft area, above the level of water in the storage cistern.
Interesting, thanks, I will try and look up your suggestion.
You are incorrect. It is not sealed by the plug. The system is vented and will release steam if boiled. They have carefully designed the system to reduce loss by evaporation, though, so the venting arrangement isn't obvious.
Christian.
In article , Christian McArdle writes
It is. Thank you for posting the link.
Did you get sued?
How can they reduce loss by evaporation and still have it vented? I looks like they have a normal pressure vessel and taken the air out o the top having the top half of the vessel open to the atmosphere. I moves up and down. This would keep a seal as the diaphragm is rubber Still confused.
Does this Pandora require a service? DPS say it doesn't. If open to th atmosphere it must allow some evaporation which would lower the wate level inside, which means it has to be topped up
-- Hands On
I'm entirely sure. However, the rubber diaphragm looks particularly frangible. There is also some sort of unidentifed valve on the side. Whether this is related, I don't know. However, I'm pretty sure they've thought about it and have designed some method for it to reliably blow at very low pressures.
It does need topping up occassionally. However, I've had mine for well over a year and there is no sign that it needs more water.
Christian.
"Frangers" are a name for condoms (antipodean I believe, or some other place with criminals like France). One hopes that they are not frangible.....
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