On Thu, 26 Jan 2006 12:12:16 -0800, Aidan wrote:
wrote:
When the water is heated and there's no demand for hot water (e.g. at
night or early morning) the pressure in the cylinder will rise
Get away.
so it is possible for the relief valve to only leak under those conditions,
No. That is the pressure relief valve working normally, relieving the
excess pressure caused by the water expanding and the air bubble being
inadequate to absorb the expansion. It is not 'leaking'. It is not
failing to reseat, which would cause it to drip continuously. Operating
the easing knob, as you have suggested would not effect this problem.
For what it's worth (see Ed's post) the pressure reducer on my unvented
system was 1bar and the safety valves, both the PRV and TPRV, were
correspondingly low rated. I'm not sure placing a 6 - 10 bar PRV when
an e.g. 3 bar one is required is a good idea.
It isn't a good idea, but then that is not what Ed said. He wrote;
"Most unventeds have two pressure relief valves. You _must_ fit the
correct
replacement it will be anything from 6 to 10 bar. "
He was referring to the Pressure Relief Valves which are factory
pre-set at something "from 3 to 10 bar", according to the cylinder
design pressure rating. You have to get the right one, set to the right
pressure, for your cylinder. A PRV set at 6 bar would be little use on
a cylinder designed for 3 bar and which fails at 5 bar.
Also my TPRV was more
like 30 quid but I'm sure I could have paid double/triple had I gone
elsewhere.
Sure you got the right one?
Aidan I didn't mean to imply that that the OP should replace the 3 bar PRV
with a 6 bar unit if a 3 bar unit is the correct one. A 1.5 bar unvented
is quite a bit less pressure that the typical unit.
--
Ed Sirett - Property maintainer and registered gas fitter.
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