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Default Glow worm boiler at 0.3 bar

Our boiler pressure has gone down to 0.3 bar, we have tried turning
the blue water knob underneath (usually works), there is no sound of
rushing water like there usually is, and the net effect of turning
the
knob is zero.

We have done a bit of research and discovered that the expansion
vessel valve can be used to pump up the pressure again. With great
difficulty we got the cap off the expansion vessel and attached a
bike
pump, we gave 20 or so pumps and turned the boiler back on, but the
pressure had only shifted from 0.3 to 0.4 - we cannot seem to get it
any higher by pumping air in.


We tested the valve, and there was a sound of escaping air, so we
guess our diaphragm is not ruptured.


We don't want to do much else because we do not want to destroy our
expansion vessel or damage the boiler in any other way.


We were wondering if we've missed any other vital steps - in another
post we read that you need to depressurise the main system first, but
we have no idea how to do that. Howe much air do you need to pump in
with the bicycle pump for the expansion vessel to regain ideal
pressure?
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Default Glow worm boiler at 0.3 bar

Thanks for your reply.

We have a filling loop, usually when we turn it on, there is the sound
of rushing water, and the pressure goes back up into the ideal range.
At the moment when we operate the filling loop, nothing happens at
all, and there is no sound of rushing water.

We were wondering if this is symptomatic of a broken filling loop, or
just a side effect of something else.

We have a car tyre pump with gauge, but we're too scared to attach it
to the expansion vessel value, in case it over-inflates the vessel
and ruins it. Also, the gauge on the car tyre gauge goes up to 250 psi
- much more than the 7 psi needed for the expansion vessel, so
it's not a very good gauge of how much pressure is in the vessel -
attaching the pump to the vessel valve barely moves the needle.

Also, is using a bicycle pump a practical way to repressurize the
expansion vessel? We pumped away for a while, but had no effect when
we
switched the boiler back on??? How much pumping should be necessary?
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Default Glow worm boiler at 0.3 bar

In an earlier contribution to this discussion,
wrote:

Thanks for your reply.

We have a filling loop, usually when we turn it on, there is the sound
of rushing water, and the pressure goes back up into the ideal range.
At the moment when we operate the filling loop, nothing happens at
all, and there is no sound of rushing water.

We were wondering if this is symptomatic of a broken filling loop, or
just a side effect of something else.


There should be *two* valves/taps on the filling loop. Are they both turned
on? [When you're not topping up the system the filling loop's flexible pipe
should be disconnected - so it needs a valve at the mains end to stop water
pouring out when the pipe is removed and, similarly, another at the heating
system end which remains with the system to prevent *that* emptying]

So you can test the filling loop by disconnecting the hose. When you open
the valve at the mains end you should get mains water coming out (so use a
bucket in which to catch it!). Likewise when you open the other valve,
heating water should come out - so this is a good way of making sure that
the system is unpressurised before you pump up the air in the expansion
vessel.

We have a car tyre pump with gauge, but we're too scared to attach it
to the expansion vessel value, in case it over-inflates the vessel
and ruins it. Also, the gauge on the car tyre gauge goes up to 250 psi
- much more than the 7 psi needed for the expansion vessel, so
it's not a very good gauge of how much pressure is in the vessel -
attaching the pump to the vessel valve barely moves the needle.

Also, is using a bicycle pump a practical way to repressurize the
expansion vessel? We pumped away for a while, but had no effect when
we
switched the boiler back on??? How much pumping should be necessary?


You can use a bicycle pump if you wish, but you *must* be able to measure
the pressure when you've done it - no-one can tell you how many strokes of
the pump are needed! The usual charge pressure is about 0.7 bar - which is
10psi not 7psi. If the gauge on your car pump doesn't provide sufficient
discrimination, buy a cheap pressure gauge such as
http://tinyurl.com/39g79n
from Halfords.
--
Cheers,
Roger
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Default Glow worm boiler at 0.3 bar

Thanks for your input - in the end, it turned out to be debris stuck
in the filling loop valve.
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Default Glow worm boiler at 0.3 bar

On Jan 7, 9:25*am, wrote:
Our boiler pressure has gone down to 0.3 bar, we have tried turning
the blue water knob underneath (usually works), there is no sound of
rushing water like there usually is, and the net effect of turning
the
knob is zero.

We have done a bit of research and discovered that the expansion
vessel valve can be used to pump up the pressure again. With great
difficulty we got the cap off the expansion vessel and attached a
bike
pump, we gave 20 or so pumps and turned the boiler back on, but the
pressure had only shifted from 0.3 to 0.4 -




The water pressure in the system and the air pressure in the vessel
are separate items. Air compresses into the limited space. If you
pump it up too much you can damage it. You should set it to the
manufactures recommended setting.

Sounds like the mains water has failed or been switched off or the
filling loop valve is either still closed or the non-return valve is
stuck. You supposed to disconnect the fillign loop once you've
filled it. The next thing is to work out why the system has
depressurised - usually it means a leak somewhere and it can be tiny
(until your ceiling falls in)


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Default Glow worm boiler at 0.3 bar

On Mon, 07 Jan 2008 16:52:22 GMT someone who may be
wrote this:-

Not true, there should be a double check valve at the boiiler inlet to
prevent the system contents from backflowing into the mains.


The double check valve is slightly better placed on the mains side,
to prevent the rather remote possibility of back siphonage via the
filling loop. It also allows draining/relieving pressure via the
filling loop. The disadvantage is that it allows those with
inquisitive fingers to turn an easy to turn valve and allow hot
water out under pressure.


--
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
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