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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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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? |
#2
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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? |
#4
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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. |
#5
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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) |
#6
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Glow worm boiler at 0.3 bar
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#7
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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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