Pressure dropping Glowworm 30 sxi

[b0ne5ish]

Hi,

I have a Glowworm 30 sxi boiler, a few days ago the heating wouldn't fire up, the pressure had dropped to 0.6 and was flashing on the screen. I topped up the pressure using the filling loop and the heating came back on. Next day same problem, the pressure had again dropped to 0.6 and after filling it up via the loop it started working again until the next day same problem etc...

I've checked under the boiler itself, I can't see any leaks, there are no obvious leaks around the radiators or in the house. The boiler pressure relief pipe outside is dripping, it's worse after the pressure is topped back up, I top it up to about 2.0 bar.

From what I've read on the net it could be the pressure relief valve that needs replacing, does this sound about right? Is there anything else it might be? Is it a DIY job to drain the system, replace the valve and fill it back up again or should I be seeking a professional?

Thanks.

 

[terryplumb]

You should only get water from the prv pipe if the pressure gets around 3 bar. When topping pressure up ,do it when cold ,and just above 1 bar. Dont take it upto 2 bar ,its too high. Monitor the pressure after c/ heating has been on for an hour ,if its gone up to more than 2.5 bar your expansion vessel is not performing as it should ,much higher and the prv will operate. Once ch cools down ,say overnight after its turned off, water contracts / pressure drops. You wake upto no heating and the cycle starts all over again. Sometimes after prv has been opened ,they dont re seat or seal properly anymore and may need replacing ,but first you need to sort out the pressure drop / re filling issue.

 

[b0ne5ish]

You should only get water from the prv pipe if the pressure gets around 3 bar. When topping pressure up ,do it when cold ,and just above 1 bar. Dont take it upto 2 bar ,its too high. Monitor the pressure after c/ heating has been on for an hour ,if its gone up to more than 2.5 bar your expansion vessel is not performing as it should ,much higher and the prv will operate. Once ch cools down ,say overnight after its turned off, water contracts / pressure drops. You wake upto no heating and the cycle starts all over again. Sometimes after prv has been opened ,they dont re seat or seal properly anymore and may need replacing ,but first you need to sort out the pressure drop / re filling issue.

Thing is the pipe is leaking even if the central heating hasn't been on, I topped it up this morning to 2 bar and the heating's not been on all day and it's now at 1 bar and still dripping cold water out the pipe. I'll switch it on for an hour like you said and see how high the pressure goes.

 

[terryplumb]

As i said earlier ,once prv has operated they some times no longer close fully. Allowing water to dribble out ,boiler off or on.

 

[b0ne5ish]

As i said earlier ,once prv has operated they some times no longer close fully. Allowing water to dribble out ,boiler off or on.

OK thanks, if I top up to 1 bar when it's cold and leave the heating on for an hour what should I expect the pressure to rise to?

 

[terryplumb]

If all is well with the EV , not much . Unless you have a very big house / lots of radiators ,should stay well less than ,2 bar.