Glow worm 30si expansion vessel?

[sailorf80]

I've got a Glow worm 30si system boiler which has been in for 5 years or so. I've had a recent issue that seems to be pointing to the expansion vessel but need to get some expert opinion.

The boiler is failing on low water pressure each time it cools back after a run. I can pressurise the syatem to 1.0 bar ish; it then runs fine and when it's completed heating a couple of hours or so later the pressure is often up aroung 2.4 bar. Overnight as it cools back the pressure falls to below 0.5 and consequently will need recharging again before it can run again.

I've checked the system for leaks and can even isolate the boiler to ascertain where the fault lies. It's clearly the boiler and not the system.

Is this an expansion vessel problem, and if so do I need to change it or is there a repair method? The book says the whole boiler has to come off to get at it, but also states that another vessel of similar spec can be added in as close to the boiler as possible.

Just hoping someone may have some idea as to what's needed. Thanks in advance.

 

[picasso]

look at the faq,s at the top of the page, there is a section there about repressurising vessels,, you will be able to get to the valve without taking the boiler off, the manufacturers havent got quite that bad yet.

 

[sailorf80]

Read the FAQ as suggested.

Got to the schraeder connection on the expansion vessel, checked the pressure; bit low but no water coming out.

Depressurised system anyway, and pumped vessel up to .8 Bar; however there is a constant drip on the relief line which is no doubt my problem. I tried snapping and re-seating the valve but no joy as it still drips.

I'll have to source a new one and fit this weekend.

 

[mickyg]

another thing to check is the pipe connecting the EV to the boiler hydraulics. These are prone to blocking. How easy was it to pump up the EV? should have took quite a few pumps.

 

[sailorf80]

I used a stirrup pump, and you're right it was quite a few pumps to get to pressure.

 

[sailorf80]

Picked up a new relief valve and fitted it this morning, job done, everything back to normal.

As a little aside I originally looked for the new part on line and the best price I could find was £25 +VAT; however out of interest I call parts centre here in Pompey and they provided one for £13 all in. Just goes to show that not everything is cheaper on the Internet.