COmbi boiler isolation valve query - do they leak?

[stevenjackson123]

Hi

I have a concern that I'd like to ask for advice on if possible please?:

I believe my expansion vessel in my boiler to be flat (over time just lost it's charge) as everytime the boiler's been on the pressure raises to 3 bar and the PRV allows water to escape. I then notice the boiler gauge goes to 0 bar and I fill up up again to 1 bar and this keeps happening. (the boiler doesn't look out though).

I have heard that when you turn the isolating valves to the boiler (underneath the combi) OFF, and then open them up again after draining/re-pressurising the vessel, that they will leak? Is this true?? If so how can I avoid them leaking/re-charge the vessel without closing them as I'd prefer not to drain dow the whole system if possible.

Many thanks for your help

My boiler is Worcester Junior 24i combi boiler

Steve

 

[Agile]

See FAQ on how to repressurise.

The ones on YOUR boiler rarely leak.

Its not essential to turn the boiler valves off.

Tony

 

[stevenjackson123]

I have read the FAQ and it seems a bit confusing! It may be me! To clarify is this correct:

drain water from the system at my drain valve downstairs until the gauge read 0 (as my boiler is upstairs will this be quicker than if it were downstairs?, obviously?!!). Then drain about 10 litres more. Remove schrader vale cap, re charge to just under 1 bar pressure, then replace cap, and re-fill system to original 1 bar pressure, venting and topping back up to 1 bar?


Thanks for helping me I am very thankful.

 

[Agile]

I have read the FAQ and it seems a bit confusing! It may be me! To clarify is this correct:

Depress air valve FIRST and see if water comes out---should not ! Let ALL the air out.

drain water from the system from upstairs as from downstairs you would take out more than needed. Its only a few litres and can be done from an air bleed screw upstairs.

until the gauge read 0

Then drain about 10 litres more. DONT DO THAT !!! It should not be in the FAQ but then I dont write them!

Remove schrader vale cap, re charge to 0.9 bar pressure, then replace cap, and re-fill system to 1.5 bar pressure, bleed rads and repressurise to 1.5 Bar.


Thanks for helping me I am very thankful.

Tony

 

[stevenjackson123]

Thanks for your help I will crack on now with this.

I will also remember this for the future in case it happens again.

If the boiler were downstairs would the process be the same, only bleed a rad downstairs, but would take longer?

Thanks for your help

Steven

 

[Agile]

You only need to reduce the pressure to zero. You dont need to drain the system.

BUT as you repressurise with air you DO need to keep letting a bit more system water out as the pressure increases to bring it back to zero.

Tony

 

[stevenjackson123]

I did it about 10 mins ago as you said (for upstairs boiler) and didn't drain more water when charging the vessel like you said in your last message on this post. Will I need to do it again?? What I did was draw water from an upstairs rad vent (same level as boiler), until the gaueg was at 0. The I recharged and topped up system again. Is this OK?

 

[Agile]

Hopefully it will be.

If you let all the air out first as I listed and no water came out then the vessel seems to be OK and should function correctly from now on.

Tony

 

[stevenjackson123]

When I charge air into the vessel surely no more water needs to be drawn as when the gauge reads 0 no more water can get back in until I top the system up again?

Sorry I am just trying to understand the science to this!!

 

[jackecole]

Whatever floor the boiler is on:

Make sure filling loop/key is removed from boiler and isolators are closed so it cannot automatically refill

Drain water from a rad valve on the same floor as the expansion vessel/boiler

Make sure the gauge reads 0

Remove vessel cap and check pressure with a gauge (pencil gauge is best)

Depress valve and check no water escapes (if it does, the diaphragm in the valve is faulty/split etc and letting by)

If no water escapes: re-pressurise vessel to approx 0.7 bar (at least 0.5 but go a bit higher)

Check pressure again with gauge

If now 0.7 bar approx replace cap

Fill system up, to about 1 bar - 1.2 bar (it's normal setting)

Vent rad (s) and top up to normal setting (eg 1 bar 1.2 bar again)

That should be fine

Turn on boiler/fire it with h/w or heating and check the prv no longer blows and that the pressure on the gauge doesn't rise to 3 bar again.