Vokera combi boiler has water dripping from overflow pipe

[glasgowgas]

it definetly points to two causes of your pressure rise

faulty expansion vessel or holed plate exchanger

note that your location is glasgow, not saying we never get holed plate exchangers,but its something i find very rarely.

to rule out a holed plate exchanger, isolate the 15mm cold inlet underneath boiler on right hand side,de pressurise to 1.3bar and run on ch

if pressure rises and starts running out PRV,then expansion vessel/expansion vsessel hose is defective.

manual will tell you how to replace it, quite a straight forward job

post back with results

 

[charliechaplinspants]

Charlie, can you explain why above would happen if the EV was knackered? What is the connection between EV and pressure rising continuously?

Am I wrong?

 

[muggles]

Charlie, can you explain why above would happen if the EV was knackered? What is the connection between EV and pressure rising continuously?

Am I wrong?

Quite possibly, but we shall see. OP seems to be suggesting that the pressure rise happens under static cold conditions as well as hot, in which case it would point to a pinholed/cracked HE. If the dripping occurred during heating up and when the system was hot, but ceased on cooling, then that would indicate an EV fault.

 

[charliechaplinspants]

Thanks Muggles, that was meant for DP who is expecting me to explain myself for giving the split diaphragm as a possible reason. I believe he feels that I should undergo some sort of test before daring to give advice on this Forum. It`s not the first time he has questioned my right to express an opinion. Like I say, I`m not a professional like you guys just giving an opinion is all. This is not the combustion chamber folks, no qualifications needed here for thinking out loud.

 

[murrayrfc]

I would like to just point out that the system pressure rises to and becomes stable at 2.7bar.

don't know if this is relevant or not but how come if there is a fault the pressure doesn't keep rising but stops at the 2.7 bar?

 

[glasgowgas]

I would like to just point out that the system pressure rises to and becomes stable at 2.7bar.

don't know if this is relevant or not but how come if there is a fault the pressure doesn't keep rising but stops at the 2.7 bar?

murrayrfc

you are giving us info in dribs and drabs

is your PRV still leaking at 2.7bar?

is your complete system filled and vented?

is your ch running ok now?

is your hot water ok now?

 

[murrayrfc]

Sorry if its bits here and there.

Firstly- PSV dripping, Pressure is at 2.5bar, Pressure goes to just
under 4bar when CH on.

I then pulled lever on PSV to lower pressure to 1bar.

As soon as I stopped draining water the pressure started rising and stopped at about 2.7 bar. PSV still dripping.

CH and hot water seems ok.

My system is unvented.

 

[glasgowgas]

have you isolated cold water inlet valve under boiler?from manual page 36 item 10

then de pressurise to 1.3bar

then run ch.

does pressure rise still?

 

[murrayrfc]

glasgowgas - I wil try this 2moro and post back

thanks for the help so far.

 

[glasgowgas]

no problems

 

[muggles]

Hang on...just noticed you've said overflow pipe. Is it a condensing combi, and is this a plastic pipe about 20mm diameter?

If it`s external then it is hardly likely to be the condensate pipe, which would be in 40mm. Or is 20mm the size of condensate pipe you use externally.

It could be, I've seen many a condensate pipe run in 20mm externally, I was allowing for the possibility of this having been done.

 

[murrayrfc]

it definetly points to two causes of your pressure rise

faulty expansion vessel or holed plate exchanger

note that your location is glasgow, not saying we never get holed plate exchangers,but its something i find very rarely.

to rule out a holed plate exchanger, isolate the 15mm cold inlet underneath boiler on right hand side,de pressurise to 1.3bar and run on ch

if pressure rises and starts running out PRV,then expansion vessel/expansion vsessel hose is defective.

manual will tell you how to replace it, quite a straight forward job

post back with results

1.I disconnected filling loop - (no signs of water getting through).
2.I then Isolated cold Inlet then de-pressurised system to 1bar which was
stable on stand by.
3.Turned on CH, pressure then raised to just over 3 bar before I
switched CH off.
4.Pressure fell back down to 1bar when CH was switched off with cold
inlet still isolated.
5.I then opened cold Inlet with CH off and pressure raised to 2.9bar.

 

[muggles]

Sounds to me like you have both problems suggested here then - the pressure rise on heating would indicate a broken or depressurised expansion vessel, and the filling when you open the cold inlet would indicate a faulty heat exchanger.

Look for the Schrader valve (same as a bicycle tyre valve) on your expansion vessel. Remove the cap and depress the valve pin briefly. Is it air or water that comes out?

 

[g20]

It's 90% that either your expansion vessel isn't pressurised (you can check it an pressurise it using a foot pump) Or the tube connecting to the EV is blocked. Remove the tube and try blow through it, if you cant then clean it out.

Had this problem on a vokera a few months back, exactly the same symptoms as yours and the tube to the EV was blocked up solid. Clean it out then fixed!

 

[muggles]

It's 90% that either your expansion vessel isn't pressurised (you can check it an pressurise it using a foot pump) Or the tube connecting to the EV is blocked. Remove the tube and try blow through it, if you cant then clean it out.

Had this problem on a vokera a few months back, exactly the same symptoms as yours and the tube to the EV was blocked up solid. Clean it out then fixed!

Even with the pressurising with the CH switched off g20???