Annoying intermittent fault any takers ....

[Riley]

Evening all

called out to an Alpha CD25C

tenant complaining of pressure loss. Get there and gauge on zero. Whilst at zero, re-pressurised exp vessel. Re-pressurised system and tested, all working correctly.

Told tenant to shout if pressure drops again. Got 3/4 way home and phone goes. As she wasn't too tough on the eye I swung round and went back. She said it lost pressure again as soon as she used the shower. Whilst shower warmed up she'd gone into the kitchen to get something and noticed that the boiler had gone right up to 2.5bar almost instantly.

I re-pressurised boiler again and spent the next hour or so trying to recreate this fault. No joy!!!
left tenant to it ️️saying to shout if it happens again. Got phonecall at 20:00 saying pressure has dropped again. Not a clue what's happening with it. PRV seems fine, exp vessel charged and holding, no let by at filling loop, and nothing from condense so looks like hex is ok.

Please can anyone help

 

[Ch4 plumbing]

The expansion pipe could be blocked mate? Is it braided hose?

 

[gasmanrob]

Not teaching anyone to suck eggs but did you open the system to atmosphere when charging the vessel?

 

[Riley]

The expansion pipe could be blocked mate? Is it braided hose?

I don't believe so. I can check

 

[Riley]

Not teaching anyone to suck eggs but did you open the system to atmosphere when charging the vessel?

No worries rob but yes it was

 

[goz666]

Evening all

called out to an Alpha CD25C

tenant complaining of pressure loss. Get there and gauge on zero. Whilst at zero, re-pressurised exp vessel. Re-pressurised system and tested, all working correctly.

Told tenant to shout if pressure drops again. Got 3/4 way home and phone goes. As she wasn't too tough on the eye I swung round and went back. She said it lost pressure again as soon as she used the shower. Whilst shower warmed up she'd gone into the kitchen to get something and noticed that the boiler had gone right up to 2.5bar almost instantly.

I re-pressurised boiler again and spent the next hour or so trying to recreate this fault. No joy!!!
left tenant to it ️️saying to shout if it happens again. Got phonecall at 20:00 saying pressure has dropped again. Not a clue what's happening with it. PRV seems fine, exp vessel charged and holding, no let by at filling loop, and nothing from condense so looks like hex is ok.

Please can anyone help

Take the hint Riley, she aint too bad on the eye, and shes calling you back for a fault you can't recreate. Nail it fella....lol. Oh and what he said above, I've done two new braided recenlty although on Worcester's both were blocked as above.

 

[Riley]

Cheers goz does make sense can't recall if it's braided though. Good excuse to pop back

 

[Alpha man]

Checked the vessel?, no flexi hose either.

 

[Riley]

Cheers alpha Man, I didn't know if you'd be able to resist the title or not. Expansion vessel has been charged to MIs. I actually called the alpha technical helpline and they said it could be down to poor circulation however I still can't understand how this would give the symptom that the tenant described. Having two outlets running and all of a sudden the pressure peaks. It should be noted that I have not managed to get it to repeat this in three visits. I am tempted just to push them towards the one-off fix all fee from Alpha

 

[southcoastboile]

If the prv is dry then it won't be a locked vessel hose, or undersized vessel was my other thought if it is going out prv.

only other thing I can think and it's clutching at straws but Mabey the plate to plate has pin holed and running the shower takes enough pressure off the water side to let the heating water into it causing it to drop. Doesn't explain pressure rise though but that could be normal expansion on the heating.

 

[Riley]

Maybe so mate. Good suggestions. As said though I am still unable to get the boiler to fault

 

[dancinplumba]

Isolate boiler and run dhw see what happens. Goes to 2.5 then zero ? Why does it go to 2.5 ? Pipe to exp could still be blocked
Did lots of water come out when you pumped up vessel ?

 

[Riley]

Nothing came out of vessel. Held pressure fine

 

[Leo21]

If the vessel pipe was blocked it would make it seem like vessel was ok.

 

[Riley]

Ah sorry yes misunderstood your point. I'll try tomorrow

 

[Millsy 82]

I've had a sludges up heat ex and plate and that caused pressure but that you could tell within about 1 min of firing it up as the boiler almost bounced of the wall.

 

[Riley]

Vessel pipe not blocked and I cannot get the boiler to fault by firing it up under any means. I'm gonna pass to alpha I think. I've wasted enough time on it unfortunately. Thank you all for your kind duggestions