Combi boiler; PRV leaking??

[terryplumb]

A long way to go ?

 

[Harry Bloomfield]

Never assume the most expensive part has failed, until the less expensive fixes have been eliminated.

 

[terryplumb]

Yes indeed.

 

[CBW]

Never assume the most expensive part has failed, until the less expensive fixes have been eliminated.

Terry hasn’t assumed anything

 

[Laurence Harvey]

OP here with an update:...I went to my sons house today;...it’s been quite warm here (Cheshire) so the heating hadn’t been on and the rads were cold.

The pressure gauge was showing approx 1.9bar. Following tp’s advice I removed the filling loop completely to check for leaks from both valves,...no leaks whatsoever.

I kept the filling loop disconnected and then set about reducing the C/H pressure down to a starting point of about 1.2bar by the opening the drain valve which is on the kitchen rad immediately adjacent to the boiler.

I drained the rad slowly and watched the pressure gauge also slowly drop, as one would expect. At 1.1 bar I closed the rad drain valve fully expecting the pressure to remain stable at 1.1bar. However, the pressure immediately started to rise again and within a minute or so was back at almost 2bar!...and this happened with the filling loop completely disconnected!

I then tested the ‘hot water only’ by filling the bath. The pressure stabilized at approx 2.1bar and there was an uninterrupted supply of hot water. No apparent problems whatsoever.

However, I then cranked up the hallway wall thermostat to switch the C/H ‘on’ and the pressure gauge immediately started to rise to about 3.7bar and the prv outlet pipe was dripping like buggery. The rads were all quickly up to temperature as per normal though.

The mains water supply appears to be pressurizing the C/H system even when the filling loop is removed;...what’s going on guys? I really need your expert guidance on this one.

Sorry for the long post but I’ve tried to give as full and accurate description as I’m able to do.

 

[terryplumb]

Plate heat exchanger is perforated,hence the cold mains is entering the sealed system and increasing the pressure.

 

[Laurence Harvey]

Thanks for the reply, very much appreciated;...the engr who did a service on the boiler (it’s 4 or 5 years old: Ideal Logic Combi ES30) about a year after my son bought the house (which was a couple of years ago) appears to have retired so I’m looking at the repair options.

In view of the potential high cost of the repair I’ve been having a look at the repair options ‘Ideal Heating’ themselves offer;...i.e. £299 fixed price repair option,...if the boiler can’t be repaired they just charge £125 for the call out,...or, their 6-months ‘repair & care plan’ @ £50/month by direct-debit for 6 months. Of the 2 options their ‘repair & care plan’ seems to be a no-brainer.

Alternatively, will I be better finding a local gas-safe engr to repair the boiler?

All advice gratefully received.

 

[CBW]

Alternatively, will I be better finding a local gas-safe engr to repair the boiler?

Could be, rough costing is £80 - 130 for plate heat exchanger (if it’s definitely this) plus fitting and carrying out essential checks afterwards, so depends on what a local would charge for this.

 

[Laurence Harvey]

Could be, rough costing is £80 - 130 for plate heat exchanger (if it’s definitely this) plus fitting and carrying out essential checks afterwards, so depends on what a local would charge for this.

Has any other work been carried out recently, eg new tap? Could be failed check valve as well.

Thanks for that;....no work whatsoever carried out.

 

[terryplumb]

Could be, rough costing is £80 - 130 for plate heat exchanger (if it’s definitely this) plus fitting and carrying out essential checks afterwards, so depends on what a local would charge for this.

Has any other work been carried out recently, eg new tap? Could be failed check valve as well.

Failed check valve Chris ? Where would that be ? And how would it increase the pressure in the primary ?

 

[CBW]

Failed check valve Chris ? Where would that be ? And how would it increase the pressure in the primary ?

Sorry, my mistake, thinking of something else. Well done Terry.

 

[terryplumb]

Sorry, my mistake, thinking of something else. Well done Terry.

No worries Chris , I was intrigued to hear your theory ....bit disappointed now !

 

[Laurence Harvey]

OP here, update for anyone remotely interested.

Having spent some considerable time trying to contact local gas-safe heating engrs I gave up and went for the ‘Ideal Heating’ 6-months ‘repair & care plan’ @ £50/month by direct-debit for 6 months.

Ideal engr arrived at 10.30am this morning exactly on-time. He replaced the plate heat exchanger, the PRV and several other valves and sensors,...I’m not sure what they were though. He also replaced the pressure gauge, re-pressurized the expansion vessel and gave it a thorough service in all the other areas that needed attention. I have to say I was rather impressed.

He left at 1.00pm;...C/H and hot-water now functioning perfectly,...and no drippy prv!

Thanks again for your previous helpful replies guys,...much appreciated.

 

[terryplumb]

Thanks for letting us know how you got on