Help a girl out!??? Please...

[Needhelpplease]

Hi, I had a new radiator fitted today and whilst re filling the system the plumber said a big leak occurred from the boiler, he thinks from the plastic manifold?
He said I am lucky this happened to him as it was obviously on the way out and could have happened anytime and flooded my garage where the boiler is!?
Obviously I have now been left with no heating or hot water and a large bill for a new part and 2 hours labour for him to come back and fix it.
Is this common, am I lucky? Or did he cause this to happen? Could this have been caused by him overpressurising the boiler? People are telling me he must have over pressurised it and he caused it??

Please help, thank you

 

[ShaunCorbs]

Worcester boiler ?

 

[Needhelpplease]

Worcester boiler ?

Yes bosch Worcester I believe.

 

[ShaunCorbs]

Left hand hydro block not that expensive and around an hour to fix if it’s the correct item that’s split so under / around the 100 mark

 

[Needhelpplease]

Left hand hydro block not that expensive and around an hour to fix if it’s the correct item that’s split so under / around the 100 mark

Thank you, he pointed to a black cylinder type shape in the bottom right?

 

[ShaunCorbs]

Did he give it a name as all as there’s a few bits in that area

 

[Needhelpplease]

Did he give it a name as all as there’s a few bits in that area

Just plastic manifold, after I moaned a little about more expense he said I may be lucky and when he opens it all up he may see that it's just the 4 seals that need replacing for like £10 instead of a £150 part?
He said its £150 for part and £100 labour, all I remember him saying was plastic manifold.

 

[Needhelpplease]

I've been told he caused it by putting too much pressure back into the boiler? Is this true?

 

[ShaunCorbs]

Sounds like the right hand block as the parts cost match but it could be a few things that attach to the part

The price seems reasonable if it’s the whole block

 

[Ric2013]

I don't think you CAN overpressure a boiler as boilers are designed to prevent overpressure by dumping the excess water. It may be he took the pressure higher than it was previously, but he won't have been able to take the boiler above its design maximum pressure as the pressure release valve would just have actioned had he tried to do so.

 

[SimonG]

Difficult to over pressurise a boiler without either taking steps to do so or an existing fault with the boiler.

And yes I have seen pressure relief discharge pipe with a speedfit stop end on it, to stop the pesky dripping

 

[John.g]

I don't think you CAN overpressure a boiler as boilers are designed to prevent overpressure by dumping the excess water. It may be he took the pressure higher than it was previously, but he won't have been able to take the boiler above its design maximum pressure as the pressure release valve would just have actioned had he tried to do so.

Could possibly happen if filling the boiler with the filling valves fully open and with no PRV installed in the mains or in the filling loop, I'd like to see the Kvs for a 1/2 ins 3bar PRV. Combi boilers often take the filling loop from their cold water supply.

 

[Scott_D]

Just bad luck by the sounds of it.
As above you shouldn’t be able to
Over-pressurise as the PRV would activate

 

[Ric2013]

Could possibly happen if filling the boiler with the filling valves fully open and with no PRV installed in the mains or in the filling loop, I'd like to see the Kvs for a 1/2 ins 3bar PRV. Combi boilers often take the filling loop from their cold water supply.

The 'Kvs'?

Doesn't a combi have the PRV internal to the boiler? Is your point that the PRV, if internal, could be slow to react in the circumstances you outline?

 

[John.g]

The PRV(s) I am referring to are the pressure reducing valves, if you had/have say 5 bar mains pressure available at the filling loop and you opened it fully to the boiler then its possible that even with the boiler PRV (safety valve full open) that the pressure might be greater than 3bar, say 4bar depending on how much water that PRV is capable of passing, and the dynamic head available (it only starts to open at 3.0bar and may well be up to 4 bar before fully open, you will only see it slightly > 3 bar with a failed E.vessel as the boiler pressure rise is relatively very slow due to expansion.
All valves have a Kvs rating which is the flowrate in M3/hr at 1 bar pressure, I have seen rad valves and thermostatic rad valves (TRVs) with a Kvs of 1.0 stamped on their data sheets, this means that these valves will flow 1.0 M3/hr at 1 bar head, when fully open, or since circ pumps head and flow rates are often given as M and LPM, this is 16.67 LPM at a 10M head or 5.27LPM at a 1M head. Its difficult and probably incorrect to assign a Kvs to a safety valve as its Kv changes as its opening but there is still a standard some where for them.