Worcester 24CDi gaining pressure after new diverter valve

rolyapples · 19 Feb 2007

Since having the diverter valve replaced on my Worcester 24CDi RSF combi boiler a few weeks ago, the boiler is suffering from increasing pressure over time. I've reduced the pressure 3 times now (using the pressure relief valve test knob) to reduce the pressure so that it's not discharging, but after a week or so it's back up to high pressure levels again.

From what I've seen on here and other sites, the most likely cause is perforation in the water to water heat exchanger, however I was wondering if there's any chance it could be a faulty water diverter. I couldn't find a description of how they work anywhere, so was wondering how well separated the mains water is from the central heating circuit in these things - does anyone know if this is a possibility?

Thanks in advance

Gasguru · 19 Feb 2007

Have you removed the white filling link key?

rolyapples · 19 Feb 2007

Gasguru said:
Have you removed the white filling link key?

Yes - have never left the filling key in place.

Thanks.

gasman26 · 19 Feb 2007

It`s possible that the diaphragm in the expansion vessel is split....
Remove the cap from the valve & check the pressure, should be roughly 0.5 bar, if you get water released from the valve as opposed to air this will confirm deteration of the internal rubber diaphragm.

HarrogateGas · 19 Feb 2007

gasman26 said:
It`s possible that the diaphragm in the expansion vessel is split....
Remove the cap from the valve & check the pressure, should be roughly 0.5 bar, if you get water released from the valve as opposed to air this will confirm deteration of the internal rubber diaphragm.

I know what your saying but I dont think is is the what the OP is describing
This would cause a pressure drop over time...not a pressure increase as it would be discharging when the heating is on. The OP said he ishaving to manually lower the pressure himself and that the pressure creeps up over a period of time.

I think the fault is the plate heat ex...ive changed about 10 for this very reason.

gasman26 · 19 Feb 2007

apologies.... mis-read the posting stating over the period of time... in that case im inclined to agree with your diagnosis of a split dhw heat exchanger....

ollski · 19 Feb 2007

A faulty diverter would bring the pressure up a great deal quicker than that, as already said the problem is a dhw hx.

gasman26 · 19 Feb 2007

posted by ollski : A faulty diverter would bring the pressure up a great deal quicker than that, as already said the problem is a dhw hx.

Who said anything about a faulty diverter? which incidently would not bring the pressure up........

ollski · 19 Feb 2007

rolyapples said:
however I was wondering if there's any chance it could be a faulty water diverter. I couldn't find a description of how they work anywhere, so was wondering how well separated the mains water is from the central heating circuit in these things - does anyone know if this is a possibility?

Thanks in advance

Agile · 19 Feb 2007

gasman26 said:
posted by ollski : A faulty diverter would bring the pressure up a great deal quicker than that, as already said the problem is a dhw hx.

Who said anything about a faulty diverter? which incidently would not bring the pressure up........

Not necessarily!

But thats not possible on most boilers because the DHW feed and system water parts are not sealed together and any leakage just results in a leak from the joint between the actuator and the manifold.

The only exception is the older Vokera 20-80 where they put a big rubber seal in the middle which seals the DHW and enables it to get into the system water.

Tony

ChrisR · 20 Feb 2007

Not possible on yours - water would leak from the holes...

rolyapples · 20 Feb 2007

Many thanks for that info - that's exactly what I was after! Guess it's time to replace the heat exchanger now.

ollski · 21 Feb 2007

Agile said:
The only exception is the older Vokera 20-80 where they put a big rubber seal in the middle which seals the DHW and enables it to get into the system water.

Tony

Sorry my point was general not model specific, in my mind was the chaff. celtic.

diynot

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Worcester 24CDi gaining pressure after new diverter valve

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