worcester bosch system cdi30 pressure keeps going too high

[adjhitch1234]

Hi All

Just had a worcester bosch System CDI30 installed with a megaflow and the pressure valve keeps going beyond 3bar - expansion valve kicks in and reduces the pressure and water is released.

In an effort to reduce the pressure I have
i) drained the radiator a few times to reduce the pressure back to 1 bar but the problem keeps persisting.
ii) disconnected the filling loop - again it keeps increasing

Does anyone have any bright ideas/ come across this before - has the expansion valve had it?

Many Thanks

A

 

[gas4you]

First idea is get your installer back.

Could be that the expansion vessel is flat, strange though a it is new.

The only other place the pressure could come from is a hole in the plate heat exchanger. Even more strange for a new boiler.

Other than that get your installer to call WB out under warranty.

 

[adjhitch1234]

Thanks Dave

Have called out installer who was pretty hopeless. He came over drank a cup of tea and didnt even open up the boiler.

The guy he used to do the megaflo seems to have gone awol.

The installer was corgi regsistered but I really cant see how! (do i shop him? - i dont want a brick through my window tho)

He suggested getting WB out under warranty as he believes its the expansion vessel. Would I be charged a call out fee if the boiler is registered? (I only registered it last week as my installer 'lost' the warranty card and had to 'find' a new one But I would be suprised if this was the case as when i reduce the pressure it inceases again within a day or two.

I've also noticed that the pressure only increases when the boiler is on 'heating' mode.

Any further suggestions? As you say it might be the heat exchanger - some how the system is compromised.

Andrew

 

[kevplumb]

how large is the system

In an effort to reduce the pressure I have
i) drained the radiator a few times to reduce the pressure back to 1 bar but the problem keeps persisting.
ii) disconnected the filling loop - again it keeps increasing

are you filling the system back up to 1 bar AFTER the prv dumps

 

[GasMan1965]

Filling loop letting by ??

Do you disconnect the filling loop after pressurising ? IGNORE that I just read back

 

[adjhitch1234]

Hi

the prv lets out a trickle keeping the pressure at a constant 3 bar.

I have this moning tried to determine if it is a hot water or boiler problem by:

1)reducing the pressure down to 1 bar by draining a radiator (this is the 4th time and drained approx 3litres)

2) completey draining the megaflow and mains water.

3) putting the heating on.

After leaving the heating on for just 40mins the pressure was beginning to creep up again (it seems to creep up by 1/4bar every hour until it reaches 3 bar when the prv lets a steady trickle out the back).

So think it's probably a boiler problem - what do you think?

 

[adjhitch1234]

ok. I drained the mega flow, turned off the incoming mains and ran the heating for a day with no pressure increase.

Once refilled the boiler behaved itself for 24hours but then old problem of pressure creeping up by 1/4 bar every hour returned.

The filling loop is detached, and once the boiler reaches 3bar it releases water outside.

Looks like this is pointing to a megaflow problem. Has anyone ever come across this before? Think it must be either:
A) a hole in the plate heat excahnger?
B) problem with the megaflow expansion vessel
C) problem with the boiler expansion vessel.

Any ideas how to eliminate any of the above from the equation/ advise would be greatly received as I am in a bit of a muddle!
or could it still be the at as the water heats up and the expansion valve is flat?

 

[twgas]

do you have a combi and a megaflow or a heat only boiler

 

[adjhitch1234]

worcester bosch 30CDi system boiler. A

 

[twgas]

in that case there will be NO plate h/ex, so its not that.

if filling loop disconned it cant be that.

so only leaves coil in megaflow or connected wrongly, ie heating circuit and domestic water connected together somewhere. or if it only happens when heating up then either pressure vessel is flat or not big enough.

 

[adjhitch1234]

thanks - I'm no plumber but:

have checked all the pipework (carpets going down tomorrow - eek) and all seems to be in order.

have also checked and identified primary flow/ return incoming mains and outgoing hot water and again all seems to be ok.

how do you check to see if the pressure vessel is flat? i assume this is within the megaflow not the boiler?

I am aware that one of the (two) valves adjacent the megaflo was on manual instead of auto for a week or two. Could this have caused the problem? Might I have cooked it?

A

 

[twgas]

exp ves will be in boiler, think it may be in sealed chamber on this model so a RGI would be reqd as it means disturbing case seal.

 

[adjhitch1234]

ok thanks. wll get it checked out by Worcester Bosch under guarantee.

A

 

[twgas]

Wise move I think.