Greenstar 4000 combi consistently high pressure

[ademanuele]

I am a not an expert and worried about a boiler installation for my mum. She is 91 and lives on her own (vulnerable adult with dementia). I had a new boiler installed (Worcester Greenstar 4000 30kW Combi) end of August as she needs a reliable boiler.

I visit my mum every 2/3 weeks (I live in north of England, she lives in London) and noticed that water was coming out of the pressure relief valve on a regular basis (water on ground in garden outside boiler). I checked the boiler pressure and it was in the red area. I tried venting the radiators when the system was cold/off, however the pressure goes back up to the red. According to the manual urgent action is required.

I have called installers on three occasions, on the first visit (I was present) they removed a lot of water out of the system. However, the pressure went back into the red area. I was not present for the second visit, I understand a loop was replaced. This did not resolve the issue and I called for an engineer who visited yesterday. Again, he emptied water out of the system and adjusted the air pressure in the boiler (he used a air foot pump). The system was hot and still in the red but the engineer said that it did not matter as long as it was not in the red when cold. This morning I checked the pressure in the system cold before it switched on and the pressure was 2.5 bar (in the red).

I do not know what to do next, issue has not been rectified on 3 visits and I am concerned given that my mum lives on her own.

1) If the boiler is working normally would you expect water to come out of the pressure relief valve?

2) This is a new model boiler, are there any known issues?

3) The boiler switches off before the thermostat gets to target temperature (was 19.3C when I checked last, target 21C and boiler off), could it be over heating?

4) How do I resolve this issue? Thanks.


Best wishes

Tony

 

[John.g]

If set up properly, the cold (say 20C) pressure should be ~ 1.7 bar and when fully hot (60/65C) with CH on ~ 2/2.5 bar. The relief valve lifts at 3.0 bar.

What is the pressure rising to when fully hot?.

Reading your post again it looks like the auto filling valve is open and set too high (apart from possible incorrect expansion vessel settings), I would get back on to the installers as its a new boiler and needs sorting out.

 

[ademanuele]

Thanks. It is 2.8 bar. I have just switched boiler off and bled a radiator for a couple of minutes and turned boiler on. Pressure in yellow now and 2.0 bar. It will creep up again…

Boiler is set to 70C. Is this a typical setting?

How is the auto filling valve adjusted? I assume the engineer would have looked at that?

 

[Scott_D]

What boiler was removed?
Can you post some pictures of the pipes around the boiler and valves underneath?
Could there be an old filling loop somewhere left open?

 

[ademanuele]

Previous boiler was a 20 year old Potterton, it was not a condensing boiler...

 

[Scott_D]

Can you take the white plate off the bottom to expose the valves and filling loop?

 

[ademanuele]

Here we go...

Also, what is the recommended temperature to set the boiler, is 70C too low?

 

[Scott_D]

I’m not familiar with the 4000
Is this an auto filling loop ? @ShaunCorbs

65-70 degrees is about right without knowing anything about the property

 

[ademanuele]

It is an automatic pressure adjusting system and engineer on 2nd visit apparently replaced the loop so assume it is an auto filling loop. It is a very new mode.

 

[Scott_D]

Sound like it is still faulty or the setting need adjusting.
You will have to call the installer or maybe Worcester for a warranty visit

 

[ademanuele]

Is there an obvious setting that needs looking at, have had three visits alread, you would have thought they would have picked up?

 

[John.g]

I think these have some fancy internal automatic filling loop. If you could identify the supply to the filling loop and shut it then it might tell you something.

70C is a quite normal boiler temp.
Is the relief valve lifting each time the boiler is hot?, 2.8 bar is just marginal (3.0 bar lift)

 

[ademanuele]

I have not been watching that closely, there is always a wet area in the garden. If boiler was working normally would you expect to see any water coming out via the relief valve?

 

[Scott_D]

Is there an obvious setting that needs looking at, have had three visits alread, you would have thought they would have picked up?

You would have to adjust via the boiler screen/buttons

 

[ademanuele]

Ok, I don’t think engineers looked at anything apart from the boiler status

 

[John.g]

I have not been watching that closely, there is always a wet area in the garden. If boiler was working normally would you expect to see any water coming out via the relief valve?

No, as long as the pressure when hot is < 3.0 bar, say a max of 2.75/2.8bar but if it has lifted then its possibly leaking now permanently.

 

[ShaunCorbs]

I’m not familiar with the 4000
Is this an auto filling loop ? @ShaunCorbs

65-70 degrees is about right without knowing anything about the property

Yes it is will fill 5 times before it faults out

Op how many radiators roughly do you have ?

 

[ademanuele]

It is a small 3 bedroom house, approximately 8 radiators

 

[ShaunCorbs]

Can you do a test underneath the boiler on the right hand side two valves the left one eg from right to left the second valve

Turn this off / clockwise and open a hot tap

You won’t have hot water for this test but drain the heating via a rad to 1.2 ish (1.5 is fine) bar and turn the heating on and report back

 

[John.g]

Looking at the schematic it looks as if the auto fill is probably taken from the mains cold water (DCW) supply to the combi, what next I wonder in this automation overkill especially for something that should only require topping up once/year or so.

 

[ademanuele]

I better not, may impact warranty.

From previous postings it may be that boiler just needs setting up correctly or valve may be leaking.

 

[John.g]

Is the relief valve dribbling constantly now if the pressure is ~ 2.8 bar.

 

[ShaunCorbs]

Call Worcester out for this week

 

[ademanuele]

Is the relief valve dribbling constantly now if the pressure is ~ 2.8 bar.

Not constantly but regularly, ground is always wet under exit pipe

 

[John.g]

Boiler PRV (relief valve) probably needs renewing as well, they should also add inhibitor as this has probably been going on since the boiler was installed.

 

[ademanuele]

I have contacted the installers. One final question, the house is taking much longer to get to temperature than the boiler it replaced. The boiler seems to turn itself off periodically and I can hear it making gentle clicking sounds. Is it switching itself off due to the high pressure or do condensing boilers take longer to get to temperature? This boiler has a higher rating (30kW) than the one it replaced.

 

[John.g]

If the boiler flow temp is the same as the old boiler then it should heat the house up in the same or less time, being a condensing boiler has no effect.
You or the installer might check if its CH output is range rated, ie output set too low.
The high pressure may be cutting out the boiler and then resetting when the pressure reduces but one might expect a alarm or status flag if this happens, mention this as well to the installer.

 

[ademanuele]

It is now some 2 weeks since I contacted the fitter and no response. I have contacted Worcester Bosch and they kindly provided the following information:

"A consistent discharge from the pressure relief pipe-work would indicate that the boiler is, or has been, regularly exceeding an internal pressure of 3 bar and thereby opening the valve to release excess water.

Incorrect pressures within the expansion vessel, the item re-pressurised with air using a foot pump, may cause issues with the system pressure when in operation. However we would not expect this from a new installation.

We would advise that ***** should investigate potential issues whereby water from the cold mains feed may be being introduced into the primary circulation within the boiler and causing a rise in pressure. This could include problems with the filling system, or a potential breach on the secondary plate heat exchanger."

What I would like to know is whether 3 months of high pressure is likely to cause any long-term damage to the boiler and what should I be asking the fitter to do. From previous postings the inhibitor needs to be topped up and pressure relief valve possibly replaced?

 

[ShaunCorbs]

No as there’s safety features but it needs sorting sooner rather than later

 

[EvilDrPorkChop]

Looks like a faulty or incorrect set Automatic filling loop to me. I've never fitted one of the new Worcester Auto ones yet, but due to this reason as i'm convinced something will always go wrong with them eventually.