Help please, Worcester Bosch greenstar boiler won't keep pressure.

[philipbsmith]

Christmas eve and the boiler has gone on the blink !!

Started with yesterday morning with a running water noise in the upstairs radiators, so i bleed them and then topped up the pressure on the boiler to 1.3bar
Ran the heating a bit, turned it of re bleed then topped back up to 1.3bar.

Few hours later no hot water from the taps and rads not getting hot.
Went back into the loft and the no pressure at all showing on the gauge.
Filled it back up, but as you fill it you can hear water trickling through the overflow into the drain pipe.
It takes 1.5bar of pressure, turn it back on and it makes a few funny noises but seems ok.
Had a shower, rads getting hot
An hour later no hot water and no pressure at all showing on the boiler gauge.

I have done this fill, use seems ok, an hour later no hot water routine 3 times now.

Any idea whats going on, definitely no leaks in the house anywhere, only thing that seems strange is that some water comes out of the overflow pipe when i fill it but not all as it will get to pressure.

The error code E9 soemtimes come son the boiler but not each time, but my guess is thats just telling me the bliler has tripped as the pressure is to low.

Thanks

 

[easyflow]

If there,s no leaks pressure relief valve is shot.

 

[philipbsmith]

I guessing thats not a 5 minute job to fix?
Even assuming i can get the bits to repair it with ?

 

[easyflow]

About 10 mins but you will need the part plus a qualified person to fix.

 

[philipbsmith]

About 10 mins but you will need the part plus a qualified person to fix.

10 minutes on christmas eve will probably be about £200

Thanks for your help, will hopefully be able to nurse it through till monday next week. Its not cold here and we have a log burner that does a good job of heating downstairs. Plus the lads are not to fussed about showering anyway and me and the wife can always share

 

[Gasguru]

By bleeding the radiators you have caused the fault code (overheat) and the safety valve to open.

NEVER EVER EVER bleed radiators on a sealed system boiler setup without checking the expansion vessel for charge pressure.

The pressure in the vessel is too low (probably flat) and now as a result or removing the air from the rad the expanded water has nowhere to go, hence the PRV opens.

On the Worcester CDi it is sometimes possible to replace the PRV without pulling the boiler away from the wall or removing the bottom end. On many of the Worcester Greenstars it's a major job. Sometimes, if the system water is clean the valve can be flushed through to clean it.

 

[philipbsmith]

By bleeding the radiators you have caused the fault code (overheat) and the safety valve to open.

NEVER EVER EVER bleed radiators on a sealed system boiler setup without checking the expansion vessel for charge pressure.

The pressure in the vessel is too low (probably flat) and now as a result or removing the air from the rad the expanded water has nowhere to go, hence the PRV opens.

On the Worcester CDi it is sometimes possible to replace the PRV without pulling the boiler away from the wall or removing the bottom end. On many of the Worcester Greenstars it's a major job. Sometimes, if the system water is clean the valve can be flushed through to clean it.

Does the PRV blow to save the system, then thats it game over, its done its job and you need a new one. Or can you reset it?

For next time, are you saying i need to pressurise the system fully to 1.5bar then bleed the rads. Then top it back up to 1.5??

Thanks

 

[Gasguru]

Yes the prv stops the system from over pressure. 1 bar is sufficient pressure for a typical property. Don't be tempted to go higher as it leaves little margin. You could pressurise to 2 and open the safety several times to try and flush it through. The real issue is a flat expansion vessel. Since it's inside the casing it's not really diy territory. As it's flat or low on air pressure the expanded water has nowhere to go when you put the heating on and the over pressure operated the prv. Bleeding radiators should never be considered as a diy operation whether you have a sealed system or conventional header tank system....in either case serious damage can be done by the unwary. A little knowledge is a....... and this couldn't be more apt.

 

[Tay7]

Bleeding radiators is not a DIY operation?

Blooming eck, I better stop refitting bathrooms & installing towel radiators and new showers then in case the world implodes on itself.

 

[Gasguru]

For all the problems bleeding radiators causes I would never advise a diyer bleeds radiators. A significant number of plumbers and heating engs should also not bleed them either. So many problems are caused either as a result of an expansion vessel low on charge or flat or a feed an expansion vessel being full of debris. Failure to check these can lead to major failure. Boiler meltdown due to lack of water or worse. One system I attended required a repipe after the owner bleed all the rads. There was no lid on the cistern, loft insulation had been placed on top and due to condensation had filled the vessel. As he bled the rads fibreglass got drawn into the system....but hey ho you know better.

 

[Razor900]

The OP said it was running into the drain pipe. If he meant the condensate pipe could well be a passing plate

 

[petit_pablo]

The OP said it was running into the drain pipe. If he meant the condensate pipe could well be a passing plate

It will be a fudged heat cell, rather than a plate if thats the case

 

[muggles]

@philipbsmith Is the water running out of the copper pressure relief pipe to outside or down the white plastic 3/4" condensate pipe and away into drainage? If it's latter, your heat exchanger is goosed. Should be a free repair under warranty provided you've had the boiler serviced every year. If you haven't, you could be looking at £500 or more