boiler pressure too high

[DIYnumptyclown]

Hi All,

I'm posting this on behalf of a work colleague.

She has a Worcester Bosch boiler (not sure which one) and the pressure keeps rising (beyond the usual 1.5). It's currently hovering around 3. She's had 4 British Gas engineers out (under her homecare plan) but the problem still persists i.e. it rectifies itself, then shoots up (the pressure) after a couple of days.

She doesn't know which boiler she's got but has a manual that refers to the following models - 24CDi, 28CDi and 35CDi.

Any thoughts before she calls out BG again.

Apologies if I haven't put this in the right forum.

Thanks.

 

[Burnerman]

Either the filling loop isn't completely closed or one of the heat exchangers is passing water into another.
John

 

[HERTS P&D]

As above.

Disconnect the filling loop to see if the water raisers.
This will tell you if is it the filling loop or heat exchanger.

Andy

 

[DIYnumptyclown]

Hi John

thanks for your quick response.

My colleague thinks that these solutions have already been explored.

Could it be anything else?

Thanks again.

 

[sooey]

There may be an expansion vessel problem, does the pressure only rise when the heating is turned on?
If it rises when the boiler is off then as said it's the loop or the plate heat exchanger.
If it rises too much when hot then check the expansion vessel and it's connecting tube.

 

[Burnerman]

The boilers pressure relief valve should lift at the 3 bar mark.....maybe it has so its worth a peek at the overflow pipe outside to see if there's water there.
The expansion vessel could well need a recharge of air but ideally the system should be completely depressurised and the EV disconnected for this to be accurately done.
I would have thought this would have been done by now though!
John

 

[DIYnumptyclown]

Dear All

thanks for the advice to date.

Will ask my colleague to check the overflow tonight - Heating not currently on. I assume it's still safe to keep the boiler switched on?

If all else fails, she'll call out BG.

Have a pleasant day!