Worcester 24cdi combi boiler Bar rises.

[Trevrev]

Hi, I have worcester bosh 24cdi combi bolier.
We haven't had the heating on yet this year, but i've noticed the bar is rising very slowly.
I always have it set to 1 bar, but it creeps up very slowly over a week or so by .3 to .4 of a bar. It can't be self filling because the filling key is taken out.

Any ideas???

Trevor

 

[gas_man_gaz]

is it rising wen in operation then drops down? or is it rising and staying there? if it is it will prob be the plate heat exchanger

 

[Trevrev]

If i've run the hot water the needle rises, when cooled it sometimes drops back, But at the moment it seems to be staying up.
As mentioned, the heating hasn't been on this year as yet, too mild, or i'm too tight ! LOL.

 

[gas_man_gaz]

what pressure is it reading? ya only have to worry if its getting up to 3bar

 

[Trevrev]

A couple of weeks ago i done my yearly, bleed of rads for any air, top - up if required. No air in rads but needed to top up slightly to get it back to 1 bar. Since doing that i have been keeping an eye on it and noticed the bar rising slowly. Last night it was 1.5 after i'd had a shower, i assumed it would have dropped back to 1bar by this morning after the system had cooled but it hadn't.
I have taken out the filling key!

Maybe i'm worrying over nothing, but it seems strange.

 

[gas_man_gaz]

its common for the plate heat exchangers on these to split internally and allow the mains pressure to pressurize the ch circuit.
if this is the case your sys pressure will continue to rise up to 3bar. if it doesn't don't worry

 

[Trevrev]

its common for the plate heat exchangers on these to split internally and allow the mains pressure to pressurize the ch circuit.
if this is the case your sys pressure will continue to rise up to 3bar. if it doesn't don't worry

Would that be a rapid rise in pressure? Over hours, or days?

I've just had the heating on for a while and the pressure went up to just above 2 bar, which is about right, I'm just letting the system cool now to see where the pressure ends up.

 

[gas_man_gaz]

it could take weeks!
the pressure rising whilst the sys is running is just the water expanding with the heat which is normal

 

[Trevrev]

Is there a test i can do to see if it is the plate heat exchanger?
Obviously, if it is that, then the problem will only get worse and the system will fill quicker.
Just draining a bit out of the rads periodically to keep the pressure down is ok for the time being isn't it?
I can feel a big bill coming up just before Christmas.

How can i find the part number for the item? Just want to check out prices.

 

[gas_man_gaz]

don't do anything! just leave it, if the sys pressure rise's to 3bar the plate has gone, if it doesn't don't worry..
ya don't have to drain any water it wont effect the safety or operation of the boiler. IF it does turn out the plate has gone, bg do a fixed price repair and it would be £189, worcester prob would but don't know how much (the part is around £100 plus 10- 20 quid for prv)

 

[Trevrev]

I'll keep an eye on it.
Thanks for your help Gaz.

 

[gas_man_gaz]

no probs, could of pressed the thanks button