Bosch 24 cd bf constant slight filling

[clancy]

Bosch 24 cd bf constant slight filling, yes as per the heading

Boiler has a constant dribble/trickle from outlet via the 'blow off valve' which is presumably because the inlet has a constant trickle/flow in, the white key is NOT in position and the blowoff valve was changed to remedy the fault and same keeps happening/continued, so as not to disturb the blow off valve i bled a radiator to release the pressure down to 1 bar, it takes approximately twenty minutes for the pressure to increase un aided and then continues to trickle/flow from blow off out let, any advice please thanks.
(boiler works well during this saga..hope this lot makes sense)

 

[kevplumb]

either the internal loop is passing

or the dhw h ex has a hole in it

 

[clancy]

either the internal loop is passing

or the dhw h ex has a hole in it

Hi Kevplumb, and thanks for super fast reply.

How might i check on the internal loop or fix the same, also i looked into the filler tap aperture and also probed with finger there feels to be something of a ill fitting rubber 'o' ring or is this normal thanks (both 'o' rings are intact on the filler key)

 

[sooey]

Read it again kev, I think the op is misunderstanding the situation.
Op it's not refilling. the pressure is rising cos the water is expanding with nowhere to go. That's what's causing the pressure relief valve to trickle. The expansion vessel wants checking, it's in the faqs.

 

[kevplumb]

Read it again kev, I think the op is misunderstanding the situation.
Op it's not refilling. the pressure is rising cos the water is expanding with nowhere to go. That's what's causing the pressure relief valve to trickle. The expansion vessel wants checking, it's in the faqs.

ok you read it again

if you drop the press then

we are assuming

 

[sooey]

Yeah, you're right, it could be the heat exchanger, but that expansion vessel wants checking though.

 

[kevplumb]

aye wouldnt hurt

 

[clancy]

Thanks again for input.

Out of curiosity what is 'op'
also how is the water getting in bearing in mind water is constantly escaping even now as you read,
thanks.

 

[glasgowgas]

op is Original Poster

water might be passing through heat ex as kev has said from cold water to ch side

 

[doitall]

Plate heat exchanger.

Common problem with WB.

Turn the mains water off ans see if it stops, give or take 10mins

 

[kevplumb]

op is Original Poster

water might be passing through heat ex as kev has said from cold water to ch side

jeez the booger ain't deed

 

[clancy]

op is Original Poster

water might be passing through heat ex as kev has said from cold water to ch side

But how does the water 'get in' and from where to pass through?
thanks

 

[glasgowgas]

your plate heat exchanger or as WB calls it your water to water heat ex could be pinholed so mains cold water is getting into the central htg side and causing an over pressurisation

no bad for a man with dreaded lurgie....am away back tae bed

 

[gavinda]

thread from the dead

the ' heat' engine has an issue apparantly. its on molded component . i've seen it once.

the boiler doesn't have a plate heat exchanger.

captain morgan may be confusing me though

edit[b/]

the shame. just reread the title

 

[kevplumb]

plate heat ex is on the mains water

same as your filling loop

there are two lots of water in there

one that heats the h ex and the other comes out of your taps