Greenstar 28i jnr bleed heat exchanger

[SEuk]

Hi I have a Greenstar 28i jnr and was told to pressurise the ev (slow air loss over 4 years) and bleed heat exchanger

is there a valve to bleed the HE and is it the plate one
cant find it in the pdf

the problem is it runs for 10 min okay with pump over run on
but any longer than 15 min its a full cut out with no pump over run
no flashing light codes just starts up after 10 mins

I was told its air in the HE but the guy coming out next week seems to think there is no bleed valve to remove air pockets from the HE

bar cold 1.5 bar hot 1.6 when okay, now bar 1.5 cold bar 2.2 hot

I know it could be told its a restricted HE but hope its air causing a hot spot?
rads good no air hot at top and bottom
high point in the system is the boiler so any air goes to boiler
system age 5 yo

not been inside, used the docs as im a pc builder and a mechanic not a boiler fixer

 

[gigz]

Its a tube inside the boiler on top of the hex. Doubt its air trapped in there as it would make a proper racket.
Number 7 on image.

 

[St0rmer66]

I don't think I have ever used that bleed point on one of these and I've worked on hundreds. The one on the pump (automatic) bleeds enough for the pump to then just push it all into the radiators.

 

[gigz]

I've only ever used it when fitting and filling from new.

 

[SEuk]

Thx for the replies guys
The rads have absolutely no air in them
The tube on the hex that would be for removing air for the boiler? And not the tube for the EV

atm it's quiet and will run for approximately 10 minutes with pump over run, any longer and it cuts out dead quiet with no pump over run
When first happened it was first noticed when the DHW ran to fill a bath
(First time in a long time) It started to bang like it was being hit with a sledgehammer and knocked of the wall (not talking pipe clicking)
The DHW was hot then cold
then when I ran the tap again the next day water came out of the pr valve at the back of the house
and also the water was cold
a day later turned on the tap and worked okay
but cant run dhw for to long or it bangs

so we aren't using DHW atm just CH

is it plausible that air is in the boiler as its the high point
I think the DHW is hotter than 55c as it was almost boiling and sounding like a kettle also

 

[sooey]

I used one the other day, opened it up with the tube into a container and a bit of kitchen roll over the electrics underneath .
Feckin tube came off the valve and the water squirted me right in the eye. Feckin Worcester.

 

[St0rmer66]

No, it won't be air or you'd have the same issue on CH. Banging on DHW means either poor circulation either due to a blockage in the boiler or less likely a slow running pump.

 

[SEuk]

No, it won't be air or you'd have the same issue on CH. Banging on DHW means either poor circulation either due to a blockage in the boiler or less likely a slow running pump.

so a new plate heat exchanger or could it be removed and back flushed
would the CH short run time be thermal then?