Worcester cd28i water / heating issue

[GKnight]

Morning all I hope you might be able to help me!!

Basicly this summer I replaced the diverter diaphram and hot water heat exchanger, no real issue just a pain of a job. System ran fine.

However came to but the CH on and noticed a slight weep from the filler loop, which I fixed last night.

Re-test and had steam coming out of the air vent and a lot of banging..... I realised that the cirulating pump had become disconneted, I've re connected drained and refilled.

No the issue is I get the boiler clicking in if its on CH or Hot water, but the radiators or the hot taps are only look warm! if I restrict the flow of water out of the tap then it does warm up.......

ANy idea's I did wonder if the pump has failed but it does spin and i do get a bit of water out of it. Could it be this at fault or is it the expansion tank or is it just an air lock in the heating matrix??

Many thanks in adavnce.

 

[ChrisR]

Trapped ait would account for much of that. Is the air vent open?

 

[dcawkwell]

You have remembered to open the flow and return valves on the boiler?

 

[GKnight]

Hi yes air valve was open, Whats the best way to bleed system ?

All valves are back were they were.

 

[dcawkwell]

Hi yes air valve was open, Whats the best way to bleed system ?

All valves are back were they were.

Air vent could be faulty.
Try switching the gas off and run the boiler with the pump screw open
to release air.

 

[GKnight]

Thanks will try that however there is a small flow of water when you un screw the cover.

 

[dcawkwell]

Thanks will try that however there is a small flow of water when you un screw the cover.

Yes that is fine. Stick a cloth under it. it should stop and any air will
be expelled. Once happy. Do it a couple of times and let the boiler
lock out. Then switch the gas back on and see what happens.

I always run the boiler without any gas when refilling to ensure
that the air is removed from the boiler before I hit the heat exchanger with the heat.

 

[GKnight]

tried bleeding but with no luck, however I did notice the pump has 3 settings and when its on setting one it does not turn but on 2 and 3 it works (I think its slower than previous?? )

 

[dcawkwell]

tried bleeding but with no luck, however I did notice the pump has 3 settings and when its on setting one it does not turn but on 2 and 3 it works (I think its slower than previous?? )

If it's not turning on setting 1. Pump is duff and need replacing.

 

[GKnight]

Hi again all!

Right I've now replaced the pump and it works on all three settings.... Problem is the water and CH are still only getting look warm (Water only if i restrict the flow).

So this is either leeding to another faulty unit some were or trapped air, so whats the best way to get rid oll all the air locks? Dont worry about stating the basics as I'm sure i've missed some thing asI never had this issue earlier in the year when I did the Diaphram and Water heat exchanger.

 

[GKnight]

seams to be trapped air around the hot water side only now.... any idea's?

 

[GKnight]

I've drained the system again and checked the heat exchanger seams to be fine, Diverter valve appears to be ok and functioning. But still no hot water......

I dont think its the following:

Thermister - as system keeps running when taps turned on
Diverter diapham changed in spring
WHE - Changed in spring
Pump - Changed last night
Air Valve - Lets air out when refilled

What else could it be? PCB, primary Heat exchanger ?

Update: Started to strip out pcb and there was a component burnt out on the board..... So looks like a new / recon PCB....