Worscester 28cdi hot water noise

[Kewat66]

Hi All,

i am am looking at a Worcester 28cdi. Everything works fine but when the hot water is turned off after 5 mins or so there is a delayed clunking taking place inside the boiler. I am thinking it is something to do with the diverter valve moving back to position? Any other thoughts?
thanks
kewat66

 

[newcastle phill]

Yes.
Are you gas safe registered ???
If so ask to join the gas forum.

If not Call a gas safe registered engineer who will know from experience what it is and save you time and money and give you peace of mine.

 

[Kewat66]

Yes.
Are you gas safe registered ???
If so ask to join the gas forum.

If not Call a gas safe registered engineer who will know from experience what it is and save you time and money and give you peace of mine.

Hi Phil,
yes I am gas safe but only a few years in and haven't come across this problem before hence my post.
thanks

 

[newcastle phill]

Hi.
Your best messaging redsaw asking for access to the gas forum.

 

[kris]

Thought he has a gs yellow badge,

 

[kris]

See its shifted and new , confused .com lol

 

[Kewat66]

Sorry I am confused? Is not the point of a forum like this to ask question on new situations or are you only allowed on if you no absolutely everything about all gas matters?

 

[Dotty]

It is, just you posted in open forum.

I've moved it, please watch where you post.

 

[Kewat66]

No problem. Thanks for the advise.
kewat66

 

[diamondgas]

After 5 minutes I'd imagine it has something to do with the overrun? The diverter is closed as soon as you turn the tap off On overrun the pump and fan will run for a period of time ....

 

[bigads28]

Does the spindle retract when the tap is turned off and the burner go out?

Sounds like you've got heat that can't escape to me. Turn the DHW stat to max and see what happens. It sounds like restrictions though.

 

[Kewat66]

You turn the tap off, burner goes off, it is quite for a few seconds then you get a grinding sound an a small shudder. Turn the tap back on and get hot water as it should.

 

[Ermintrude]

No external bypass? Over heating

 

[bigads28]

It's deffo heat trapped. You aren't getting the temp drop anymore because the water isn't running and the boiler has to lose the heat. It's struggling to do this. It's basically boiling.

For me that issue would be caused by sludge but more likely a blockage on the primary circuit some where. Probably the pump or diverter valve.

I can't say if scale would cause that as I've no experience of it, my water is very soft.

 

[Kewat66]

Yes same as. Soft water area but yes my thoughts were the diverter valve but I think I will take it apart and clean through.
thanks

 

[goz666]

Is it a greenstar or the old WB 28CDI

 

[Kewat66]

The old wb28cdi

 

[goz666]

The old wb28cdi

I agree with bigads, pump or blockage somewhere.

 

[diamondgas]

You turn the tap off, burner goes off, it is quite for a few seconds then you get a grinding sound an a small shudder. Turn the tap back on and get hot water as it should.

Does the pump keep running when you turn the water off? Certainly sounds like latent heat but in theory the overrun should take that away. It maybe something as simple as the heating stat being faulty, pump overrun not operating?