Worcester Greenstar 30si combi

[craig777]

Was wondering if anyone is familiar with this boiler and it's running operation?

When I run the hot water (from any tap), the boiler fires up fine and I get hot water as I should, when the tap is turned off the boiler continues to run for approx. 10 secs or so, then when the boiler does shut off there's a clunk/knock noise.

I was thinking it's a case of 'water hammer', but could it be anything else?

 

[gremlin16]

how old is the boiler

 

[craig777]

Under a week. Plumber is coming back to look into it, but I like to be prepared just incase I get fobbed-off.

 

[Corgigrouch]

Is it just the fan/pump that continue to run or does the burner stay on for an extra 10 seconds? (Check the green burner light)

Does the clunk come from the boiler itself or from the pipework, when does the clunk occur? when turning off the tap or shortly after?

 

[craig777]

I'm pretty sure the fan/pump/burner all stay running for 10 secs or so after a hot tap is turned off (I'll double check later).

When the fan/pump/burner switch off it's at this exact same time the clunk/knock sound happens. It doesn't happen as soon as the tap is turned off.

It sounds to me like the noise is from the boiler (a valve shutting inside?) but you can hear the noise pretty much anywhere in the house because of it echoing along the pipes. It's not a massively LOUD noise, more of a dull clunk/thud.

 

[craig777]

Right, just got my mrs to do a test whilst I was on the phone to her.

Turn on hot tap, boiler fires up and hot water comes through as it should. Turn off hot tap, fan/pump/burner light stay on for about 5 secs, burner light goes out, fan/pump continue to run for another 5 secs, then the noise happens at the exact same time as the fan/pump switching off.

Clear as mud?

 

[ibby]

Loose pipes ?

 

[gigz]

Could be a dead leg on the hot pipe. Did the installer just cap it off in the loft ?