Combi boiler vibrates when water turns off

[Siw81]

I had my boiler serviced last month and he made a tweek to make it burn better. Since the service if the hot water tap is turned on and off before the boiler ignites we get 3 loud vibrating noises from the boiler, any idea what this is? Other than this it runs fine

 

[ianmcd]

are you sure it is before the boiler ignites ?

 

[Siw81]

Yes, just before the boiler kicks in, it only happens as my wife had the habit of quickly washing her hands when she does anything and I have noticed it is before the boiler fires up, if the hot water is on long enough for the water to fire up then there are no vibrations on the boiler

 

[ianmcd]

sounds like water hammer mate, I know she will never listen , but if you need HW run the HW dont turn the HW tap on for 10 secs then back off, you will never get hot water, use the cold, the boiler will thank you for it

 

[Siw81]

Just told her.. I'm in the dog house haha

 

[Siw81]

Water hammer was what I was also thinking, just strange how we have got this issue since the service unless he has changed the flow rate

 

[ianmcd]

Water hammer was what I was also thinking, just strange how we have got this issue since the service unless he has changed the flow rate

possibly that during the service he turned off the inlet water valve, different boilers use different valves, and on opening it back up again it is now at a different setting

 

[Danieljamesrobinson]

On a combi service what would require you to turn off the cold water inlet? What boiler are we discussing OP?

 

[jj4091]

Check your stopcock is fully open.

 

[Razor900]

On a combi service what would require you to turn off the cold water inlet? What boiler are we discussing OP?

The clue could well be in the first post. If there was too much water flow for the boiler to heat he may have restricted the inlet valve to get the temperature up.

 

[ianmcd]

On a combi service what would require you to turn off the cold water inlet? What boiler are we discussing OP?

Because we are not all poke and go merchants and some of us remove and clean water filters/strainers when advised in the MIs