VAILLANT EcoTEC plus 831 sounds like a helicopter landing

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FredBasset

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Just had my boiler serviced, two hours after the engineer left, the boiler suddenly started making a very very loud humming/buzzing noise. The vibration went through the house and through me. It sounded like a truck was about to come in the patio doors. The experience lasted 2 minutes and then everything went back to normal. The boiler works completely fine, but now nce or twice a day the same thing happens ... though not nearly as violent as the first time, it now lasts up to 10minutes.

I have spoken to the engineer (private company I've used multiple times), and he suggested I rule a few things out. Turning on the cold tap doesn't stop the noise, while turning on the hot tap does. I've removed the TRV heads from all radiators, so it's not them setting up a vibration.

Any thoughts our there? I've seen similar threads, but never a documented resolution sadly. Seems incredible coincidence it started just after the service.
 
mine did the same it was a gas regulation issue , engineer should have monitored the gas flow , seems funny as it started as soon as boiler was serviced
 
It can also point to a blocked heat exchanger, might be worth getting the gas flow rate checked. Was it a service or safety check/poke and go?
 
It was the annual service. I'm going to ask him back to retrace his steps, but could do with a few pointers. Heat exchanger is a good suggestion. Are they easy to unblock, or is it a new one?
 
Also, it's literally only a couple of times a day, the rest of the day all is normal.
 
Thanks Chris_W, would a normal gas flow rate rule out the heat exchanger as the problem? Also, 2 hours after the service, is that a coincidence?
 
It can be coincidence, and I’ve seen it where engineers have been before me and turned the hot water dial down to overcome the heat exchanger issue (temporary of course). A normal gas flow rate wouldn’t rule out the heat exchanger, and abnormal one might.
 
So here's what's happened. It started making the noise 2 hours after it was serviced. I got him back to check the CO2 readings .. and since he did those checks, which were fine, it's stopped making the noise. Could it be he left something loose after the service? Either way it's fine again.
 
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