We' ve recently replaced an aging Gloworm cast-iron boiler with an Ideal
Response 120 combi. It works fine, apart from some noises.

Most of the radiators are fitted with thermostatic valves (only one radiator
is not). When a valve upstairs is on the point of closing, it seems to set
up a horrendous vibrating noise, that can be felt and heard through the
whole house, but loudest at the value. If I switch the value up or down a
little, so it is fully on or off, the vibrating stops.

The vibration seems to resonate around 20 to 30Hz - but that's just an
estimate - it is very loud though. It happens on several of the valves, but
not all.

We don't have any cold spots or radiators that don't heat up. We also never
had this problem on the old boiler (though it did sound like a giant kettle
boiling and thumping around). Switching on a hot tap stops the vibration,
for as long as it is on. I have no idea why that should be, as the taps and
radiators should be independant.

I was just wondering what the problem could be, and how I could go about
confirming and/or fixing it.

Thanks,

-- Jason
(newbie here)