All my radiators are fitted with thermostatic valves. These do a reasonable job of keeping the house comfortable, but a couple of them start whistling when they reach their set temperature. The whistle is infuriating, but stops as soon as I adjust the temperature setting slightly either way.

The house is 3 years old, and they've done it since new (I think - took me ages to work out where the noise was coming from). Any ideas on how to shut them up?

A.

Hi Andy..
The whistling noise is the velocity of the water travelling through an reduced opening (when the TRV starts closing down).If all your radiators have TRV's then you should really take one out and replace with a normal valve so that the heating system can circulate easily at all times, the bathroom radiator is usually the best choice.

Mog

Like Mog says,its no good if you have t/stats on all rads.
One needs to have just normal lockshield valves,usually the bathroom rad as its useful heat.
If all the rad stats get upto temperature and switch off, the pump cant sense that and could cause the boiler to overheat(unless you have a bypass installed somewhere)

Sometimes the noise is due to the fact that the thermos are installed on the wrong pipe,but this is usually a hammering noise.

Most NEW stats can be fitted on either the flow or return,but we generally find that they work better on the flow pipe and arnt as noisy.

It might be worthwhile changing them to the flow if its getting on your nerves,but it means a drain off.

Duncan

Or you could fit an Grunfos Alpha pump which is resistance sensitive and works very well on sysytems with all TRV's as when the TRV's start shutting down the pump will start to back off.

Mog

not used one of those pumps yet mog.are they any good??
how much compared to a normal 15-50 grunfos?

About £10 more, they quite good for larger systems in the summer when only the hot water circuit is running or systems with TRV's.

Mog