Heater hissing?

[Ticktock80]

One radiator is hissing. When I turn the little white control knob handle on it wither up or down, it stops. So it's like on that one setting it is letting to much water flow in maybe? As it is the only heater in the house doing it and only on the one setting! What is it? Thanks in advance.

It sounds like you have a thermostatic radiator valve that has been fitted on the wrong way round, by a person who does not know much about plumbing.

Until you have it changed (in summer) look at the lockshield valve on the other end. If you take the plastic cover off, then screw it fully closed then open about half a turn, it will probably reduce the flow enough to make the hissing quoted, but not so much that the radiator goes cold. You only need a fraction of a turn from closed to make a difference. Try it and do not adjust the spindle more than a quarter turn either way per hour.

If it starts to leak round the spindle, quickly turn it fully open or fully closed and it will probably stop. But it will need to be replaced in summer.

It is not a gas part so you do not need a gas engineer, a plumber can do it.

...make the hissing QUIETER...

Thanks john! It worked a treat.