"Christian McArdle" wrote in message
.. .
Ideally, you should remove the thermostatic head *before* draining
the rad, and replace it with a screw-cap which should have been
supplied with the valve for this very purpose. That will hold the
pin firmly down whatever the temperature.

Also, some designs feature a genuine "off", where you twist another
quarter turn after passing the "0" frost setting.

Christian.

IF the valve doesn't have an 'OFF' position, place a penny under the
thermostatic head and over the pin- then the * = Frost setting will
positively close off the valve.

--

Brian