3 port CH/HW valve clicking and cycling in mid position

20 Jan 2008
Reaction score
United Kingdom
When my 3 port valve is in the mid position it is constantly clicking one of the micro switches. The valve constantly moves back and forward a tiny amount in this mid-position. This causes interference with radio and TV signals throughout the house and is a pain.

Also the CH does not run under some conditions. The programmer is asking for HW and CH and the CH thermostat is asking for heating, but the HW thermostat is not asking, CH does not come on. If I turn the HW thermostat to ask for HW the whole system starts and then when I turn it back to HW satisfied the heating continues as it should.

I don`t know how it gets into this condition yet.

The valve is a Siemens Landis & Staefa MA-V3 3 port mid-position valve.

Help would be greatly appreciated
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