Hi. My home heating system has developed a fault in the past two weeks which I can't fathom out. It's been fine for years up to now.
When CH is called the mid position valve moves to the CH position. When DHW is requested the valve stays in the CH on position. When CH demand is satisfied (room stat trips out) the valve stays in CH position and the boiler keeps running. If I then turn DHW off at the programmer the boiler shuts down and the valve moves to the DHW position. If I then turn on DHW again the boiler restarts and the valve stays in the DHW position.
I have checked all wiring connections ok. Checked room stat and cylinder stat for correct switching ok. Both programmer and room stat are less than 3 years old. Spring return valve is a 20 year old Barlo 3PV-2 (looks like a Drayton MA1).
Is this a knackered switch in the valve head? Looking for advice before I spend money on a new valve and system drain down to fit it.
When CH is called the mid position valve moves to the CH position. When DHW is requested the valve stays in the CH on position. When CH demand is satisfied (room stat trips out) the valve stays in CH position and the boiler keeps running. If I then turn DHW off at the programmer the boiler shuts down and the valve moves to the DHW position. If I then turn on DHW again the boiler restarts and the valve stays in the DHW position.
I have checked all wiring connections ok. Checked room stat and cylinder stat for correct switching ok. Both programmer and room stat are less than 3 years old. Spring return valve is a 20 year old Barlo 3PV-2 (looks like a Drayton MA1).
Is this a knackered switch in the valve head? Looking for advice before I spend money on a new valve and system drain down to fit it.
