Heating system

[i=p/u]

Looking at a heating system tonight, grasslin 24 hr time clock and 3 Zone valves ,down stairs heating , upstairs heating and hot water.

Upstairs heating and hot water not firing boiler. But valves are lit up. So when I turn upstairs heating stat down the valve light goes out but you don't hear the quizzing of the valve closing like it should , can the valves jam open and stop sending power to boiler? If it was jammed open , would the water not flow to heat from downstairs loop.?? Is their a way of fixing jammed valves or isit bin thx trev.i

 

[diditrain]

Some valves are a lot quieter than others. Have you tried seperating the oranges and verified that you get the correct voltages back out of the individual valves when you are calling for your heating and hot water? I am presuming that the greys have been used as a permanent supply