Hi All,

The pushrod on the DHW pressure differential valve wasnt operating when hot water was called for, so I replaced the valve assembly including diaphragm but it still doesnt operate.

I've removed and cleaned the cold water inlet filter gauze and the filter in the inlet/return manifold. I've also removed and cleaned the small copper tubes that go between the inlet/return manifold and the diaphragm assembly but still the pushrod doesnt operate. There's plenty of flow at the hot tap so I'm stumped as to where the blockage might be.

Could a brand new pressure differential valve have a sticking pushrod? I didnt check it was free before installing it and now I'm wondering....

Any other suggestions?

Cheers,
Mark

Thanks TT. I read something similar in another post but didnt think it sounded possible, but maybe a faulty pump affects the correct operation of the pressure differential system? Also, I have heard the pump make some strange noises in the past 6 months so I think I'll try that.

Mark