Telford tempest cylinder fault?

[lupieloo]

Hi

I have a Telford tempest unvented cylinder and I'm finding that when the hot water is on and I turn it off on the programmer the TPRV opens and let's the hot water out. Only stops running when it cools down again.

What I find strange is that it only happens if I turn the programmer off. If I have the immersion heater on all day it doesn't happen. I thought it would be the TPRV but surely this would open if the immersion heater was on aswell and was faulty?

Any ideas?

 

[steadyon]

1. These cylinders need an annual service. Has this been done?
2. If the programmer is part of the indirect (heating coil boiler driven) circuit, I would suspect a problem with the motorised control valve, particularly if a three port valve has been used alone, rather than the cylinder having a dedicated 2 port.
3. The immersion heater may not be raising the temperature high enough to trigger the TPRV.
4. You need a G3 qualified technician to investigate and rectify. The cylinders are NOT DIY.