Cold header tank Hot

[kevplumb]

have you got isolation valves on your shower

 

[dextrous]

have you got isolation valves on your shower

Finally, I've got your meaning, er, I think.

What you're suggesting is that, regardless of whether the shower is on or not, cold water is indeed bypassing into the hot pipe and forcing hot water to backfeed through the CWS. This is exacerbated by the lack of check valves being installed. Since the cylinder will always have hot water in it, it will appear to be the case regardless of whether the HW or CH system is on.

In which case, the water level should be rising. In which case, op, can you advise as to whether or not your cold water tank has overflowed.

 

[Dolgoed]

I am at work now i will have a look when i get home as the heating will be off and your theory tells me that the cold water header tank should still be leaking through the overflow.

After 1 1/2 hours of the system in service again this morning (ie the system being shut off all night) the radiators were up to temp but the hot water was only luke warm.

I also have a feeling that the the previous motorised valve was a three port diverter valve, and now the plumbers have fitted a mid position motorised valve when i asked them to change it.

Update i have phoned Honeywell and they say the fitting of the mid position valve would cause the problems I have.

Also thank you everyone for your help

 

[Dolgoed]

Ok changed midpoint valve to diverter valve problem still exists with cold water tank heating up. NRVs in pipes to shower mixer tap, sink mixer has isolation valves. If i turn off the boiler and pump and use immersion heater to warm water and hot water does not back up to the cold water tank does this mean I have a burst heating coil in my hot water tank?

 

[Dolgoed]

Could i fit a NRV into the the cold fill line to the boiler

 

[Dolgoed]

Fitted NRV to shower hot water pipe now all fine.