Model CL250. Over pressure valve on cold water inlet bleeds warm water.
New pressure/temp valve fitted. New combination valve assembly fitted.
Over pressure valve on water inlet still bleeds. Regulator factory set
to 3 bar. Over pressure valve factory set to trigger at 8. What possible
problems or faults match these symptoms?

"Janet Bale" wrote in message
...
Model CL250. Over pressure valve on cold water inlet bleeds warm water.
New pressure/temp valve fitted. New combination valve assembly fitted.
Over pressure valve on water inlet still bleeds. Regulator factory set to
3 bar. Over pressure valve factory set to trigger at 8. What possible
problems or faults match these symptoms?

Failed air bubble - read the replenishment instructions

Janet Bale wrote:
Model CL250. Over pressure valve on cold water inlet bleeds warm water.

i.e., expansion relief valve dripping; refill air bubble as stated
above. The expansion bubble/expansion tank isn't required in most other
countries, where the expansion relief valve just dumps the extra water
volume down the drain. The expansion tank or bubble is a UK Water
Bylaws requirement to prevent waste of water.

New pressure/temp valve fitted.
Why? They would have had to drain the heater, and so refill the air
bubble, to fit a new T&P relief valve. The T&P valves rarely fail.
New combination valve assembly fitted.
Why?
Over pressure valve on water inlet still bleeds.
I've been told that you can get a recurring loss of the air bubble in
some areas, due to the water quality. In this case the fix is to fit an
external expansion tank, or refill the air bubble regularly. Ring the
manufacturers for technical advice.
Anyone doing work on an unvented water heater should have passed the
relevant training course (IoP, CITB, etc., ). If you're going to ask
for a refund for any unnecessary work from the installer, ask for the
relevant certificate number and check with the issuing body.