>> Newbie post from a long time lurker here. Hoping someone can help. >>
>> As part of a loft conversion, we replaced the old boiler system. >>
>> The old was a 'traditional' open vented boiler system with a pump and a >> hot
>> water tank, a salamander shower pump and a Bensham thermostatically
>> controlled shower mixer. The new is a Worcester Bosch (WB) 28CDi RSF >> combi
>> in the loft.
>>
>> Since installation (by a plumber working for the building contractor) the
>> heating has been fine, but the 'hot' water has been tepid.
>> The plumber went through the trouble-shooting routine, said that a flow
>> sensor was defective and called WB. Today the WB guy came, tested >> everything.
>> He says the sensor is fine but that we had a 'cross'leak'. He thinks that
>> the shower mixer is allowing cold water up the hot side and into the taps
>> (which he tested by switching off the hot supply and getting a good flow >> of
>> cold water out of the bath hot tap).
>>
>> The local bathroom place says this is a good quality mixer suitable for
>> mains pressure and disputes the diagnosis. Any thoughts please - just >> trying
>> to make sure i'm not getting dicked around and looking forward to a hot
>> shower again.
>
> The diagnosis by WB guy is plausible. Quite a few but not all shower
> mixers and bath-shower mixers have this 'feature'. A number of
> manufacturers but not all put non-return valves in the inlet to the mixer
> to ove come this 'feature'.
>
> The shop may be right in saying what they say about the mixer but that
> won't stop the problem in this case.
>
> As a temporary work around try turning the mixer all the way to full hot
> or full cold and see if the 'feature' goes away. If you have the sort that
> only have one control that goes from off to cold through hot then you
> can't, off course. One or maybe two non-return valves added to the supply
> to the mixer will fix it properly.
>
Well the plumber has been and put a non return valve on the hot side. We now have good hot water to all outlets but still a tepid shower. any further thoughts from the jury ?