HW only when CH also on - motorised valves installed incorrectly?

[nervous123]

Following on from my previous thread http://www.ukplumbersforums.co.uk/c...251-hw-only-works-when-ch-other-problems.html I've had a registered engineer come round, who queried the position of the 2 motorised valves. (see my sketch below)

(Electrician had written A = heating, B = hot water.)

The engineer said the position of motorised valve B is incorrect, as both valves should be independent of each other, whereas here, the flows in both pipes pass valve B.

Does that make sense? Is it a big job to rectify (haven't yet got a quote from him, how much should I expect)?

Thanks to all

 

[Rodreguez]

jus to clarify could you put the arrows on with direction of flow?

 

[nervous123]

i have no idea, sorry... I'm not a plumber myself!

 

[fuzzy]

if the water is flowing down the pipe with the 2 port and then the tee then yes he is correct

 

[JimH]

Looking at photo 3, valve "B" is definately in the wrong place. Should be - pipe from tank to a "T" piece - 2 seperate pipes off - one leading to the "HW" valve, the other to the "CH" valve.
fuzzy is right, the engineer is correct.

It will also depend on your programmer - if it operates like mine & the boiler only comes on with the "CH" then the pipework is correct - you will only get "HW" when the "CH" is on.

 

[nervous123]

It will also depend on your programmer - if it operates like mine & the boiler only comes on with the "CH" then the pipework is correct - you will only get "HW" when the "CH" is on.

Programmer is Honeywell ST9400C - separate buttons for CH and HW - so seems pipework is the problem.

A subsidiary problem is that because we turn on the HW button for the CH to operate, the thermostat has no effect (it thinks the HW's on...) and as a result, in this cold weather the CH is basically on all day and all night. Which can't be cheap!

Is it a big job to fix??

 

[JimH]

Programmer is Honeywell ST9400C - separate buttons for CH and HW - so seems pipework is the problem.

A subsidiary problem is that because we turn on the HW button for the CH to operate, the thermostat has no effect (it thinks the HW's on...) and as a result, in this cold weather the CH is basically on all day and all night. Which can't be cheap!

Is it a big job to fix??

Mine has seperate buttons as well (different programmer), but still only operates the "HW" as a secondary control - so before you get an engineer in, best find out what your programmer can and can't do - I'll see if I can help.

 

[JimH]

"ST9400 is an Electronic Programmer which provides accurate time control for central heating systems with separate programmes for heating and hot water. ST9400A is a 1-day version and ST9400C is a 7-day version."
Looks like the pipework is wrong - It's a case of a small bit of pipework & re-positioning the the valve... shouldn't think it would be that expensive - call-out + work? Best get a 2/3 of quotes.