Hot water on when heating on!?

[targett]

I have a keston 25 boiler and a megaflo hot water tank.
When my hot water is on at the control unit/timer I have hot water and heating activated despite the heating being off at the control unit/timer...

I've checked the valves and the actuators in the airing cupboard (1 for heating and 1 for hot water) and both are working mechanically and electrically but still the heating comes on.

Any thoughts?

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[diesel_ltd]

are you saying your rads heat up when you have h/w only seleted?? has this been the case from the system was installed?

 

[targett]

It's never done it before.
Only started after we got back from holiday (system off / holiday mode).

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[kay-jay]

you must be missing something then! if the valves and actuators were running mechanically and electrically you wouldn't have a problem.

are all wired connections tight. did you check wether the current was passing from controller to heating valve on hot water only, if so then its a wiring problem because this circuit should only be live 'on demand' .

 

[secret squirrel]

If I were there I'd (with all respect) ignore what you've said and check the valves, its easy enough to do.

Put your hand on the hot water coming up from the boiler make sure its hot then, put my hands on the pipes leading out of the valves, if they're both hot and only the hot water is on on the timer its a valve.

If it was working fine and now its not then its normally something simple.

If it is the valve change it. Remembering you should have an unvented ticket to work on these things....

Do you need it to change a 2 port honeywell or the like, I think so....

 

[secret squirrel]

It's never done it before.
Only started after we got back from holiday (system off / holiday mode).

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May have seized while you were away, just because it hasn't done it before.....

My gearbox went on my van been driving for over 25+ years owned numerous vans and cars and never had a gearbox go!

 

[targett]

If I were there I'd (with all respect) ignore what you've said and check the valves, its easy enough to do.

Put your hand on the hot water coming up from the boiler make sure its hot then, put my hands on the pipes leading out of the valves, if they're both hot and only the hot water is on on the timer its a valve.

If it was working fine and now its not then its normally something simple.

If it is the valve change it. Remembering you should have an unvented ticket to work on these things....

Do you need it to change a 2 port honeywell or the like, I think so....

I was convinced it was the hot water actuator not working (the motor was v. hot and had no movement) but after I took it apart to inspect it the motor started working (no longer over heating) so put it back together and have checked it's still working - Which it is.

The actuator for the heating is and has always worked.

Feeling the pipes they are all hot and manually moving the valves makes no change
I wonder if it is the actual valve that needs replacing? - Any thoughts?

The hot water is a 2 port honeywell (272848 normally closed)
The heating is a 'Drayton ZA5' - Is this a 'normally closed' actuator?

With regards to the actuators:
1. Honywell - When activated by the control panel the mechanics move as does the valve.
2. Drayton - When activated by the control panel the mechanics move but the valve appears not to rotate/move (the valve is not stuck as I can easily rotate it with my fingers/spanner)

 

[jase158]

Drayton - When activated by the control panel the mechanics move but the valve appears not to rotate/move (the valve is not stuck as I can easily rotate it with my fingers/spanner)

when you turn it by hand does it stay in the position you turn it to, does heating stop heating up???

 

[targett]

Here are some pics of the pipework...

 

[targett]

when you turn it by hand does it stay in the position you turn it to, does heating stop heating up???

The valve rotates and stays put where it's left but I don't think it changes the heating coming on or not...

Think I have just worked out my problem valve! - Now to work out how to replace it...
I'm guessing I'll have to empty the pipework/system so I can remove the valve and replace with a new one. I an hoping that I'm correct in thinking that I'll only need to drain the flow/return pipework to and from the tank and the boiler (not opening the boiler of course). I can see the drainage taps/ports underneath the boiler casing - Do I just open, drain, replace and refill?
I guess that the hot water tank won;t need draining as it's a separate water system????

 

[jase158]

http://www.ukplumbersforums.co.uk/c...novice-drain-down-refill-system-properly.html

 

[targett]

Thanks Jase
The guide talks about an open system with a tank in the attic, mine is a closed system. Do you think I treat it the same?

 

[targett]

Someone on the novice draining thread said that I shouldn't have my pressure (closed system) above 1 bar - I think it's about 1.5 bar right now...
Do you think that could stop the valve closing? (Going to try reducing the pressure in the morning and see what happens...

 

[Gray0689]

Nothing to do with pressure 1.5bar is fine
All
You need to do isolate flow return drain off pressure using a drain off get a small bucket under the motorised valve that is faulty the one in pic that you have case off undo nut catch excess water in bucket have new valve ready when not a lot off water coming out swap over valve tighten nuts rewire exactly the same
Re pressurise system to 1 to 1.5 bar
Then test

 

[targett]

That's what I was thinking of doing.
Unfortunately the valve is just above floor level - no way of getting a bucket in...

Think I'll drain top & middle floor (town house) rads and flow/return pipes to swap it...

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[stevetheplumber]

they often work when of the valve body its usually the valve thats tight just change it