pump continues to run!

[riffman]

strange one this.
I have a fully pumped system with two motorised valves, one for ch and one for hw...
Timer reaches set "off" time, hot water valve closes(i can hear and see it move) but pump continues to run. only way to stop it is to first manually turn the central heating on on the timer, then turn hot water off, then turn central heating off!! thought during cold weather it was the a frost stat in the boiler keeping the primary circuit flowing but it still does it now we have warmer weather!!
Timer problem or aux switch on the hw motorised valve??

 

[tommyl18]

is the central heating valve turning off when the timer sets to off?

 

[Lower]

What boiler is it? The is a classic circuit board failure on a baxi solo.

 

[twgas]

The wiring may be wrong, I'd suspect a valve brown and grey connected together in the wiring centre.

 

[riffman]

is the central heating valve turning off when the timer sets to off?

yes it does.
boiler is an ideal icos HE18
wiring not touched and it used to work ok
what stop/ starts the pump?

 

[twgas]

You need to start by isolating the power to system, then turn HW and CH on and off, one at a time, noting what moves/heats up/makes a noise etc.
Then do them together and observe some more - post obs and we'll try to help.

 

[riffman]

Press HW on timer, motororsed valve opens pump starts, boiler starts= all ok
Press HW button again to turn off, motorised valve shuts but pump remains running and goes onto recirc via the PRV bypass. Boiler cuts in occasionally as water temp in primary circuit drops

Press CH button, motorised valve opens, pump starts and boiler starts
Press CH button again to turn off, motorised valve shuts pump stops boiler stops

Only way to Stop the pump when running for HW only (as i now am) is the following:
Press HW on button on timer
Press CH on
Press HW again to turn off
Press CH again to turn off and pump stops!!