Boiler won't switch off

[I'm inajam]

Hi, I have an Ideal Logic 24 boiler governed by a Dayton LP722 programmer. The programmer is selected to "off" for both HW and CH but the boiler HW system continues running. Its a new problem after five years of good operation.

I have reset the boiler, checked the wiring to the programmer, switched off the boiler, removed the cover of the programmer and switched the boiler on again but the problem persists.

 

[Dan Robinson]

Zone valve.

 

[I'm inajam]

Thanks Dan. Is it located in the boiler or the programmer. Being a "valve" I assume the boiler. How easy a fix is it.

 

[ianmcd]

have a look where your HW cylinder is located it is common for the zone valve(s) to be located there you will have either 1 three way valve (Y plan) or 2 x 2 way valves (S plan) once you have found these come back and let us know which system you have and we will tell you how to find out which fault you have , they might not be next to the HW cylinder they might be somewhere else but will probably be next to where your pump is

 

[I'm inajam]

I have an S plan but if the programmer is selected to "off" so no demand for CH or HW how could the zone valve be singling the boiler to run. Are the zone valves not just to direct water to the correct place. My problem is the boiler is running when it shouldn't be.

 

[Dan Robinson]

Because the valve is jammed open.

 

[ianmcd]

the way a zone valve works is when you select what zone you want on, power is sent to the motor which opens the valve and when the valve is fully open the motor makes the end switch which then powers on the boiler and the pump so as Dan says either the motor is seized in the open position or the motor is OK and the end switch is jammed in, when the boiler is on but everything switched off feel the pipes at the zone valves and if one is hot then that valve motor is seized if neither are hot then one of the end switches are stuck

 

[I'm inajam]

Its sorted men!!, thank you. Yes the valve was stuck in the "B" position. Once I moved the black reset lever to the side it popped back into the correct position and the problem is solved.

Should I replace the motor on the valve now or do these problems tend to be just one offs.

 

[ianmcd]

you have cheap ****ty valves then if it has a black plastic leaver, if it keeps sticking you can replace the actuator (the white box on top of the valve) this contains the motor and the end switch and can be replaced without draining the system