3-way valve problem

[davidr]

Hi

I think I have a problem with a 3-way valve and would appreciate your advice - thanks

My system is fully pumped and uses a 3-way ACL Lifestyle valve (779H340). All was working well until I decided to flush and clean the CH and replace X100.

CH is now much quieter and rads get hotter BUT rads now stay on even when set for HW only. With HW only, black lever and indicator springs back to HW only position but rads without TRV's get very hot.

Boiler, programmer, stats and pump are all working fine.

I've tested the voltages across the 3-way:

WHITE ORANGE GREY
HW ONLY 27 238 0
HW+CH MID 238 238 64
CH ONLY 238 238 238

This seems about right but I don't understand the 27 and 64 - shouldn't these be zero?

Could the spring be failing to pull the valve fully closed on the CH side or is this more likely due to dirt in the valve body?

The motor seems to work ok but could the micro-switches have failed?

The ACL does not have a replaceable actuator and a full drain down may be needed (again) if the valve part has jammed up.

Thanks for any advice or insight

David

 

[seco services]

as you say all seems to be ok.
but it may have a bit of crud lodged in the heating port stopping it fully shutting it off when only hw on, it don't take much to restrict it from fully shutting.

 

[gas4you]

What happns on CH only?

If pipe to HW cyl still gets hot then it is definately the valve body not shutting properly.

 

[davidr]

Thanks for the advice -

I took the motor out of the actuator and manually moved the lever back and forward for a few minutes then lubricated the spindle. This seems to have cured the problem. All ok now - thanks.

BTW - it looks like it would be easy to cannibilise a new actuator to replace a failed synchron motor, micro-swtiches or circuit board instead of replacing whole 3-way. My 3-way is old type with actuator riveted to the valve body.