Honeywell 3 port diverter snag?

[SJB060685]

If the valve is sticking causing your problem of both CH and HW on at same time then there’s only so much you can do to prolong its life. Like I mentioned above as well with this particular design of valve the synchronous motor is likely to burn out over time leading to nuisance replacements. You’re best bet is to save time and money and replace the whole valve, be it you or an engineer. I personally don’t like these valves because of the problems we’ve mentioned, I always preferred an S plan but again they fail over time as well

 

[Johnm]

this particular design of valve the synchronous motor is likely to burn out over time leading to nuisance replacements.

The motor is designed to be permanently stalled. The motor is fed through resistors & a diode and my last valve failed because one of them had failed. I didn't realise that was the problem until after I had changed it to an S plan. Now have changed it back to Y on boiler mfrs recommendation to avoid need for bypass. If the spindle turns easily you don't need to replace the entire valve, just the motor or head. There should never be a long term demand for heat or HW.

 

[SJB060685]

What I meant John is if CH was last port of call then the motor will burn out over time. I know how the valve is held in mid position if you read one of my above comments. Am I wrong?

 

[Johnm]

When the CH is satisfied the valve should move back to midpos and then be held there by the rectified pulses. However, if there is a demand for HW it will unpower and spring would take it to HW.

 

[SJB060685]

This suggests to me that it’s last port of call is held and it doesn’t return to mid position. If I’m wrong then I’ve been wrong for years lol

 

[doitmyself]

These diagrams show what happens in the different positions. When CH only has been satisfied, the valve still stays in the CH only position due to voltage from the HW stat SAT or programmer HW OFF.

 

[SJB060685]

Like I said above @doitmyself

 

[John Armstrong]

Though this might be useful for diagnostics: I removed the powerhead then turned the supply back on (yes I put the cover back on the first!) Then turned on the CH/HW.

I can move the valve manually and I can hear it kicking over, so I’m guessing the valve is fine.

The powerhead isn’t behaving as it should, though I did wonder if that was because it isn’t physically attached to the valve?

My money is on a duff powerhead. What do you guys think?

 

[Harvest Fields]

I only ever change the heads first unless I know the body is passing, but then again I also have bodies on the van.

 

[John Armstrong]

I changed the powerhead.....
and it seems to have done the job.

 

[Harvest Fields]

I changed the powerhead...
and it seems to have done the job.

Awesome news

 

[Riley]

If you have bought the whole valve I would keep the brass bit as the other one definitely sounded like it wasn’t moving that freely

 

[John Armstrong]

If you have bought the whole valve I would keep the brass bit as the other one definitely sounded like it wasn’t moving that freely

Sure
And in the meantime it’s going to be perfect for lobbing at that cat that keeps coming to take a s**t on my lawn.

 

[John Armstrong]

Nearly forgot:
Thanks all for your time and expertise.
Cheers