Honeywell 4073 Sundial-Y diverter valve

[MrMan]

Hi all. I'd like a quick sanity check if possible please. Just replaced the motor in this (15 year old?) Honeywell 3-way valve head. Now HW alone (spring return) is working fine. CH + HW (mid-position) works fine... spring return initially, then motor drives to 1st microswitch click and stops. CH alone... motor drives from HW return position through 1st and 2nd microswitch clicks, but keeps going. After a few minutes running CH alone, the head starts making noise and vibrating, like the motor's still trying to drive the valve further. Is this normal? I was expecting it to stop at the 2nd microswitch click. I've taken the head off and twisted the valve by hand - it turns easily from HW to CH without sticking. I'm now nervous about running the CH because the old motor (cracked open) has all the teeth missing from the only non-brass (nylon?) cog. Thinking this might be a failure of the 2nd microswitch, I've opened that and cleaned the contacts, checked they're good, and re-assembled. The motor still seems to run continuously with CH only selected. Is this how it's supposed to work, or am I looking at buying more new motors because of some other failure? Hoping someone can help...

 

[ChrisR]

You opened the microswitch to clean the contacts? Gosh that's a bit keen, you can get new ones for a quid.
But yes, they just stop at the end with power still applied. There are motor-open motor-closed designs, but they cost more and don't seem to be wonderfully reliable.

 

[MrMan]

Thanks Chris. Yes, keen indeed - brought on by a cold house and unhappy wife (solely because of the cold house). I really cleaned the contacts because I had the thing apart anyway. So the buzzing from the motor when CH is running (even after the room thermostat has switched it off) is a design "feature"? As long as that's how it's supposed to be, and it won't continually eat motors, then I suppose that's alright. Thanks very much. Now looking forward to the comfort of a warm house, and a warm wife.