Potterton MSV 322 3 way valve problem

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Hi hope someone can help? I've got a problem with my 3 way valve, I've changed it twice and both times the actuator has failed after a few months. I assume that there is a problem with the voltages going to it. I've measured the voltages and copied them below, any advice would be welcome.

everything off

Grey 240v
Orange 18v
White 90v
Blue 0v

Central heating only

grey 240v
Orange 17v
White 240v
Blue 0v

Hot water only

grey 0v
Orange 240v
White 8v
Blue 0v

Heating & Hot water

grey 60v
Orange 240v
White 240v
Blue 0v
 
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half of them are wrong.

what other controls have you programmer, cyl stat, boiler ?
 
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Hi thanks for replying, I have a Siemens RWB9 programmer, RAA02 room thermostat, Ram1 tank stat and Vailant VC GB 182 EH boiler.
 
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you say the actuator has failed.
what happens so you know its failed ?
you boiler won't fire up when heating called for ?
 
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Hi again, yes the boiler doesn't fire up. to be honest I've been living with this problem for years and can't remember what else I did to confirm that the actuator failed. However i do remember that first time it happened I bought a new actuator and everything was fine for a month or so. So I'm pretty sure it's that.
thanks
wynn
 
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that a dear expence replacing the whole actuator for a failed motor.
so its only heating that is not firing up the boiler then ?
 
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That's right hot water works fine, I've kept the valver in the mid position setting and rely on TRVs to control the central heating, but that's really ineffective and I want o get this sorted.
 
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That's right hot water works fine, I've kept the valver in the mid position setting and rely on TRVs to control the central heating, but that's really ineffective and I want o get this sorted.
The valve is not powered up for hot water only, which is why that works OK.

Unless the valve is very old, you can separate the actuator (metal box) from the valve body and inspect/test the two parts separately.

The spindle in the valve body should rotate easily, but not a full rotation about 20° max. If it is stiff, a small amount of WD40 or similar lubricant may help.

As for motor, you should be able to see if it works when you put the heating on.

If the valve is OK and the motor works we need to test the actuator.

Replace the actuator
Turn power OFF to heating system
Turn CH and HW OFF at programmer and both HW and CH stats down
Turn Power ON
White and Orange wire = 0V
Grey wire = 240V
Turn HW ON.
White and Orange wires = 0v
Grey wire = 240v.
Turn HW stat up
Grey wire = 0v
Orange wire = 240v
Boiler should run and HW heat up (Check pipe)
Turn CH ON and CH stat up.
The motor should run, then stop.
Boiler fires (check both pipes from valve are hot)
White wire = 240v
Grey wire = 0v.
Turn HW stat down
Motor should run then stop.
White wire and Grey wire = 240v.
Boiler should fire (It may stop and restart. (Check CH pipe is warm and HW pipe is cooling down)
Turn HW OFF at timer.
White and grey wire = 240v
Motor may run and stop.
Boiler should fire (It may stop and restart) (CH pipe still hot, HW cold)
Turn the CH down at stat
Boiler should go off
Grey wire = 240v
White wire = 0v
The orange wire should have about 100v. It will vary but be well below 240v.
Turn CH OFF
Grey wire = 240v
White wire = 0v
The orange wire should have about 100v. It will vary but be well below 240v.

WE can only remove the voltage on the orange wire by removing all power from the valve; this resets the valve.

PS The blue is neutral so it will always read 0v. Voltages should be measured between the relevant wire and neutral.
 

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