help needed motor valve

19 Oct 2010
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United Kingdom
have recenty changed a 3port m/valve , i now have the problem with the rads heating when the hot water is on the m/valve seems to move correctly

1st - inside the electrics cover of the m/valve there are 2 micro switches what do they control , reason ( the switches on the new unit seem to be seated differently, (both units are the same make)

2nd - it would appear that something is either over riding the control or is faulty, would the hot water cylinder stat cause this , I am wondering if the small micros switches have any bearing on the control or if the switches are making would this override the cylinder stat
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Did you change like for like and get the wiring correct?Did you ft it the correct way round.The B port feeds the cylinder.
oh yes all is the same Iam practiced at this as i have replace every couple of years , its the switches that are puzzling me, on the one a took out the switches are soldered parallel to the pcb, on the new one the switches are tilted towards the cam on the spring loaded pivot one with red rocker (top) and one with a white rocker (lower) which controls what
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The valve uses a spring return motor. The HW position is the 'rest' position.
The valve moves over one or two sections depending if its going to stop at mid position or going through to CH position.
It relies on two power sources.
Room stat makes white wire live which drives motor via micro switch (contacts A). At mid point contacts A open and contacts B close.
This allows power from grey wire to take over and drive motor over second section.
If the grey wire was not live then valve would stay put at mid position because the cut off power would be left with a modified voltage, produced by a circuit board.
This circuit board is also fed from the white wire via the second micro switch (contacts C).
If the valve continues beyond mid point to CH position the modified voltage is not required and the micro switch is triggered so the white wire connects to the orange wire to fire boiler (contacts D)
The switches operate differently. 1st switch has 2 inputs (white and grey) and 1 output (motor). 2nd switch has 1 input (white) and 2 outputs (motor) and (orange)
Hope it helps.
thanks for the definition i can work back from that without takeing volt readings At present cant comment on that part ,however seeing that the boiler is firing up and the pump running i think i can assume that all is ok there, would i be right in saying that the cylinder stat would also control m/valve along with boiler

ok/ all cold, timer switches on HW boiler fires, m/valve over to cylinder pipwork to heat HW at temp stat controls boiler to shut down,

same goes for CH except for a different stat and the M/valve switches to rad pipe network

if both are HW & CH are called then it must be the stats that are controlling the m/valve switching water flow depending on what is called for and the boiler at temp if both HW & CH are both upto temp the boiler would shut down If I have this wrong, and the stats are only controlling boiler at temp then what controls the the m/valve

if this is the case then its the stats that i need to be looking at. which one would be the most likely culprit?
There's a situation that's not always easy to grasp. If CH was last to be switched off, it means room stat is out of action so no supply to valves white wire and no supply to boiler. But the grey wire is still live. So although there's no heating the valve remains at the CH position until next time the system is used. Yes it means the motor is continually energised throughout the night or while you may be away. The way to avoid this is to make sure HW is the last to be turned off after valve has dropped back to HW position.

If you're starting from cold and you switch on HW the valve will be at HW position, or it could have been at CH position when last switched off but will drop back to HW position. (see above)
The valve stays put, no power to room stat and no power to move valve.
Power from programmer HW ON supplies cylinder stat which supplies boiler.
Cylinder stat when satisfied diverts the power to second terminal which supplies power to the valves grey wire. In this situation it has no effect because the valve is not in the mid position.
You can see the valves innards plays no active part when using HW only.

When you select both HW and CH. The HW behaves like before, but now the room stat supplies power and moves the valve to the mid position.
It can't go further because the grey is not live. The 230v is dropped but the modified voltage produced through the second micro switch remains and this is enough to hold the valve against the spring pressure.
At this stage it depends which demand gets satisfied first. Usually the HW.
What happens is the cylinder stat cuts out and stops boiler. It makes the grey wire live, which in turn now drives the valve forward.
During this movement the second micro switch drops the no longer needed modified voltage and make the orange wire live and boiler re-lights.
If CH got satisfied first then room stat would cut off supplly to white wire and valve would drop back to HW only until CH was again in demand.

If you choose CH only. the grey is already live ( that's through the wire from the programmer HW OFF terminal) So room stat supplies power to white wire. At mid position grey wire takes over and goes to CH only.

If you have hot radiators when HW only is selected it questions if the valve is the correct way round as already suggested, or the motor/gear/spring mechanism is preventing the valve from returning to the HW position.
You need to verify the valve does move to all three positions
thanks once again for the comprehensive advice i have printed this of and i will keep this ,

I can verify that the valve is defiantly the correct way round , i can also verify the three position work I am intend to remove the pcb from the old unit and re install it in the new one to see if the micros are the problem it would make sense that as you say the switches need to be in certain positions making sure the volts run to the correct component at the right time if these are wrong it will not work could be the prob I will look tomorrow I will re post if you would like to watch for my post.

once again a big thanks to all that have advised
Can't really see how the micros can be the problem if valve moves to all three positions.
valve moves from HW to mid position, means 1st set of contacts in Sw1 is ok
Valve moves from mid position to CH position, means 2nd set of contacts in Sw1 is ok.
Valve remains in mid position when appropriate, means 1set of contacts in SW2 is ok
If boiler lights when in CH only position, means the 2nd set of contacts in SW2 is ok.
It might be worth operating the system with the actuator head removed so you can operate the spindle by hand. I'm thinking the CH port cannot be fully shut off when in HW only mode.
Is the valve spindle too stiff
Is it possible the return spring is not correctly located and not returning the valve fully, could be damaged teeth on the quadrant. The spring will not be as strong as it nears the HW rest position so the slightest restriction may bring it to a halt before its fully home, leaving CH port partially open.
using the great advice from you guys i have solved the problem, and it was the switches basically the top micro was making at the wrong time due to the tilt on the switch I used the board from the old M/valve and walha all working. It just goes to show how important communication is. Iam happy and you guys should also be happy for helping sort a problem out once again a big thanks
I still can't see how one of the micro switches operating at the wrong time is responsible.

If CH comes on when you have HW only selected, where do the micro switches come into the problem.

For the radiators to get heat, the CH port must be at least partially open.

The grey wire is dead until HW is satisfied or turned off, and when it comes live it cant do anything until the 1st micro switch is triggered. (switching from white wire to grey)
It can't be triggered because the motor does not move when HW only is selected

With CH off there is no supply from the room stat to the valves white wire and therefore no motor movement and none of the switches are active.

However you have it sorted so I'm happy about that.
just a quick reply i think the reason for the problem was that both the micros were making at the same time I dont kown the total ins and outs of them and bow to your experience. I have since re solderd the original micros on the board now mathching the new one, this one now works ok as well. maybe if this still does not ring true it has something to do with the wireing of the whole system i never installed it and it would definatley not supprise me one little bit
I think it is more likely to be a wiring fault.
The fact is that if only HW is selected and not CH, then the quadrant/valve never moves from the rest position, so the switches don't get triggered at all in this situation. CH has to be on for the quadrant/valve to move
I think it is more likely to be a wiring fault.
The fact is that if only HW is selected and not CH, then the quadrant/valve never moves from the rest position, so the switches don't get triggered at all in this situation. CH has to be on for the quadrant/valve to move

Hi mandate long time no see
just to clarifiy, you are perfectly correct in your thinking,but that only applies to a perfectly working valve,which the OPs' wasn't
for example if microswitch 2 is stuck toggled over then the valve will start to drive open whenever there is a call for heat on the boiler via the orange regardless of any call from CH.
Incidently in the above situation the valve will seem to be at mid position but it wont be stalled,it will wind back and forth around the mid while microswitch 1 is making and breaking,
if there is any power on the grey then it will power fully open as normal, so may appear to work as in the OPs case

this one is fun ay commenting on the post that says "the micros would not be activated because the quadrant would not move" my whole point was that the micros were tilted in such a manor that the micros were both making when the quad was at the non energised park position

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