3 Port Valve testing wiring faults

[Ginettamad]

I have a 3 port valve which has stopped moving to mid point and central heating only positions. I have firstly swapped the motor with no success then swapped the valve head complete for an aftermarket one supplied as the replacement.
The original was a honeywell V4073A1039.
The replacement head will now move from HW to mid point but the motor and spring then oscillate back and fourth continually clicking but again not moving to CH on?

So the replacement head unit (wired to match the old one) may be the wrong one or the problem could be electrical possibly from the controller.
So to test is the White wire the one that should be live to move the motor from HW to Mid point then again to CH only? Do I test with a multimeter neutral to neutral blue and the red MM lead to white?

Maybe the room stat has gone but it still clicks ok?

I'm guessing the original Head unit was probaly ok now I've wasted a day trying to fix it!

Read more: //www.diynot.com/forums/viewtopic.php?t=95780&start=15#ixzz24UBgkfNn

 

[MANDATE]

The white wire is made live by the room stat.
When it enters the valve head it feeds two micro switches.
It supplies 240v through micro switch (a) direct to motor.
there 2 sets of contacts in (a) so at mid position (a) is triggered and the 240v is no longer available, but breaking 1st contacts means 2nd contacts are now made.
The grey wire supplies power (if demand is there and not satisfied) so this takes over from where the white left off and drives head to CH.
If the grey is not live then the valve stays at mid position.
The valve will probabley not stay at Mid position very long when both HW and CH are selected. HW will most likely become satisfied well before CH so making the valve go to CH until there is a demand for HW when it will lose the 240v on the grey wire and allow valve to drop back to mid position.
If CH is turned off or becomes satisfied the 240v on white wire is lost and valve drops back to HW only position.
Most problems are
Faulty motor ( after being constantly energised)
Faulty micro switches ( contacts being dirty/burnt from arcing ,then failing to make or break contact)
Faulty room stat (failing to supply 240v to white wire)
Failure to supply 240v to the grey wire from programmer HW OFF terminal or the satisfied terminal on cylinder stat.

If valve does not move beyond mid position suspect micro switch or no voltage on grey wire.
Note A good point to start, is with both HW and CH off the grey wire on the valve should have 240v.

 

[Ginettamad]

Thanks for the info will take along my multimeter next time I go!
I have swapped the valve head so it cant be the micro switch contacts.
To test each option and each stat do you have a sequence of where to test each component?
Hot water is working fine switching pump on and off when needed but its just not allowing the CH to switch the valve and pump on at CH position?
Thanks

 

[45yearsagasman]

These are the power combinations and can be tested at the wiring centre. View media item 30560

 

[MANDATE]

First thing is to verify if valve moves to mid position. Should be able to hear it or see it with the head off the spindle
If it does then, it proves room stat is working ok.
If it does not proceed to check input voltage on room stat, then output voltage with stat turned up. then check the connection at terminal block where wire from room stat joins the white wire of valve.
If head has just been replaced, white wire may not be making contact correctly or could be in wrong terminal.
The same situation applies to the blue neutral wire, it may not be making proper contact.
In both cases make sure the insulation on wires is not causing the problem.
There is no point dealing with the second half of the valves movement until the first half problem (if there is one ) has been resolved

 

[mysteryman]

With neutral on the blue wire, powering up the white wire makes the valve move to mid-position. Powering up white and grey together moves it to the 'heating only' position. If this is not happening as described, the valve is faulty.

[When the valve reaches mid-position, from either direction, the Synchron motor is fed DC from the pcb via the microswitches. DC is effectively zero frequency AC, so the motor stands still, holding the valve in mid-position. Clever, or what?]

The orange wire sends out a switched live to the boiler [and the pump as well, maybe via the boiler, depending upon the exact system].

In the 'hot water only' position, the valve runs back by its spring, and the boiler is fired by the 'call' terminal on the cylinder thermostat [connected also to the orange wire]. Thus, the white and grey are power in to the valve, and the orange is power out. Blue is neutral, and green/yellow is earth.

Your heating call goes to white; hot water satisfied goes to grey. This comes from the 'satisfied' terminal on the cylinder thermostat, and also the 'hot water off' terminal on the programmer, if 'heating only' can be selected. It is failure to make this connection that causes most confusion.

There is an excellent description of the operation of these valves on the Honeywell website.

 

[Ginettamad]

Tested for a fault and found this set of results today but not sure what the problem is still.

CH & HW on live on white and orange OK.

HW no heating Live orange OK.

CH & no HW live only white live grey dead but if the cylinder stat is turned off then grey goes live then? Not ok is it?

All off live on grey OK.

What i have also found is that when all off if I turn the cylinder stat on demand it turns on the pump orange live and Hw heats up even with programmer both sides set to off. Surely this is not correct either?

Strangely the cylinder stat works by turning off when water is hot but I think even with all CH & HW both off at the programmer it will continue to heat the water to the set temp and only then turn off?


Also when (with the new valve head on) and the valve moved across to CH ok but the pump and boiler will only turn on again if I turn the cylinder stat on demand beyond water temp? Again this is wrong as its preventing CH only working when the HW tank is Hot?


So I'm confused to say the least but does this sound like a cylinder stat fault?

Any ideas before I give up and call a plumber!

H

 

[MANDATE]

How the valve gets to mid position is fairly simple.
It is driven there by 240v on the white wire. There is also a modified voltage produced by a pcb and this is enough to keep the valve at mid position against the strength of the return spring. That is providing the grey wire is not live.
If the grey wire was live, it supplies 240v and takes over when the micro switch is triggered (breaks contact with white makes contact with grey).
So to get from mid position to CH it needs the grey to be live.

When valve is in mid position both HW and CH are receiving water from pump, but it won't stay like this for long. Usually HW soon becomes satisfied and the cylinder stat switches boiler off, but it also diverts the 240v through the satisfied terminal to the grey wire which then drives valve to CH.
During this movement and second micro switch allows power out from the valves orange wire to connect with boiler. So no sooner has the boiler/pump stopped it lights up again.
The difference being the source of the power. When HW is involved power to boiler comes from cylinder stat, but if only CH then it comes from valves orange wire. Of course the wires going to boiler would be joined together.
Diverting the power when HW is satisfied at cylinder stat to the grey wire is the key to moving the valve from mid position onwards.
But what if HW is not switched on? There is no power to divert!
Another source has to be provided and this is achieved by another wire taken from the programmers HW OFF terminal.
Providing the grey is made live by one of the above methods the valve will move (assuming everything else is correct)
Of course the valve moving correctly is only part of the action. The second micro switch if faulty may prevent power leaving the valves orange wire so boiler cant light.
I can only suggest the wiring is traced and proved correct and that all connections are OK

 

[mysteryman]

Check that grey is connected to 'hot water off' at the programmer AND to the 'satisfied' terminal on the cylinder thermostat.

 

[Ginettamad]

Sadly I'm really finding the descriptions re the valve workings hard to get my head around.
None of the previously working system has been changed and the original Valve just stopped going to CH only one day. Suspecting the valve head I changed it for a new head using the same wiring colours as the old one so no wiring changes have been made and the new Valve unit will have new micro switches suggesting they also should be ok. As it was all-ok last year I thought the valve had gone faulty hence the new one but I'm now thinking of putting the old one back on to see what that does now.
So because the wiring had not been changed anywhere I was assuming something else may have failed such as one of the 2 stats or the programmer.
Of course the new Valve me be the wrong replacement or faulty as that seems to miss mid point now and go over the CH ok but then not turn on the boiler & Pump. So as this does something different to the original Honeywell which would move to mid point or CH but when pushed manully to CH the pump came on ok? (wrong or faulty new valve head).
The house is empty and I don’t get much time to go and check the system so I'll try and find some local help if I can and if possible check each component.
A plumber last year was doing some other work at the house and after a quick look just said replace the valve, which I did.

What I don’t know is what he did when fiddling? He could possibly have changed some wiring to make it run HW only but that was ok beforehand? So doubtful I think?

It does seem odd that the HW will carry on working with the programmer switched off now? As such once the HW is to temp the CH wont work but I’m yet to try the set up when the HW is cold because its been running all the time over winter. The tank stat is now turned right down for now!

All my wires lead to a wall box with the connections all made with choc block connecters and I could do with a schematic for where each 3 or four core wire colours should connect with each other. Sadly it’s not a later purpose made connection box with number terminals (late 70's). I can easily see which cable goes to the pump, valve and cyl stat as they are near but then I need to know which cables are from the Programmer, boiler and room stat too.
Inside the programmer wiring box is L N and terminals 1 2 3 and 4 I think and I found a yellow wire a little loose so I tightened it up. I can’t remember which terminal it was on from memory 2 or 3.
So all in all a bit baffled but if I knew where all the connections should be it may help but they shouldn’t have been moved?

 

[mysteryman]

You need to do the basic checks as described above. I suspect a wiring, programmer, or thermostat fault.