3 Port Honeywell valve problem

[TG2015]

Hi all,
I'm hoping that someone might be able to help me with a problem I'm experiencing with my central heating/hot water system. The valve is Honeywell V4073A three way.

Mostly the system works fine, except for one condition.

The symptom is that when the CH is operating, and then HW is called, the 3 port valve doesn't move to the mid position - it just stays on CH.

However, if CH is cancelled, and HW called, the valve will correctly return to HW only position.
Then, if CH is called, the valve will correctly move to the mid position and stop, providing both HW and CH.

The boiler and pump are working fine.

I'm not certain what might be causing the problem. Having looked at the schematics, I'm wondering if a failed micro switch (SW1) in the valve might cause the problem?

What doesn't help is whether this is a new or existing problem.
Usually we have called for HW before CH, and it's only recently that we noticed that HW isn't available if the System was in CH mode first.

The control panel show the correct lighting, indicating that all is well, and the boiler etc operate just fine. It 's just that the valve will not return from CH to mid position.

Any suggestions would be gratefully received,
Many thanks
Tony

 

[PrenticeBoyofDerry]

Sounds like the motorised head is faulty, they can be purchased and replaced without having to drain the water off.
You may need some one how is electrically skilled to replace this.

 

[TG2015]

Thanks, I'd already removed the head to inspect it, so it wouldn't be too much of a challenge to swap it.

It was just that I didn't want to pay out for a new head, before being sure that's where the problem really was.

Inspecting the wiring diagram for the Honeywell valve, I'm struggling to see what part could be faulty that would enable the valve to correctly stop in mid position when moving from HW only, but not ever stop in mid position when moving from CH only as described above.

It is a bit of a head scratcher!

 

[D_Hailsham]

The symptom is that when the CH is operating, and then HW is called, the 3 port valve doesn't move to the mid position - it just stays on CH.

When you say "HW is called", do you mean turned on at the programmer? If so, what happens if you then turn the cylinder stat up?

 

[TG2015]

I made sure that the cylinder thermostat was set high, so that the valve would be expected to move.

 

[D_Hailsham]

OK

Have you checked if the valve is sticking? Here's how:

1. Remove actuator
2. Try turning the spindle using fingers only. It should move very easily, but only a few degrees, eg. from 11 to 1 on a clock. If sticking, oil the seal with silicon lubricant.
3. Replace actuator
4. Move the lever at the end from Auto to Man. You should feel resistance as the valve is being opened.
5. Release lever. It should automatically return to the Auto end.

 

[Steelmasons]

If a 3 port then the lever won't always return to auto , will depend on what is being called for.

 

[TG2015]

Appreciate the replies, thanks.

Yes, I removed the head to check the spindle moved freely, it does.
Reassembled it, and then moved the lever from auto the manual.
It was exactly as expected and as you described.

The valve works perfectly except when set to CH and then HW is activated by the control module - the valve simply stays at CH despite the fact that HW is being called for by the system (thermostat set high, and control light indicating that HW is selected)

So, if I then cancel CH on the controller, select HW, the valve moves to open HW only. Then selecting CH will move the valve to the mid position, as it should, to allow both HW and CH.

The question is, how can I tell if its a fault in the head unit of the valve, or whether the fault lies elsewhere?

 

[Terry7556]

Further down the listings page is a post about Glowworm flexicom 18 sx and similar troubles to your system
Have a read of that one

 

[D_Hailsham]

The symptom is that when the CH is operating, and then HW is called, the 3 port valve doesn't move to the mid position - it just stays on CH.

With the boiler running for CH, call for HW. Does the boiler stop and restart, even though the valve has not moved to mid position?

Does the valve move to HW only (& boiler continue to run) if the CH is then turned off?

You might like to check out Mid-position valve operation and fault finding

If a 3 port then the lever won't always return to auto , will depend on what is being called for.

That's true under working conditions, but I was talking about testing the valve when no power was connected. I think the OP was aware of this, but I should have made it clearer for casual readers.

 

[TG2015]

Thanks.
Yes, was aware to test the spring return with no power.

Answer to your questions:

The boiler does not stop and start when running CH and HW called. The valve simply stays in CH position.

If the CH is turned off, valve returns to HW only.

Have also checked voltages at grey and white wires in all positions.
CH/HW both off: white = OFF, grey = LIVE
HW only: White = OFF, Grey = Slight voltage (around 55 or so)
HW & CH both on: White = LIVE, Grey = slight voltage (around 55 or so)
CH only on: White = LIVE, Grey = LIVE.

When in CH mode only and HW is called, the voltage on the WHITE stay at LIVE.
Reading the diagram, it suggests it should be OFF.

Will study the fault finding link carefully now, thank you.

 

[D_Hailsham]

The boiler does not stop and start when running CH and HW called. The valve simply stays in CH position.

Just to confirm, does the boiler continue to run when HW is called?

All the voltages you mention are correct. The low voltage is to be expected.

When in CH mode only and HW is called, the voltage on the WHITE stay at LIVE. Reading the diagram, it suggests it should be OFF.

You must be looking at the CH Satisfied diagram. You say you want to have both CH and HW called, which is mid-position. This requires the white to be live and the grey off. If the white was off the valve would return to HW only, not mid-position.

 

[TG2015]

Yes the boiler continues to run when HW is called, its just that the valve doesn't move.
So, in this instance, the external controller shows green lights on for both HW and CH, the boiler continues to run, but the valve remains in the CH only position. Switching off CH, the valve returns to HW and the boiler continues to run correctly.

I've been trying to understand what condition will cause the valve to move back to the Mid position from CH only when HW is called.
Yes, I can see now that its GREY that needs to be OFF.
Just checking again, and the GREY remains LIVE when HW is called when valve in CH position.

So is it correct to think that the problem is not with the actuator or its micro switches, or is it too early to assume that?

Also, the internal wiring diagram for the actuator is different in the link you provided from another two that I've seen;

http://www.diyfaq.org.uk/plumbing/controls/midpositionvalve.htm
http://www.gasheating.co.uk/Mid-Position-Valve.html

The difference is that R2 links from Orange to between the Diode and R1 in the two above.
However, in the earlier one R2 is permanently connected from Grey to Orange - I suspect that that is an error, but I'm not sure.

I really appreciate your patience with helping me, many thanks!

 

[D_Hailsham]

Just checking again, and the GREY remains LIVE when HW is called when valve in CH position.

So is it correct to think that the problem is not with the actuator or its micro switches, or is it too early to assume that?

You need to find out why the grey wire is live when HW is ON.

I can't remember where my internal wiring diagrams came from; I do know that valve manufacturers' have their own way of achieving the same objective. My diagram is not wrong; you would still get a low voltage on the grey terminal under the same conditions from the other diagrams. The important thing is that there is not 240V on orange when 240V is on grey after CH only has been satisfied.[/QUOTE]

 

[TG2015]

Done some more testing!

There are two wires that are connected to the 3-way valve Grey wire; one is from the Cylinder Stat, and the other (I presume) is from my LP 522 Drayton Programmer (in a different room, with cables chased into the wall)

On the positive side, I now know that the Honeywell three way valve is not faulty.
When I remove the 230v load from the Grey wire, the valve moves to the mid position - hurrah!
I also know that the erroneous 230v is not coming from the cylinder stat.

On the negative side, I now need to understand why the other wire from (I presume) the Drayton Controller should continue to provide 230 volts when the CH was active and the HW is switched on at the programmer.
As pointed out to me yesterday, the voltage on the Grey wire (fed from the controller) in this situation should drop to zero.

As I wrote in the first post, its not clear whether it has always been like this and badly wired somewhere, or whether it a new condition caused by something going faulty.

Any suggestions on how to proceed would be much appreciated.
Thanks