Mid Port Valve only provides hot water and heating

[nelectric]

Mid port valve Honeywell V4073A. With heating off and water on (at the programmer) getting both hot water AND heating on (radiators are getting hot).

Took cover off valve and tried different settings. With fused switch off (cutting power to this part of electrical circuit) the valve moves under spring pressure, presumably to rest position. Turn on power and motor turns valve to a position - not sure which but can only assume A+B. No matter which combination is selected at the programmer (water on/off heating on/off) the valve does not move unless all power is cut. There is buzzing coming from the valve motor, like it is straining to move but can't.

I have only dealt with the V4043 before - that is a simple on/off operation.
Should the V4073 move to more than one position? If so, how much further to the next position? Do these symptoms point to a blocked valve? If so, can you remove the top plate on the valve to check/clear it?

 

[nelectric]

have done a bit more research - seems to point to ball valve needs replacing. Honeywell part no 40003918-007 because hot water is leaking into the heating system. Does not explain the buzzing noise though.
Before I do this, can anyone confirm how much movement there should be in the valve? Before I removed the head, I used the lever to (presumably) put it into the open position (though whether that is A, B or A+B I do not know). The stub sticking out is at 90 degrees to the top of the tee, i.e. straight above the bottom of the tee and pointing neither to the left or the right.
Then using pliers I tried to turn the valve. There was a little movement, perhaps +/- 5 degrees. Did not put much pressure on though. How easy should it be to turn the valve by hand like this, and how far should it move?

 

[seco services]

With fused switch off (cutting power to this part of electrical circuit) the valve moves under spring pressure, presumably to rest position.

yes position B water only open.

Turn on power and motor turns valve to a position

if hw/heating off valve should stay in relaxed position B open until heating called for.

in this position the only wire with 230v on should be the grey.

Should the V4073 move to more than one position?

has 3 positions
hw only
heating/hw
heating only


don't sound like faulty paddle to me sounds like a elecy fault.
check with a multi meter.

turn fused spur off to reset valve then turn back on with no call for hw/heating.
you should only have 230v on the grey and 100v on the orange and the lever on the end will have resistance on it.

hw calling only 230v on orange terminal from cyl stat.
lever has resistance

heating only 230v on orange and 230v on white.
grey 230v.
lever will be floppy.

hw/heating on 230v on white, 230v on orange lever floppy.


if you say the valve moves to a position when fused spur turned on and you have no call from either hw/heating
sounds like you are getting power to the white wire.

 

[nelectric]

Been back today for another look.

The valve does actually move into three positions B, A+B, A

Turned off power at fused spur. Ensured valve at B. Turned on power
CHoff HWoff Wh=0.1v Gy=250v Or=0.1v valve=B
(Now you said Orange should be 100v but it definitely was 0.1v)
CHoff HWon Wh=6.2v Gy=86v Or=250v valve=B
CHon HWon Wh=250v Gy=66v Or=250v valve=A+B
CHon HWoff Wh=250v Gy=250v Or=250v valve=A

so apart from orange not registering 100v with CHoff HWoff all seems ok

Tried playing with the water thermostat (stat goes from 40 deg to 80 deg)
CHoff HWon stat=40 Wh=0.1v Gy=250v Or=0.1v valve=B
CHoff HWon stat=80 Wh=6.2v Gy=86v Or=250v valve=B

CHon HWon stat=40 Wh=250v Gy=250v Or=250v valve=A
CHon HWon stat=80 Wh=250v Gy=66v Or=250v valve=A+B

So the stat seems to be behaving as expected

now for the odd part

Sometimes, with CHon HWon then turning them both off, valve moved from A+B to A (unexpected)
when it did this I got Wh=0.1v Gy=250v Or=0.1v

Then other times from CHon HWon to CHoff HWoff the valve moved from A+B to B (as expected)
when it did this I got Wh=0.1v Gy=250v Or=0.1v

It didn't matter which control went off first, if both turned off, sometimes valve moved to A and other it moved to B

And once or twice the valve went from A to A+B when I changed CHon HWoff to CHoff HWoff

I even tried exerting pressure on the spring when it went to A instead of B but it did not move.

So whenever CHoff HWoff am getting 0/250/0 and the valve goes EITHER to A OR to B whereas I should be getting 0/250/100 and the valve ALWAYS goes to B

Writing this up I realise I didn't look at what else orange is connected to, and it seems to be the orange that is not as it should be.

Are you sure orange should be 100v?
Any ideas on what could cause the orange to be 0v when it should be 100v?
Would you expect the valve position to be variable if orange is not at 100v?

 

[mysteryman]

The 100 volt figure is misleading. Honeywell valves have suppressor capacitors and they can cause false readings, especially if you test with a digital multimeter. You should regard anything other than 240 volts as zero volts.

All power off = spring return to DHW only. The valve stays in this position for DHW only and the boiler is powered by the call terminal on the cylinder thermostat; this is also connected to the orange wire.

White live = valve motors to mid position for CH & DHW and powers boiler via orange; the boiler is also powered via the cylinder thermostat call terminal which is 1 on a Honeywell valve.

White and grey live = valve motors full travel to CH only and powers boiler via orange

 

[nelectric]

So white and grey are inputs to control the valve, and orange is the output to fire up the boiler. And any readings on my digital meter less than 240v are effectively zero. Understood.

With HW only, you say orange is 240v, white and grey are 0v, so what feeds the 240v to the orange? Or is the orange also connected to the programmer? Is it that the programmer doesn't need to turn on white or grey because it expects the valve to already be at B, but it has a direct connection to the orange so it can fire up the boiler without activating the motor on the valve ?

Aha! So if the valve is not actually at B, then when the customer is expecting hot water to be on, he is in fact getting either only CH (if valve at A) or CH+HW (if valve at A+B). This would explain why his radiators are getting warm during the summer when CH is off.

So what would cause the valve to come to rest at A or A+B as I occasionally observed instead of at B where it is supposed to be? Does this point to the small circuit board on the zone valve containing the diode and two resistors having a fault? Perhaps they are leaking current through the resisitors onto the motor, driving it when it should not be powered? Would the diode and resistors be pretty standard components I could get from Maplins and replace those currently on the valve?

Sorry about the long posts - am thinking out loud while I type.

 

[picasso]

Its too early to go through your post , this might help

http://octaveblue.co.uk/c_heating/index.htm

 

[mysteryman]

The orange wire is a switched live coming out from the valve when in CH mode, power comes from the grey via one of the microswitches.

The boiler is powered in DHW mode directly from the call terminal on the cyl 'stat - also connected to the orange wire. Orange is not a sgnal in to the valve.

The diode is there to provide DC - direct current = zero frequency alternating current - to stall the valve in mid position. Clever, or what?

You can get replacement heads for all but the earliest valves. These are held on by two pozi screws, and these heads can be changed without draining the system - the early ones can't.

Check that the valve spring returns correctly to DHW only with all power off. Then select DHW and power back up. The valve should not move, and the boiler should be powered - via the cyl 'stat. If the valve moves at this point, the problem is elsewhere - perhaps the programmer.

 

[heatserve]

The orange wire is a switched live coming out from the valve when in CH mode, power comes from the grey via one of the microswitches.

Power goes to the grey from either HW off from the programmer or HW satisfied via the cylinder stat.

 

[mysteryman]

Yes, we are both right, more or less. I meant white, not grey.

My point is that the orange wire sends power OUT TO the boiler from the valve for CH only operation. This power GOES IN TO the valve from the white wire which is the CH signal. The grey wire is a 'hot water off' signal. When grey and white are live for CH ONLY, the boiler is powered from orange with the valve motored to the end stop, and stalled mechanically.

 

[heatserve]

I know people get, understandably, confused by the voltages on 3PV's, but what is very, very clever is the 28mm 6-wire zone valve used when converting semi pumped systems to 'C' plan.

Unless you saw an internal diagram of the relays, it is completely impossible to understand, at least is is for someone with a small brain like me