CH not firing working possibly mid position valve

[Banter10]

Had a plumber out last week to fix a problem we had that the hot water was only getting warm which turned out to be a sticking mid position body.

Now he changed the danfoss mid position valve for a tower one and that fixed the problem and he left with the heating and hot water both on and working but after turning them off the heating will not fire up the boiler. hw side everything is fine but nothing on the heating side.

Programmer seems fine (swapped hw and ch wires round to check) and thermostat ok.

is it a faulty valve?
looks like the hw off wire has been wired into a perm live would this have blown something in the valve?

The plumber been out and scratched his head for an hour and now said he needs to come back with an electrician to have a look.

Any ideas?

 

[MANDATE]

The valve operates over two halves.
For the first half it requires the room stat to provide power to the valves 'white' wire. This takes valve to mid position only where both HW and CH receive heat. When HW is satisfied or if CH is selected it requires the valves 'grey' to be made live.
This is achieved in one of two ways.
If the HW was on and has become satisfied the cylinder stat cuts power to the boiler, supplies power to third stat terminal which then leads to 'grey' wire and valve moves to CH. During this travel a micro switch is triggered and power leaves the valve 'orange' wire which now re lights the boiler.

Of course if the HW was never selected then the above method is not appicable.
To overcome this the HW switch on the programmer is a two way, so if HW ON is off then HW OFF is on (live).
This HW OFF wire also has to go to the valves 'grey' to drive the valve forward to CH.
This wire cannot be permanently live, otherwise the valve would not stop in the mid position. It is live however when HW is off

 

[Banter10]

swapped the HWoff wire to the correct place and it still fails to fire up the boiler when CH is selected and the thermoatat is up.

Any more help please?

 

[MANDATE]

Three actions are required to have CH only.
The valve head/valve has to move first to mid position. the room stat provides the power to the valves 'white' wire. You need to verify this.

With HW off and arriving at mid position, micro switch (A) drops the power from the 'white' and picks up power from the 'grey'. This moves the valve head/valve from mid position to CH only position. Again you need to verify if the valve moves.

When the valve head/valve travels over the second half, micro switch (B) is triggered and the 'orange' becomes live and lights the boiler.

Working backwards, boiler not lighting so micro switch (B) not triggered or at fault.
This operation does not apply when HW is involved, power comes from progammer 'HW ON' switch to cylinder stat lights boiler. The wire to boiler of course joins the 'orange'.
So the main question is does valve move to mid position, if it does,followed by does valve move from mid position to CH only.
Also with both HW and CH off the 'grey' wire should be live (it's waiting to supply the motor when valve gets to mid position after switch CH on) So perhaps this should be the first thing to check

 

[Banter10]

with HW and CH off power is at the grey wire only, with CH selected power is also at the white wire but the valve fails to move so Im guessing that means a faulty valve?

Thanks for the info your giving MANDATE!

 

[Armo74]

Possibly faulty motor.

 

[MANDATE]

With the white being live it comes down to either the motor or micro switch (A). Power from 'white' has to go through this micro switch to drive motor.

The valve spindle also could be stuck/stiff and creating too much resistance for the motor.
If you can remove the head from the valve spindle and try CH only it would indicate if problem is valve or the actuator head.
There should be a lever which is used to move valve to mid position when refilling after a drain down.You could try moving this just to make sure there is no problem with the gears fouling. remember to leave the lever off the latch so it does not remain locked in mid position.
Another point! The 'white' and 'grey' wires may be live when they should but nothing will work unless the 'blue' is connected to neutral.
So it might be a poor connection in the terminal box. eg terminal screw on the insulation instead of the copper wire.

 

[Banter10]

Hi MANDATE

The blue is connected to neutral ok as everything is working fine on the HWside of things. I can manually move the lever no problem and this allows the flow to CH side but with the head removed from the body it still fails to operate correctly so I guess its looking like a faulty microswitch.

 

[DP]

Would it not be easier to get the person who changed the valve, to return and fix?

 

[MANDATE]

The neutral (blue) from the valve head relates only to the valve motor and has nothing to do with the HW side.
For the HW side power goes to boiler and pump through the cylinder stat.
Boiler and pump have their own neutrals and will operate without involving the motorised valve.
The valve motor serves two purposes, it moves the valve to mid position and CH position as required and also provides the power to boiler and pump.

Although it could be faulty motor or faulty micro switch, it is a new head so you would not expect the head to be at fault.
Hence the reason for suspecting a wiring issue.
I would not rule out the connections for white grey and orange.
It's easy to be mislead when the insulation on the wire at the terminal screw is the cause of the problem.

 

[Banter10]

View media item 45348
Im at work at the min MANDATE but is there anything obviously wrong that you can see in this pic?

Now I know that the grey wire is wrong as the brown wire is the one that has power when there is no call from the HW stat.

 

[MANDATE]

I can't see anything obviously wrong, but then I don't know what is connected to what.
I can see the orange and white wires entering the terminal block, but if these have been put too far in, the insulation can prevent a proper connection. I'd be tempted to check the terminals relating to the valve by removal and replacing them. ie white grey orange and blue.
remember with HW and CH off the grey is still live so remove all power

 

[Banter10]

I can't see anything obviously wrong, but then I don't know what is connected to what.
I can see the orange and white wires entering the terminal block, but if these have been put too far in, the insulation can prevent a proper connection. I'd be tempted to check the terminals relating to the valve by removal and replacing them. ie white grey orange and blue.
remember with HW and CH off the grey is still live so remove all power

Checked all connections and they seem fine. If I manually click the microswitch then it fires up the boiler so I can only presume its the motor gone in the valve.

green/yellow - earth
Blue - neutral
grey - hot water off power
orange - cylinder stat call
white - room thermoatat call

That's how its wired up

The plumber seems to have given up cos he said it cant be the valve as its new and is now blaming previous work done even though its been working fine in the past.

 

[Banter10]

I can't see anything obviously wrong, but then I don't know what is connected to what.
I can see the orange and white wires entering the terminal block, but if these have been put too far in, the insulation can prevent a proper connection. I'd be tempted to check the terminals relating to the valve by removal and replacing them. ie white grey orange and blue.
remember with HW and CH off the grey is still live so remove all power

Checked all connections and they seem fine. If I manually click the microswitch then it fires up the boiler so I can only presume its the motor gone in the valve.

green/yellow - earth
Blue - neutral
grey - hot water off power
orange - cylinder stat call
white - room thermoatat call

That's how its wired up

The plumber seems to have given up cos he said it cant be the valve as its new and is now blaming previous work done even though its been working fine in the past.

 

[MANDATE]

what I've done in the past, is to remove the head and make up a simple test rig on the bench. Surprising what you can do with plug/ cable/ bulb holder/bulb/couple of switches and bit of wire.

A live wire with switch to valves white wire
A live wire with switch to valves grey wire
A wire from valves orange wire to 240v bulb holder with bulb
A wire from bulb holder to mains neutral
Valves blue wire also to mains neutral
Valves green wire to earth.
Now you can try the three positions.
white off grey off HW only mode
white on grey off mid position
white on grey on and after mid position white off
Switch grey off with white already off, valve drops back to rest position HW
Switch grey off with white still on, valve drops back to mid position.
Bulb gives clear indication that boiler is supplied with power from orange wire.
If it does not work on the bench, then it won't work in situ and its easier to test