Three port diverter problem

[Howardws]

I changed the cylinder stat 'just in case' - it made no difference.

I've done a continuity test from the grey wire to HW off and it's ok.

The programmer is the same as mine at home, I wonder if it's worth swapping them to see if it makes any difference? Grasping at straws here!

Test 3 - 6 is the same as my result - HW off, all stops, v/v cycles and CH restarts 240v G 240v O I think so I've covered the bit you missed off.

 

[MANDATE]

The boiler receives its power from one of two sources, both of which come through the terminal holding the valves 'orange' wire.
With HW it comes from programmer HW ON terminal.
Goes via 10 terminal box to cylinder stat.
Across the stat to the 'orange wire' terminal.
From 'orange wire' terminal to boiler/pump.

When CH is added it is the same as above power wise.
With CH power comes from programmers CH ON terminal.
Goes via the 10 terminal box to room stat.
Across the room stat and via the 10 terminal box to feed the valves 'white wire.
Putting power on the white drives the motor/valve to mid position only.
Here it is 'held' until either HW or CH is satisfied or turned off.
So boiler is still receiving power from cylinder stat.

Usually it the HW thats becomes satisfied first, so the cylinder stat diverts the power to the valves 'grey' wire(so no power and boiler stops)
The power now on the 'grey' drives the motor/valve forward to the CH only position, closing the HW port.
During this movement it also triggers a micro switch. this diverts power out of the valves 'orange' wire. (boiler restarts)

Your problem seems to be either.
(a) the valve is not moving from mid position forwards.
That would be due to no voltage on the grey from the cylinder stat,( if HW is on and satisfied) or a dirty/burnt micro switch which power passes through to feed motor.
(b) If the valve does move to the CH only position, then the second micro switch contacts are dirty/burnt and preventing power leaving through the 'orange' wire.

 

[Howardws]

Thank you for that comprehensive description of the system. I've checked the wiring using a wiring diagram a number of times but perhaps a systematic work through using your description wouldn't go amiss.

The valve is only a few days old so I'm not sure that the contacts would be burned yet.

I'll report back on Wednesday or Thursday, when I next try to sort things out.

 

[MANDATE]

The fact there is two soures of supplly to power the boiler, it may be an advantage to separate the 'orange'when testing
Likewise there are two supplies to the 'grey' one from cylinder stat and one from HW OFF terminal, so again it may be an advantage to separate.

If its a new valve just installed I'd be re checking the wiring in the 10 terminal box.
A wire could be in the wrong terminal or even if in the correct terminal the wire insulation may be stopping the connection.

 

[D_Hailsham]

I returned to my son's this morning - the results -

1,2,3 test done, nothing happens, 240v on grey, wire continuity checked back to stat and ok.

Just re-read this.

What do you mean by nothing happens? Are you saying that the boiler does not light?

I presume the room thermostat was turned up high.

If unsure, run test 1-3 again with roomstat high and check voltage on valve White wire (should be 240Vac).

 

[Howardws]

Correct, the pump doesn't start and the boiler doesn't light - the room and tank stats were on max for all the tests I did.

I'll check the voltage at white tomorrow morning. If no volts what's next please?

 

[D_Hailsham]

I'll check the voltage at white tomorrow morning. If no volts what's next please?

Voltage on white comes from the room stat.

Prog CH ON --- Room stat common --- Room stat call ---- Valve white.

 

[Howardws]

Thanks, I'll check that out.

 

[MANDATE]

The fact you get CH along with HW means the valve has moved from HW only to mid position.
For this to have happened means the room stat is operating correctly.
The motor is working and there must have been 230v on the white.

The problem is related to the valve moving from mid position forward to CH only and/or supplying power to light the boiler.

If we rule out dirty/burnt micro switch contacts which the power has to cross within the actuator head because its all new we are left with.

Does the valve move from mid position forward to CH only or not?
Reasons why it would not move
No voltage on the 'grey'
Voltage on grey comes from cylinder stat (satisfied terminal) if HW is on and satisfied.
If HW is turned off and cylinder stat not active then programmer HW OFF terminal supplies the power to the 'grey'

If the valve does move to the correct position, Is the orange wire live or not.
If not, micro switch is not being triggered or if it is live then poor connection in terminal box or in wrong terminal.

 

[matt1e]

I returned to my son's this morning - the results -

1,2,3 test done, nothing happens, 240v on grey, wire continuity checked back to stat and ok.

4.5.6 test done HW stops heating.

With both CH & HW stats on high I get the following -

All off - 240v G 0v O ----this is ok
CH switched on - won't start 240v G 0v O----this suggests there is no power on the white which should be at 240v
CH & HW on together - starts, v/v cycles to HW position - 0v G 240v O ----this is ok
HW off, all stops, v/v cycles and CH restarts 240v G 240v O----I thought you said CH was not working on its own this line says it is
HW on by itself - 0v G 240v O ----this is ok

If have both running and I turn the HW stat down the CH keeps going but won't restart after a stop.

that sounds as though the valves grey and white cores are mixed up, but that does not agree with the very first statement (All off - 240v G 0v O)
I would check your wiring again.
any chance of any photos of the wiring centre?

Matt

 

[Howardws]

The connector box is a cat's cradle of wires which seem to have been thrown in by someone who wanted to get the job done as soon as possible!

CH won't initially start unless HW is on, however it then starts when HW is switched off.

 

[matt1e]

The connector box is a cat's cradle of wires which seem to have been thrown in by someone who wanted to get the job done as soon as possible!
.

It doesn't matter I will have seen worse mate,post one anyway

 

[Howardws]

I'll do that in the morning when I get to my son's house. Thank you.

 

[Howardws]

I've worked my way through the electrical system and realised that there is no power from the CH 'on' wire from the programmer. I've linked it out so that 240v is available to the room stat and CH starts with no problem, whether HW is called for or not. I think I'm going to bring my identical programmer from home and try it before I do anything else!

 

[MANDATE]

Are you saying there is no power at the programmers CH ON terminal.
Or is it, there is power there, but its not reaching the room stat.
Whichever it is , it seems almost resolved.

Can't understand though how, without power to room stat or white wire on valve, there could be any Central Heating.