Vaillant ecotec plus 438 no heating or hot water

You don't have to do that if you do it in the way I suggested when next it occurs, the fault may not be with the progammer but at the boiler itself, if you have 230V between the SL & N or earth then probably something in the boiler itself.
At least locate/see where these connections are and if easibly accessible from underneath the boiler.
Am waiting for it to play up

Edit. Switched live didn't have 240v just 0!
 

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You don't have to do that if you do it in the way I suggested when next it occurs, the fault may not be with the progammer but at the boiler itself, if you have 230V between the SL & N or earth then probably something in the boiler itself.
At least locate/see where these connections are and if easibly accessible from underneath the boiler.
Just turned it on, nothing happened. 0v at switched live, moments later the pump kicked in and then i got 240v.

But boiler not firing up.

Edit it has now fired up
 
Just turned it on, nothing happened. 0v at switched live, moments later the pump kicked in and then i got 240v.

But boiler not firing up.

Edit it has now fired up
Which terminal are you probing for the switched live?, your schematic is showing a brown wire in both terminal 3 & terminal 4.
On some boilers, the boiler circ pump is started first, then when a slight rise in head is detected the burner fires up so not sure what the implications, if any, on your system.
 
Just turned it on, nothing happened. 0v at switched live, moments later the pump kicked in and then i got 240v.

But boiler not firing up.

Edit it has now fired up

Things do not happen instantly where heating systems are involved, there is a slow sequence of operations. Valve actuators move to the correct positions, boilers run purge sequences etc.. So you need to wait, for these to complete.

The terminal box in your airing cupboard, has 12 terminals inside it. Let us number them 1 to 12, left to right, and as I explained, report back the voltage you measure on each of those terminals, when your heating system fails to do what you expect.

Something like this...

1 - volts measured?
2
3
4
5
6
7
8
9
10
11
12
 
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Which terminal are you probing for the switched live?, your schematic is showing a brown wire in both terminal 3 & terminal 4.
On some boilers, the boiler circ pump is started first, then when a slight rise in head is detected the burner fires up so not sure what the implications, if any, on your system.
I'm probing the sleeved brown going into the green block. It's hard to see in the pic but it does have a brown sleeve on the blue indicating it's a switched live.

3 and 4 brown wires - ones going into the 3 port valve and the other into the programmer.
 

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One might think that the "programmer one" would be from the programmer and thus the switched live?.

Did you just install a new actuator to the existing 3 port valve body or the complee valve?, its possibly that the valve is sticking in one position and taking ages to move across although it shouldn't take 30 minutes, maybe 10 to 20 secs, if allready in either the HW position then, sticking or not should give that SL, if HW only selected.
 
Did you just install a new actuator to the existing 3 port valve body or the complee valve?, its possibly that the valve is sticking in one position and taking ages to move across although it shouldn't take 30 minutes, maybe 10 to 20 secs, if allready in either the HW position then, sticking or not should give that SL, if HW only selected.

On the first page of the thread, he said 'a valve head'.

Maybe the OP could remove the head and try turning the actual water valve spindle manually?

It should be possible to almost turn it with your bare fingers, but pliers might be needed. If it's tight or turns with a rough motion, it is faulty.
 
One might think that the "programmer one" would be from the programmer and thus the switched live?.

Did you just install a new actuator to the existing 3 port valve body or the complee valve?, its possibly that the valve is sticking in one position and taking ages to move across although it shouldn't take 30 minutes, maybe 10 to 20 secs, if allready in either the HW position then, sticking or not should give that SL, if HW only selected.
Just the head as the spindle did move freely.

Yes you are correct that is switched live.
 
Why not just give the boiler SW 240v direct?

If it fired up: Bingo.

If not, £££
 
Why not just give the boiler SW 240v direct?

If it fired up: Bingo.

If not, £££
Is that the same as what the manual suggests here between 3 and 4? Or would you mean from L to 3?
 

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Just the head as the spindle did move freely.

Yes you are correct that is switched live.
That's the one to watch IMO, you could possibly install a low wattage indicator (bulb) between it and neutral to monitor if its switching consistently or/and as suggested above, just short between PL & SL to see if pump and burner start up within a few seconds of each other, you will then be narrowing down the problem.
 
That's the one to watch IMO, you could possibly install a low wattage indicator (bulb) between it and neutral to monitor if its switching consistently or/and as suggested above, just short between PL & SL to see if pump and burner start up within a few seconds of each other, you will then be narrowing down the problem.
Switched live had 240v despite not selecting heating or hot water.

It shouldn't have any, am I correct in saying this?
 
Switched live had 240v despite not selecting heating or hot water.

It shouldn't have any, am I correct in saying this?
Measured where? At the boiler?
If so, and it is the SL, you have PCB issues. (I would guess).

Or you have fannied around with a setting or sumert.
 
Measured where? At the boiler?
If so, and it is the SL, you have PCB issues. (I would guess).

Or you have fannied around with a setting or sumert.
That be a progammer issue no? If it's sending voltage when it shouldn't be?
 
That's the one to watch IMO, you could possibly install a low wattage indicator (bulb) between it and neutral to monitor if its switching consistently or/and as suggested above, just short between PL & SL to see if pump and burner start up within a few seconds of each other, you will then be narrowing down the problem.
No difference.
 

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