On Sun, 25 Sep 2016 12:18:23 +0100
Graeme wrote:

However, there is something else odd. Looking at another actuator,
when the motor runs, a little tab moves and presses the micro switch
to fire the boiler, but on the defective actuator, the tab does not
move far enough to press the micro switch, when using the manual
lever.

That is normal, manual operation does not usually operate the switch.

--
Davey.

In message , Davey
writes
On Sun, 25 Sep 2016 12:18:23 +0100
Graeme wrote:

However, there is something else odd. Looking at another actuator,
when the motor runs, a little tab moves and presses the micro switch
to fire the boiler, but on the defective actuator, the tab does not
move far enough to press the micro switch, when using the manual
lever.

That is normal, manual operation does not usually operate the switch.

Ah! OK, thanks.
--
Graeme

On 25/09/2016 12:18, Graeme wrote:
In message , Roger Mills
writes

Are the internals free to move? If, with no power applied, you move
the manual lever to the 'open' position, can you feel some resistance,
and hear the gears whirling? When you let go of the lever, does the
spring move it all back to the closed position?

Back to basics. The motor, when removed from the actuator assembly,
works perfectly when connected to an ordinary domestic 13 amp plug.
Plenty of torque - I cannot stop it turning, with my fingers.

The valve stem, with actuator assembly removed, turns easily with
fingers. The radiators then work with another zone calling for heat.

Looking at another zone valve, the wiring is correct.

There is a five core cable (including earth) from the programmer to the
zone valve. Using a meter, there is 240v across the brown/blue, whether
or not the programmer is on (calling for heat) or not BUT the motor,
hanging loose from the actuator head, does not turn whether or not the
programmer is on.

There is a little micro switch within the actuator - pressing that in
with a screwdriver blade causes the oil fired non combi boiler to fire,
even if the programmer is off. However, clicking the micro switch in
does not power the motor, whether or not the programmer is on or off.

Ignoring the earth, the wiring is thus :

Four cores from the programmer to the junction box. Blue, brown, black
and second black.

Another four cores from the junction box to the actuator. Blue, brown,
grey and orange.

They are connected at the junction box :

From To
programmer Actuator

Black Brown

Black Orange

Brown Grey

Blue Blue

The brown and blue wires on the actuator side connect to the motor, so
not connected directly to the incoming 240v (brown/blue) from the
programmer.

However, there is something else odd. Looking at another actuator, when
the motor runs, a little tab moves and presses the micro switch to fire
the boiler, but on the defective actuator, the tab does not move far
enough to press the micro switch, when using the manual lever. Something
has 'slipped'?

I suppose next stage should be to swap actuators.


There's something wrong with that wiring!

The functions of the actuator wires are as follows:
Brown - Live to the motor. Should be live when the programmer/room stat
are calling for heat
Blue - Neutral to the motor
Grey - Permanent live to the micro-switch
Orange - Switched live. Provides feed to boiler/pump when the valve is
fully open

The 4 wires from the programmer to the actuator need to fulfill the same
functions. I cannot say which is which because it depends on how they
are connected at the other end.

The fact that manually operating the micro-switch makes the boiler fire
suggests that the two wires connected to that (brown/grey and
black/orange) are ok. On that basis, the blue wire should be connected
to Neutral in the programmer and the other black wire should be live
when the programmer/stat are calling for heat. My hunch is that there's
discontinuity in one or other of those wires.
--
Cheers,
Roger
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On Sunday, 25 September 2016 17:51:57 UTC+1, Roger Mills wrote:

The fact that manually operating the micro-switch makes the boiler fire
suggests that the two wires connected to that (brown/grey and
black/orange) are ok. On that basis, the blue wire should be connected
to Neutral in the programmer and the other black wire should be live
when the programmer/stat are calling for heat. My hunch is that there's
discontinuity in one or other of those wires.

Apologies for the two year delay! Very briefly, for the last two winters I have just used the little switch on the side of the valve to turn on heating for that zone, which is fine as long as another zone is already calling for heat.

Taking Roger's point, I checked the cable coming from the controller today, and yes, of the four wires, one is dead whether or not the controller is on or off. Removed the controller from the wall then had a (very late) brainwave. Four zones, all with identical controllers, so swapped a known working controller, and all works perfectly, so it is the control box (programmer) which is not working. Tried cleaning the contacts, no change.

Why didn't I think of that, two years ago?

The programmer (Drayton LP711) has changed in appearance since ours was fitted 14 years ago, although the connections look the same. Is it likely a more modern version of the same model number will be a simple plug in replacement?

--
Graeme