Honeywell to Drayton Wiser - CH wiring.

[WLNessie]

Hi all, just looking for a bit of advice moving from a Honeywell ST6400C to Drayton Wiser programmer for the central heating/hot water.

I hoped it would be a straight swap but it appears not that easy. The new programmer won't turn the heating on unless hot water is also on. Putting the old programmer back on it works absolutely fine.

The back plate doesn't have a wire in Terminal 2 (CH NC), which I guess might be related? A pic of the backplate is attached.

I would be gratedful for any advice. Thanks.

 

[Deleted member 267285]

Is that the wiring for the Wiser backplate? What was the wiring for the Honeywell, any different? Did you copy the wiring over? It’s nothing to do with terminal 2.

 

[Rodders53]

That's the Honeywell backplate. Drayton supply a black one with earth terminal in bottom rh corner.

Which model of Wiser? 1 channel, 2 channel or 3 channel?

OP has turned old room stat to max or disconnected it and joined the two wires so as to 'call for heat' all the time?

 

[ericmark]

I will guess Y Plan and the problem is a stuck micro switch in the motorised valve.

 

[Deleted member 267285]

Putting the old programmer back on it works absolutely fine.

I will guess Y Plan and the problem is a stuck micro switch in the motorised valve.

 

[WLNessie]

Hi, thanks for the replies so far.

Yes, that's the original Honeywell back plate which the Drayton controller doesn't fit onto. I have replaced with the Drayton one and re-wired identically - have just verified that it is the same.

Room stat turned up to maximum so as to take it out of the equation.

It's a 2-channel Drayton.

It's odd because when the Drayton programmer is on there and central heating only is active, there is no response at all from the boiler - it stays off. As soon as the Honeywell is back on, and calling for CH only, the boiler fires up.

 

[Deleted member 267285]

Can you show the wiring for the Wiser and the back of it to confirm definitely 2 channel?

 

[ericmark]

There are two micro switches in most three port valves. And when one fails CH will not indicate but will continue running if DHW has been running first.

It will also often run when the bleed arm on the three port valve has been latched across.

My daughter had a faulty valve from moving into the house and was unaware until her husband cleaned airing cupboard and dislodged the bleed arm.

There is no difference how the thermostat and programmer are wired. So if one works so should the other, so seems likely the fault still there with programmer but masked.

 

[RandomGrinch]

A simple troubleshooting step, may be to bypass the C/H on the Wiser, by adding a short link wire between L and C/H on.
If the C/H operates correctly with the H/W off, then the issue may be with the Wiser - possibly a sticky relay, or an incorrect cofiguration, when setting it up.

 

[Rodders53]

So the OP has been swapping back plates / wiring repeatedly?

A manual over-ride of the CH on the wiser box via the push-button should be tried as well. I assume the CH led lights when the Wiser wireless room stat is calling for heat? One can hear the relays click when near the box.

A meter on the correct terminals in the connections box could confirm if mains is present or lacking on the CH call for drive to the actuator?