Issues replacing Drayton Tempus 7 with Wiser 2

[clawman]

Hi,

I had a Drayton Tempus 7 programmer (2 channel) and wired thermostat and the programmer screen died. All heating/hw and the thermostat were working fine.

I bought the wiser 2 kit to replace the old programmer, however the old Drayton backplate was very old and too big for the new programmer. I have attached a picture of the old Drayton Tempus wiring diagram and also how it was wired up when i removed the old programmer (images 1 and 2).

I've also put a picture of the wiring diagram for the new Drayton wiser 2 (image 3).

I first tried wiring up to exact same terminals as was on the old backplate. I get power to the new programmer, can connect to the app and wireless thermostat. Old wired thermostat has been put to max so always on. New wireless thermostat sends the fire up signal to the new programmer but no CH comes on, no boiler fire up. Also tried the manual override and again no CH firing up.

I've since checked wiring diagram for the new programmer and two terminals appear to be switched compared to the old (terminals 2 and 3). Should I be switching these wires around (terminal 2 was empty before)? Anything else I could be doing wrong/should try?

Any help, greatly appreciated!

Thanks very much!

 

[Deleted member 267285]

Wiring seems the same, although what's weird is the earth/CPC has been used as a live, but sleeved green indicating earth/cpc, and should be changed really. However, can you post a photo of the wiring you've done for the wiser?

 

[stem]

As you can see, the two units have identical terminal locations as per your photos. So, the wires should be moved from the Drayton to the Wiser terminal for terminal like for like, and any empty terminals would remain empty.

The old thermostat can't just be disconnected as the heating wiring would be left open circuit and not operate. So for now leave the old thermostat wired up and on its maximum setting. If you need help with decommissioning it and the associated wiring mod that can be done later. Details of the old thermostat would be required.

You don't give any info about the type of heating system it is connected to. If it's the type of system that has Gravity HW then the heating won't work without the hot water being on at the same time (as per the note on the Drayton) That's a restriction of the plumbing not the controls. Having said that, the link does still appear to be in place in your original photo of the Drayton. So maybe it's not gravity HW. It might be worth seeing if the CH works when the HW is on.

EDIT
You can probably ignore that last statement as the presence of a wire in terminal 1, indicates a fully pumped system with a 3-Port motorised valve.

 

[Deleted member 267285]

The old thermostat can't just be disconnected as the heating wiring would be left open circuit and not operate. So for now leave the old thermostat wired up and on its maximum setting. If you need help with decommissioning it and the associated wiring mod that can be done later. Details of the old thermostat would be required.

Thermostat set to max mate

 

[stem]

If that's for me, sorry don't understand why you've posted it.

 

[Deleted member 267285]

If that's for me, sorry don't understand why you've posted it.

You've said you can't just disconnect old thermostat and needs to be set on max, which is what the op has done.

 

[stem]

Ah OK thanks, I originally read that to be in past tense i.e. before the Wiser was installed. Having read it again I see not.

 

[clawman]

Thanks for quick replies, wired up exactly the same as previous backplate (see attached). The new wiser programmer says the heating is on but it doesn't fire up the boiler. We've got a main multipoint boiler and a baxi, the hot water seems to come on, on demand even when programmer is not in the wall, so maybe its wires don't matter?

 

[Deleted member 267285]

Wires should matter, are you sure about the multi point? If yes, maybe that's what's delivering hot water on demand, or maybe an immersion heater is turned on? Seems like could be a wiring issue or motorised valve issue

 

[stem]

the hot water seems to come on, on demand even when programmer is not in the wall, so maybe its wires don't matter?

As @CBW I think the Main Multipoint only produces hot water on demand, so isn't being controlled by anything other than it fires up and heats the water instantaneously when you open a hot tap that is connected to it.

Is the Baxi just for the radiators? Or does it have a hot water cylinder connected to it as well? The wiring in your diagrams suggests that it does (or has at some point in the past). Under normal circumstances a system that is wired as yours is has a hot water cylinder that is heated when terminal 3 is made live and the radiators come on when terminal 4 is made live.

What happens if you push the manual 'Heating' button on the wiser?

 

[clawman]

If I push the manual heat,. the programmer shows heating as on, it shows as on on the app and on the wireless thermostat but the boiler doesn't fire up.

 

[RandomGrinch]

If you temporarily link the yellow/green (C/H switched live 4), to Live, does the boiler fire up?

...and is this just a mark, or damage to the cable?

 

[clawman]

If I put the central heating wire into the live terminal, boiler also doesn't fire up. I think the programmer is wired up correctly though as, when the power is on (either in live or terminal4), if I put the old wired thermostat up to the max, I can hear the pump upstairs kick and in and start whirring. I'm no expert but tells me the correct signal is going from the thermomstat so programmer must be OK....the issue is somewhere between the thermostat and the boiler (or the boiler itself)....thoughts?

 

[stem]

I'm no expert but tells me the correct signal is going from the thermostat so programmer must be OK....the issue is somewhere between the thermostat and the boiler (or the boiler itself)....thoughts?

That all depends...... With some old systems usually pre 1980's, the HW channel of the programmer controls the boiler, and the thermostat just the pump. However, with more recent systems [e.g. S-Plan & Y-Plan] the thermostat only opens a motorised valve, and it's the motorised valve that operates the boiler.

The older systems don't require a wire in terminal 1 (HW Off) so the presence of a wire in that terminal would indicate that you have a 3 port motorised valve [Y-Plan] in which case the three port valve will start the boiler when central heating is required, and the hot water cylinder thermostat when hot water is required.

From your before and after photos it does appear that the wires are still in the same places. So, from an electrical point of view you have swapped one product with an identical product. Nothing else should have changed.

I'm still a bit puzzled by the green / yellow wire mentioned earlier by @CBW. it's odd that it also has green tape on, unless it's been put there to cover damage. Normally where a green/yellow wire is used as a live (which is not ideal btw) it has a brown sleeve on, but if it was in terminal 4 before when the system was working, that's where it needs to remain.

Have you tried overriding the 'Hot Water' and 'Heating' at the same time, so that both are 'on' simultaneously to see if the boiler fires up then?

Is there any possibility that the boiler has been inadvertently switched off, has insufficient pressure (if applicable) or has gone into a fault mode etc.,

Has anything else been changed that you haven't mentioned?

Any chance you would you be able to tell us what the wires in terminals 1, 3 and 4 are connected to at their other ends?