Sunvic to Netatmo Thermostat

[Ispookie666]

We are in the process of moving house and currently have a Netatmo thermostat along with a bunch of radiator valves.
Our new home has Oil central heating and hot water.
There are two thermostats - One in the hall way and the other next to the boiler(which is in the garage).[GALLERY=media, 105761]20201223_132521 by Ispookie666 posted 29 Dec 2020 at 10:06 PM[/GALLERY]
[GALLERY=media, 105764]20201224_174554 by Ispookie666 posted 29 Dec 2020 at 10:06 PM[/GALLERY][GALLERY=media, 105765]20201224_174609 by Ispookie666 posted 29 Dec 2020 at 10:06 PM[/GALLERY]
This one has 3 wires; the yellow with red sleeve has 240 V mains (when the thermostat is off) the others don't have any voltage, but when the thermostat is on and calling for heat none of the 3 wires have any voltage.

The heating and hot water programmer is Danfoss CP715
[GALLERY=media, 105774]20201228_140528 by Ispookie666 posted 29 Dec 2020 at 10:07 PM[/GALLERY][GALLERY=media, 105772]20201228_140506 by Ispookie666 posted 29 Dec 2020 at 10:07 PM[/GALLERY]
The CP715 Danfoss does not seem to have any control over the thermostat (looks like the thermostat is completely independent for heating). When the thermostat is not calling for heat pins 2 and 4 have no power but then the thermostat calls for heat 2 and 4 have power.
Also, the terminal marked Neutral has 240V

There are two two port valves aswell.
[GALLERY=media, 105770]20201226_164329 by Ispookie666 posted 29 Dec 2020 at 10:07 PM[/GALLERY]
[GALLERY=media, 105763]20201224_164533 by Ispookie666 posted 29 Dec 2020 at 10:06 PM[/GALLERY]
All I want to do is replace the thermostat with a Netatmo or add Netatmo somewhere so that it controls the heating.

Any help would be appreciated.

 

[MeldrewsMate]

This one has 3 wires; the yellow with red sleeve has 240 V mains (when the thermostat is off) the others don't have any voltage, but when the thermostat is on and calling for heat none of the 3 wires have any voltage.

This doesn't appear to make sense. With respect to where are you measuring these voltages?
The wiring may be left over from when the two zone valves were motor - open - motor - close types, because with Danfoss HPA2 (spring return) valves only terminals 3 and 4 are used on the programmer.
I assume the thermostat pictured is the room-stat (not the one by the boiler which is probably a frost-stat).

Also, the terminal marked Neutral has 240V

To which N terminal do you refer, the programmer backplate or the room-stat. I have assumed the roomstat.

Generally this is what you should be measuring, relative to a reliable Neutral.
1. When HW is ON terminal 3 of the programmer is 230vac.
2. When CH is ON terminal 4 of the programmer is 230vac.
3. Check that terminal 4 has the same red wire as is connected to the stat terminal 3. It should only be live when CH is ON. If not, disconnect and isolate the yellow and blue from the stat terminals 1 and 2, and retest.

Before changeover to the 'Netatmo' first get the old system to work!

 

[Ispookie666]

Yes the thermostat pic is the room stat.
I first checked with a tester, then used a multimeter to check for voltage across the various terminals

The Neutral I am referring to is in the programmer !
When the Hot water is on I get voltage on Terminal 3, but when CH is on I get voltage on both terminal 2 and 4 .
The system seems to work.. but not sure how and trying to get to the bottom!!!

I'll disconnect and isolate 1& 2 and then test

 

[MeldrewsMate]

Look at the prgrammer wiring diagram conveniently printed on it.
Term 2 will be live when CH is OFF, term 1 will be live when HW is OFF, therefore CH ON and HW OFF will properly give you what you have just described.

Test, measure, and check to see if the blue and yellow on programmer terms 1 and 2 go to the room thermostat.

 

[Ispookie666]

Does that mean, the HW and CH have been wired the other way around?

Is there an easy way to check if the wires from Terminal 1 and 2 of the programmer are the same going into thermostat? Never had to do this in the past.
Also do I need to do anything about the Neutral terminal on the programmer having a live connection

 

[Ispookie666]

This is what I found
The mains power switch works perfectly

The wall thermostat (Sunvic LX 2356)
1. yellow with red sleeve (has power when thermostat is off)
2. Blue with red sleeve ( has NO power when thermostat is off)
3. Red has no power when the thermostat is off

When the thermostat is ON(calling for heat) - If the programmer is off the wall(I mean if I remove it and leave the backplate )
The Terminals 1,2 and 3 on the thermostat have Power; the boiler does not come on

When the programmer is replaced and the thermostat is calling for heat
Terminal 1, 2 and 3 on the thermostat have no power; the boiler works and heats

The heating control on the Programmer has no effect on the heating, but the HW side does cause the boiler to come on and off.

Frost Thermostat
Same make and model as well stat - Sunvic Tlx 2356 - same colour wiring to terminals but no sleeves
When the wall stat is off - there is no supply to any wire, but when the wall stat calls for heat - all 3 wires have mains power

The Yellow (terminal 1) on the frost stat seems to be connected to the two two port valves via Grey wires

The two port valves are 4 wires

 

[Ispookie666]

I think I have sorted this out.

All the problems were due to the Live and N being switched around from the mains switch to the programmer, which was causing a lot of complexity.
Once I wired them in the correct way (Black wire to N and Red to L from the mains to programmer). The yellow sleeved wire became switched Live on the thermostat. I interfaced the Netatmo relay to the 2 port valve and left the wall thermostat at maximum.

Seems to be working.

Thanx for your input @MeldrewsMate