Wiring new Secure/Horstmann HRT4 ASR-ZW thermostat

[Sophiesethy]

I bought a brand new Secure/Horstmann HRT4 ASR-ZW thermostat with boiler switch. Manual: https://www.robbshop.nl/media/45/da/33/1670501179/SEC_SRT322_download_1.pdf

Reason that I bought it was I wanted to control the heating through Home Assistant, and this was the only Z-Wave one I could find for the price of 70 euros, but maybe I'm wrong, it does seem to be very old (it's not too late to return it)

I'm trying to connect it to the Vaillant ThermoCOMPACT VCW 255/4 E VR Combiketel 12,8 - 24,4 kW CW3 closed Manual: https://www.vaillant.nl/pdf-neu/thermocompact-vcw-255-4-en-cwk-245-4-144564.pdf

First thing that goes wrong is that there are no 230V L/N connections on the boiler panel. No RT connections either. Only 24VDC room thermostat connections at the numbers 7, 8 and 9, and 24VAC room thermostat connections at 3' and 4'. There is an 230V X12 at the bottom for "an added module" but it would require soldering.:

Thermostat connections:

I did my best attempt at wiring it, however, in the way it makes most sense. I wonder if it's just not compatible at all.
Here is my attempts:

Boiler unit, left to right.
REDWIRE1 connected to 4'
BLUEWIRE1 connected to 3'
BLUEWIRE2 connected to 7(24V)
REDWIRE2 connected to 8(24V)

Thermostat unit, left to right.
REDWIRE2 connected to N,
BLUEWIRE2 connected to L,
BLUEWIRE3 bridged between 2 and 3
BLUEWIRE1 connected to 2
REDWIRE1 connected to 4

I hope you guys can give me some guidance, I would very much appreciate it!

 

[RandomGrinch]

I couldn't find the english version of the manual for your specific boiler.
Just for confirmation, here is the translation...

Your wiring is partially correct.

REDWIRE1 connected to 4'
BLUEWIRE1 connected to 3'

BLUEWIRE1 connected to 2
REDWIRE1 connected to 4

Terminals 3' and 4' on your boiler would connect to the volt free terminals 2 and 4 on the HRT4.

BLUEWIRE3 bridged between 2 and 3

There shouldn't be a bridge wire - leave this out.

First thing that goes wrong is that there are no 230V L/N connections on the boiler panel.

The HRT4 is designed to run from an AC power supply of between 50V and 230V. It may not operate correctly, when supplied with only 24V DC.
You do have 230V on the panel - it should be possible to connect another cable, with wires joining into the existing L, N and E terminals....

Although I would add that the wires you are using, appear slimmer than I would like, to carry 230V - a 0.5mm2, or 0.75mm2 three core flex, would be far better for powering the HRT4.

Please ensure that the mains voltage wiring is kept apart from the 24V wiring, or an expensive repair to the boiler PCB may be required!

The amount of bare copper showing on the wires going into the HRT4 backplate terminals, should also be minimised.

 

[Sophiesethy]

I couldn't find the english version of the manual for your specific boiler.
Just for confirmation, here is the translation...

View attachment 362670

Your wiring is partially correct.


Terminals 3' and 4' on your boiler would connect to the volt free terminals 2 and 4 on the HRT4.


There shouldn't be a bridge wire - leave this out.


The HRT4 is designed to run from an AC power supply of between 50V and 230V. It may not operate correctly, when supplied with only 24V DC.
You do have 230V on the panel - it should be possible to connect another cable, with wires joining into the existing L, N and E terminals....
View attachment 362671
Although I would add that the wires you are using, appear slimmer than I would like, to carry 230V - a 0.5mm2, or 0.75mm2 three core flex, would be far better for powering the HRT4.

Please ensure that the mains voltage wiring is kept apart from the 24V wiring, or an expensive repair to the boiler PCB may be required!

The amount of bare copper showing on the wires going into the HRT4 backplate terminals, should also be minimised.

Okay, this is the end result. Can you double check if it's safe to turn on to check if it works?

 

[RandomGrinch]

Okay, this is the end result. Can you double check if it's safe to turn on to check if it works?

Looking good
A bit less copper showing on the red wire would be better, but it's not a big issue!