Slimline Thermostat - Shelly Replacement

condord

Hi,

I have a "Daikin Altherma 3 R F - EHVH-E6V" heatpump. There is an external thermostats upstairs which is a "Heatmiser Slimline-E V3".

This is how it is currently wired:

I want to be able to remotely control the heat-pump and call for heat upstairs using Home Assistant. I think I can use a Shelly Plus 1 in Dry Contact mode to replicate the volt free switching the Slimline is providing. I would hope to leave the Slimline wired in also to give temp readout in the room.

My wiring diagram would be as in this picture.

Any comments / suggestions?

I really don't want to risk damaging my heat pump!

Thanks,

Conor

10-10-20

Edit: Correction.

Hi, you have a miswire there.

The SW pole is for the wall-switch and not the output from the Shelly.

What you need to do remove the black wire from A2 on the stat and move it to Either 0 or I on the Shelly, then pass a wire from A2 into the other side of the relay on the Shelly1. So the Shelly in this case then 'gates' the output from the stat.

Make sense?

https://kb.shelly.cloud/knowledge-base/shelly-1-gen3#Shelly1Gen3-Basicwiringdiagrams

condord

https://www.boards.ie/discussion/comment/122369606#Comment_122369606

Hi, thanks so much for the reply.

In your configuration, am I right in thinking that the Slimline will no longer be able to call for heat on its own? If it calls for heat, but the Shelly is set to "off", the signal won't pass to heatpump. I was hoping that either the Shelly or the Slimline could call for heat. Reason being, it will be easy to hit a few buttons on the Slimline to call for heat, rather than having to go on the phone and call for heat through the Shelly.

You made me think though, the Shelly is designed to be used with a physical light switch which will turn on/off, as well as allowing on and off through interface. So you think I could wire it like a light switch, with the output of the Slimline going to the SW port on the Shelly? See this pic for my example.

Thanks,

Conor

10-10-20

In your configuration, am I right in thinking that the Slimline will no
longer be able to call for heat on its own? If it calls for heat, but
the Shelly is set to "off", the signal won't pass to heatpump

Correct. Effectively an AND gate. Shelly on AND stat on = Call for heat.

If you want to be able to call for heat using the Shelly, then wire up A1 and A2 to 0 and I on the Shelly. That would be an OR gate. Although that overrides the stat and means that the heating will be on full - if that's what you want.

You made me think though, the Shelly is designed to be used with a
physical light switch which will turn on/off, as well as allowing on and
off through interface. So you think I could wire it like a light
switch, with the output of the Slimline going to the SW port on the
Shelly? See this pic for my example.

Yes, that's probably the best way to smarten it up. If you setup the Shelly in toggle switch mode then you get remote control of the boiler OR the stat can be left to decide. You can then set an auto-off timer so that the Shelly doesn't stay on for an extended period.

The one catch is that if you manually switch on the Shelly then if the stat turns off it will also toggle the Shelly's output off.

10-10-20

If you're using Home Assistant you could setup the Shelly with something like the HA Smart Thermostat (PID controlled) as it works with a relay-driven heat source (as opposed to using variable control such as a valve of between 1 to 100).

https://github.com/ScratMan/HASmartThermostat/tree/master

You would need to have an input temperature device for the zone (target_sensor) and control device (switch of Shelly). Then you would need to put the climate PID into autotune mode and see if it gives you some good kP, kI or kD values.

climate:  
- platform: smart_thermostat

  name: Smart Thermostat Example

  unique_id: smart_thermostat_example

  heater: switch.relay4_direct
  # invert_heater: True
  target_sensor: sensor.downstairs_trv_temp_median

  min_temp: 14

  max_temp: 25

  ac_mode: False

  target_temp: 19

  keep_alive:

  seconds: 60

  min_cycle_duration: 00:10:00

  min_off_cycle_duration: 00:04:00

  away_temp: 14

  kp: 5

  ki: 0.01

  kd: 500

  pwm: 00:10:00

Maybe that's OTT for you, but I hope it helps. 😁

condord

https://www.boards.ie/discussion/comment/122371343#Comment_122371343

Yeh, I was hoping to do something like that once I have the setup working. I have temp sensors in all the upstairs rooms that I want to use to call for heat as opposed to just the Slimline in the bedroom. Thanks for your input.