Itho daalderop HRU 400 modbus ESPhome

ESPHome
1

Hi All,

As a few others have attempted here:
https://gathering.tweakers.net/forum/list_messages/1976492/0
and here:

I also have a HRU 400, but without any fancy zones or whatever so the config will need adjusting!

The Manual can be found here:

(page 31 or section 6.2 if you want to help along :slight_smile: )

Generic modbus question:

For some reason I cannot get 40101 till 40104 (or 100 till 103) not to display any form of logical serial number that matches the serial number of the device. How would you go about reading these modbus values

HRU specific question:

As I do not have any fancy zones on the unit so I would need to play with these values to set the fan on / off:

Screenshot 2023-10-13 at 23.13.23
Screenshot 2023-10-13 at 23.13.23758Ă—281 35.2 KB

register 42012 (2011) 0 seems to be the auto mode? and 1 seems to be set the fan to the value 1-399 where 399 is max cap. (register 2010) I dont see the logic here, also there is “ask for ventilation inlet” and “ask for ventilation outlet” which seem to do the same thing so not sure if you need to set them the same at the same time?

Thanks in advance for the help :slight_smile:

1 Like
2

Did you ever figure this out?

I have the same setup: HRU400 w/o zones, connected via modbus.

I would like to control the ventilation level via home assistant, did you succeed?

Thanks

3

Hey,

I sure did, its working great!
Even have a fan tile for the WTW.

The only down side is, if you control the WTW trough HA the external remotes no longer work.
This is a limitation in the firmware of the HRU400…

4

Added a bypas setting for the HRU 400:

###
# Bypass
###
  # 0 = down 
  # 550 = open
  # Inside air is directed to the ourside without passing the heat exchanger
  # Thus cold outside air does not heat up from the hot inside air
  # Must be used with override mode to max 200 out of 399.. The unit should do this automatically...
  - platform: modbus_controller
    modbus_controller_id: hru
    name: "Bypass valve - on/off" # 0 = auto 1 = Manual
    id: HRU_bypass_valve_on_off
    register_type: holding
    address: 2033
    min_value: 0
    max_value: 1
    step: 1
    use_write_multiple: true
    icon: mdi:toggle-switch-variant

This still needs a automation in code that it also turns on your fan into manual mode and set it to 199 :slight_smile:

5

With:

    on_value_range:
      - above: 0.5
        then: 
          - number.set:
              id: HRU_fan_demand_value
              value: 199
      - below: 0.5
        then:
          - number.set:
              id: HRU_fan_demand_value
              value: 0.0

It will turn the above code into an actual functioning bypass valve :slight_smile:

6

I you stumble upon this conversation.
Currently all code / control can be found here: