Heat pump room temp improvement with home assistant

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dazzanz

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#321457 18-Aug-2025 11:32

I have 5 Daikin units in a multi-split system and their built-in temperature sensors are terribly inaccurate, often reading ~25°C when the actual room temperature is 17°C. My Mitsubishi heat pump reads accurately, so I know that it should be possible.

I was originally planning to get Faikin controllers to use external Bluetooth sensors, but then discovered the versatile thermostat plugin for Home Assistant: https://github.com/jmcollin78/versatile_thermostat

Since all my heat pumps have WiFi, I simply bought 5 external temperature sensors and set up each heat pump as a versatile thermostat device in Home Assistant. Now they maintain room temperature within 0.3°C of the target. Cheaper than getting Faikins for those who have home assistant and WiFi enabled heat pumps already.

SumnerBoy

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#3405299 18-Aug-2025 11:48

That looks like a very powerful component, wasn't aware of it so thanks for sharing.

I have a number of automations to handle things like "away mode", "window open" etc, so this might be something that simplifies my automations significantly!

pih

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#3405381 18-Aug-2025 14:38

Likewise, I hadn't seen that before, thanks! That should help with some complex automation I've been dealing with.

acetone

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#3405389 18-Aug-2025 15:04

What were the physical external temperature sensors that you purchased?

dazzanz

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#3405410 18-Aug-2025 16:30

Xiaomi temperature sensor 2. https://www.pbtech.co.nz/product/HOMMIX27012/Xiaomi-Mi-Home-Temperature--Humidity-Monitor-2-Rea

I flashed them to use zigbee though but they work with Bluetooth before flashing firmware.

rbensonx

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#3408144 28-Aug-2025 14:06

I have a ducted Fujitsu system and one standalone Fujitsu heatpump and have used the ducuted systems room thermometers to drive everything. The ducted system uses the AdvnatgeAir platform and the standalone one uses something different. Reverse engineered the web interface for the standalone and now control the lot through home assistant. Works much better than the fujitsu controller

timmmay

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#3408149 28-Aug-2025 14:20

That's an interesting sounding component, thanks for sharing! I had started writing my own similar thing a while back but lost interest, so I'll have a look at this. My ducted system with Airtouch keeps the temperatures well, but the Daikin high walls in the kitchen and office are terrible - set them to 21 and within a few hours it'll be 24 degrees.

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timmmay

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#3408196 28-Aug-2025 16:40

I had a quick read of the docs... they're not particularly easy to understand. It looks like a powerful, flexible component and they're always somewhat difficult to use.

dazzanz

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#3413075 9-Sep-2025 19:26

It has a lot of features so it is a bit hard to know what you can ignore, I just gave it a try and it didn't take more than a couple of times in the settings to get what I want. I was so disappointed with the Daikin units before I found this component, I got them very cheap and installed for free so I couldn't really complain either. If they ever fail I will not hesitate to go with Mitsubishi. Ducted would be preferred but our house doesn't lend itself towards retrofitting that.

Definitely give it a go with your two Daikin units, for me it maintains temperature so well with the external thermometer.

mentalinc

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#3413081 9-Sep-2025 20:21

Are you able to share some screenshots on how you've got it working?

Seems you need a external thermometer to provide a temperature elsewhere in the room and use that to target when the heat pump to stop heating/cooling, instead of the heat pump using it's own built in thermometer.

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dazzanz

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#3413643 11-Sep-2025 09:02

These are what I've set up. Temp sensor is the one I mentioned previously in a reply, and the devices to be controlled entity is my heat pump. The self regulation part, I have on medium for this room but for a different room I have it on strong, don't recall why but both are working fine. I turned off the heat pump just before taking the screenshot but you can see it was set to 19 degrees and it was at 19.2 degrees.

johno1234

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#3413646 11-Sep-2025 09:11

Could room temperature sensor location could be the original problem?

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dazzanz

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#3413649 11-Sep-2025 09:18

johno1234:

Could room temperature sensor location could be the original problem?

The Daikin heat pump room temperature sensor is in the unit and whatever algorithm they use to estimate the actual room temperature doesn't appear to work well. Using the external temperature sensor and the home assistant component to control it corrects this.

johno1234

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#3413665 11-Sep-2025 10:32

Haier have a useful "I Feel" mode where the remote control senses the room temperature so you can put the remote where the people are to drive the thermostat.

dazzanz

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#3413732 11-Sep-2025 12:06

johno1234:

Haier have a useful "I Feel" mode where the remote control senses the room temperature so you can put the remote where the people are to drive the thermostat.

I'm not sure why most heat pumps don't have that, they just have old "dumb" IR remotes. My gas fireplace also uses the remote as the room temp source.