Configuring third party dongle for Ecodan local control

Majordennisbloodnok · 2025-11-28T16:49:40Z

This is a spin-off thread from here in order to clarify and hopefully simplify the instructions given, particularly for @morgan. The bit of hardware we're discussing is this one. It's an adapter that plugs into the CN105 socket on the circuit board of the Ecodan's FTC (flow temperature controller) unit. You should be able to see that, next to where the wire plugs into the little rectangular doohickey there's another empty socket. The idea is that, after turning off the heat pump so there's no power to the FTC, you remove the existing Mitsi wifi adapter from the CN105 socket on the circuit board and plug the free end of the long lead in the picture above into that socket in its place. You then plug the Mitsi wifi adapter back into that free socket I've just mentioned, effectively ending up with a really long lead between the FTC and the Mitsi wifi adapter, but with the new doohickey in the middle of the chain. Once you're done with that, you can put the cover back on the FTC box and turn the heat pump on again. At this point, your Mitsi wifi adapter will connect again to Melcloud and you're in exactly the same situation you were before you started. In addition, once the power is on again, you'll see the little doohickey showing a blue LED. That means it's in its default config and ready to be set up. Recapping for a moment (as outlined in the previous thread), a prerequisite for using this little box of tricks is that you've set up something for it to talk to - technically known as an MQTT broker (or server). @morgan, you've already done this by setting up the Mosquitto addon in Home Assistant, and creating a new Home Assistant user that'll be dedicated to just this conversation. The bits of information you'll need access to now are: the name of our home wifi network and the password to connect to it the name of your Home Assistant server (almost certainly homeassistant.local) the name and password for your new Home Assistant user you've set up for this job Moving back to the doohickey again, whilst it's glowing blue it's acting like another wifi hotspot. Using your phone, you can go to the wifi settings and, instead of connecting to your home wifi network, you should be able to see and select a new wifi network called "Ecodan Bridge AP". As soon as you connect to that wifi network, you will be able to fire up your phone's browser and put in an address ofOnce you've done that, you'll see the WiFiManager screen the documentation tells you about. It looks like this (except for being entitled "WiFiManager"). You need to click the Configure button and you'll see a new screen looking like this. The bits you need to fill in are the ones I've marked with red arrows. The SSID and password are the name of your home wifi network and the password to connect to it. The primary MQTT server is the name of the Home Assistant box. Most likely you'll fill it in with exactly what I've got in my screenshot. The primary MQTT username and password are the username and password of the Home Assistant user you created. If it's easy enough to fill all those bits in on your phone, do so, but the key is the wifi network/password combination so the little doohickey can be visible on your home network. Once you've filled in the necessary fields, use the blue button at the bottom to save the config and then you can disconnect your phone and reconnect it to your home wifi again. At this point, your new little doohickey should be glowing green which signifies it's connected to the wifi network successfully. If you should need to get back to that config page for any tweaking of MQTT settings, you can now do so much more easily by simply going to one of your home PCs, opening up a browser and going toNow we move our attention to Home Assistant. If you go to your Home Assistant page and then, on the left-hand bar, click on the Settings cog you can navigate to your Devices and Services page. Assuming everything's been set up OK a few weeks ago you should now see a new device in the top left corner marked "MQTT". That'll be because Home Assistant has autodiscovered this new device talking MQTT to the broker. You can now click on that MQTT icon and it'll take you to a page that looks like this Given you've used Home Assistant before, I'm guessing this won't look too unfamiliar for you, but at the bottom of each of the boxes in the middle column you'll have a link to "add to dashboard". This will add all the stuff in that box to a dashboard of your choosing so you can find it easily. From that point, you've got your Ecodan added to your Home Assistant so it can do some local control, but you've also got the heat pump still talking with Melcloud so you can still do what you always did before and Havenwise can still do its stuff exactly as it was doing before. Nothing lost and much gained. The only thing remaining now is, as @sheriff-fatman said, to tidy up your dashboard(s) so you can see key information easily rather than just be presented wi...

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F1p

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15/12/2025 7:05 pm

Appreciate the great write up @majordennisbloodnok and i'm glad the documentation was clear enough that you got it all working! 😊

Few points from me:

Step 13 & 14 shouldn't actually be required, when you send:

"active": true

If you aren't already in Fixed Flow, it will perform the swap for you.
This will only happen on the transition from "active:" false to "active:" true though, so probably why you mentioned it here as a required step.

I should also point out that if everything goes wrong and you can't make head nor tail of it all, all you need to do is change the heat pump back to "Heating Compensation" mode instead and the Mitsi WC curve will be obeyed again and the dongle's WC curve ignored. It's a quick and easy get-out clause.

This is correct, you can only write a Flow Setpoint in a Fixed Flow mode, so changing away from fixed flow it cannot write anymore.
You can also press that button around the LED to perform a soft restart, while you will remain in Fixed Flow mode it will de-activate by setting "active": false

There is a proposed change in the next firmware release that making that switch to a mode other than Fixed Flow will also perform the de-activation.

Finally, as i mentioned previously, this is the most complex feature on the device and there are a lot of steps involved. Home Assistant doesn't have a particularly accessible way to do this, so you do need to go through it line by line.

For MELPump subscribers i mentioned previously that this is coming to a nice web based design tool in the coming weeks, you can draw out your curve points in the App and it generates what is described manually above and sends it over to the adapter.

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F1p

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15/12/2025 8:33 pm

However, I've found the documentation doesn't work exactly as laid out and I needed to make a tweak.

Please let me know what this was so I can update the documentation

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Sheriff Fatman

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15/12/2025 10:34 pm

Posted by: @f1p

↑

For MELPump subscribers i mentioned previously that this is coming to a nice web based design tool in the coming weeks, you can draw out your curve points in the App and it generates what is described manually above and sends it over to the adapter.

Logically, I'll fall into that category so the natural step would be to wait for it for the functionality to become available to do this.

However, I suspect there's a great learning opportunity from trying to follow the technical steps. Whether I'll ever use that knowledge again remains to be seen, but I've come this far down the rabbit hole already, so I might as well burrow a bit further for now.

It's hard to believe that this started a few weeks ago with the simple plan to try Mel Pump's free trial via my MELCloud account for a better output of data, and has somehow descended (or perhaps ascended is more appropriate, given the additional functionality I've discovered from there) into me being a purchaser of a Home Assistant Green box, plus the CN105 dongle, discovering from there that I can tap into the Open Energy Monitor reporting ecosystem, and am now clinging onto the coat-tails of people doing funky things with their combined coding expertise.

This post was modified 4 hours ago by Sheriff Fatman

130m2 4 bed detached house in West Yorkshire
10kW Mitsubishi Ecodan R290 Heat Pump - Installed June 2025, currently running via Havenwise.
6.3kWp PV, 5kW Sunsynk Inverter, 3 x 5.3kWh Sunsynk Batteries
MyEnergi Zappi Charger for 1 EV (Ioniq5) and 1 PHEV (Outlander)

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