Homey already has one app for Nilan heat pumps, but it only supports CTS700.
I have created a very comprehensive support for heat pumps running with CTS602.
Connection requires TCP Modbus bridge. I recommend cheap Elfin EW11 (I use it).
Sources: https://github.com/oskarirauta/homey-nilan-app
For now, app is not yet published, but ones wanting it early, can get testing version from here: Nilan | Homey
Okay, some updates here; There’s new version at GitHub repository for this;
Pretty much a complete re-write, it’s much better now. App submission has for the moment been redacted because there is already a Nilan App - though it doesn’t support CTS602, only CTS700 - and people at Homey would love these 2 to be combined to same app.
So, because CTS602 (at least on feature set that I have given for it) is much larger than original Nilan app’s CTS700 support, I decided to port CTS700 support to my creation instead of beginning it from the fresh again to add it to existing app.. Less work this way.
I have contacted original author of CTS700 Nilan App and requested for collaboration and testing, since I don’t have CTS700 board. But anyone owning CTS700 can test it (at least if you have setup Homey development environment and use homey app run with this repo)
So testers would be welcome; hopefully original app’s developer reaches me.
Yes, on version 1.1.0 I have basically re-written almost all of the code, and made a lot of changes - which are not very much visible for end-user (besides cts700 support), but make code much easier to read. Feel free to test and report here on your journey with app, please 
