Interface with Proliphix NT20e IP Thermostat

After unpacking, connecting and testing the NT20e the time had come to start testing the software i had already made in the past days to let my HA system interface with the thermostat.

With the very good and accurate Proliphix API documentation available, it was quite easy to start coding for the API without actual hardware to test with. The object oriented architecture i use in my Home Automation system really paid off this time. I mean, a thermostat with dozens of values/settings that can be read or written, is something completely different then for example a Door/Window sensor. Or not?

No, it doesn’t have to be. Whether you’re dealing with a thermostat or whatever type of sensor, they are both Devices with 1 or more DeviceValues. So all i had to do is focus on the device-specific code and ‘rewrite’ the API information to Delphi code. For example the code to define all the types and constants is 900 lines of code, the code that does the actual low-level interfacing with the NT20e is 430 lines and the code for the NT20e itself is 400 lines. In total less then 2000 lines of code of which only 1000 executable, not bad! The less new code means less new bugs 🙂

The result of these 1000 lines of code is total integration in the rest of my HA system. Complete exposure of the thermostat and its functionality: storing historical data to the database, creating events, manipulating the thermostat from the website, touchscreen or one of my other GUIs, everything instantly available.

Sometimes i am very glad i chose to create my own Home Automation system 3 years ago… this is one of those times :-).

Testing the interface. Before the thermostat would be placed on the wall in the livingroom, i wanted to make sure the interface was working properly. Only some minor bugs were found, mainly caused by making mistakes in translating the API documentation into constants. Currently the NT20e interface is running on my PC where it will run for some time before i am confident enough to take the next step: relocating the thermostat to the livingroom and start using it 🙂

Testing my Domotica system with the NT20e

Testing my Domotica system with the NT20e

Connecting the Proliphix NT20e thermostat

Ethernet and power

Needless to say that connecting this IP thermostat needs an Ethernet connection nearby. Fortunately i have a 1Gbps switch only 3 meters away from the place where the thermostat will be placed. The thermostat also needs 24V DC power to operate. POE (Power Over Ethernet) is being used to power the NT20e. An EPA-20 can be used to inject the power into the Ethernet cable that goes to the thermostat:

Proliphix EPA-20

Proliphix EPA-20

The EPA-20 is capable of powering 2 devices (not necessarily being Proliphix thermostats).

Dry testing

Before connecting the thermostat to my central heating, i decided to do some ‘dry’ tests first: connecting the Ethernet cable and power, but not the 2 wires that go to the central heating. I attached a multimeter to the connections i thought were the right ones for the combination of my central heating (Remeha Calenta) and the NT20e. My guess was i had to use the connections labeled RH and W1, so i monitored what was happening on these 2 connections when the relay switched. I tested voltage and resistance; and as i expected, no voltage is applied and resistance was either 0 or infinite; exactly the behavior i expected (and need).

Proliphix NT20e back plate

Proliphix NT20e back plate

Back side of the NT20e thermostat

Back side of the NT20e thermostat

The thermostat is ready to be used, but first: testing the interface to my Home Automation system with the thermostat still in the office! (will save me a lot of running from office to living and back again while testing) 🙂

Proliphix NT20e IP Thermostat

Yesterday i received a NT20e IP Thermostat made by Proliphix:

NT20e IP Thermostat and EPA-20 Power supply

As a logical followup on the Remeha Gateway disaster where in the end i was forced to disconnect the Gateway, my attention shifted towards using a thermostat to achieve my goal: being able to change the setpoint of the central heating from my Home Automation system. I’ve looked at several products, and in my opinion the Proliphix Uniphy Network Thermostats looked the best in terms of offered functionality, connectivity and professionalism. Pieter Knuvers from Bwired and i discussed this thermostat and Pieter was just as enthusiastic about this thermostat as i was. Pieter and i do a lot of things together; testing hardware is one of those things. Last Thursday a Proliphix NT20e and a POE Power injector arrived from the USA. Pieter received the same parts and we started testing.

– Compatible with fossil (oil, gas) as well as heat pump systems
– Support for Single stage heat and Airconditioning
– Wired TCP/IP communication
– Password protected, built-in Web Browser control interface (TMI)
– Email alerts
– Support for 2 additional external sensors
– 366 day programming
– 4 temperature periods per day
– 3 year scheduling
– Scheduling of vacation and other special days
– Energy Star compliant.

The first looks after the NT20e confirmed my expectations – the Proliphix Thermostat looks and feels very sound.

– It weighs more then the average thermostat i’ve ever held in my hands;
– The buttons on the front give a good, solid ‘click’;
– The LCD is backlit which makes it very good readable;
– The internals look solid and firm, good for years & years of operation.

One minor thing i think that could use some attention is the thickness; the dimensions of the NT20e are 14.2 x 9.5 x 4.3  cm.
This is quite thick, however you have to keep in mind that this thermostat has a lot to offer – more then the usual Dutch thermostat i know of, so that will probably cause the slightly higher volume.

This thermostat is the ultimate tool to achieve what i’ve wanted for years and years, even before i knew what Domotica meant: controlling the temperature setpoint without having to stand in front of the thermostat!