Phase 1: controlling the heating in the living room - a review

Raspberry Pi connected to ZWave and WiFi networks

One of the most frustrating aspects of our original system was the amount of energy we wasted heating a large living room (approx 27' by 27') which is rarely occupied. The usual pattern is for one or more of us to enter the room in the evening to watch some television - maximum time spent is probably around two hours. The three TRVs were manually turned to the max setting.

Invariably we forgot to turn them off. This meant when the central heating came on the next morning we wasted about 2-3 hours re-heating a room we didn't go in. And in the depths of Winter when we had the heating on all day this problem only got worse.

So, phase 1 was to address this problem.

I already had a raspberry pi, so I just bought the following items to get going with:

3 Danfoss Living Connect TRVs
1 razpberry daughter card
1 Hostmann Controller
2 TRV adapters (required for 2 out of the three radiators)

Here is a layout of the room and where all the components were sited.

At first, I programmed the setup so that the TRVs matched the set point on the Hostmann controller. This made it simpler to turn the heating up or down in the room as it now only required one action. But it did not entirely address the problem of forgetting to turn the heating off on exit. Zway does provide a built in web page UI from which it was possible to adjust the Hostmann control remotely:

This was an improvement as we could at least turn off the TRVs after we had gone to bed rather than try to remember to do so early in the morning.

This worked very well and ran pretty much like this throughout the winter.

I am certain we saved on our gas bill but it would be difficult to put an exact figure on the savings.
There was a definite drop in gas usage from the previous year, but the winter of 2015/16 was milder than the previous one. However, this was a great first experiment and really highlighted how much better things could be. I looked forward to expanding the network.