Fast Hot Water Using Recirculation Pump with Occupancy Control

We have been upgrading a 1960’s vintage Bungalow on the St. Lawrence in Eastern Ontario, Canada. The boiler is at the east end or the basement and the Kitchen, Laundry and new Bathroom at the west end about 75 feet away. There was a long delay for hot water which we eliminated with a pump $99, a temperature controller $16, foam pipe insulation $80, an Insteon switch module 2443-222 $50, and miscellaneous parts $40. Total about $285.

Earlier our contractor had installed an Ecobee3 smart thermostat, which has two Occupancy Sensors, and we had chosen an Insteon Starter kit $60 and Leak Sensor $25. We also have an old PC running Linux Ubuntu as our home media server.

The picture shows the pump and controller next to our Navien combo boiler. The Inkbird Temperature Sensor is wired to the Thermistor at the far east end of the basement.

When enabled the pump is on until water at the east end reaches 110F. This on time is about 3 minutes. The temperature switch turns the pump off until water temperature gradually cools to 90F. The off time is about 22 minutes. As long as the pump is enabled this cycle repeats.

If the house is unoccupied or we are asleep at the west end of the house it saves some energy and pump and boiler wear to disable recirculation when instant hot water is not needed. This is what my first little Openhab2 application does. I use the Ecobee and Insteon add-ons. Both of these (by vendor design) work over the Internet, not the local network. I have the Ecobee remote sensor at the east end of the house. It takes about a minute for the Ecobee server to report Occupancy to my Openhab2 system on my home server. A few seconds later the Insteon switch enables the pump. Ecobee (by design) hold Occupancy ON until about 30 minutes after the last motion detected. This is fine for my purpose here.

I found working with Openhab2 has a somewhat high starting barrier. It is a large complex body of great work that is in transition from Version 1 to 2. I found Openhab in searching for a way to integrate the already existing parts into the setup described above. There were few if any open-source alternatives.

Thanks to the developers.