Entry # 128
Brief overview of the project
The project is a 3,800 sq. ft. home and ranch in Portola Valley, Calif. The application was for infloor heating and chilled water and infloor cooling for the contemporary "Farm House" designed by Field Architects. You can take a look at the project here.
We used a WiFi thermostat Ecobee3 that split the heating and cooling calls into two different zone boards that in turn send their calls to twinned 4 Ton Altherma air-to-water heat pumps. A backup gas boiler was also installed with mixing valve for backup heat and DHW. We used the following Caleffi products:
(2) ZVR106 Zone Valve Control Boards
(5) Z45 Zone Valves
(1) 1" Sweat DISCAL Air Separator
(1) 1" Sweat MIXCAL 3-way Thermostatic Mixing Valve w/ Temperature Gauge & Check Valve
The goal of the project was to give a completely unobtrusive heating and cooling solution to make the family comfortable while maintaining the strong contemporary and clean interior architecture. The project makes use of the high mass floor as thermal flywheel, moderating the temperatures both heating and cooling while the outside temperatures swing 30-40 degrees during the typical day.
The only challenge was designing a simple control strategy that used the two zone boards connected to the same zone valves. This caused a mixed signal from the two end switches on the boards to the Altherma unit, limiting the auto change-over from heating to cooling. This was fixed by intercepting the signal with a few 24V relays and a DPDT relay to isolate the heating or cooling call.
The project was new construction: cooling, heating and domestic hot water. There are plans to add additional solar thermal to the project.
House is super comfortable and the system runs like a champ! We are soon to add a whole house monitoring system to data log the energy performance. We will be posting energy use and temperature, logging the data on our website soon.