Entry # 60
Brief overview of the project
This is a residential HVAC system that includes 15 tons of geo-exchange water-to-water heat pumps, three (3) solar-thermal collectors (30 tube evacuated-tubes each) and a propane-fired condensing boiler to provide radiant floor heat, second stage hydro-air heat, indoor pool heating and domestic hot water. Innovative Construction & Design Solutions, LLC was both the design engineer and the automation system integrator for the HVAC and energy systems.
Caleffi products used:
2” 548 Hydro Seperator
Z2 2-way zone valves with Z1 actuators
The design goal was to provide heating and cooling for the house as well as year-round heating for the indoor pool and domestic hot water. The operation of the system is focused on finding the most sustainable energy source available and using it with the energy utilization order as follows:
- Natural gas
All of these sources connect to a common heating loop with automation used to decide the most viable and/or sustainable source. The common heating loop is connected to the heat pump load side using a Caleffi 548 Series Hydro Separator to provide back-up heating to the building during a power outage (i.e. heat pumps not on emergency power) and/or to utilize heat from the geo-exchange system for the pool (Note: the pool heat exchanger is designed for 103°F entering water to make 95°F pool water). Geo-exchange source energy is conserved with a VFD driven pump that reduces flow to the heat pumps that are not running (flow is shut off using a Caleffi zone valve).
Also in the cooling season, when there is a demand for pool heat and chilled water, the heat pump condenser loop can be redirected to the pool to utilize the waste heat.
This was a 100% new installation. The most significant challenges were:
- Indoor pool moisture control
- Dialing in the automation control sequence to optimize sustainable energy sources and minimize fossil fuel and utility electricity consumption
The systems were recently serviced and appear to be operating very well. As we go through seasons and use patterns of the house and pool, we are making control sequence changes as necessary to improve efficiency and control.