The six pipe simultaneous chiller/boiler
A marvel of efficiency
The six pipe simultaneous chiller/boiler (aka heat recovery chiller) is a larger-than-residential heat pump system composed of linked, connectible modules in graduated 20-to-80 ton capacities. When deployed as five dual scroll modular units, these can throttle back to 10% of their staged full capacity (15% with four linked modules) while they maintain simultaneous cold and hot water circulating loops at target temperatures. These (four of the six pipes) supply fan coil heating/cooling delivery points throughout larger buildings.
Multiple modules can serve the hot and cold water loops in any control configuration to equalize the run time among them. The remaining two pipes (comprising a third loop) travel from the modules’ heat exchangers to a liquid-to-liquid heat exchange loop in typical geo heat exchanger fashion if/when necessary.
The advantages of this six pipe equipment is superior efficiency and flexibility, including the likely use of shared thermal loads within the same building or campus setting. When cooling, one zone’s heat rejection can be transferred into the hot loop to serve heating or hot water needs. When heating, cooler water is transferred to the cold water loop.That makes this system a highway for transporting and exchanging thermal energy among conditioned spaces. The only time the remaining two pipes in the geo exchange loop become involved is when either or both of the thermal ranges in the hot and cold loops cannot be maintained.
Without constant ground loop pumping there is much less power required. With proper engineering, the necessary ground loops required on such projects have become reduced by over 50% in some cases, a major capital cost reduction.
My own 2013 residential water-to-air dual speed compressor system is rated at a COP of 4.9 on low speed. That means I get 4.9 times the thermal energy from a Kilowatt hour than electrical resistance heating provides.
Six pipe simultaneous chiller/boilers operate at COPs of 8.0, EERs of 27, and power consumption at full load of only 400 watts per ton. There is nothing in the conventional HVAC equipment world in either heating or cooling that can touch them for efficiency. When aiming for LEED Platinum or Zero Net Energy performance, fewer solar panels will be required, further cutting costs and speeding the return on investment.