Fujitsu has just released their latest heat pump, the RLS-2H which maintains it’s rated output down to -15°F. That’s a pretty amazing feat! The 15,000 BTU RLS-2H produces 15,000 BTU/hr at -15°F and 20,000 BTU/hr at 0°F.
How it does this is a little less amazing.
The RLS-2, reVision heat’s choice heat pump for cold weather heating applications, produces 100% of it’s output at 5°F and operates down to -5°F. To increase it’s functionality, Fujitsu added a larger heat exchanger and a high capacity compressor to create the RLS-2H.
Another change from the RLS-2 to RLS-2H is a resistive electric “drain pan heater”. Drain pan heaters sit below the heat exchanger on a heat pump and catch condensation that could otherwise freeze at very low temperatures. Other brands of heat pumps require the addition of a drain pan heater for systems installed in cold climates. reVision heat uses them in our Daikin Altherma systems as well as our Mitsubishi Hyper Heat systems. The RLS-2 doesn’t require one.
What this means for home owners
The addition of the drain pan heater means that the system works reliably to colder temperatures, but it also means that they work less efficiently than the RLS-2. The drain pan heater comes on at 30 degrees, dropping efficiency and pushing the output of the system to a colder temperature. The HSPF, which is a measure of efficiency of heat pumps, of the RLS-2H 15,000 BTU system is 10.3, where as the HSPF of the RLS-2 15,000 BTU system is 12. Another way to look at it is, seasonally, the RLS-2H will use 16% more energy than the RLS-2. In applications where primary heating is required, and the difference between 15,000 and 20,000 BTU’s matters, we’ll spec the RLS-2H, where systems don’t need to be as robust, the efficiency of the RLS-2 will win the day.
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