Keep Warm This Winter: How Mitsubishi's Flash Injection Heats at -13°F
Quick answer: Mitsubishi keeps North Country homes warm in deep cold with a patented process called flash injection, which lets the compressor keep running at high speed in subzero air. Combined with an inverter that modulates instead of cycling, the result is 100% of rated heating capacity at 5°F, operation to -13°F (-22°F on H2i Plus), a room that holds one steady temperature, fast recovery, and heat that costs a fraction of oil, propane or baseboard. That is why a Hyper-Heat system is primary heat in Ticonderoga, not a shoulder-season helper.
What flash injection does
A typical heat pump refrigerant loop collects heat energy outside and releases it inside. The trouble in cold air is that the refrigerant carries less heat and the compressor cannot move enough of it. Mitsubishi's flash injection process adds a bypass circuit that reroutes a portion of the refrigerant to two places:
- Hot refrigerant flows back to the indoor coil to enhance heating output.
- Cooler refrigerant is injected into the compressor, which keeps it from overheating so it can run at higher speed and produce a strong heat exchange.
That is the mechanical reason a Hyper-Heating INVERTER (H2i) unit produces full rated heat at 5°F, where a conventional heat pump has already lost a third of its capacity. A smart defrost cycle completes the package, clearing frost from the outdoor coil only when sensors call for it, so the unit spends its time heating rather than defrosting on schedule. Read more on our Hyper-Heat page.
What inverter-driven heating feels like
- Consistent room temperature, no ups and downs. Conventional heat pumps and furnaces cycle fully on and off, so the room swings. An INVERTER-driven system self-adjusts continuously and holds the setpoint even when it is below zero outside.
- Only the energy you need. Zoned inverter systems deliver exactly as much warm air as the room requires to hold temperature, no more.
- Heats up quickly. High compressor speeds bring a cold room up fast; traditional systems take far longer to reach setpoint.
- Even, steady energy use. Every time a conventional compressor starts, current surges. Variable-capacity heat pumps start softly, so there is no spike on your service or your bill.
Cold climates were left out. Not anymore.
For decades, homeowners in extreme climates were left out of the electric heat pump era, tied to electric baseboard, propane heaters and oil burners. Those days are gone. Independent field research, including a Minnesota study by the Center for Energy and Environment, keeps confirming that cold-climate heat pumps deliver efficient, consistent comfort no matter how low the thermometer goes. In the Adirondacks we see it every January: a 200-year-old house switched from oil that "has never been so warm," a Newcomb cabin, farmhouses in Crown Point and Westport. See heat pumps in cold weather and our cold-climate design page.
Warm and cheaper at the same time
Because the electricity only runs the compressor and fans, a Hyper-Heat system delivers roughly three units of heat per unit of electricity across a North Country winter. Electric baseboard delivers one. Oil and propane cost more per unit of heat than either at typical prices, and they have to be delivered. The savings calculator shows what your home would cost to heat with three Mitsubishi options next to what you pay now, and completing it earns $250 off your install. NYS Clean Heat rebates through NYSEG or National Grid and 0% financing cover part of the first cost; see rebates and savings.
Keep it warm: a short winter checklist
Set it and leave it
Inverter systems are most efficient holding a steady temperature. Skip deep nightly setbacks in January.
Keep the outdoor unit clear
Brush snow off the top and keep the sides open after storms. Steam and a gurgle during defrost are normal.
Wash the filters monthly
A packed filter costs capacity on the coldest night. See filter cleaning.
Aim the vanes down
Warm air rises; pointing the louvers toward the floor keeps the room even.
Get the fall service
Charge, defrost and electrical checks before the cold; included twice a year in Adirondack Shield.
Frequently asked questions
What is flash injection in a Mitsubishi heat pump?
A patented bypass circuit that sends hot refrigerant back to the indoor coil to boost heating while injecting cooler refrigerant into the compressor so it can run at high speed in very cold air without damage. It is why Hyper-Heat holds full capacity at 5°F.
How cold can it get before a Mitsubishi heat pump stops heating?
Standard Hyper-Heating INVERTER models operate to -13°F; H2i Plus models operate to -22°F. Capacity declines gradually below 5°F, so we size to your town's design temperature.
Should I lower the thermostat at night with a heat pump?
Small setbacks of a few degrees are fine, but deep setbacks cost more than they save in deep cold because the system has to recover at full speed. Inverter heat pumps are most efficient holding a steady temperature.
Is a heat pump cheaper than baseboard heat?
Much cheaper to run. Electric baseboard makes one unit of heat per unit of electricity; a Mitsubishi Hyper-Heat system delivers about three. Converting baseboard rooms is where we see the largest savings.
Talk to us
Have questions about your home? Call Adirondack Heat Pumps at (518) 812-1958, stop by the showroom at 15 Montcalm Street in Ticonderoga, or request a free in-home estimate. We serve Essex County, the Lake George and Lake Champlain shores, the High Peaks and Addison County, Vermont.