Do heat pumps work below freezing?

Yes — modern cold-climate units deliver useful heat far below 0 °C, some rated to −25 °C and beyond. The honest caveats: capacity at those temperatures is a fraction of nameplate, efficiency falls with it, and defrost cycles nibble further. The design question is never 'does it work' but 'where is the balance point for THIS house, and what carries the load below it'.

Is sizing the same for both?

Cooling sizing is identical — same load calculation. The heat pump adds the heating side, and the two pull in different directions: oversizing for winter can leave summer cooling short-cycling. Cold-climate practice sizes near the heating load with variable-speed compressors absorbing the mismatch; the calculators here run both loads so you can see the tension rather than have it hidden.

What about dual fuel?

Often the adult answer in gas-heated cold climates: the heat pump handles the shoulder seasons and mild winter days at its efficient best, and the furnace takes over below the economic balance point. The controls do the switching. You keep the cheap deep-winter fuel and displace the easy majority of heating hours with moved heat.

Honest comparison

Heat Pump vs Air Conditioner

In cooling they are the same machine. The heat pump adds a reversing valve and becomes your heating too — the question is what your winters and your existing heating make of that.

Start from the fact the marketing skips: in cooling mode a heat pump IS an air conditioner — same compressor, same coils, same physics, same efficiency class. You are not choosing between two cooling machines; you are choosing whether the machine should also run backwards. The reversing valve that lets it do so turns the outdoor unit into a heat source that moves heat indoors at multiples of the electricity it burns.

Winter is where the decision lives. A heat pump's capacity and efficiency both fall as outdoor temperature drops, exactly when the house needs more — the balance point where its output meets the house's demand decides how much backup you need. Modern cold-climate units have pushed that point impressively low, but the physics never disappears; the sizing calculator's job is to find YOUR balance point, not to assert one.

What already heats the house frames the economics. Replacing electric-resistance heating, a heat pump is close to arithmetic-guaranteed savings — it delivers the same heat for a fraction of the kilowatt-hours. Against cheap gas the answer is genuinely local: tariffs, climate and how long you will own the system decide, and anyone who claims a universal answer is selling one of the two boxes.

The factors that actually differ

	Heat pump	Air conditioner (cooling-only)
Cooling performance	Identical machine, identical job.	Identical machine, identical job.
Heating	Included: moves heat indoors at 2–4× the efficiency of resistance heat, falling with the temperature.	None — winter belongs entirely to whatever else you have.
Cold-climate behaviour	Capacity declines as demand rises; balance point + backup strategy are the design.	Sits idle; irrelevant.
Defrost reality	Outdoor coil ices in cold damp weather; defrost cycles cost some output and make steam-cloud theatrics.	None.
Runtime and wear	Works year-round — more hours, earn-back in displaced heating fuel.	Seasonal duty, seasonal wear.
Upfront cost	Modestly higher for the reversing capability and controls.	The cheaper box for the same cooling tonnage.

Choose heat pump when…

Anything currently heated by electric resistance — the savings are structural.
Moderate winters, where the balance point sits comfortably below your normal lows.
One system doing both seasons appeals more than maintaining two.

Choose air conditioner (cooling-only) when…

Heating is already solved cheaply and you only need summer handled.
Brutal winters where a heat pump would lean on backup exactly when running costs peak — unless you are specifying a true cold-climate unit deliberately.
Minimum upfront cost for pure cooling capacity.

Now run your own numbers

This page holds no prices on purpose — a national average is wrong for almost every real project. Quantify both options with your dimensions and your local quotes:

Heat Pump Sizing Calculator →Air Conditioner Size Calculator →

Frequently asked questions

Do heat pumps work below freezing?: Yes — modern cold-climate units deliver useful heat far below 0 °C, some rated to −25 °C and beyond. The honest caveats: capacity at those temperatures is a fraction of nameplate, efficiency falls with it, and defrost cycles nibble further. The design question is never 'does it work' but 'where is the balance point for THIS house, and what carries the load below it'.
Is sizing the same for both?: Cooling sizing is identical — same load calculation. The heat pump adds the heating side, and the two pull in different directions: oversizing for winter can leave summer cooling short-cycling. Cold-climate practice sizes near the heating load with variable-speed compressors absorbing the mismatch; the calculators here run both loads so you can see the tension rather than have it hidden.
What about dual fuel?: Often the adult answer in gas-heated cold climates: the heat pump handles the shoulder seasons and mild winter days at its efficient best, and the furnace takes over below the economic balance point. The controls do the switching. You keep the cheap deep-winter fuel and displace the easy majority of heating hours with moved heat.