Written by the service team at K2 Cooling & Heating in Deer Park, NY: licensed and insured HVAC contractors serving Suffolk and Nassau County, rated 4.8 across 352+ Google reviews.
It is the first thing almost every homeowner says when a heat pump comes up: "Those don't work when it gets really cold, do they?"
It is a fair question, it comes from real experience, and the answer has changed significantly in the last decade. It has also not changed as completely as some marketing suggests.
Here is the honest version for a house in Deer Park, Babylon, or Dix Hills — including the part where a heat pump is not the right answer.
The Short Answer
Yes. A properly selected cold-climate heat pump will heat a Long Island home through winter, including the coldest nights of a normal year. The technology is genuinely different from what earned the bad reputation.
The real questions are not whether it works. They are:
- What does it cost to run compared with what you heat with now — and this is where the answer depends entirely on your current fuel
- What backs it up on the handful of extreme nights, and how that backup is configured
- Whether your house, ductwork, and electrical panel can support it
Those three determine whether a heat pump is a good decision for you. The "does it work" question is settled.
Where the Bad Reputation Came From
It was earned, and it is worth understanding rather than dismissing.
Heat pumps installed through the 1980s and 1990s used single-speed compressors and lost capacity steeply as outdoor temperatures dropped. By the time it was in the thirties, the unit could not keep up. Below that, it largely handed over to electric resistance strip heat — essentially a giant toaster in your ductwork.
Electric resistance heat is the most expensive common way to heat a house. So on exactly the nights you needed heat most, the system switched to its most expensive mode. People got a January bill that they still talk about thirty years later.
That experience is real. It is also a description of obsolete equipment, and anyone selling you a heat pump should acknowledge it rather than waving it off.
What Changed
Three things, and together they are the reason the answer is different now.
Inverter compressors. Modern cold-climate units use variable-speed compressors that ramp up as it gets colder rather than running flat out or shutting off. That is the core change — the compressor can work harder to compensate for falling outdoor temperature instead of simply losing output. The same technology is covered in our guide on variable-speed systems.
Improved refrigerant cycles. Techniques such as vapor injection let modern units maintain far more of their rated heating capacity at low outdoor temperatures than older designs could.
A defined cold-climate standard. "Cold climate heat pump" is not just marketing language — there are recognized performance criteria and published listings of models that meet them, showing how much capacity each retains at low temperatures.
The practical upshot: current cold-climate units are typically rated to deliver a large share of their capacity at 5°F and to continue operating well below zero.
One thing worth asking any contractor: is this model on a recognized cold-climate performance list, and what is its rated capacity at 5°F? A good answer is specific. A vague one tells you they are quoting standard equipment.
How Cold Does It Actually Get Here?
This is the part that reframes the whole conversation, and almost nobody does the arithmetic.
Heating systems are sized against a design temperature — roughly, the coldest it reliably gets in your area, excluding rare extremes. For Long Island that figure sits in the mid-teens Fahrenheit.
That is meaningfully milder than upstate New York or New England, because the surrounding water moderates our winters. Deer Park does not get Syracuse weather.
And here is the part that matters most: the overwhelming majority of our heating season is spent at temperatures well above that design figure. Most winter hours on Long Island are in the thirties and forties — exactly the range where a heat pump is most efficient.
So the picture is not "will it cope with 10°F." It is "it will run efficiently for the vast majority of the season, and needs a plan for a small number of hours." Designing around the rare worst night, rather than the typical night, is how people end up with oversized, expensive systems — the same mistake covered in our guide on why bigger is not better.
What Happens on the Coldest Nights
Every heat pump installation needs a backup plan. There are two approaches and the difference matters a lot on your bill.
Electric backup heat
Electric resistance elements in the air handler take over, or supplement, when the heat pump cannot meet demand alone.
The advantage: simple, no second fuel, works anywhere with adequate electrical service.
The catch: electric resistance is expensive to run, particularly at Long Island electricity rates. That is tolerable if it runs for a few hours a season. It is painful if the system is badly configured and the strips engage more often than they need to — which is precisely what went wrong with older systems.
The controls detail that matters: the changeover should be set so backup engages only when genuinely needed, rather than any time the thermostat sees a gap. Ask how the backup is configured and at what outdoor temperature it is set to engage. This single setting is the difference between a reasonable bill and the one people remember from 1994.
Dual fuel
The heat pump handles the season, and an existing or new gas or oil furnace takes over below a set outdoor temperature. Also called a hybrid system.
The advantage: you get efficient heat pump operation through the mild majority of the season and a proven high-output furnace for the cold snaps, with no electric resistance in the picture at all. The changeover point can be set where the economics actually cross over for your fuel and rates.
For Long Island specifically, this is often the smartest configuration — particularly for homes that already have a working gas furnace. You add cooling and efficient shoulder-season heating without abandoning a heating system that works.
Which one is right for you
- Currently heating with oil or propane: a heat pump with electric backup often makes strong sense, and dual fuel with the existing boiler or furnace is worth pricing too
- Currently heating with natural gas, furnace in good condition: dual fuel is usually the better route
- No existing fossil heat, or removing it: cold-climate heat pump with properly configured electric backup
- Electric resistance or baseboard heat now: a heat pump is almost certainly a large improvement in running cost
The Running Cost Question, Answered Honestly
This is where we are going to be more direct than most heat pump content, because the honest answer depends entirely on what you heat with now.
The physics in your favor: a heat pump moves heat rather than creating it, so it delivers more heat energy than the electrical energy it consumes — often several times more in mild conditions, and still meaningfully more than one-to-one in cold conditions. Electric resistance heat, by contrast, is always one-to-one.
But running cost is efficiency multiplied by fuel price, and Long Island has high electricity rates. So:
- Versus electric resistance or electric baseboard: a heat pump is dramatically cheaper to run. This is the clearest case there is.
- Versus oil: a heat pump is usually cheaper to run, and the gap widens when oil prices rise. This is where most of our strongest heat pump candidates are.
- Versus propane: typically a clear win for the heat pump.
- Versus natural gas: often roughly a wash, and sometimes more expensive to run. Natural gas is inexpensive per unit of heat on Long Island, and our electricity is not cheap.
That last line is the one most heat pump marketing leaves out, and you should be suspicious of anyone who does.
So why would a gas-heated home consider one at all? Usually for reasons other than winter running cost: you need air conditioning anyway and a heat pump provides both from one system, you want to reduce combustion in the home, you are attracted by the incentives, or you want efficient shoulder-season heating with the furnace held in reserve. Those can all be good reasons. "It will cut your gas bill" generally is not.
If you currently heat with oil, this arithmetic is very different and usually favourable. Our guide on whether to repair or replace covers the timing side of that decision.
Four Things That Make or Break It
A cold-climate heat pump performs as promised when these are right, and disappoints when they are not.
1. Correct sizing. Heat pumps are sized against the heating load, the cooling load, and the capacity curve at low temperatures. It is a more involved calculation than for a furnace, and it cannot be done by matching the old equipment. A Manual J load calculation is not optional here.
2. The building envelope. Heat pumps deliver heat more gently than a furnace, so a leaky, poorly insulated house shows up faster. Attic air sealing and insulation work is worth doing before or alongside a heat pump install, not after.
3. Ductwork. Heat pumps move more air at a lower supply temperature than a furnace does. Ductwork sized for a furnace is sometimes undersized for a heat pump, and undersized returns are the most common problem we find. Static pressure needs measuring before anyone commits to equipment.
4. Electrical capacity. A heat pump — particularly with electric backup — needs adequate service. Older Long Island homes sometimes need panel work, and that needs to appear on the quote rather than as a surprise on installation day.
A contractor who covers all four is designing a system. One who quotes a tonnage off your old furnace is not.
What It Feels Like Day to Day
Worth setting expectations, because two normal behaviours surprise people.
The air feels cooler at the vent. A furnace delivers short bursts of quite hot air. A heat pump delivers a steadier stream of warm air at a lower temperature — comfortable, but it does not feel hot on your hand the way furnace air does. The room reaches the same temperature; it just gets there differently.
Homeowners who expect furnace-style blast heat sometimes think the system is underperforming when it is working exactly as designed. Knowing this in advance prevents a service call.
Defrost cycles are normal. In cold damp weather, frost forms on the outdoor coil and the unit periodically reverses briefly to melt it. You may see steam rising off the outdoor unit and hear a change in sound. That is correct operation, not a fault — though steam being mistaken for smoke has generated more than one alarmed phone call.
It runs more of the time. Long, steady operation is how heat pumps work best. A unit that seems to be running constantly on a cold day is usually doing precisely what it should.
When a Heat Pump Isn't the Right Call
Five situations where we would tell you to keep what you have or choose something else.
- Cheap natural gas and a furnace in good condition. If your furnace is eight years old and works, replacing it with a heat pump for running-cost reasons alone usually does not add up. Consider adding cooling, or revisit at replacement time.
- A poor building envelope you are not addressing. A heat pump in a leaky, under-insulated house will struggle and cost more than it should. Fix the envelope first, or budget for both.
- Electrical service that cannot support it, where a panel upgrade pushes the project out of reach. That is a real cost and it has to be counted.
- Ductwork that cannot carry the airflow and cannot practically be modified. Ductless may be the answer instead, or the project may not be right.
- A short ownership horizon. If you are selling within a couple of years, the payback window does not exist, though the buyer appeal may still matter to you.
Anyone who tells you a heat pump is right for every home is selling, not advising.
Incentives Change the Math
Heat pumps attract the most generous incentive support of any HVAC equipment, and it is substantial enough to change the decision.
New York State Clean Heat and utility programs offer incentives on qualifying heat pump installations, with amounts depending on system type and efficiency. These programs have their own application rules and contractor requirements, so confirm them directly before you commit. K2 is not a PSEG Long Island participating contractor and does not file incentive applications. Our separate guide on PSEG Long Island heat pump rebates covers what is currently available.
One correction worth knowing: the federal §25C tax credit that offered up to $2,000 on qualifying heat pumps expired for equipment placed in service after December 31, 2025. If a contractor is still including that federal credit in your numbers, they are working from outdated information — and that is worth noticing about the rest of their quote.
Because programs change annually and paperwork takes time, this is another argument for planning a heat pump project in a shoulder season rather than after a furnace fails.
Find Out What Your House Actually Needs
The "heat pumps don't work in the cold" objection is out of date, and it deserves a better answer than enthusiasm. The honest answer is that the technology works here, the running-cost case depends entirely on what you heat with now, and the outcome depends on sizing, envelope, ductwork, and electrical capacity.
If you heat with oil, propane, or electric resistance, a heat pump is very likely worth pricing. If you heat with natural gas and your furnace is healthy, the honest conversation is a narrower one — and we will have it with you either way.
K2 Cooling & Heating serves homes within about 15 miles of Deer Park. We size heat pumps with a load calculation, check ductwork and electrical capacity before recommending equipment, and will tell you plainly when your current system is the better option.
Call or text (631) 414-7141, or toll-free (800) 531-2160. You can also request an estimate online. We serve Deer Park, Babylon, West Babylon, North Babylon, Dix Hills, Huntington, Farmingdale, Massapequa, and the surrounding Suffolk and Nassau communities.
Already decided to go ahead? Our heating installation page covers what the work involves, and a maintenance plan keeps a heat pump performing — they need annual service on both the heating and cooling side.
