Heat pump or new furnace? How to decide
The old answer was that heat pumps are for the South. The equipment changed, the incentives changed, and the answer now depends on your fuel, your climate and your ductwork.
A furnace at the end of its life used to mean one decision: gas or electric, and which brand. Now there is a third choice that is often the best one, and a lot of homeowners are getting an answer from whoever happens to come to the house rather than from the numbers. Here is the decision, in plain terms.
What a heat pump is
An air conditioner that runs backwards in winter. Instead of burning anything, it moves heat from the outside air into the house. Because moving heat takes less energy than making it, a heat pump delivers two to four units of heat for every unit of electricity it uses. A gas furnace, however efficient, delivers less than one.
The old objection was that heat pumps lose capacity as it gets cold and became useless below about freezing. Modern cold-climate units hold most of their capacity well below zero, and every one of them can be paired with a backup, either electric strips or your existing furnace, for the handful of coldest days.
When the heat pump wins
- You heat with electricity, propane or oil today. Any of those is expensive per unit of heat, and a heat pump cuts the bill by half or more.
- You need a new air conditioner anyway. A heat pump is an air conditioner. You are buying one machine instead of two.
- Your climate has more mild days than brutal ones, which is most of the country.
- You want the federal tax credit and any utility or state rebate. Together they can take a large share off the installed price. The credits have changed more than once; ask your Pro for the current numbers, in writing.
When the furnace still wins, or the pair does
- You heat with natural gas and gas is cheap where you live. A high-efficiency furnace can still be the lower monthly bill in the coldest states, though the gap has narrowed a lot.
- Your electrical panel is full. A heat pump with electric backup may need a panel upgrade, which is a real cost. A dual-fuel system, heat pump for most days and the gas furnace for the coldest, avoids the backup strips and the panel work, and it is what many Pros recommend in cold climates.
- Your ducts are undersized. Heat pumps move more air at a lower temperature than a furnace, and starved ducts make them noisy and inefficient. A Pro who measures static pressure will tell you; one who does not is guessing.
Questions that separate a good Pro from a salesperson
- Did you do a Manual J load calculation, or size from the old equipment? Old equipment was almost always oversized.
- What is the heating capacity of this unit at 5 degrees, from the manufacturer's table?
- What is the backup, and when does it come on?
- What are the incentives, itemized, and who files for them?
- What does my electrical panel need?
The short version
If you burn propane, oil or electricity for heat, a heat pump is very likely the answer. If you burn natural gas in a cold climate, a dual-fuel system is very likely the answer. A plain furnace is the answer when gas is cheap, you already have an air conditioner that is fine, and you want the lowest installed price. Get two quotes with load calculations, and compare the ten-year cost, not the day-one cost.
Trades this touches: HVAC, Electrical.
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