What is a heat pump and how does it work?

An electric system that moves heat instead of making it. The Department of Energy: "Like your refrigerator, heat pumps use electricity to transfer heat from a cool space to a warm space"; in winter they bring heat indoors, and in summer they move heat from the home to the outdoors.

What is the difference between a heat pump and an AC?

An air conditioner only moves heat out of the house. A heat pump does that and also runs in reverse in winter to bring heat in, so the DOE calls it an alternative to both a furnace and an air conditioner. Seattle files both together; the usual heat pump or AC permit there was filed at $8,000.

How are heat pumps and air conditioners similar?

Both are refrigerant systems with an indoor coil and an outdoor unit that move heat rather than burn fuel; in summer a heat pump cools the way an AC does. That is why Seattle records them under one permit type, with 15,441 permits in three years.

How do you know if you have a heat pump or furnace?

Read the rating plate. A furnace's plate is on the indoor cabinet and lists a fuel (natural gas, propane or electric) and heating input. A heat pump's outdoor unit plate says heat pump in the model description, and the unit runs in winter as well as summer. Some homes have both: a heat pump with a furnace as backup.

How long does a heat pump installation take?

We cannot time the install itself, but the permit is a fair measure of the whole job: in Seattle the usual heat pump permit took 105 days from issue to final inspection, against 66 for a furnace permit.

How can you lower what you pay for a heat pump?

The federal 25C credit ended for heat pumps placed in service after December 31, 2025 (IRS). What still works: get quotes from firms in the lower half of your city's range (in Seattle the middle half of firms usually file $6,000 to $15,000), ask your utility about rebates, and book outside the June peak. Our financing guide covers loans.

What is a heat pump? Heat pump vs AC vs furnace

Heat pump, air conditioner or furnace: the table

	Heat pump	Central air conditioner	Furnace
What it does	Heats and cools	Cools only	Heats only
How	Moves heat with refrigerant, both directions	Moves heat out with refrigerant	Burns gas or oil, or uses electric resistance
Fuel	Electricity	Electricity	Gas, propane, oil or electricity
Useful life (Fannie Mae)	15 years (condensing unit, one dwelling)	20 years (outdoor condenser)	20 years
ENERGY STAR: consider replacing after	10 years	10 years	15 years
Seattle permits, 3 years	15,441 (filed with AC)	(filed with heat pumps)	18,668 (furnace and heating)
Seattle usual filed value	$8,000	(filed with heat pumps)	$7,550

The DOE describes heat pumps as "an energy-efficient alternative to furnaces and air conditioners" and lists types: ducted air-source, geothermal (ground-source), which "can reduce energy use by 30%-60%", and ductless mini-splits. On cold climates it says air-source units were once unsuitable for long subfreezing spells but "now, they're a legitimate option for colder regions".

When an AC plus a furnace still makes sense

A heat pump replaces both machines, so the comparison is one install against two. If your furnace is young (under ENERGY STAR's 15-year mark) and only the air conditioner has failed, replacing the AC alone keeps a working furnace in service; a heat pump can also be paired with the existing furnace as backup. If both are near the end, one heat pump is one job, one permit and one inspection. Our city guides compare the filed costs directly: heat pump vs furnace in Seattle and in San Diego County.

What heat pump installs are filed at

	Seattle	Burlington, VT
Heat pump permits (3 years)	15,441	674
Firms filing them	272	83
Usual days, issue to final	105	70
Reached final	85.6%	83.1%
Busiest month	June	October

In Seattle the middle half of heat pump firms usually file $6,000 to $15,000 a job, and the five busiest firms hold 28.7% of permits. 36 of the firms filing heat pump permits had a matched Washington registration that was expired, suspended or otherwise not active, so check before you sign. Burlington's filed values are not a guide to whole-system cost (its usual value is far below Seattle's), so we leave them out.

Is there still a tax credit?

Not a federal one. The IRS: the 25C energy efficient home improvement credit "will not be allowed for any property placed in service after December 31, 2025." The DOE article quoted above still mentions a 30% credit; it was written in 2023, before the law changed. Utility and state rebates are separate and still exist in some places; ask your utility.

Check a heat pump installer in five minutes

Open the Seattle heat pump compare page (or your city's HVAC page) and find the firm.
Check its permit count and finished share against the city's 85.6%.
Look up its registration on Washington L&I's Verify a Contractor page.

See every Seattle heat pump installer's permits →

What this does not tell you

Most cities file heat pumps under general HVAC or mechanical permits, so only two in our data separate them, and Seattle mixes heat pumps with air conditioners. A permit does not say whether a heat pump replaced a furnace or was added beside one. Filed values are the contractor's own figure, before rebates.

How we know this

Heat pump permits are those Seattle and Burlington file under a heat pump work type in their three-year windows (Seattle's ends September 2026, Burlington's March 2026); Seattle's furnace and heating permits are counted separately. The usual filed value is the median of permits that carry one; days is the median from issue to final; "reached final" is the share of permits a year or more old that the city closed with a final; licence status comes from matching each firm to Washington L&I's registration file. Descriptions and savings figures are the Department of Energy's; lifespans are Fannie Mae's and ENERGY STAR's, read 22 October 2026.

Numbers come from City of Seattle (SDCI) building, trade and electrical permits on single-family and duplex homes (the city's open-data exports); City of Burlington permits on 1–4 family homes, condos and mobile homes (the city's OpenGov permit feed), data through October 17, 2026. Nobody paid to be on this page and nobody can.

Questions

What is a heat pump and how does it work?
An electric system that moves heat instead of making it. The Department of Energy: "Like your refrigerator, heat pumps use electricity to transfer heat from a cool space to a warm space"; in winter they bring heat indoors, and in summer they move heat from the home to the outdoors.
What is the difference between a heat pump and an AC?
An air conditioner only moves heat out of the house. A heat pump does that and also runs in reverse in winter to bring heat in, so the DOE calls it an alternative to both a furnace and an air conditioner. Seattle files both together; the usual heat pump or AC permit there was filed at $8,000.
How are heat pumps and air conditioners similar?
Both are refrigerant systems with an indoor coil and an outdoor unit that move heat rather than burn fuel; in summer a heat pump cools the way an AC does. That is why Seattle records them under one permit type, with 15,441 permits in three years.
How do you know if you have a heat pump or furnace?
Read the rating plate. A furnace's plate is on the indoor cabinet and lists a fuel (natural gas, propane or electric) and heating input. A heat pump's outdoor unit plate says heat pump in the model description, and the unit runs in winter as well as summer. Some homes have both: a heat pump with a furnace as backup.
How long does a heat pump installation take?
We cannot time the install itself, but the permit is a fair measure of the whole job: in Seattle the usual heat pump permit took 105 days from issue to final inspection, against 66 for a furnace permit.
How can you lower what you pay for a heat pump?
The federal 25C credit ended for heat pumps placed in service after December 31, 2025 (IRS). What still works: get quotes from firms in the lower half of your city's range (in Seattle the middle half of firms usually file $6,000 to $15,000), ask your utility about rebates, and book outside the June peak. Our financing guide covers loans.