Heat Pumps on a Home Inspection: What Inspectors Check

If the house you're buying has a heat pump, the HVAC section of your report is playing by slightly different rules, and it's worth knowing them. Heat pumps are now the most common heating system in new U.S. homes and standard equipment across the South, and increasingly everywhere else. A heat pump on a home inspection gets evaluated like an air conditioner and like a furnace, because it's both. The same refrigerant circuit that pumps heat out of the house in July runs in reverse in January and pumps heat in.

That reversibility is the source of everything distinctive in this part of the report: the extra components (a reversing valve, a defrost system, backup heat strips), the extra failure modes, and one aging fact buyers consistently miss. A heat pump works all year, so it wears out faster than either machine it replaces.

How a heat pump inspection differs

An inspector runs the same functional, non-diagnostic test they'd run on any system (operate it from the thermostat, observe the response, measure the temperature split) with a few heat-pump-specific additions and one big seasonal caveat.

The additions:

• Both modes get tested where weather allows. Heating and cooling are two different operations of the same circuit, and a system can work in one mode and not the other. A failed reversing valve does exactly that.
• The temperature split reads differently in heat mode. Heat pump supply air is typically 85–92°F: warm, not hot. A furnace blows 120°F+ air, and buyers who grew up with gas heat routinely mistake normal heat-pump supply air for a defect. Inspectors know this; sellers' agents sometimes don't.
• Auxiliary heat gets exercised. Most heat pumps have electric resistance strips as backup, and the inspector will try to trigger them from the thermostat ("emergency heat") to verify they respond.
• Outdoor unit condition matters yearround. Because the outdoor coil runs in winter too, inspectors look for ice damage, coil frosting patterns, and clearance. A heat pump buried in shrubs or with its base pan rusted out is a finding, not cosmetics.

The caveat: in cold weather, cooling mode often can't be tested (running a compressor for cooling below roughly 60–65°F risks damaging it), and in hot weather, heating gets only a brief run. A line like "heating mode not fully evaluated due to ambient conditions" is standard practice rather than evasion. But it does mean one of the machine's two jobs went unverified, which is worth remembering when the system is old.

The findings unique to heat pumps

Auxiliary heat running when it shouldn't

The backup strips exist for cold snaps and defrost cycles. But electric resistance heat costs roughly two to three times as much per unit of heat as the heat pump itself. A system quietly leaning on its strips (because of low refrigerant, a failing compressor, or a miswired thermostat) heats the house fine while doubling the winter electric bill. A typical finding: "Auxiliary heat observed energizing during normal heating call at moderate ambient temperature; recommend evaluation by an HVAC contractor." This finding looks harmless on the surface: the house is warm, nothing is visibly broken, and the problem only shows up on utility bills the buyer hasn't paid yet. If the sellers' utility history is available, winter electric bills are worth a look.

Defrost problems

In heating mode the outdoor coil runs cold and frosts over; the system periodically reverses itself for a few minutes to melt the ice. Failed defrost controls or sensors let ice build until the unit is a frozen block, and ice physically crushing the coil or fan is a genuinely expensive outcome. Findings citing "heavy ice accumulation on outdoor coil" or "evidence of ice damage to fan blades/coil fins" deserve a technician's look. (A brief steam cloud and a whooshing sound during defrost, by contrast, is the system working. That's another normal behavior that alarms new heat-pump owners.)

Reversing valve failure

The valve that flips the system between heating and cooling can stick or leak internally. The classic symptom is a system that cools but won't heat (or vice versa). It's one of the pricier single repairs on a heat pump, often $600–$1,500, and on an older unit its failure commonly tips the repair-vs-replace decision toward replacement.

Dual-fuel setups

Some homes pair a heat pump with a gas furnace as the backup instead of electric strips: a dual-fuel system that runs the pump in mild weather and the furnace in deep cold. Inspectors verify both appliances respond and flag control problems (both running simultaneously, or the furnace carrying the whole load). If your report covers a dual-fuel system, the furnace half ages on its own clock and deserves its own read (see the furnace age and life guide), because you're effectively buying two heating plants with two remaining lifespans.

Age and the shorter clock

Here's the aging fact that shapes the whole negotiation: a heat pump runs in summer and winter, so it accumulates compressor hours roughly twice as fast as an AC that rests half the year. Typical service life is 10–15 years, versus 15–20+ for a furnace. An inspector reads the manufacture date off the outdoor unit's data plate, and the arithmetic is blunt. A 12-year-old heat pump is nothing like a 12-year-old furnace. It's in the window where compressors, reversing valves, and coils start failing, and where any major repair competes with replacement money.

Refrigerant type sharpens this further. A pre-2010 unit likely runs R-22, which makes every refrigerant-circuit repair disproportionately expensive. The same phase-out math that applies to old air conditioners applies doubly to a machine you need in January.

What heat pump repairs and replacement cost

Climate zone, tonnage, and efficiency tier move these ranges substantially.

One planning note that softens the top rows: heat pump replacements currently qualify for meaningful federal tax credits and, in many states, utility rebates. Programs change, so verify what's live when you budget, but an aging heat pump is one of the few big-ticket findings where incentive money routinely takes a real bite out of the replacement number.

How to handle heat pump findings in the deal

1. Weight age more heavily than you would for a furnace. A 13-year-old heat pump is an end-of-life conversation even if today's test passed. Anchor with the 10–15 year lifespan rather than furnace intuitions.
2. Take "one mode untested" seriously on older units. If heating couldn't be verified and the unit is past 10 years, a technician's evaluation during your contingency is cheap relative to what it rules out.
3. Treat aux-heat findings as an operating-cost issue. The seller's system "works"; your argument is about the electricity it silently wastes and the underlying fault. A technician's diagnosis converts it from a vibe into a number.
4. Fold small wear items into one ask. Capacitors and a defrost sensor belong in a bundled credit rather than a punch list, and the whole request should sit inside the framework from the main HVAC guide.

Reading the section with heat-pump instincts

A heat pump's report section rewards a different set of instincts: warm-not-hot air is normal, steam clouds are normal, but a 12-year age stamp, strip heat running on a mild day, or an untested heating mode are the quiet lines that carry real money. Read the age first, the mode-coverage second, and the component findings third.