Buying a Home With a Heat Pump
or Ductless Mini-Split
More Portland and SW Washington listings come with heat pumps every year. Here’s what the inspection looks at, where its limits are, and what to ask for before closing.
Heat pumps used to be rare in older Portland houses. Now they show up all the time, often as a ductless mini-split added to a house that still has an old furnace, or as a full replacement for a gas or oil system.
That’s good news for comfort and energy use. It also means buyers are looking at equipment they don’t know much about. What does a home inspection cover on these systems? And where does it stop?
The three setups you’ll see
Most heat pumps in Portland and SW Washington homes fall into one of three setups.
A ducted heat pump replaces a furnace and air conditioner. It has an outdoor unit and an indoor air handler connected to the existing ductwork. From inside, it looks a lot like a furnace.
A ductless mini-split has an outdoor unit and one or more indoor “heads” mounted on walls or ceilings. Each head heats or cools its own room or zone. These are common in older homes without ducts, and in additions, ADUs, and finished attics.
Some of those older homes heat with resistance cable buried in the ceiling instead. Russ explains how to spot it and test it in radiant ceiling heat in older homes.
A dual-fuel or hybrid system pairs a heat pump with a gas furnace. The heat pump handles most of the year, and the furnace takes over in the coldest weather.
A house can have more than one of these. A 1920s bungalow might have a mini-split upstairs, a gas furnace serving the main floor, and an old oil tank that was never removed. Each piece gets looked at on its own.
What the inspector looks at
The inspection is visual and non-invasive. The inspector looks at the accessible parts of the system and runs it with its normal controls. Here’s what that usually covers.
- Data plate, manufacture date, and approximate age when readable
- Pad or stand, whether the unit sits level
- Clearance from shrubs, fences, and walls, and debris in the coil
- Bent or damaged coil fins
- Missing electrical disconnect, or damaged wiring or conduit
- Line set insulation that is missing, cracked, or broken down by sun
- Gaps around the hole where lines pass through the wall
- Line covers and how the lines are supported
- Response to the normal controls in the mode that can be tested
- Dirty filters, or staining on the wall below a head
- Condensate leaks, or a drain line that ends somewhere it shouldn’t
The condensate drain gets more attention than most buyers expect. Every indoor head and air handler makes water when it cools. That water has to go somewhere. A drain line that ends inside a wall cavity, drips onto a roof, or runs uphill is worth fixing before it causes damage.
Real Inspection Photos
Heat Pump Findings in Russ's Reports
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Damaged foam insulation on the refrigerant line at the outdoor unit. UV-resistant insulation helps efficiency and limits condensation dripping. -
Bent fins on a one-year-old heat pump coil. Flattened fins restrict airflow, and an HVAC pro can usually comb them straight. -
The outdoor unit was not running, so the thermostat switched to auxiliary heat. Backup electric heat costs more to run, and a technician should find the cause.
What the inspection can’t tell you
A home inspection is a generalist inspection. It isn’t an HVAC service call. Some things are outside it:
- Refrigerant charge and pressures. Measuring them takes gauges connected to the system, which is HVAC contractor work.
- Sizing. Whether the system is the right size for the house takes a load calculation.
- Efficiency, or how much the system will cost to run.
- Inside the equipment. The inspector doesn’t take covers off sealed units.
- How long it will last. The report gives an approximate age, not a prediction.
Weather limits testing, too. In cold weather, a heat pump runs in heating mode. Many manufacturers advise against running cooling mode when it’s cold outside, so the cooling side may not get tested in January. The report notes what was and wasn’t tested. If you’re inspecting in the rainy season, this post on home inspections in the rain and cold covers the other seasonal limits.
Age, refrigerant, and paperwork
The data plate on the outdoor unit usually shows a manufacture date, or a serial number that encodes one. That’s how the inspector gives an approximate age.
Refrigerant type is on the plate too. Older systems used R-22, which is no longer made in the U.S. If you see it, this post on R-22 refrigerant and aging AC systems explains why it matters. Most systems from the last 15 years use R-410A, and newer equipment made under the federal refrigerant phase-down generally uses refrigerants like R-454B or R-32. None of that is a defect. It’s useful to know when you’re thinking about future service.
Paperwork fills in what the plate can’t. Ask the seller, through your agent, for:
- Install date and installing contractor
- Warranty registration, if the manufacturer required it
- Service and maintenance records
- The mechanical or electrical permit
- Terms of any rebate or incentive used, if any carry over to a new owner
A property history report can show permits for the address from both BuildFax and BuildChek. A heat pump install usually involves electrical work, so a permit record is a reasonable thing to look for. Coverage varies by jurisdiction, so a missing record is a question to ask, not proof the work wasn’t permitted.
After closing
A heat pump needs regular attention like any other system. Indoor head filters on mini-splits are usually washable and need cleaning more often than most owners think. Keep plants and debris clear of the outdoor unit. Have a contractor service it on the schedule the manufacturer recommends.
Ducted heat pumps and furnaces have a filter at the air handler too. The post on furnace filters that are dirty, backwards, doubled up or the wrong size covers what Russ finds there.
If the house also has an old furnace or a gas water heater, this guide to HVAC systems in Portland homes covers what else tends to come up.
Trusted Home Inspections includes thermal imaging at no additional charge on every inspection, and Russ is a licensed general contractor as well as a Certified Master Inspector® (CMI®). See what a buyer’s inspection covers, or schedule online seven days a week.
Heat Pump Home Inspection FAQ
