March 24, 2022

9 Recommended Practices for Cold-Climate Ductless Heat Pump Installations


A version of this article was originally posted to, which was retired on April 1, 2022.

Did you know that some ductless heat pumps are designed to operate in cold climates? When properly applied and installed, research has shown these ductless heat pumps work well for heating homes and saving energy. Due to the more demanding conditions in which they operate, installation mistakes, shortcuts and oversights can dramatically impact how well these machines perform.

BetterBuiltNW has nine recommendations for cold-climate ductless heat pump installations that can help installers provide their customers with maximum heating performance and long-term satisfaction.

Locating the Outdoor Unit

1. Avoid installing outdoor units on walkways and patios. Defrost cycle meltwater can re-freeze on ground surfaces and create a dangerous slip hazard.

2. Do not install outdoor units under a roof's driplines. Rain, icefall, and snowmelt from roof overhangs and driplines can re-freeze on the compressor’s coil surface and overwhelm the unit's defrost cycle. When needed, outdoor units should be installed with drip caps or shields.

3. Do not install outdoor units facing into the wind. If the outdoor unit is facing into dominant wind direction, this could cause counter-rotation of the outdoor fan and lead to failure of the fan motor, fan circuit board, or both.

4. Locate outdoor units where noise will not disturb occupants. In colder climates, defrost cycle and full power operations occur frequently and run at higher decibels than typical operations. In homes with little or no insulation or single pane windows, full power noise may bother occupants.

5. Install outdoor units above average snowfall depths. Outdoor units need free-flowing air at all times. Install using wall brackets or an equipment platform that will raise the outdoor unit above average snow levels.

Additional Considerations

6. Avoid any kinks or partial kinks in the lineset. Even a partial kink can result in reduced capacity in low temperatures and may result in a callback. This can be a very difficult problem to solve. Adding more refrigerant will only exacerbate the problem. Locating a kink requires removing the line-hide, feeling along the lineset to locate hot spots, and potentially replacing the entire lineset.

7. Ensure outdoor units stay level.

The outdoor unit must be level (front-to-back and side-to-side) and remain so for its useful life. This is important to ensure the defrost cycle works properly and to prevent ice buildup in the outdoor unit.

8. Ensure insulation covers the entire lineset, including flare fittings.

Make sure insulation covers the flare nuts, as well as the entire lineset length. This ensures liquid or frost will not develop under the flare nut and cause cracks. Full insulation coverage also retains heat and improves system efficiency.

9. Air-seal and insulate the wall penetrations. Unsealed holes cause internal temperature sensor errors which can lead to serious performance issues. Low temperature conditions will exacerbate these issues.

We encourage installers to download a printable version of the installation guidelines for an illustrated list of these nine installation recommendations.

Looking for more detailed information on cold-climate ductless heat pumps? The Northwest Energy Efficiency Alliance’s Cold-Climate DHP Specification and Recommendations document provides more detailed information on system selection and installation guidelines. To learn about specific ductless heat pump models that can perform in the Northwest’s colder regions, visit the Northeast Energy Efficiency Partnership’s Cold-Climate Air Source Heat Pump List. To determine if a system meets the Northwest specification, review the detailed listing to confirm the unit’s HSPF and ensure it meets 80% rated capacity at 5°F.

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