Noise and neighbors

What the rating measures

AHRI Standard 270 is the industry method for a published sound rating of outdoor unitary equipment, including the outdoor section of an air-source heat pump. AHRI 270 The result is a decibel rating under that test. It is not a measurement at your property line, and it does not include a reflecting wall, a snow well, or a night when the unit is in a loud part of its operating map.

NRCan’s heat pump guide treats sound as something you compare between models, in decibels, and separately warns that forcing more air through undersized ducts makes the indoor side noisy too. NRCan Two models can carry the same AHRI heating number and not the same sound number. Ask for both.

Placement does more than the brochure

• Do not put the fan aimed at a bedroom window or a neighbour’s deck if another wall works. A few metres and a turn around a corner change what people hear more than a small difference in the rating.
• Hard surfaces next to the coil reflect sound. A unit in a narrow alcove is louder at the opening than the same unit in the open.
• A unit on a bracket bolted to a bedroom wall can put vibration into the framing. That is structure-borne sound. The AHRI outdoor rating does not describe it. A ground stand with a break in the structure avoids that path.
• Defrost and high-speed heating are not the same noise as low-speed ticking over on a mild day. If the quote only quotes the quietest published figure, ask what it corresponds to.

This page does not give a maximum decibel number. No northern bylaw was reviewed for this guide, and a single “typical” decibel figure would hide the spread between models.