The answer depends on how and where they were installed.

In multi-family environments, I frequently see outdoor condensing units installed too close together.

Condensing units and heat pumps should have a specified minimum amount of free air space around each unit to facilitate heat rejection – the technical term for the discharge of heat that is removed from indoor living space. Manufacturer’s installation instructions always specify how much clearance you should have between the condensing unit and adjacent walls, fences and shrubbery, and between adjacent units.

Depending on the application, 10 to 24 inches of clear space may be necessary. The excerpt (below) from one brand’s installation instructions show that for a residential application, 20 inches is required between adjacent units and 10 inches is needed between the unit and the nearest wall.

When units are installed too close together, the units compete against one another for cool air, which is drawn across the coil and discharged upward.

There are real consequences for failing to maintain these clearances:
• The system will work harder and longer to meet cooling demands.
• The system will consume more energy to meet demands.
• The system will be less effective at moderating interior temperatures.
• Longer run-times will shorten the useful life of the system, leading to more frequent replacements,

Your tenants’ energy bills will be affected, but, perhaps more importantly, your operating costs will climb as you spend more replacing compressors, fan motors, and entire condensing units because of reduced service life.

Also, keep an eye on your landscapers. It’s common practice to plant shrubs around condensing units to hide them from view. But as the shrubs grow, if they are not cut back, the growth creeps in on the free air space necessary for heat rejection.

Rob Milam is the CEO of zumBrunnen, Inc. He has 25 years of diverse experience in the construction industry. Rob has worked in multiple market sectors and in all phases of construction management. During his career, Rob has worked on a broad range of facilities including senior living, residential, multi-family, industrial, office, and healthcare.

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