How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manufactured and modular homes
Why does an air conditioner condenser unit need to be level?
Thursday, July 12, 2018
Refrigerant travels with the lubricating oil through an a/c system. When the condenser is out-of-level, the oil can separate and the compressor may operate without adequate lubrication. Most manufacturer installation manuals specify that the unit be mounted on a level surface. When we called tech support at Goodman Manufacturing (maker of both Goodman and Amana air conditioning systems) to find out what the acceptable tolerance was for leveling a heat pump or air conditioning condenser, the answer we got was “level means level.” They did not offer any range of deviation for a condenser to tilt and still be acceptable.
While we are sure that slightly out-of-level is not a problem, if a condenser is noticeably leaning we put a SmartTool® on it to define how far it’s leaning and write it up in our home inspection report. The condenser shown at the top of the page was leaning an excessive 12.2º, but it is typical to see an older condenser leaning 4º or more on a sloped site with soil subsidence, as shown below.
A diligent a/c contractor will install to the manufacturer’s specs, but soil subsidence from roof rainwater runoff will cause the ground to shift under the pad over time. A mounting pad elevates the base of the unit a minimum of three inches above the ground at installation and, unfortunately, the settlement is often accompanied by the pad sinking into the dirt. The minor vibration generated by a condenser, combined with its weight, creates a low-energy, but repetitive tamping action that can slowly ease the condenser pad into the soil a little over time.
Other manufacturer standards for installation relate to clearance around the condenser for heat dissipation. Typically, a minimum of one foot clear around the sides and five feet above it is specified. Also, installing a condenser at an inside corner is not recommended because of the reduced natural air circulation.
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To learn more about heating and air conditioning systems, see these other blog posts:
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