The Correct Way to Set Up an Outside Residential HVAC Unit

Ensure that the condenser you intend to set up is appropriate to the climate zone and the size of the space to be cooled. The cooling output of the machine is measured in British Thermal Units, or BTUs, and its efficiency is measured as a Seasonal Energy Efficiency Ratio, or SEER, value.

In brief, a higher BTU rating translates as the machine being capable of cooling a larger space without undue stress to its components, while a higher SEER rating translates into more economical function. Minimum required cooling capacities can be calculated using a table available from the Association of Home Appliance Manufacturers.

Measure the dimensions of the space and enter them, along with geographical location and a number other variables, including wall type and insulation values. The resultant figure defines the optimum air conditioning setup for the application.

Construct a concrete slab to support the condenser. Locate the slab where connecting the condenser to the rest of the central air conditioning system will not be problematic. Both high-pressure pipes and electrical wires must be run to the location, so it should be close to the building to be cooled and be situated to minimize risks of accidental contact by vehicles, lawn mowers and the like.

Dig out a shallow footing, enclose it in perfectly level shuttering forms, construct a reinforcing grid of rebar and pour in a high-strength concrete mix. Trowel off the top to be smooth and without any flaws. Allow the concrete to cure before installing the condenser.

Follow the condenser manufacturer’s instructions concerning attaching the unit to the slab. Connect it to both the refrigerant lines and the electrical supply. As most manufacturer specifications differ, it is important to observe all directions specifically, even if you have previously installed outside air conditioner condensers.

Check that the electrical connections are tight, free from verdigris and atmospheric contamination, and that the insulation is in good order on all wires and components. If any material is present on the inside of the condenser coil fins, or the “radiator," clean with a garden hose.

Use a proprietary pressure gauge set to read and adjust the refrigerant charge in the system. This is vital for optimum performance and value for your electricity expenses. There should be charge information and a pressure chart attached to the condenser in the form of a sticker or a stamped data plate. If the information is absent or illegible, most manufacturers have this information under the model name or number on their websites. Specialty companies that supply the A/C industry may also have access to a library of manuals.

Ensure the compressor is not running and that you have the correct type of refrigerant for the system. Connect the canister of refrigerant to the hose attached to the gauge set’s center manifold. Purge the hose and the regulators. Connect the hose on the gauge set’s "Plain Pressure" gauge to the A/C’s liquid line. Open the regulator and then close it when the desired pressure is displayed on the gauge.