How to Extend the Life of Your HVAC Equipment – This Summer and Beyond (Part 2)

Michael W. Dickenson, P.E., CFEI

There are admittedly times when HVAC service calls are unavoidable. However, in today’s discussion, we hope to reveal some practical ways to try and avoid unnecessary service calls, whenever possible.  

Condensate: Avoid Unnecessary HVAC Service Calls

The term condensate refers to the water removed from the conditioned space.  Once the condensate is removed via the cooling coil, it needs to be disposed of.  A common disposal method is to discharge the condensate to the outside.  While very effective, the condensate drain piping is another area that should be checked on a regular basis to help prevent unnecessary service calls and unit interruptions.  Varmints and/or insects could find condensate piping to be a handy entry point for trying to enter your home.  It’s also a good idea to ensure the discharge piping is free of debris.  Located within the discharge piping is what is known as a ‘p-trap’.  The p-trap’s job is to allow liquid condensate to drain while making a seal to prevent unwanted air, debris, or varmints from entering through the piping.  The condensate p-trap can have issues of its own, such as microbial growth/scale build-up inside, or the liquid seal can dry.  For example, if excessive odors are observed or insects discovered originating from ductwork, there may be an issue with the condensate p-trap.  A qualified technician should be consulted if issues with the condensate drain piping are suspected.

An   HVAC contractor will pour a chemical solution in the interior drain pan of the unit which will ensure any blockage is removed.  To help ensure the condensate p-trap maintains its liquid seal, the piping must maintain the correct slope.  If the slope is not maintained, the liquid seal may be allowed to dry.  In addition, if the liquid seal becomes dry, conditioned air from the cooling coil will be able to pass through the condensate piping and as a result, the exterior of the piping will sweat.  Sweat, or condensation in this case, forms when a surface reaches the dew point.  In most scenarios, condensate piping is routed in unconditioned, humid areas such as attics or crawlspaces.  It is not uncommon to see water stains on ceiling surfaces where condensate piping (routed above the ceiling) has a dry p-trap seal.  As a result of the dry p-trap seal, moisture condenses on the piping surface and drips onto the ceiling below.

For more information regarding condensate in HVAC systems, take a look at the Condensate Drainage post on this blog page.

Insulation: Boost Your HVAC Efficiency

Generally speaking, our homes contain many types of insulation.  HVAC systems use ductwork to move the conditioned air where needed.  The ducts passing conditioned or return air, often referred to as supply and return, must maintain an insulative barrier.  Note – exhaust ductwork, such as clothes dryer exhaust, does not contain insulation.  In addition, exposed ductwork (sometimes referred to as spiral-wound) will contain an internal insulation liner rather than the external insulation.

The ductwork insulation serves multiple purposes, such as slowing energy transfer to/from the interior of the duct (little to no insulation increases energy costs) and preventing condensate from forming on the exterior surface of the ductwork (or sweating).  Ductwork is constructed of fiberglass and metal materials.  Regarding metal ductwork, the metal surfaces can reach the dewpoint; the insulation prevents this.  Good maintenance consists of periodic visual checks of the ductwork, checking for tearing or inconsistencies with the insulation.  In addition, if there is a break in the ductwork insulation and the metal surface sweats, signs of moisture will be visible. The repair of ductwork and insulation requires the use of correct methods, such as approved foil-backed adhesive tape and mastic to ensure a continuous seal.

For split-type units, refrigerant piping is used to transfer refrigerant from the outdoor equipment to the indoor equipment.  The refrigerant piping consists of two (sometimes more) refrigerant lines referred to as the liquid and suction lines.  Refrigerant piping is copper, which can sweat if exposed to elevated humidity levels.  To prevent sweating, as well as maintain efficiency, the refrigerant piping must be insulated.  Periodic visual checks should be conducted on any refrigerant piping, looking for any breaks in the insulation or even the piping, itself.  Consult a qualified, licensed HVAC technician should any issues with refrigerant piping and its insulation be suspected.

Consider a Programmable or Smart Thermostat

A small but effective way to aid in reducing HVAC related energy costs is to use a programmable or smart thermostat.  This type of thermostat offers an advantage in that it has the ability to be programmed to accommodate different settings during the times the space will be occupied.  The thermostat is then able to adjust heating/cooling around your schedule.  For example, a programmable thermostat may be programmed to set the temperature desired (or setpoint) five to ten degrees above what would otherwise be required, during times the space is unoccupied.  This provides a degree of automation to your home; multiple temperature adjustments would no longer be needed.

Most programmable thermostats can be installed with basic tools and resources by a typical do-it-yourself homeowner.  However, since the wiring on some HVAC systems can vary, the best practice would be to consult a qualified, licensed technician, to determine what is required to install a programmable thermostat on your particular HVAC system.  

Next week, in Part 3, we will conclude our discussion of How to Extend the Life of Your HVAC Equipment with a discussion regarding refrigerant charge, as well as the HVAC technician’s practice for checking refrigerant charge in your HVAC system.

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You can read part 1 here and part 3 here.