HVAC Preventative Maintenance

Basics

• This page aims to go over the various forms of Preventative Maintenance for HVAC Systems
• Design for Cleaning in terms of overall design of the HVAC system is a HIGHLY relevant matter, but will be addressed on another page

List

Coil Cleaning

• Every so often both the Condenser Coil and the Evaporator Coil should be cleaned

Procedure

• This is best done by:
  • 1.) LOTO on the Machine
    • If a Soft Starter is not installed, it is also best practice to turn down/off the Thermostat so that the system doesn’t go “from zero to 60” when you reconnect it
  • 2.) Remove Debris as best you can while it is still dry
    • A Vacuum Cleaner (+ Dusting Brush Tool / Crevice Tool ) and/or some sort of Cleaning Brush and/or a Cordless Air Duster will come in handy for this
  • Check Warranry / Manufacturer Warnings First + Proceed with Caution, BUT:
  • 3.) Gently Rinse with Water
    • If sufficient one can stop here, if it looks like further cleaning is needed:
  • 4.) Spray Down with a Gentle Cleaning Solution / Gentle Soap such as “Simple Green” or A Diluted Minimum Viable Soap
  • 5.) Rinse + Inspect
    • If sufficient, one can stop here, if it looks like it still needs further cleaning:
  • 6.) Get HVAC Coil Cleaner either in Aerosol Can form, or as a Liquid Concentrate which can be diluted + put into a Foam Cannon Nozzle
  • 7.) Final Rinse with Water
  • 8.) Gently Dry Off / Wait for it to Air Dry
  • 9.) Reassemble Device
  • 10.) Undo the LOTO then Turn it back on and check that everything is operating as expected

Products

In Concentrate Form

• ”Simply Green”
• ”Purple Power”

In Aerosol Can

• ”Nu-Calgon”
• ”Viper Coil Cleaner”

Related Links

• A Reddit Post in r/HVACAdvice Titled “ Does Coil cleaner actually work? Does any particular brand work better than another?”
• A Video by the YouTube Channel “ Clean It Up “ Titled “The Best Way to Clean Your AC Unit and Coils”
• A YouTube Short by the channel “HVAC_Tips” Titled “3 Pro Tips for Cleaning Your Evaporator Coil!”

Condensate Drain Preventative Maintenance

• Due to being a wet+damp environment, the Condensate Drain Lines on HVAC Evaporator Coils (As well as Dehumidifiers and to a lesser extent Refrigerators / Freezers etc ) are at risk of Bio-Fouling
• Thus every so often one should dump some Dilute Bleach Solution or a similar substance down the drain, and check that enough was added that it flows to the drain location
  • Having another person with a Radioactive or Cellphone can help with this
• If need be, a Shop Vac can also be used to clear/drain the line
  • A High Volume Inflator or similar device can also be used, although using positive pressure to clear a blockage runs the risks of leaks

Maintaining Accessibility

• Outdoor Evaporators in particular may run into the issue of falling behind on landscaping leading to making the job of getting to + repairing one difficult
• This is moreso a Design for Cleaning / Design for Maintenance concern, but relevant enough to mention

Optimal Operating Conditions

• Unless a dedicated Humidistat and Dehumidifier are installed, and to an extent even then, Condensation will form on the Condenser Coils
  • If an HVAC Unit is run in the “Constant Fan” mode, this will increase humidity due to the airflow evaporating far more of these droplets than how much water will drip down (At least after initial startup + the Dewpoint equivalent of Iceover
  • If a Unit is Put into “Auto” Fan Mode and it has reached the set temperature and/or the unit is occasionally turned off, it will have time for droplets to make their way to the Condensate Drain and/or the Dehumidification Function of the coils is more efficient due to less time spent being a Swamp Cooler of sorts

To-Do’s

• Look into if Cleaning the Coils (RE Water Beading Test ) and/or Hydrophobic Coatings on the coils can reduce this issue
• Look into active systems akin to a Pulse Jet Bag Filter Baghouse or Knocker that enhances flow of Condensate off of the coils via compressed air or mechanical means etc
  • It would be mechanically complex, but a wiper assembly or something akin to the Super Sopper may be used as well

Duct Cleaning

• RE HVAC Duct Cleaning
• May not be needed with sufficient Filter Installation + Change Intervals?
• May be worth getting an Inspection Camera and checking regardless at a regular interval

Filter Maintenance

• As with Internal Combustion Engines having clean filters may be annoying to maintain, but saves many more headaches, and typically money.
• If a Mesh Prefilter is installed, periodically cleaning those can prolong main filter life
• Some HEPA Filters can be GENTLY Vacuumed and/or cleaned off with a Cordless Air Duster outside or over a Downdraft Table etc to “juice” out some extra life
• All in all though, clean your filters and change them out!
• Inspecting Gaskets (RE Sealed System HEPA ) is important as well as leakage past a filter negates it’s effectiveness

Special Considerations for Some Systems

• Checking the Heat Exchange Fluid in a Hydronic Heating and/or Hydronic Cooling system for debris/rust, as well as Changing Filters + Adding Fluid and/or a Corrosion Inhibitor and/or a Biofouling Inhibitor may be warranted as well
• In Fired Heaters such as a Fuel Oil Furnace or Natural Gas Furnace / Propane Furnace etc, special maintenance is required, mainly
  • Checking Fuel Levels (if Relevant)
  • Routine Checks for Leaks/Damage
  • Cleaning Out the Natural Gas Condensate Trap (if relevant)
  • Checking Ignition Mechanisms
  • Turning Off the Fuel Supply + Pilot Light in the “ Off Season “
  • Checking for Soot buildup / Coking (if relevant)
  • Checking Pyrometer / Thermocouple status (if relevant)
  • Checking Blower Fan status (if relevant)
• Checking Refrigerant Levels shouldn’t be needed, assuming a system is built well, but could in theory be added to the list of tasks