Maintaining split HVAC units
By Cliff Hockley, President
Bluestone and Hockley Real Estate Services
One of the challenges residential and commercial property owners and managers face today is budgeting enough time and resources towards maintaining their HVAC systems. Most building owners don’t understand the need to have a regularly budgeted plan to clean HVAC units and especially their coils, and unfortunately its expensive.
HVAC coil cleaning largely ignored
Most HVAC vendors do the service basics on either a quarterly or semiannual basis as allocated in their contracts (see following checklist), but due to the inaccessibility of window and rooftop units and the cost (it takes time to clean a unit), HVAC coil cleaning is typically ignored.
Not cleaning condenser coils means that dust, debris and other airborne particles often accumulate in the condensing and evaporator coil of the air conditioner or package unit resulting in reduced efficiency and capacity. This is critical since the air flow through the coils keeps the temperatures and pressures of the unit regulated. Accumulating dirt on coils inhibits heat transfer, forcing the compressor to work harder, increasing the temperature and head pressures as much as 75 percent as well as limiting the dehumidification process. The resulting overheating will also put undue strain on all electrical and mechanical components of the system causing premature failure.
Dirty Split Coils
Cleaned Split Coils
Coils should be checked at every maintenance visit and cleaned as necessary, normally every one to three years to keep HVAC units running smoothly and with less down time. Businesses such as restaurants and hair salons that have a higher amount of airborne debris and/or a larger volume of foot traffic will require more frequent cleaning. Also, if properties are near green spaces they will tend to accumulate a lot of debris on the condenser coils and will need more frequent brushing or cleaning. If this is done compressors and other parts that fail due to overwork (caused by filthy coils) will have a much longer lifespan. See attached YouTube Video that shows cleaning of unit from inside out (the correct way to clean the coils).
Remember that typically there is no water or power on most roofs which means you need to be creative to get water and or a portable cleaner to a rooftop to clean the coils.
What are our options?
1. We could use a portable coil cleaner, see attached video:
Speed Clean Coil Jet Portable Coil Cleaning System with Foaming Coil Cleaner
(Note: The author has no stock in this company and is sure there are other options out there. We are using this video strictly as an example.)
2. And we should require HVAC technicians to accomplish the HVAC unit service basics as outlined in the checklist below:
For Outdoor Units:
Maintenance inspections for Rooftop Units include the following, done semiannually, heating components inspected in fall and winter, cooling components inspected in spring and summer.
*Items inspected Quarterly.
• * Check for particulate accumulation on filters, change filters.
• * Check control system and devises for evidence of improper operation.
• Check P trap.
• * Check fan belt tension. Check for belt wear and replace if necessary to ensure property operation. Check sheaves for evidence of improper alignment or evidence of wear and correct as necessary.
• Check variable frequency drive for proper operation.
• Check for evidence of build up or fouling on heat exchanger surfaces.
• Check for proper operation of cooling coil, heating coil, or heat exchangers and for damage or evidence of leaks.
• Check for air filter fit and housing seal integrity.
• * Check control box for dirt, debris and or loose terminations.
• Check motor contactor for pitting or other signs of damage.
• Check fan blades and fan housing.
• Check refrigerant system temperatures.
• Check fan drive for wear or problems due to poor alignment or poor bearing seating.
• * Check integrity of all panels and curbs on equipment.
• Assess field-serviceable bearings. Lubricate if necessary.
• Check drain pan, drain line, and coil for biological growth and for restricted drain openings – remove obstructions as necessary
• Check evaporator coil fins.
• Inspect for evidence of moisture carryover beyond the drain pan from cooling coils.
• Check for proper damper operation.
• Inspect air cooled condenser surfaces for damage or evidence of leaks.
• Check low ambient head pressure control sequence for proper operation.
• Check combustion chamber, burner and flue for deterioration, leaks, moisture problems, condensation and combustion products.
• Visually inspect insulation and areas of moisture accumulation for biological growth.
• Check compressor oil levels and/or pressure on refrigerant systems having oil level and/or pressure measurement means.
• Inspect compressor and associated tubing for damage
• Make sure air intake is not blocked
o Before and after photos should be taken at time of cleaning. This is especially important for split row coils as once you put the unit back together you cannot see what is inside to verify it was done correctly.
For Indoor Units:
• Inspect and clean blower assembly (includes blower housing, blower wheel and motor)
• On older models, lubricate motor and inspect and replace fan belt if needed
• Check combustion blower housing for lint and debris and clean (and vacuum) as necessary
• Inspect evaporator coil, drain pan and condensate drain lines. Clean as needed
• Inspect for gas leaks in gas furnaces
• Inspect burner assembly – clean and adjust as needed
• Inspect ignition system and safety controls – clean and adjust as needed
• Inspect heat exchanger or heating elements
• Inspect flue system – check for proper attachment to the furnace, any dislocated sections, and for signs of corrosion. Replace if necessary.
• Inspect control box, associated controls, wiring and connections
• Clean and / or replace air filters
? (This needs to be done no less than 4 times a year)
? (Note Running your commercial HVAC systems with clean air filters can lower energy consumption by up to 15%.)
Visually inspect conditioned airflow system (ductwork) – check for leaks (usually completed outside of regular maintenance).
While your system is operating
• Monitor system starting characteristics and capabilities
• Listen for abnormal noise
• Search for source of unusual odors
• Monitor air conditioning and heat pump systems for correct refrigerant charge
• Measure outdoor dry bulb temperature
• Measure indoor dry and wet bulb temperature
• Measure high and low side system pressures
• Monitor gas furnace for correct line and manifold gas pressure – make adjustments as needed
• Measure temperature rise and adjust airflow as needed
• Check vent system for proper operation
• Monitor system for correct line and load volts/amps
• Monitor system operation per manufacturer’s specifications
• Provide system operation report and recommend repairs or replacement as necessary
If we budget for the regular servicing of HVAC units and cleaning of the coils, HVAC units will last much longer and have fewer failures and use less energy. Owners and property managers should consider developing a scope of work as outlined above to share with their HVAC service vendors. They should also have a plan in place to regularly clean all HVAC units and cabinets, clean the return and supply registers and replace their filters if there are any, and let’s not forget that every five years one needs to plan for interior duct cleaning to keep the operation of HVAC units in tip top shape.
For more detailed technical information you might want to visit this web site:
I want to thank Sharon Nelson of Willamette HVAC, for editing this article and adding many valuable suggestions.