Cleaning Your Home or Office HVAC System

Josh Feinmann, Clean Air Advice
September 2006

How do you determine whether or not your system needs cleaning? Not all HVAC systems necessarily do. Answer the following questions to determine whether are not your system needs a good cleaning:

1) How dirty is the ambient air in your town or city? Outdoor air quality comes into your home or office. If you live in a big polluted city, your air filters need changing more often and HVAC system cleaned more often. If you live at the beach or in the desert where humidity is lower and air quality better, you may need less system cleaning.

2) How old is the HVAC furnace system? If the system is more than 10 years old, it probably needs a good cleaning. Furnaces systems contain the evaporator coils and blower assembly necessary for blowing the air into your house. If these are dirty, the air going into your house will never be clean.

3) What quality of air filters have been used? Use high quality pleated micro allergen filters in your system.

4) How often have the filters been changed? Change once a month during hot months when the AC is running constantly and change once every month or two during less active times. This will help tremendously in your struggle for clean air.

5) If you're not sure about the answers, your system probably needs cleaning. Have a reputable HVAC company inspect your system to determine if it needs cleaning.

One of the key steps in making sure your indoor air quality is not contaminated is having your HVAC system cleaned. This is especially necessary in older homes with older HVAC systems. A new HVAC system should be cleaned every 5 to 10 years or so depending on how often you replace the filter, the quality of the filter used and how dirty outside air is. Only a professional HVAC company should clean the HVAC system due to heavy chemicals, acid and pressure used to clean the various components. As well, all HVAC systems have to be completely disassembled in order to properly clean the system, which requires special tools and reassembly know-how. Asking a few simple questions can help you distinguish whether or not the HVAC company knows how to properly clean your system:

1) Ask the HVAC contractor what their procedure is when cleaning an HVAC system.

2) Do they remove the evaporator coil to clean or clean it in place?

3) Do they remove the drain pans to clean?

4) Do they remove the blower assembly to clean?

5) What do they use to clean the evaporator coil with?

6) Take notes as they answer the question.

7) Match up their answer with the following:

Here are the answers you're looking for to make sure that the HVAC company you hire will properly clean the system. If they're going to do the job right, they should follow these steps:

1) Disassemble the entire system

2) Remove evaporator coil from system and clean and dry

3) Remove blower assembly and clean wheels and dry

4) Remove drain pans, determine condition and clean

5) Clean condensation exit piping to make sure system is draining properly

6) Determine condition of grime build up in ductwork

If the HVAC company says anything about vacuuming the system clean, this is not the company to hire. Vacuuming does little to clean your HVAC system. Do not waste your time or money if this is part of their response.

Below are pictures of an old office HVAC systems condition before and during cleaning. There is large caked fungal growth in the overflow drain pan where years of fungus and mold have grown unimpeded. During the winter, the fungus/mold lies dormant, but in the spring and summer when overflow condensation is flowing into it, spore production flourishes. The blower assembly blows the mold spores straight into the ductwork and into your breathing air. Inhaling large amounts of mold spores will compromise your immune system and make you sick.

Mold and fungal growth caked in the A/C drip pan.

The evaporator coils are caked with years of dirt from the incoming air flow from unchanged filters. You can see why it is necessary to remove the coils in order to clean them. It takes some seriously strong industrial cleaning agent (acid used to be the norm) to clean these coils. It must be done outside and with a hose handy to properly wash the coils. It should not be reinstalled until dry.

Years of dust buildup in the coils.

The wheels of the blower assembly will always be caked with dirt if the evaporator coils are dirty. The air passes first through the evaporator coils, then into the blower assembly, then on into the ductwork.

Caked dust and dirt in the blower assembly.

As you can see, the entire system is filthy and it will not matter if the ductwork is cleaned, the filters are clean or the building occupants use a fancy air cleaner or air purifier, the air will always be dirty, polluted, and mold ridden until the HVAC system is thoroughly cleaned.

This system will continue to pollute your air until it's properly cleaned.

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