THE AIR HANDLER
Air Duct Cleaning Specialists in Jacksonville
7 Heat Strips
6 Blower Fan
6 - Blower
FIGURE 2 Packaged Unit
AIR HANDLERS -- KEEP THEM WORKING LONGER WITH SIMPLE MAINTAINENCE.
Before you can maintain and clean your Air Handler you will need to
know something about it. So Lets Get Started
WHAT IS AN AIR HANDLER? :
HVAC Systems are made up of two (2) distinct major components: the
Air Handler and the Condenser. The Air Handler does just that! It handles the airflow and temperature of the air in your home.
HOW DOES IT COOL AND HEAT MY HOME?
The principle of air conditioning is that Freon gas under pressure
cools when it expands. You may have noticed this when you let all the
gas out of a Co2 cartridge fast. The cartridge feels cold. The same
thing happens in the AC system. Pressurized Freon gas is allowed to
expand in the "evaporator coil" in the Air Handler. The cool
gas then absorbs the heat in your home when inside air passes over
the coil. It is brought back to the Condenser at a warm temperature
and low pressure but still mostly as a gas. The warm gas must be
condensed and changed to a liquid once again. This is done by
"pumping it through the outside condenser (the big noisy fan
outside). The Freon is pressurized again and sent back to the Air
Handler and the cycle is repeated.
The return plenum brings inside air from your home to the air handler
and the supply plenum delivers air to the inside of the home. In
Cool mode (air conditioning on) the supply air is cold (usually in
the mid 50's) and the return air is in the mid 70's. In heat mode it
is the opposite. The supply air is usually in the 90's and the
return air is in the mid 70's.
WHERE CAN I FIND IT?
You can usually find it indoors by listening for the fan noise. Most constructed homes will have the Air Handler located either in
the garage or in the home in a closet or Utility Room (see figure
1). Sometimes even in the attic mounted horizontally (laying down).
Most manufactured or mobile homes will have what is called a
"packaged unit" (see figure 2). Both the Air Handler and Condenser
are combined together in one unit, which is always located outside.
FIGURE 2: OUTDOOR MOBILE HOME PACKAGED UNIT
WHAT DOES IT LOOK LIKE?
Most Air Handlers look like the picture above (also see figures 1 and
2 above). They are roughly two feet square and 4-½ feet high gray
metal box with a silvery box above it (the supply plenum) and below
it (the return plenum).
HOW CAN YOU GET INSIDE IT?
You can get access to the inside of the air handler by removing the
NOTE: NEVER attempt this unless you have turned off the system (on the thermostat, turned the power off at the "disconnect box" (a 10 by 8 inch gray metal box usually located within eyesight of the air handler), and/or turned off the breakers labeled "Heat" and "AC" or "Air". The upper panel or cover is held in place by four hex nuts (either ¼ or 5/16 depending on the manufacturer). The lower panel is held in place with 6 – 8 ¼ or 5/16 hex nuts.
WHATS IN IT?
The Air Handler has eight major components:
1.INTERNAL INSULATION: Insulation is important because Air Handlers
can be placed outside the home environment such as in the garage or in the attic. Most manufacturers will produce the unit with the "silver" liner facing outward from the frame. This is done so particles such as mold and biological matter cannot adhere to the inside easily. If the insulation is facing outward so you can see it when you open the panel, you might want to replace it -- Especially if it is discolored. Contact your local AC Company to have it replaced.
The evaporator coil is located at the bottom of the Air Handler. It looks like a car radiator and has the shape of either an inverted "V" or a slanted "I". Air is drawn across this coil from the bottom of the unit up (sometimes the larger and newer mobile home models will have a split system installed with the ducts or vents in the floors. In thus case the Air Handler is mounted upside down and the coil is at the top). Check the face of the coil where the air comes from for debris or dark dusty discolorations. If you see it you need to have this coil cleaned. If you cant see that side of the coil it
would be best to have a professional clean it because you would have to cut the return plenum and if you don't completely seal it again you will have problems. If you can see the coil and have access to it you can clean it yourself. Go purchase a spray can of "no acid" Coil Cleaner from your local AC parts distributor and follow the directions on the can. It should cost you about $8. If the debris is thick and you need to brush off the fins where the air flows in to it but be very careful not to crush them.. They are very fragile. If you do you can repair them. Your local air conditioning distributor sells a tool call a "fin comb" that will comb these fins back into
nearly original condition.
3.ELECTRICAL CONTROLS: When you open the front top panel of the
air handler you will see a metal plate ( on some models) at the top that has 4 screws and a warning sign. Behind this plate is the electrical control area. It usually contains a control card, a number of connectors, a terminal bar, and the back side of the heat strip assembly. It is not recommended that you do anything in this area as it contains live 220 volts. This component of the air handler does not fail often and no air flows through it so it should be left
4. CONDENSATE PAN:
The evaporator coil sits directly above the condensate pan. When the
system is cooling the coil is cold and warm indoor air is passing over it. As a result moisture in the air condenses to water and drips from the coil to the pan. This is where the condensation from the cooling coils drips. If you have a flat drain pan, the stagnant water will become infested with mold growth. In which case, a sloped drain pan should be used, so the water runs off to the proper location. You also need to check to make sure that drain lines are flowing properly. Some pans are flat and some are slightly angled
so the water can drain to the drainpipe and outside. Unfortunately there will always be some water that does not drain and it becomes stagnant. Make sure you periodically wipe any biological growth from the coils. This condensation provides a perfect place for mold and bacteria to grow. The drain pan and drain need to be cleaned. Disinfectant should be periodically applied to the coils. You can also use an in-duct ultraviolet (UV) light air purifier, installed near the coil, to destroy mold before it has a chance to grow. It will also destroy mold and other microbes that are caught in the filter. To clean this pan you must remove the ¼ or 5/16 hex
nuts from the bottom panel, carefully remove the panel, and clean the pan. Many AC parts stores sell drain pan cleaner but you can do just as well by using Bleach or white distilled vinegar. Pour a half water and half bleach solution in the pan and scrub with a brush all you can reach. Then pour a half vinegar and water solution in the pan. Then pour about a quart of water in the pan and let it drain. This should be done only on an as needed basis. The drain PVC (connected to the outside of the air handler) should also be cleaned
periodically (See "Cleaning your condensate pan and drain News Report). Periodic cleaning of your condensate pan and drain will save you on service calls when your drain clogs and overflows. It will also avoid flooding and water damage and mold infestation.
5. OUTER METAL FRAME:
Most people don't pay much attention to the outer frame. What they fail to realize is that if there are air leaks in the frame,
dirty air is sucked in and bypasses the filter. For all intents you might as well throw out your filter. It can trap all the dirty particles in the world but the leaks are only re-introducing them into your home. And if you paid good money for a high efficiency filter you've wasted your money. Most AC Companies neglect to seal these leaks when they install the system so you need to check this.
Heres how to check for leaks: There are two (2) copper "pipes"
connected to the air handler a large one (suction) and a small one
(pressure). Check where they enter the air handler and see if they are sealed. If they are not you will see telltale signs such as accumulated dirt and dust at the joint. Sometimes you can hear the air whistling at the hole and even feel the air being sucked in. There are also two brown wires entering the air handler typically on the right topside. Check where they enter and see if the hole has been sealed. If the air handler is in a closet or utility room in the house your problem is not that bad. If the air handler is in the garage it is sucking in exhaust fumes, dust, and dirty air. If it is in the attic it is sucking in fiberglass insulation, dust, outdoor air, and possibly rodent feces. Buy a sealing putty from your Hardware Store and seal all these holes. Sealing the outside of your air handler will keep the inside clean and increase your indoor air quality.
6. THE BLOWER FAN ASSEMBLY:
The Blower Fan assembly consists of the motor and the "squirrel cage", and the housing. The Squirrel cage looks like a big gray metal treadmill (like pet hamsters have). It is attached to the motor shaft with a square headed set nut. The Squirrel
Cage has many fan blades on it. Each blade has a curve on it to increase air-moving efficiency. Unfortunately this design also allows dirt and biological particles to easily attach and adhere to each blade. After a period of time it must be pulled and cleaned of mold and biological pollutants so they wont break free and circulate into your duct system and through your home. You can also save up to 10 percent of your utility bills if you clean the blades. It is said that 1/5 of an inch of build up decreases your efficiency by 20%. You can have your AC Contractor come and pull and clean it but it will cost you approximately $150 to $300 and it might not be done correctly. If you are even slightly mechanically inclined you can do this yourself. The squirrel cage cannot be removed from the air without removing the whole assembly first.
NEVER attempt this unless you have turned off the system
(on the thermostat, turned the power off at the "disconnect box" (a 10 by 8 inch gray metal box usually located within eyesight of the air handler), and/or turned off the breakers labeled "Heat" and "AC" or "Air". With few exceptions (such as Trane, Carrier and variable speed Systems which have connectors) there are three (3) wires that connect the blower assembly to the air handler. Each one has a quick disconnect connecter at its end or a 3-wire connecter on the motor in the blower assembly. These 3 wires go up to the electrical control box. Write down a "map" of where these wires are plugged in and then unplug each wire. The blower assembly is mounted in the air handler on two slide rails. It is held in place by two 5/16 inch hex nuts as shown in figure 4. After you have disconnect the wires, unscrew the nuts and slide the whole assembly out from the air handler. Be
very careful not to drop the assembly. It will dent and damage the fins of the evaporator coil below it.
Once the assembly is removed, it will be necessary to remove the motor to avoid getting it wet. Remove the three or four screws of the motor mount and disconnect the two brown wires from the Capacitor (see figure 4). Also disconnect the green wire from the Housing. Next unscrew the square head nut that holds the squirrel cage to the motor shaft (see figure 3b). You should be able to slip the motor and shaft out of the assembly. Sometimes it sticks and you must use penetrating oil. Once removed the squirrel cage will roll around inside the Housing. Remove the rectangular plate and then remove the squirrel cage. Once removed spray the cage with a good disinfectant/cleaner like Lysol, Lestoil, etc. Let it sit for about 5 minutes and then rinse with a good high-pressure water jet from the hose. Lastly spray the cage with a half and half solution of water and white distilled vinegar. Reverse all the above steps to re-assemble.
Make sure that the squirrel cage is centered on the shaft in relation to the housing. Spin it a few times to make sure it doesn't rub against the housing. Also line up the motor shaft slot to the screw hole and then tighten the screw.
If you remove and clean the blower yourself you will not only save $150 to $300 but 10% of your utility bill and possibly avoid an expensive duct cleaning job. You will also increase the air-flow in your home allowing it to heat and cool quicker.
As mentioned earlier, the heat strips are installed right behind the electrical control box (there are some exceptions such as in Rudd and Rheam systems). If your system is a Heat Pump the Heat Strips are used for two purposes:
1. They heat the air in the winter months when the thermostat is turned up 3 to 5 degrees over the current temperature. This is because all Heat Pumps cannot heat the air more than 90 to 95 degrees. This temperature is fine when the Heat Pump only needs to maintain the current temperature but if the home needs to be heated quickly the heat strips turn on and bring the output temperature above 90 to 95 degrees.
2. They are used to heat the cold air during the "defrost cycle"(see The Condenser for more detail). When in the heat mode the outside coil gets cold – so cold that frost builds up. When this happens the
condenser goes into a defrost cycle and switches to Cold mode and
blows cold air out. The heat strips keep the air warm until the defrost cycle is over.
The Heat Strips look like the coils in a toaster. They are rated in Kilowatts (K) and range from 2K up depending on the size of the AC system. Most residential homes have 5K, 8K, or 10K strips. The heat strips are pretty much maintenance free and should be left alone. However, if your system is old, the strips may deteriorate. If you notice that it takes a long time to heat your home when you turn up the thermostat more that 3 to 5 degrees you may need them replaced.
The filter is usually mounted at the bottom of the air handler. Air flows from the return plenum upward through the filter and into the air handler. It is very important that the filter should be replaced at regular intervals. If you currently have a "blue" filter you should consider getting a "three month" pleated filter. The blue filter is a manufacturer's filter and is made to only trap large particles from entering the air handler and clogging the
evaporator coil. They do nothing for your indoor air quality.