Air Conditioner Condenser Electrical Components

Posted on March 27, 2013 by Richard Ashworth

air conditioner condenser electrical components There are many electrical components inside an air conditioner unit. From relays to contactors to electric motors and wiring it has to work together and working properly for your air conditioner to run smoothly. It is almost like a ballet and the air conditioner sequence of operation follows a specific sequence to work properly For the purpose of brevity the focus of this article will be on the condenser and the electrical components in an air conditioner condenser. From the disconnect box on the wall next to the condenser all the way through the control panel and into the components we’ll cover all the various electrical components and how they work together to make your air conditioner work.

Fuse Box or Disconnect

The disconnect is attached to the wall behind the condenser. Line Set Runs Neatly Up the Side of the House to the Attic.

The fuse box or disconnect for the air conditioner condenser is required by NEC code and should be within reach of the condenser. The fuse box should have a way of protecting the circuit for the condenser. Despite the breaker in the main panel an air conditioner disconnect box needs to be fused or have some sort of trip protection in case of an electrical problem occurs inside the condenser with an electrical component. The protection should be sized according to the ampacity of the air conditioner as rated by the manufacturer. This information is available for unit ampacity and fuse size on the name plate on the side of the condenser. The wire supplying the air conditioner unit should be sized according to NEC tables at 125% of RLA or Run Load Amps which is also rated on the unit plate with other air conditioner nomenclature. The fuse should be sized no larger than 175% of RLA of the unit and with exceptions can be raised to no more than a maximum of 225% of RLA. This allows for the fuses to be able to overcome the start amps of the unit. Start amps are usually referred to as LRA or Locked Rotor Amps which can far exceed the RLA for the first split second when the unit starts. Refer to Article 440.22 of the NEC for more information on this but those are the basics for disconnects, fusing and wiring for the disconnect. On a side note – the fuses used in a fused disconnect should be dual element fuses and often referred to as slow blow fuses. These fuses are designed to handle the inrush current on equipment start-up.

Wiring and Components in the Condenser

Wiring inside the condenser can be classified as control wire and line voltage wire. The control wire in residential air conditioner systems originates at the thermostat and is 24 volts. This controls all the relays and contactor in the air conditioner and runs through any safety or limits in the condenser. What type of safeties can be in the condenser? Refrigeration pressure switches are commonly used in the higher rated equipment. Some manufacturers put high pressure refrigeration switches in all their condensing units. In higher end condensers you will also find low pressure refrigeration switches. These switches will trip the system shutting it down because extreme high pressure and low pressure in the condenser can cause serious issues and it is better to shut the system down as it needs repair to correct the problem. Additionally an air conditioner condenser can have a delay switch in the control circuit to prevent the condenser from short cycling in various cases. Short cycling is bad for the electrical components in the air conditioner condenser especially the compressor which can be irreparably harmed if short cycling occurs.

Start Capacitor with Potential Relay

The line voltage wiring carried the voltage and amps to the fan motor and the compressor. It is very important that all the connection in the line voltage circuit are very tight. Lose connections cause problems with build up of heat and corrosion on the connections. Eventually the heat and the corrosion will cause the wire to break off from the connection altogether and failure of the compressor or fan motor. In the line voltage circuit inside a condenser of a residential air conditioner are a contactor, run capacitors for the compressor and condenser fan motor, and the condenser fan motor and the compressor. If the system requires a start capacitor the start capacitor for the compressor will also be in the circuit for the air conditioner condenser. There will be a potential relay in the circuit that will also be wired to line voltage as the potential relay uses line voltage and not control voltage.

These are the main electrical components in the air conditioner condensing unit. Additional information on air conditioner condensers can be found in the air conditioning category and the refrigeration category.

Air Conditioner Condenser Electrical Components

Air Conditioner Sequence of Operation

Posted on March 27, 2013 by Richard Ashworth

When a technician is troubleshooting a problem with any piece of equipment it is important that the technician understands the sequence of operation for that equipment. When there is a problem with the equipment, including air conditioners, the technician will know the problem if the equipment or air conditioner does not follow the sequence of operation. Sometimes it is that easy and other times it is not that easy when troubleshooting equipment. However, it is important to understand the sequence of operation for an air conditioner so the technician can troubleshoot the air conditioner system.

Continue reading “Air Conditioner Sequence of Operation” »

Evaporator Coils Dirty and Ice On Air Conditioner

Posted on February 18, 2013 by Richard Ashworth

Dirty Evaporator Coils

It was a very hot day and I got a ticket to respond to a call for no cooling. The customer said there was ice on the air conditioner. The secretary instructed the customer to turn the air conditioner off so the ice could thaw before I got there to figure out the problem. It needs to be thawed before any air conditioner troubleshooting can occur. There are two main causes why the evaporator coil will freeze and cause ice on the air conditioner. One is decreased or no air flow and the other is a low refrigerant charge.

condensation pump helps drain water for cooling systems

Condensation Pump for Draining Condensation

For low air flow the homeowner can possibly fix the problem depending on how serious the issue is. This problem can be because of dirty air filters for the air conditioner or heat pump. The problem is easily solved by thawing out the evaporator coil changing the dirty filter for the air conditioner or the heat pump system. Air conditioner or heat pump systems equipped with a low refrigerant pressure switch will not freeze as the low air flow condition will cause a drop in refrigerant pressure and cause the low pressure switch to trip the compressor thereby shutting off the compressor and preventing any freezing until the pressure increase closing the low pressure switch allowing the compressor to run again. People with air conditioners or heat pumps that have low pressure switches will likely need to call a technician but only after checking the air filters.

Bad Blower can cause ice on air conditioner or heat pump

Bad Blower can also cause ice on air conditioners

Other conditions that will cause low air flow include a bad blower motor, collapsed duct work, and a dirty evaporator coil. All three conditions will likely require the attention of a technician. The call I responded to on that day turned out to be a dirty evaporator coil. The customer failed to keep a filter in the system. The air handler was in a closet next to the kitchen. It turns out they kept the trash can next to the louvered door where the air handler was located. All the dust and dirt and some of the things that were thrown in the trash were found in the evaporator coil. That caused the reduced air flow and for the air conditioner to get ice on it.

insulation blocking air flow causing problems

Insulation Blocking the Air Flow to a Rooftop Unit Evaporator Coil

Why does the air conditioner get ice on it when there is reduced air flow? The air in your home has moisture or humidity in it. Part of the process on air conditioning is to remove the moisture from the air. In air conditioning and heating engineers and engineering technicians use a psychrometric chart to determine the properties of air. This is the basis for calculating the size of air conditioning or heating system you need to for the load or demand. The moisture in the air contains heat along with air containing heat. The heat in the moisture in the air is called Latent Heat and the heat in the air is called Sensible Heat. Both forms of heat need to be removed from the air and that is what your air conditioner does. It removes the latent heat by dropping the evaporator coil below the dew point. When the evaporator coil is operating below the dew point the moisture in the air condenses. When moisture condenses it turns into a liquid and needs to be drained off through condensation piping or pump. This is why you see piping on your air conditioner that drains the water to the outside or see window units dripping water outside. It is the moisture in the air being drained outside after the evaporator coil condenses it. The heat is also removed from the air (the sensible heat) by being absorbed into the cooler evaporator coil. The refrigerant in the evaporator absorbs the heat and carries it outside leaving you and your home feeling comfortable.

New Clean Evaporator Coil for a Heat Pump

When there is a lack of airflow the refrigerant temperature drops below freezing. The moisture in the air around the evaporator then begins freezing to the coil and any refrigerant piping leaving the evaporator going to the compressor (Technically the suction line). The solution to fixing the ice problem is to fix the air flow problem. The evaporator coil on that day was completely plugged up with dust and debris. When I arrived the ice was thawed and I quickly identified the problem. Because of how dirty the evaporator coils was I had to pull the coil from the air handler requiring a major operation on the air conditioner system. After removing the evaporator coil I took the coil to a car wash. I sealed off the refrigeration piping so prevent water or moisture from getting inside the piping. I then completely sprayed the evaporator with coil cleaner and got the nozzle for the car wash and spray the coil cleaned being careful to angle the spray as to not damage the coil fins. All the dirt and dust and trash was cleaned from the coil and the evaporator coil re-installed.

dirty filters can cause serious problems with heating systems

Dirty Filters will cause bad effects to your air conditioner or heat pump

After it was re-installed everything was returned to normal. The air conditioner was started and it cooled the home as a normal air conditioner would cool a home.The customer was instructed as to the importance of keeping a clean filter in the air conditioner system. If you have ice on your air conditioner because of dirty evaporator coils it is likely because someone failed to maintain a good air filter in the air conditioner. There could possible be other reasons for ice on your air conditioner and it will most likely require the services of a good HVAC contractor. Before you call make sure you check the air filter. If it is dirty change it and thaw out the system by leaving the fan on but the air conditioner off for several hours.

High Performance HVAC Air Conditioning and Heating Systems

Dirty Evaporator Coils and Ice On Air Conditioner

Proper Humidity Levels and Factors for Home Comfort and Health

Posted on June 9, 2012 by Richard Ashworth

The Contents and Make Up of Air and Humidity

Proper Levels of humidity Factors for Home Comfort and Health Humidity is important to our home and health and it is important to maintain the correct humidity in our homes and workplaces for our health. What is humidity? Humidity is simply little water droplets in the air. Cold air is nearly saturated with these little water droplets because the contents of cold air allow the air to hold more water droplets or humidity. As air is heated it expands and holds less humidity. When you heat the air in your home using a furnace, boiler, or heat pump this air expands and becomes drier. It is air with less humidity relatively speaking before it was heated and compared to the outside air. Air that is 30° F with 80% humidity will only be 15% humidity at 75° F. That is a big difference in humidity levels in the home after the air is heated. Granted, you are not heating air from 30° F to 75° F with your furnace. Depending on the set up of your thermostat and heating system you are most likely heating air that is 68° F to around 70° F to 75° F depending on the thermostat setting. The point is unless you have a source providing humidity to the air stream you are simply reheating dry air from inside the structure. There will be minimal infiltration humidity but the infiltration humidity will never be enough to bring the humidity levels up to healthy levels inside the structure for the inhabitants, plants, and furniture.

The Study of Psycrometrics

Psychrometric Chart content and make up of air

Psycrometric Chart

Yes, that is psycrometrics and it has nothing to do with psychology. It is the study of air and its properties. It is used in HVAC by HVAC technicians and HVAC engineers to determine the contents and make up of air. The HVAC industry uses Psychrometric Charts to plot the contents and make up of air. Using the Psychrometric Chart a technician or engineer can determine the relative humidity, enthalpy value, dry-bulb temperature, wet-bulb temperature, dew point and vapor pressure if they have a few of the listed values. With this data engineers and technicians can solve problems or assign values and set points. For example, an economizer system that is controlled by the building automation system can be controlled by an enthalpy value. This value associated with an And Gate will only allow the economizer to open under certain conditions that will allow the mechanical cooling systems to shut down and take in free cooling from outside the structure. The temperature, humidity, and all the contents and make up of the air will be optimum for free cooling using the economizer. By knowing the contents and make up of air one can set up HVAC systems to work better and one can also use the data provided by knowing the contents and make up of air to troubleshoot problems with HVAC and building systems.

Indoor Air Quality and Humidity

It is important to maintain correct levels of humidity in the home for many reasons. Comfort is on factor, indoor air quality is another factor, and saving energy is another factor. All three are related in one way or another but each are separate factors. If you reside in the northern climate regions where the average temperatures are less than 20° F you want the indoor humidity to be relative to outside air humidity. Temperatures about 20° F the recommended relative humidity inside the home or business is 35% to 45%. The construction of the home or business will also determine the amount of humidity. If you have vapor barriers and good tight windows and doors you need a good mechanical ventilation system. Humidity levels can rise above 60% causing excessive moisture inside the structure which will lead to mold, mildew, and possible water damage. Make sure you have a good mechanical ventilation system inside your structure to avoid moisture issues. Bathroom ventilation fans, hood fans over stoves, and other type of exhaust fans inside the structure pull out excessive moisture when cooking or showering. If you have this problem it most likely shows up in the form of mold growth inside closets, kitchens, bathrooms, and ceilings. Additionally, if you have excessive moisture problems your windows will frequently fog or have a lot of moisture on the windows.

Low Humidity

Low humidity levels cause problems also. Static electricity, dry skin, dry sinuses, and other health problems including increased flu illness can occur. Additionally, low humidity levels cause problems with wood inside the home. To test for low humidity levels in the home make a glass of ice water and set it somewhere away from the kitchen or bathroom. If after five minutes water droplets do not form on the outside of the glass then you have a problem with low humidity levels in your house and you need to get a humidifier. If your structure is suffering from low humidity levels you will also feel cooler resulting in a desire to turn the thermostat up. Therefore adding a humidifier to the HVAC system will cause you to turn the thermostat down. The correct levels of humidity in your home can increase comfort, save you money on your utility bills, and make you healthier.

Warm Air Expands

Remember that your furnace or heat pump DOES NOT remove the moisture from the air. The furnace or heat pump simply makes the air warmer and warmer air expands making the percentage of moisture in the air less than when it was cold. Relative Humidity is the amount of water vapor percentage that is in a given amount of air at a given temperature. Air is considered to be saturated with moisture when it reaches 100% relative humidity however you can quickly change the 100% relative humidity in air by increasing its temperature. Decrease the temperature and the moisture condenses from the air or it can be considered rain. When you heat the air you increase its volume and without a humidifier adding moisture to the air you are decreasing relative humidity. Adding a whole house humidifier to your home will always help maintain higher levels of moisture in the house and that will counter all the problems associated with low humidity levels.

High Performance HVAC

Humidity Levels and Factors for Proper Home Comfort and Health

Humidifiers and Comfort

Posted on June 9, 2012 by Richard Ashworth

Humidifers and Comfort It’s winter time, and your skin and sinus’s are dry. Did you know that this condition not only extends to yourself and your health but also to your home? The furniture, doors, and other wood products in your home are all affected by the level of humidity.

Ever notice in the winter time the doors don’t close just right inside your home? Ever get static-shock when you touch something or someone? This is caused by dry air. The solution is a humidifier. There are many types of humidifiers from portable to fixed. The prices for these humidifiers also vary. Naturally the fixed will cost more and you will most likely have to hire a contractor to install it, but the humidifier will definitely make a big difference not only for your health, but also for your home. Proper Humidity Levels

Summer Humidity

In the summer, a lot of the energy consumed by your air conditioner is used to de-humidify the air. In most geographical locations in the U.S. and Canada there is an abundance of moisture in the air. The process of heating your home in the winter time, especially for heat pumps, dries the air out in your home. It then becomes necessary to humidify the air (unless you choose to ignore it) to keep a comfortable level of moisture in the air. Ideally, you want the humidity level in your home to be around 30 to 50 percent. In the summer this is not a problem. In the winter it is a problem. This level of humidity will also help you feel more comfortable. If the humidity level in your home is high in the summer you will not feel cool. If the humidity level is low in the winter you will not feel warm when the thermostat is set at an average temperature. This will result in turning the thermostat up to compensate and you will use more energy to stay warm. A properly designed and installed system will keep the proper levels of humidity in your home.

Dust, Dust Mites, Pollen, Viruses, Bacteria, and Humidity

Aside from the comfort factors of having the proper humidity levels in our homes, there is another aspect of having proper levels of humidity in the home. Humidity affects what is in our air also and this is why a humidifier is an integral part of a system that maintains optimum indoor air quality standards. Too much humidity promotes the growth of molds and mildews. Low humidity levels promote bacteria, viruses, and other organic and non-organic things that can be hazardous to our health. Below is a chart that will help you see that keeping the proper humidity levels in your home will also keep out things that can affect our health and our home.

Those people who have forced air systems I usually recommend having the whole house duct mount humidifiers installed. These are generally maintenance free except for a water panel that needs to be replaced on an annual basis. It will require the installation of a humidistat so that the proper amount of humidity is maintained in the dwelling. This system is automatic with no worries about manually filling up a pan or moving a large appliance like you have with the portable humidifiers. All you have to do is set the humidistat and change the water panel annually (or have a service technician do it when you have preventive maintenance done). Remember, humidity in your living and work space is important for your health. The are many different brands to choose from when selecting a whole house humidifier. Generally, Honeywell Whole house Humidifiers and Aprilaire Whole House Humidifier are good brands to choose from but there are others. Check with your HVAC Contractor for what they recommend for humidifiers.

Humidifier Conclusion

Whether you have a Honeywell humidifier, Aprilaire humidifier, or other brand, remember there is required annual maintenance to your humidifier. Typically, humidifiers have water panels inside of them that some people refer to as humidifier filters. These humidifier filters as they are referred to treat the water that is channeled into the humidifier. This humidifier water filter needs to be changed at least annually to have the proper effect. Your HVAC contractor can arrange a maintenance agreement with you to maintain the humidifer and change the water filter so you do not have to worry about it.

Whole House Humidifier Video

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Home Humidity Problems Maintaining Proper Home Humidity

Posted on June 9, 2012 by Richard Ashworth

Is 60% Humidity in the Home Too High?

HIGH HUMIDITY 60 % +. Within the last month, I moved into a new house. It has dry walls and not plaster walls. The furnace and hot water tank were installed a week or so before we moved in to the house. Last week we determined that there is a humidity issue when the windows were sweating. We are trying to determine the source of the humidity. The contractor feels it may be the high efficiency furnace. I have a Lennox g61mp. The combustion air is pulled from within the un finished basement. Should the air be pulled from the outside? The gases are vented via PVC pipe which slopes back to the furnace.

Could the furnace be causing the humidity problem? If yes, what could be causing the humidity problem? The installer said it is not the furnace.

Answer…….

Maintaining the proper humidity levels in the home is important not only for health (as indicated on High Performance HVAC Humidifiers Page) but also for the wood products in the home including doors and windows. The quick answer to your question about the furnace causing the humidity problems is no. Gas furnaces and other heating appliances tend to dehumidify the air and do not create any more humidification. I wonder where your supply vents are located and are they directed to blow hot air towards the windows? Condensation is created when the temperature of air is colder than the dew point. A prime place for this to occur is windows and doors. This is part of the reason why many supply vents for forced air systems, and radiators for hot water systems, are placed near windows and doors. It keeps the windows warmer and above the dew point and also makes the air warm from your heat loss near these locations.

Lennox G61MP Gas Furnace

The furnace you describe, the Lennox G61MP, is a condensing furnace and having the combustion air intake in the basement actually contributes to removing humidity from the basement. It sucks the air from the basement for use in the combustion process and the humidity in this air is condensed during the combustion process in the heat exchanger. This condensation is gotten rid of down a condensation drain near the furnace or blown out the exhaust where the combustion gases are expelled. If your supply vents are located near the doors and windows and you still have this problem then it may be time for new doors and windows as you have too much heat loss at these places and all the humidity is being condensed around the windows in your home.

Proper Humidity Levels

High Performance HVAC

Home Humidity Problems Maintaining Proper Home Humidity

Air Conditioner Condensation Water Dripping

Posted on June 4, 2008 by Richard Ashworth

Water Leaking

It’s the heat of summer or even the beginning of the season when you first turn on your air conditioner. Hopefully you’ve already had all the preventive maintenance checks done and there are no problems. Everything is working fine at least for now. Suddenly you notice water around the air conditioner and you know you have a problem. This problem is often referred as an air conditioner condensation water leak and often customers call an HVAC contractor and say their air conditioner is leaking water. This is not a unique problem and many people have dripping air conditioners during the season. Here are the likely reasons why your system is dripping water. Hopefully the AHU evaporator coil is not in an attic because you could be buying a ceiling unless precautions were taken. Continue reading “Air Conditioner Condensation Water Dripping” »

Air Conditioner Leak Repair – Condensation Drain Plugged – Clogged

Posted on April 4, 2008 by Richard Ashworth

Labor time (approximate): 1 hour in some cases, several hours in others

Air Conditioner Leak Repair - Condensation Drain Plugged - Clogged

It is important for preventive maintenance to be performed on your system to avoid problems. Condensation water leaking near the air handling unit can be avoided with proper air conditioning repair and preventive maintenance. Normally this is a very simple problem that can be fixed in less than 30 minutes. Here is a list of what can cause water around the outside of the air conditioning air handler unit.

The black insulation (called Rubatex) has a tear in it or doesn’t cover the entire suction line. This line normally (in Air Conditioning air condition mode) operates below the dew point and will sweat if it is not insulated. It must have a sealed vapor barrier to be effective.
The insulation surrounding the air handler supply transition or ductwork is torn. The supply transition and duct can operate (under the right conditions) below the dew point and sweat. It is important that the transition have a vapor barrier around it. This scenario is especially true for those that have over sized units.

Continue reading “Air Conditioner Leak Repair – Condensation Drain Plugged – Clogged” »

Frozen Air Conditioner – Ice on Air Conditioner

Posted on April 4, 2008 by Richard Ashworth

When Your Air Conditioning Freezes Up – Frozen Air Conditioner

This is a common problem for people and it can be caused from one of two things.

Lack of airflow across the evaporator coil or
A problem with the refrigeration system.

Most people figure out they have this problem of a frozen air conditioner when they are outside and see ice building up on the outside condenser unit or ice on the refrigeration pipes. Others know they have this problem when they see the air handler and the pipes running into the air handler have ice. This in addition to a noticeable decline in cooling capacity is a sure sign you have frozen air conditioner problems that need to be resolved immediately. The best thing to do once you notice your air conditioner is frozen is to turn it off. If it is summer and you have a frozen heat pump (a heat pump provides heating and cooling using the process of refrigeration) you can turn it to heating mode and everything will defrost. However, be aware that if an excessive amount of ice is on the evaporator coil (located at the air handler usually inside the home) defrosting the frozen heat pump may overwhelm the condensation drain and you will have some water damage as a result. This may happen either way you defrost the system especially if the air handler is located in a hot attic. Turn the frozen air conditioner to the off position and turn the fan switch to on (manual on) on the thermostat selector switch. This will help aid the defrost of the frozen evaporator coil and the frozen air conditioning unit. Continue reading “Frozen Air Conditioner – Ice on Air Conditioner” »

Air Conditioner History

Posted on March 4, 2008 by Richard Ashworth

Air Conditioner History Air Conditioning has become a necessity in modern times as building designs have changed making it necessary to have some way to air condition and cool buildings where windows cannot be opened. Throughout history, all the way up to the 70′s, many people just opened windows or turned on a fan to keep cool and air conditioning, what was once considered a luxury, has now practically become a requirement. From the time people leave their homes in the morning to the time they return home many are in conditioned air most of the day and many people don’t even think about air conditioning unless the air conditioning is broken. Air Conditioning is definitely nice to have to remain comfortable throughout the day and is an expectation for most people working inside. Continue reading “Air Conditioner History” »