Cooling questions


What are the different types of air conditioners?
Can I have central air if my home has baseboards?
Do central air conditioners use CFCs?
Do I need regular maintenance on my air conditioner?
What is the average life expectancy of central air conditioner?




Answer section

Question: What are the different types of air conditioners?


CENTRAL Air Conditioners: Central air conditioning units will cool a large area by using an air distribution system. The most common application is to add a central air conditioning unit to an existing forced air furnace. The air conditioner unit (condensor) is placed outside and is connected to the evaporator coil, inside the furnace's ductwork. VARIATIONS: Attic installations. In some warmer areas central air units may be installed with their own ductwork. In these cases a blower coil is used to circulate air through the ductwork. The ductwork can be installed in the basement or attic. SPACE Air Conditioners Window or room air conditioning units are designed to cool a small room only. Usually these units are placed in a window and are removed after the cooling season is over. Sometimes window air conditioners can be permanetly installed through a wall.


Question: How does an air conditioner work?


Air conditioning systems work by moving heat from inside your home to the outside. In a central air conditioning system air is drawn into the ductwork system through the return air system. Installed in the return air ductwork is an evaporator coil. This coil is connected to the condensor, the unit that is outside your home, by copper tubing, the lineset. Refrigerant is pumped from the condensor to the evaporator coil. As the refrigerant passes through the inside of the evaporator coil, warm air from inside your home passes over the outside of the coil. Because the refrigerant is cooler than the warm air, the refrigerant absorbs heat from the air. The refrigerant is then sent outside to the condensor unit. When the warmed refrigerant is in the condensor unit it is compressed by the compressor; the compression of the refrigerant causes it to boil. As the refrigerant boils it gives off the heat it picked up from inside your home. The refrigerant is then passed through the coil in the condensor unit where it gets cooled again and is ready to go back inside to pick up more heat from your home. As this whole process is going on, the temperature and relative humidity in your home are both lowered. The relative humidity level drops because cooler air cannot hold as much moisture. As the air cools, it gives up some moisture and it gets collected in the base of the evaporator coil and is then drained away.

Question: #3?





Question: I have had several quotes for air conditioning and the contractors are reccomending a 2 ton unit for my home. Should I have a 2 ton unit installed, just to be sure?

Answer: NO!

There is sometimes a tendency to believe that BIGGER is BETTER. Sometimes that maybe so, but not in air conditioning units. Actually with central air conditioners, SMALLER is SMARTER. The first thing an air conditioner has to do to cool your home is to remove humidity from your home. If the air conditioner is too large, the air is supercooled before the humidity is removed. This will make you feel cool and clammy, much like a rainy fall day. An oversized air conditioner will also come on more often for shorter periods of time. When this happens it is very hard on the compressor and can lead to premature burn-out.


Question: Do air conditioning units use CFC's ?


Most residential air conditioning units use a refrigerant called R-22 which is an HCFC not a CFC. Ok, so what's the difference? Well without getting into the complete chemistry (which I really don't understand anyway) an HCFC has a much smaller impact on the Ozone layer. Although R-22 dosen't have as great an impact on the Ozone layer as some of its CFC cousins do, it is still a greenhouse gas.


Question: What do I do if the refrigerant is leaking out of my air conditioner?


Turn your air conditioner OFF. Call your service contractor immediately. Refrigerant leaking is no simple matter. Gone are the days when it was more economical to just add more refrigerant to the unit and ignore the leak. Today it is against the law to knowingly allow an air conditioner to leak, and it is also very expensive.

Question: Do I have to cover my air conditioner when it rains?


No. Your air conditioner is made to be exposed to rain and summer weather. However it is a good idea to cover your air conditioner in the winter, especially if you live in an area that gets a lot of ice and snow in the winter.


Question: I would like to landscape around my central air conditioner, how close can I put shrubs and other plants?


This will depend on the type and make of your central air conditioner, however all central air units require some clearance from trees and shrubs to allow for air flow around the condensor coil. Generally speaking you should try and keep any items that may interfere with air flow at least 30" from your unit. To keep dust from getting inside the delicate coils, try and keep a ground cover around your air conditioning unit. If your unit is near a flower bed, a heavy mulch on the bed will keep dust down.


Question: Is it necessary to have my air conditioner maintained regularly?


Absolutely! Annual maintenance on your air conditioner can mean big savings on your cooling bills. Some studies have shown that proper annual maintenance can save you up to 30% on your energy bills. A well maintained unit will also last longer and break down less, saving you more money in the long run.

When choosing a contractor to perform your tune-up there are some things you should look for keep in mind.

  • Can the contractor service your entire system? Having one contractor for your heating and a one for your cooling system leads to confusion.
  • Make sure you get a written checklist of the work performed
  • A comprehensive tune-up should take an hour to perform, anything less and you may not be getting value for your money.
  • Ensure that your contractor is licensed to work with refrigerants. Most states and provinces now require that technicians take special refrigerant training.

In addition to professionally performed annual maintenance you also play an important part in keeping your system operating efficiently by making sure your furnace air filter is kept very clean. A dirty filter will affect the efficiency of a central air conditioning system much quicker than a furnace. Clean or change the filter regularly!


Question: I've noticed ice forming on the hoses that runs from my furnace to air conditioner, what does this mean?


Ice forming on the hoses (lineset) or the coil inside the furnace will usually be caused by a restriction in the air flow across the evaporator coil or your unit is low on refrigerant. If the problem is an air flow restriction, you can probably correct the problem yourself, if it is the refrigerant you will have to call in a service technician.

Restricted or reduced air flow can be caused by one, or a combination of the following:

  • Furnace air filter is very dirty and needs to be cleaned or changed.
  • Your evaporator coil is plugged with dirt and needs to be cleaned.
  • Your condenser coil (outside unit) is plugged and needs to be cleaned.
  • Your furnace fan, or blower coil, motor is not moving enough air. The motor may be burnt out, a pulley may be broken or a fan belt may be broken.

If your unit is low on refrigerant it is because there is a leak in the system. The leak must be repaired BEFORE new refrigerant can be added. Leaks can be very tricky to find and may require several visits by a service technician.


Question: If it cools down outside, is it ok to turn off my air conditioner?


There is no easy answer to this question. A lot of people like to turn off the air conditioner at night, or when it cools off for a day or two. If you live in an area with high humidity, this can be a problem. A central air conditioner's first job is to remove the moisture or humidity from the air in your home. Often this process will take several days. Once the humidity has been removed, it is much easier for your unit to maintain a comfortable temperature. If the relative humidity outdoors is higher than the relative humidity indoors, turning off your unit and opening the windows will cause the humidity level to rise again inside the house. When the temperature rises again, your air conditioner will have to work harder to lower the level once again. If the humidity level outdoors is low, and the temperature drops a few degrees, then open the windows for a few hours and get some fresh air indoors if you like.

Question: What is the best temperature for my air conditioner?


The short answer is the temperature at which you are most comfortable, but most people find the 68-74 degree range ideal. It's best to shut it off completely when you're not there, for example when you go to work. When choosing a temperature, remember that your central air conditioner will lower the relative humidity in your home, allowing you to be comfortable at a higher temperature. During the winter you might find 72F but in the summer you'll probably be comfortable at 76-78F. The important thing to remember is not to vary the temperature too much. Your air conditioner is constantly struggling to maintain the delicate balance of humidity and temperature, every time you adjust the temperature, you can potentially upset that balance.


Question: We are having trouble getting cool air upstairs in our two story home, what can I do to make the upstairs more comfortable?


A comfortable main floor and a warm second floor is a common complaint with central air conditioning systems. This temperature variation is caused by the fact that cool air is heavy. Heavy air requires more effort to move, especially upwards. Your furnace fan has to work much harder to get the air up two stories. Additionally, cool air, unlike warm air, tends to fall, so that once you actually manage to get the air upstairs, it will naturally fall back to the first floor.

Don't despair, there are some things that you can do.

  • Make sure your furnace fan is on the highest possible setting. Most furnaces installed today will have a multi-speed, direct drive fan motor. Have your service contractor check to make sure that the highest speed is being used for air conditioning. If your fan motor has belts and pulleys, check with your contractor about installing a larger pulley.
  • Adjust the balancing on your ductwork to force as much cool air upstairs as possible. If your ductwork is accessible from your basement, and has dampers installed in each of the supply air runs, make sure the dampers for the upper floor are fully open. You can also close any dampers for rooms on the first floor that do not get much use, or are very small. Some examples may be a powder room, formal living or dining room. You should keep the dampers fully open for the kitchen and the main living or family area. If the ductwork is not accessible, or doesn't have any dampers, don't despair. You can balance the air flow by opening and closing the dampers in the supply air registers. If you cannot get a register closed, we have been told that covering the register with a telephone book works well. Don't forget to re-balance the ductwork system when you switch over to heating. During the heating system you want most of the warm air delivered to the first floor, it will rise on its own to the second floor.
  • Use fans to help move cooler air. Placing a large fan at the top of the stairway can help to draw the cooler air up. A ceiling fan installed on the second floor can also be a big improvement.
  • Check the return air grills. Make sure they are clean.
  • Consider installing "High Wall" return air grills on the second floor. High wall return air grills are installed near the ceiling, not near the floor. This enables the furnace to draw the warmest air from the top of the house back into the system. Your service contractor can give you more information and let you know if it is possible to install high wall grills on your system.
  • Consider a 2-zone system, wherein the temperature can be regulated in each of 2 zones independently of each other.

Question: What is the most important thing to look for when I buy a central air condtioner?


The most important thing to look for when purchasing a central air conditioner, has nothing to do with the actual air conditioner and everything to do with the contractor you choose.

The best piece of equipment, if installed incorrectly, will not give you the comfort you deserve.

HVAC equipment, and cooling equipment in particular, requires that great skill and care be taken during the installation process. If just one weld is not correct it could lead to leaks of refrigerant in to the atmosphere, and potential contamination in the refrigerant system. These items could be costly to repair, not to mention time consuming and an aggravation for you.


Question: What is the life expectancy of a typical air conditioner?


Life expectancy is one of those things that will vary widely from location to location. Obviously a air conditioning units in warm climates will probably need to be replaced more frequently than units in cooler climates. How close you are located to the ocean will also be a factor.

Generally speaking units in cooler climates tend to last 15 to 18 years. In warmer climates the range is usually 11 to 15 years. Of course you are going to find exceptions to these numbers, but these can be used as a general guideline.