Residential Air Conditioning

Knowing your air conditioning system and how it is supposed to work can save you big $$$$ on service and possibly prevent you from over paying for service. Everything following on this newsletter is important for you to know... unless you have money to burn.

You should record the name plate information off of your air conditioner and your furnace. The out door part of your cooling system is called the condenser and the nameplate will be on the outside of the unit and accessible without the removal of any panels. The furnace inside your home may require the removal of the front panel. The label will provide you with the manufacturers name, model number and serial number. This is all the information you require. The model number tells the capacity and the serial number "dates" the unit. The same applies to your furnace. If you have options such as a humidifier, high efficiency air filter or air cleaner, HRV (heat recovery ventilator) or an air purifier (using ultra-violet light to kill viruses, mold, bacteria and odors) you should record this information also.

This information when passed on to your contractor, that you call for service will save time and money and get you back in operation sooner. You should also record the phone number of your service contractor. Leave this information with anyone that is house sitting while you are away on vacation so they would know who to call incase something goes wrong in your absence. Every year we get calls from "Widows" who say "my husband always looked after that".

You should mark on your calendar to call for the seasonal maintenance (spring and fall) before the system is needed. Don't wait until that first hot or cold day to test your system!!!

Brief description of the components of your air conditioning system...

• The outdoor section is called a condenser rated in "BTU's" or "tons" of cooling, 12,000 BTU's per ton of cooling.
• A 2 ton unit would be 24,000 BTU's and a 3 ton 36,000 BTU's etc.
• The indoor cooling coil is called the evaporator and the size corresponds to the size of the condenser.
• The condenser and evaporator are connected with 2 copper lines called a lineset.
• One copper line has a rubber insulation on it (suction line). The insulation is required as this line is the cold line and will form condensation on it from the surrounding air if not insulated.
• The other, bare copper line is called the liquid line and will normally be neither hot or cold to the touch.
• The furnace that provides you with heat in the winter also provides the air circulation for the cooling system.
• The air filter cleans the air, but only when the fan in the furnace is running. Filters come in a wide range of efficiencies and sizes.
• The humidifier adds humidity during the heating season and should be off while in cooling mode.
• The thermostat controls the operation of both the furnace and air conditioner. There are many models to choose, from digital, wireless, high definition, programmable etc.
• The HRV (heat recovery ventilator) is common in new homes that are tightly sealed to exchange stale inside air with fresh outside air.
• The UV (ultra violet) air sterilizers, kill viruses, bacteria, mold and odors of all types.

Common Misconception:

The temperature set button or lever on your thermostat is not an accelerator. "Cranking" the thermostat will not achieve set point one milli-second faster than setting the temperature for the desired comfort level. When your air conditioner is running it is operating at full capacity (residential units).

The following are some helpful hints on the use of your air conditioner and energy costs.

Hints:

If you are in the habit of turning your unit "off" or raising the temperature when away, be advised that it will take about one hour per degree to lower the temperature when you restart the system.

You can reduce the load on your system by doing any of the following...

• Turning off lighting, that is not required.
• Use the BBQ instead of the stove for cooking.
• Close draperies, to reduce solar gain from the sun.
• Turn the fan switch of your thermostat to the on position (particularly important for 2 story homes) to circulate the air and use ceiling fans.
• Wash the coil of the outdoor unit with your garden hose to rinse away dirt, grass clippings and debris.
• Keep shrubs and plants well back from the outdoor unit. Any blockages of the unit will make it run hot.
• If using the shower or bath, be sure to run the exhaust fan to clear the humidity from the bathroom.
• If you have a Heat Recovery Ventilator (HRV) turn it off during extreme heat periods.
• Keep the windows and doors closed as much as possible.
• Most important to make sure the air filter in your furnace is clean.
• Be sure your humidifier on the furnace is turned off, the by-pass damper closed, humidistat to off and the water turned off.

History fact:

Willis Carrier developed air conditioning to dehumidify the air in textile mills. The main purpose of your air conditioner is still to dehumidify the air. The cooling effect is simply a by-product of that process. The first building to be air conditioned for "people comfort" was the Sears Tower in Chicago.

Comfort is based upon a combination of temperature and humidity. If you have been to Las Vegas you'll know that you can be very comfortable at 85 F because the air is so dry. In the same respect you can "feel" uncomfortable at 73 F (23 C) if it is a high humidity day. Your air conditioner can only remove the humidity when the system is running and on the hottest day of the summer your unit may run 22 hours of the day. System Design conditions for southern Ontario for cooling is 15 to 20 degrees F. lower than the outside temperature. If it reaches 100 on those few days of the summer the best you should expect indoors is 80 to 85 F. In the same respect your furnace is designed to maintain 70 F. on a day when the temperature outside is (-10 F.)or an 80 degree differential. For the mathematics geek's this is a 4 : 1 ratio in size (furnace to A/C)which is a reliable method of sizing your A/C system.

Knowing that your A/C is 1/4 of the capacity of your furnace, it is obvious that recovery time from set-back or initial start-up will take longer to reach set point temperature. One degree per hour is a close approximation of what to expect.

A comfortable range of set-back is 3 - 5 degrees F., for cooling. You may have experienced a phenomena where the temperature in your home increases after the sun sets in the evening. This is referred to as the "Sling Effect". The heat radiation from the sun has been doing its' best to beat a path through the insulation in your walls and attic all day and it is around sundown when this heat makes its' way into your home.

Questions and Answers on Air conditioning

Question: My unit does not reach set point on really hot days. Is there a problem?
Answer: Your system (for southern Ontario) is designed to provide 15 to 20 degrees F. (10 to 12 degrees C.) lower temperature than outdoors.

Question: My furnace fan is running, but there is little or no air flow at the registers and house is getting hot.
Answer: If your filter has not been changed in months, it is possible that the filter is so dirty that it is restricting the air flow. This can result in the cooling coil (built into the sheet metal "plenum" on top of your furnace) turning into a large block of ice that will totally block the air flow. There are only 3 conditions that will cause the system to ice up... A) any restriction of the air flow through the furnace (dirty filters, too many vents or return air intakes blocked off or shut, failed fan motor or fan belt) B) a leak in the system that has allowed some of the freon to escape from the sealed system or C) operating the system at too low a set point when the outdoor temperature drops down into the low "teens digits" on the Celsius scale or below 60 on the Fahrenheit scale.

Question: How many degrees should I set back my A/C system when at work or in the evening.
Answer: 3 to 5 degrees Fahrenheit or 2 to 3 degrees Celsius when away for more than 4 hours, but bear in mind on a hot day the system may take one hour per degree to recover when you come home. Your A/C system is about 1/4 of the capacity of your furnace and therefore will take longer to cool than it would to heat up.

Question: The temperature is okay, but it is still very humid in the house.
Answer: Your A/C will only remove humidity when it is operating. If the system was oversized for your home it will lower the temperature more quickly and shut down before the humidity is under control. Big is not better when it comes to air conditioning. There could be other problems with the home in that too many basement outlets have been closed off or insufficient return air from the basement. It is still a wise idea to operate a dehumidifier in the basement during the spring and summer months. If you do, it is wise to position the dehumidifier over a floor drain so that the reservoir can be eliminated. This will save you having to remember to empty the reservoir every other day.

Question: Water is leaking out around my furnace. What could be the cause.
Answer: This could be a simple matter of the drain line becoming clogged to the cooling coil freezing as described earlier. The cooling coil in the top of your furnace acts like a secondary filter during the cooling season as it is wet with condensation when the system is on. The wet coil will trap dust and dirt that your air filter may not have removed. The dirt will wash down into the drain pan around the base of the coil and can plug or clog the opening to the drain pipe that takes the water to the floor drain. Some installers like to cut a corner or two to save money on the install by reducing the size of the drain line or by using flexible hosing that can create a "double trap" in the line. Size matters when it comes to drain lines. The pipe should be of rigid plastic or copper and slope continuously to the floor drain. If the end of the pipe is open at the floor drain you could try "blowing through the pipe". If there is resistance then a release you may have solved the problem for a period of time, but really what you have done is pushed the dirt around... not removed it. You may have to call a technician to open the sheet metal and flush the drain pan of the cooling coil or cut open the drain line. A plugged drain can make quite a mess if your basement is finished so it is wise to check the furnace room every so often.

Question: My system is blowing hot air and the unit outside is not working.
Answer: There are separate circuit breakers in your hydro panel for the furnace and the A/C. A single width breaker controls your furnace and a "double" width breaker powers your outdoor section of the system. Check the breaker and reset if necessary. Should the breaker "trip" when reset... do not try to reset again as there is a problem and you need to call your contractor. Even if the breaker is "off" you may still hear a buzzing or "hum" at the outdoor unit. This sound is from the electrical switch (called a contractor) that is energized by a low voltage signal from your thermostat, through the wiring in your furnace. Should all the breakers be in the on position, check the outside unit and listen for any noises or the unit trying to start. It is possible the outdoor fan has failed and the compressor that circulates the freon gas through the system will get soooo hot that it will shut off to prevent damage to the compressor. Sticking a popsicle stick or piece of wire through the fan grill on top to see if the fan spins freely or is seized will also direct your contractor to knowing the problem before incurring an unneeded service call. We have seen all kinds of little creatures from cockroaches to mice burnt to a crisp on the contacts of the contractor. Unless you are very sure of your understanding of electricity, I would advise you call a contractor for further investigation. Even with the breaker turned off there is a part in the unit that holds an electric charge called a capacitor. The jolt you can receive from a capacitor can "stop your heart". If the fan motor is thought to be the cause, turn the A/C off at the thermostat to prevent the compressor from cycling on and off, as this could cause further damage.

Question: My contractor has reported the compressor has failed and requires replacement. What should I ask?
Answer: Most manufacturers have a five (5) year warranty on the compressor. The labor warranty is normally only one year. After the first year and before the end of year five, only the compressor is provided under warranty. Additional costs such as, freon recovery, welding charges, a freon drier, system evacuation and labor would be charged extra. A normal residential compressor can normally be replaced in 4 - 6 hours. If your system is over 15 years old it would be wise to consider replacement of the unit for a higher efficiency unit. The newer systems use a different refrigerant gas called R-410A or "Puron" and circulates a synthetic oil throughout the system with the freon. This oil is not compatible with the oil or freon of the old R-22 systems and therefore requires replacement of the outdoor unit (condenser), the indoor coil (evaporator) and the copper connecting lines (lineset). The same electrical supply can be used with the new system. Compare the cost of replacing the compressor and the general condition of the unit with the cost of a new system. A new system may qualify for a hydro rebate, but in either case the new unit will use less electricity and most likely be considerably quieter. Knowing what caused the original compressor to fail could prevent it from happening again. Dirty coils on the outdoor condenser cause the compressor to run hot and also result is a loss of efficiency. This could be compared to running your car engine without antifreeze coolant in the radiator... your engine will overheat and burn out. Not all compressor failures are "burnouts". Mechanical failure can also occur and there is usually a reason for this also. Ask you technician why? The new compressor will only carry a one year warranty and the labor for the replacement may only be 30 to 90 days... ask for the warranty in writing.

Question: Can I turn my furnace off for the summer, now that we are into cooling weather.
Answer: You can, but only if you don't want cooling either. The fan in your furnace used to circulate the heat throughout the home in winter is the same fan used to circulate the cool, dehumidified air in summer. The furnace electrical power also provides the electrical power to your thermostat and the electrical signal to the outdoor condenser to turn it on.

Question: Does it help to turn on, or leave on an exhaust fan in the washroom or at the kitchen range to "suck" out the heat.
Answer: A simple little bathroom fan will exhaust about 100 CFM (cubic feet of air per minute) Should the fan be left on for an hour it will exhaust 100 cubic feet of air X 60 minutes =6,000 cubic feet of air. The average house is around 1,600 square feet with 8 foot ceilings for a total volume of 12,800 cubic feet of air space. Divide the cubic footage of the home by the air exhausted in only one hour of the average bathroom fan (12,800 by 6,000) and you can see that every inch of air in your home will be removed in just over 2 hours. That is a ton of air for a simple little fan. Now because your home cannot go into a "vacuum" it is obvious that the replacement air has to come from somewhere. It comes from outside, through every crack in the home and every time the door is opened. This air is unfiltered, hot and humid and your A/C system cannot keep up with the additional load. Other appliances in the home that exhaust air are, clothes dryers, central vacuum systems, kitchen range hoods. Each of these items exhaust more air than the average bathroom fan. Houses of newer construction, built from 1995 and on are effectively sealed against outdoor air leakage. This is as a result of better windows, vapor barriers, door seals and insulation.

Question: My old house was a 1,200 square foot bungalow with a 2 1/2 ton (30,000 BTU) air conditioner. My new home is almost 3,500 square feet and the builder has only installed a 2 1/2 ton unit. Have they made a mistake?
Answer: Not likely. New home construction is more energy efficient than the old house, meaning you can easily get by with a furnace and A/C of smaller capacity.

Question: I'm shopping for a new A/C for my home.... what should I look for.
Answer: More important than what to look for is what to LOOK OUT for. You could buy the best unit on the market, but if the unit is not properly installed it will not work as well as a BRAND "X" unit that is installed correctly. Air conditioning units are like cars in the sense that they come in different colours, sizes, prices and options. Any of the big manufacturers of A/C units will also have more than one line of unit ranging from the Chevrolet to the Cadillac and the price can vary greatly between the quality or features you wish to budget or pay for. Surprisingly enough most of the manufacturers do not make the components for their systems. They will purchase compressors, fan motors, thermostats, electrical switches, copper and electronics from the same company that all the other manufacturers are buying from. Even the cabinets could be identical on some units from different makers. The Sears Company is a good example of this as they simply have their nameplate on ICG (Keep-Rite) units. Then there is Carrier, Lennox and York that sell their "brand name" to only authorized dealers that meet a long list of qualifications in order to sell their product line. These same manufacturers sell "Knock-offs" under a different name to wholesale outlets and the only difference in the equipment may be the paint finish. The important selling features of one unit over another are as follows...

SEER (seasonal energy efficiency ratio). This is a number that will presently range from 13 to as high as 17.5. The higher the number the more efficient it is. Your old system may be as low as a SEER 10. The Canadian Gov't has a minimum standard presently of SEER 13.

SONE or DBR (decibel rating) The numbering on this is opposite to the SEER. The lower the Sones or DBR the quieter the unit is. Things that make one unit more quiet than another are the type of compressor (scroll compressors are quieter than reciprocating compressors)

A 2 speed outdoor or condenser fan motor will make less noise on low speed on moderate days than a single speed unit.

The "Pitch" or angle of the fan blades on the outdoor unit can cause air turbulence and noise, but all have to circulate enough air to cool the freon inside the coils.

The compressor on some units can be equipped with a sound blanket to reduce the noise or on some deluxe units the compressor will be inside a separate compartment of the outdoor unit that is insulated to dampen noise levels.

The paint finish, design and actual style can vary between manufacturers that has no bearing on how the unit functions and is therefore a personal choice of aesthetics. It could be a square box or have sweeping, sculptured corners with a automotive finish.

Copper coils are a must. The new environmental refrigerants operate at much higher pressures than the old R-22 systems. Some makers used aluminum tubing and it could not last and was near impossible to repair if a leak occurred.

Price: Picture a company that has met the qualifications for a "dealership" and hires factory trained, experienced staff. They will be paying their staff more money per hour than the guy selling BRAND X units and working out of his garage. It is understandable then why the low ball price should be avoided. The dealership will also have the staff and parts available to service and maintain your equipment.

Question: Can I install a fence or shrubs around my condensing unit to hide it from view?
Answer: The condenser must have free air flow around it to permit the refrigerant gas in the system to be cooled to the condensation point. Any obstruction such as fences, bushes or even dirt on the coil section will cause the unit to run hot. Excessive heat can "burn out" the compressor which is the most costly component of the system. Any blockage of air can also result in a loss of capacity to cool your place on a hot day.