Air Conditioning Systems

1/4/2020

Welcome back to the Homeowner’s Advocate Newsletter where we give you useful information each month to help keep your house in great shape so you can enjoy it for years to come. Preserve your investment—and keep your family safe and healthy—by maintaining your home using the following tips.

HVAC = Heating, Ventilation & Air Conditioning

Your home's central air-conditioning system must be regularly inspected and maintained to function efficiently. An annual inspection by a trained professional is recommended. However, you can do a lot of the work yourself by following the tips offered here. I am including information here for the most common type of Air Condition systems we use here in Texas. If you have an older home with an evaporative cooler or live in a different climate zone, there are other maintenance routines that will apply to you and are not included here. Give us a call if you would like more information.

Clean the Exterior Condenser Unit and Components

The exterior condenser unit is the large box located on the side of the house that’s designed to push heat from the indoors to the outdoors. Inside of the box are coils of pipe that are surrounded by thousands of thin metal "fins" that allow the coils more surface area to exchange heat.

Follow these tips when cleaning the exterior condenser unit and its inner components --
after turning off power to the unit, of course.

Remove any leaves, spider webs and other debris from the unit's exterior. Trim foliage back several feet from the unit to ensure proper air flow.
Remove the cover grille to clean any debris from the unit's interior. A garden hose can be helpful for this task.
Straighten any bent fins with a tool called a fin comb.
Check your owner’s manual for specific instructions on maintenance you may be able to do yourself. I am big on reading manuals - it's the least you can do for such an expensive item!
Clean the evaporator coil and condenser coil at least once a year. When they collect dirt, they may not function properly.

Inspect the Condensate Drain Line

Condensate drain lines collect condensed water and drain it away from the unit. They’re located on the side of the inside fan unit. There should be two drain lines—a primary drain line that’s built into the unit, and a secondary drain line that can drain if the first line becomes blocked.
You can inspect the drain line by using the following tips, which take very little time and require no specialized tools:

Inspect the drain line for blockage from algae and debris. If the line becomes blocked, water will back up into the drain pan and overflow, potentially causing a safety hazard or water damage to your home.
NOTE: Water in your drain pan is a sign your primary drain line is clogged!
Make sure the drain lines and all connectors are secured and fit properly. Leaks can occur at joint in your drain lines as well.
Adding 1/4 cup of bleach to the "maintanence port" on your primary drain line every six months is a common technique for keeping the drain line clear of clogs. BE CAREFUL when using bleach as the vapor is toxic!

Replace the Air Filter

Air filters remove pollen, dust and other particles that would otherwise circulate indoors. Most filters are typically rectangular in shape and about 20 x 25 inches, and about 1 inch thick. They slide into the main ductwork near the inside fan unit. The filter should be periodically washed or replaced, depending on the manufacturer’s instructions. A dirty air filter will not only degrade the quality of the home’s indoor, but it will also strain the motor to work harder to move air through it, increasing energy costs and reducing energy efficiency. The filter should be replaced monthly during heavy use during the cooling seasons. You may need to change the filter more often if the air conditioner is in constant use, if any family members have respiratory problems, if you have pets with fur, and/or if it’s particularly dusty indoors.

Read the features on the air filters at your local store and try different models to see which filter type provide the best results for your home.

Thermostats

Thermostats are designed to control the heating and cooling system in the home so that the air temperature and humidity level remains comfortable. You should understand how thermostats operate, as well as the more common problems associated with them. Start by reading your manual and learn how to program your thermostat.

Thermostats can be manually controlled or programmed. Most thermostats contain two meters: the “set” temperature that the thermostat is asking for, and the actual temperature. On a traditional dial-type thermostat, the user can increase the set temperature by rotating the dial clockwise, and lower it by rotating it counter-clockwise. Newer thermostats usually have digital displays, touch screens and even apps for your smart phones, which can be used to adjust automated heating and cooling schedules.

Apps for controlling modern thermostats can provide lots of useful features and information on how you are using your HVAC equipment. They can even save you money! I estimated my first "smart" thermostat saved me about $50 per month in the hot summer months by detecting when we were away from our home and automatically changing the temperature so we were not waisting money cooling the home when we were away for extended periods. Smart thermostats are a game changer for me and I think they can be for you as well. There is a good chance you can tackle an upgrade to a smart thermostat yourself. Do you research and hire a pro for the install if you are squeamish about doing this on your own.

Programmable Thermostats

Using a programmable thermostat in the winter, you can automatically turn down your heat at night or when you’re not at home. In the summer, you can save money by automatically turning your air conditioner up at night or when you’re at work.
You can also adjust the times that the heating and air conditioner go on and off according to a preset schedule. As a result, the equipment doesn't operate as much when you’re asleep or when the house (or a part of it) is empty. Programmable thermostats can store and repeat multiple daily settings (six or more temperature settings a day) that you can manually override without affecting the rest of the daily or weekly program.

Sleep experts also say your body temperature drops when you sleep and many people report falling asleep easier by automatically lowering the temperature of the home one or more degrees about an hour before bedtime! WOW! Who new a programmable thermostat could help you sleep better!

Location

In order to avoid false temperature readings, which will cause unnecessary furnace or air-conditioner cycling, the thermostat must be installed so that it correctly reads the room temperature. The following locations may cause the thermostat to give false readings:

near a heat source, such as a fireplace, hot water pipes, bright lights, direct sunlight, and electrical appliances that produce heat;
in a drafty hallway, or near a window or exterior door that is left open often; and
on an outside wall. Outside walls are affected too much by outside temperatures, which may make the thermostat "think" the air in the house is warmer or cooler than it really is.

Common Thermostat Problems and Solutions

erratic operation or fluctuating temperature. This is often caused by poor pin connections between the thermostat and the backplate when the backplate is flexed against an uneven wall. To allow the backplate to flatten out, loosen the screws that attach the backplate to the wall, then snap the thermostat back onto the backplate.
a thermostat that doesn’t respond to changes in room temperature. This can happen when there is air passing over the temperature sensor from a hole in the wall behind the thermostat, through which wires enter from the air-handling unit. To rectify this, insulate the hole behind the thermostat with fiber insulation, spray foam, or any other insulating material.
a temperature reading that is inaccurate. A convenient way to test the temperature sensor is to tape a thermometer to the wall next to the thermostat and wait 15 minutes. A faulty thermometer needs to be recalibrated. Instructions for recalibration vary by manufacturer, so read your manual.
loss of power. This may be caused by the following two situations:

If the air handler powers the thermostat, check the circuit breaker meant for the air handler and make sure it has not tripped.
If batteries power the thermostat, make sure they are lithium, not alkaline. Alkaline batteries will die rapidly or cause erratic thermostat operation.

Maintenance and Other Tips

On older dial-type units - give the thermostat's interior a light dusting with a small, soft-bristle paintbrush. Canned air can also be used to blow off dust. Twist the screws to remove the cover. Be sure to clean the contacts, which are small metal plates within the unit. The wires coming from the transformer attach to the contacts. Do not touch any of the interior parts with your fingers.
If the base is loose, re-tighten the screws. Check the wires coming from the transformer. If any corrosion is present, remove the wire from the contact and clean it. Use a wire stripper to remove the surrounding insulation, cut back the wire, and reconnect it.
Make sure the terminal screws are tight.
For wireless thermostats, make sure the model number of the thermostat matches the model number of the receiver. If the model numbers don’t match, the thermostat and receiver will not be compatible and won’t function properly together.
Make sure that your thermostat has been set to the proper position for the season: cooling or heating. The air conditioner will not run with the switch set to "heating" and, conversely, the heating system won't run if the thermostat has been set to "cooling."
Thermostats that contain a mercury switch must remain perfectly level or they may not control the temperature setting.

A Few Notes on Energy Savings

Many people believe that furnaces work harder than normal to warm an area back up to a comfortable temperature, which will counteract energy savings gained from turning the thermostat down. This belief is a misconception that has been disproved by years of studies and research. Fuel is saved between the time the temperature is stabilized at the lower level and the next time heat is needed, while the fuel required to re-heat the space is roughly equal to the fuel saved while the building drops to a lower temperature.
According to the U.S. Department of Energy, consumers can save 10% on their utility bills by setting their thermostat lower by 10° to 15° for eight hours. This can be easily accomplished with a programmable thermostat.
Be careful not to set the thermostat so low in the winter that indoor plumbing pipes freeze, or so low during the summer that mold may be allowed to grow prompted by excess indoor humidity.

Moisture Intrusion

Moisture intrusion can be bad for the house and the people and pets in it. You should have at least a basic understanding of how unwanted moisture can enter a home and where problems commonly occur.

Some common moisture-related problems include:

structural wood decay;
high indoor humidity and resulting condensation;
expansive soil, which may crack the foundation through changes in volume, or softened soil, which may lose its ability to support an overlying structure;
undermined foundations;
metal corrosion;
ice damming on the roof during the winter (not a big issue here in Texas!); and
mold growth. Mold can only grow in the presence of high levels of moisture. People who suffer from the following conditions can be seriously (and even fatally) harmed if exposed to elevated levels of airborne mold spores:

asthma;
allergies;
lung disease; and/or
a compromised immune system.

People who do not suffer from these ailments may still be harmed by elevated levels of airborne mold spores.

How does moisture get into a house?

Moisture or water vapor moves into a house in the following ways:

air infiltration. Air movement accounts for more than 98% of all water vapor movement in a home’s building cavities. Air naturally moves from high-pressure areas to lower ones by the easiest path possible, such as a hole or crack in the building envelope. Moisture transfer by air currents is very fast (in the range of several hundred cubic feet of air per minute). Replacement air will infiltrate through the building envelope unless these unintended air paths are carefully and permanently sealed;
by diffusion through building materials. Most building materials slow moisture diffusion, to a large degree, although they never stop it completely;
leaks from the roof;
plumbing leaks;
flooding, which can be caused by seepage from runoff or rising groundwater, which may be seasonal, or flooding may be a catastrophic;
wind-driven rain, which is the main cause of moisture intrusion through the building envelope; and
human activities, including bathing/showering, cooking, washing dishes, and washing and drying clothes. Indoor plants, too, may be a significant source of high levels of indoor humidity.

Climate Zones

In the southern U.S., the problem is largely driven by high outdoor humidity and low indoor temperatures during summer months. Mixed climates are exposed to both conditions and can experience both types of problems. Humid climates, in general, will be more of a problem than dry climates.
Homeowners can check for moisture intrusion in the following areas.

Roof

A roof leak may lead to the growth of visible mold colonies in the attic that can grow unnoticed. Roof penetrations (such as chimneys, skylights, and vent stacks and pipes) increase the likelihood of water leaks due to failed gaskets, sealants and flashing.

The number of roof penetrations may be reduced by a variety of technologies and strategies, including:

consolidating vent stacks below the roof;
routing exhaust fan caps through walls instead of the roof;
using high-efficiency combustion appliances, which can be sidewall-vented;
installing electrically powered HVAC equipment and hot water heaters that do not require flues; and
making sure there is adequate flashing. Flashing is often discovered to be missing, incorrectly installed, or corroded.

Plumbing

Distribution pipes and plumbing fixtures can be the source of a large amount of moisture intrusion. If a wall is damp and/or discolored, then moisture damage is already in progress. Most plumbing is hidden inside the walls, so serious problems can begin unnoticed.
One of the most important means of moisture management in the bathroom is the exhaust fan. A non-functioning exhaust fan overloads the bathroom with damp air. If the exhaust fan doesn’t turn on automatically when the bathroom is in use, consider switching the wiring or switch. The fan should vent to the exterior, not into the attic.
The bathroom sink, in particular, is a common source of moisture intrusion and damage. Although an overflow drain can prevent water from spilling onto the floor, it can become corroded and allow water to enter below the sink and into the cabinet.
Bathroom windows need to perform properly in a wide range of humidity and temperature conditions. Check to see if there are any obvious breaks in the weatherstripping and seals. Are there are stains or flaking on the painted surfaces?
Check showers and bathtubs. Is the caulking cracked, stiff or loose in spots? Are there cracked tiles or missing grout that may channel water to vulnerable areas? If some water remains in the bathtub after draining, it may be a warning sign of possible structural weakening and settlement in the floor beneath the tub.

Utility Room

Your water heater tank should be clean and rust-free.
The area around a water softener tank should be clean and dry.
Check that all through-the-wall penetrations for fuel lines, ducts, and electrical components for a heating system are well-sealed, clean and dust-free.
The air-supply registers in the house should be free of dust.
Filters, supply lines, exterior wall penetrations, vents, ductwork and the drainage for the cooling system must all be in good working order to prevent moisture problems.

Attic

Look for stains or discolorations at all roof penetrations. Chimneys, plumbing vents and skylight wells are common places where moisture may pass through the roof. Any such locations must be inspected for dampness, a musty smell and/or visible signs of mold.
Are there areas of the insulation that appear unusually thin or dark? Dark staining indicates wind and/or rain being blown into the attic. Thin areas of insulation should be added to.
Rust or corrosion around recessed lights is a sign of a potential electrical hazard.

Foundation

Model building codes typically require damp-proofing of the foundation. The damp-proofing should be applied from the top of the footing to the finished grade. Moisture problems at the foundation can be complicated and a pro should be consulted if you have evidence of water penetrating your foundation.

Parging of foundation walls should be damp-proofed in one of the following ways:

a bituminous coating;
3 pounds per square yard of acrylic modified cement;
1/8-inch coat of surface-bonding cement; or
any material permitted for waterproofing.

Condensation Inspection

Condensation, also called sweating, forms on building materials when the temperature drops below the dew point, which is the temperature at which droplets of water vapor are forced so closely together that they coalesce into liquid water. Because of their characteristic thermal conductivity, components made of metal are usually the first places where condensation will appear in a home.

Condensation can be a problem because droplets can pool and destroy surrounding building materials, such as when condensed water chronically drains from a toilet and weakens the bathroom tile floor and sub-floor. Condensation can also pool and encourage the growth of mold, which is a serious health hazard. Dripping overhead pipes can be a problem in a finished basement, as they may damage carpeting, furniture and valuables. Pooled condensation can even cause an electrical fire, or electrocute someone.

Where does condensation typically form?

plumbing drains. Condensation may collect on cast-iron or copper drain piping if a leaking plumbing fixture sends cold water through the home’s drainpipe system;
cold-water pipes. In humid environments, condensation will quickly form on water pipes that distribute cold water;
water pressure tanks. Especially in colder or more humid climates, water pressure tanks may experience condensation when water is flowing at a high and steady rate;
at plumbing fixtures that are in constant use or are defective and constantly refilling, especially toilets. Toilets commonly sweat in the summer due to high indoor humidity, unlike windows, which host condensate in the winter when the outside temperature is very low; and
in windows. Aluminum windows are often found with moisture on the interior frames which can drip down damaging sills, walls and the inside of the wall.

Metal that does not come into contact with cold water or air rarely exhibits excessive condensation, even though it’s exposed to the same moisture-laden air as everything else around it. A water pipe that carries only warm water, for instance, seldom cools below the dew point. And non-metal building materials that do come into contact with cold water or air (such as plastic drains and piping) often lack the thermal conductivity to become cold enough to be the source of condensation.

Condensation in Older Homes

Condensation is more of a problem in older homes, which often lack a vapor barrier or sealers in the concrete. In such instances, moisture in the ground is forced through the foundation and masonry, which is why condensation is commonly found in the basements of older buildings. The two strategies used to reduce condensation are to lower the relative humidity of the indoor air and to keep surfaces from becoming cold.

These strategies can be practiced in the following ways:

Use a dehumidifier. This is a simple, effective appliance used to lower the humidity of the air, as it forces water vapor to condense into a water tank so it cannot condense elsewhere. An air conditioner can also dehumidify the air.
Reduce the number of plants in the home. This will help decrease relative humidity, as their transpiration of moisture is a significant source of water vapor.
Insulate cold surfaces. Insulation will keep surfaces from becoming cold, and it can easily be applied to water pipes and water pressure tanks. Fiberglass insulation should be avoided, as it’s ineffective when it becomes wet and it can be the source of mold growth. Plastic foam wrap is an adequate material for this purpose. Keep in mind that by adding thermal insulation to water pipes, they can no longer be counted on to supply radiant heat to their surroundings.
Ventilate the basement. However, this tactic might be counterproductive if the outside air is more humid than the indoor air.
Add heat where condensation is a particular problem.

Also, keep in mind that what appears to be condensation may actually be a water leak. If insulation and dehumidification don’t seem to improve the condensation problem -- especially if it’s appearing in only one place –-contact a qualified plumber.

If you would like to read about a particular topic, Hot Spot Inspections Homeowner's Advocate Series would love to hear from you! Drop us a line and we will write a custom article on your favorite topic!

Regards,
Matthew McGregor
Hot Spot Property Inspections, llc
The Homeowner's Advocate

The Homeowner's Advocate Series