HVAC Equipment

AC / Furnace Equipment

What brands of equipment does McCullough service?

McCullough Heating & Air Conditioning services all brands of equipment. We like to say, “We sell the best and service the rest!” Our professional service technicians are some of the best trained in the industry.


What is a “cracked” furnace? How serious is this?

The part that transfers heat from the gas flame to the air in the house is called a “heat exchanger”. If the heat exchanger has a crack or rust hole in it, the fumes (including carbon monoxide) enter the air that comes out of the supply registers into your home or office. This is why a “cracked” furnace can be so dangerous. A small crack may not be dangerous yet, it will get bigger and even small amounts of carbon monoxide can be dangerous. Heat exchangers can be replaced, however, if they are out of warranty, you are usually better off to install a new higher efficiency furnace.


Won’t my carbon monoxide detector tell me when I need a new furnace?

Every home should have a carbon monoxide detector, but the fact that it is not going off doesn’t mean everything is safe. Carbon monoxide detectors vary in quality and virtually all of them must be replaced every few years because their sensors become ineffective. Also, even small amounts of carbon monoxide have an accumulative effect in the body, and — to prevent false alarms — detectors have to detect a minimum threshold of carbon monoxide over a period of time before they sound their alarm. If your alarm does go off, turn your furnace off immediately (and any other possible sources of carbon monoxide such as gas ovens, gas dryers, gasoline or diesel powered generators, car or lawnmower engines, etc.) and get all people and animals out of the home or office at once. Once the home or office has been thoroughly aired out and ventilated, you should be able to return safely, however, do not use your gas furnace, or other equipment that may be a source of carbon monoxide, until you have it checked out by a qualified technician. Call McCullough Heating & Air Conditioning so that a service technician can check your furnace.


How long should my old furnace and air conditioner last?

The answer to this question often depends on the equipment you have, how well it was installed, and how well it has been maintained. Home builders often use lower grade “builder models” offered by otherwise well-known manufacturers (including Trane, Rheem/Ruud, and Lennox). Builders’ models may not last much more than 8 to 12 years, whereas premium models from these companies will typically last much longer. If you believe you may have a builders’ model, you may want to consider taking advantage of rebates and warranties offered with a new systems once your equipment is 10 or 12 years old. Oftentimes, utility bill and repair savings alone will more than offset the cost of a new high-efficiency system.

Regular professional maintenance is an important factor, too. Even lower quality equipment that has been frequently serviced and maintained can last 20 years or longer. Many times the proud owners of such equipment will decide to replace the equipment in order to obtain equipment that offers improved efficiency or new features, not because the equipment is failing. Because of our extreme Central Texas weather, premium equipment that has not been maintained will typically last between 12-18 years. However, because of efficiency improvements that are continually made by manufacturers, once a system is 10 years old it may pay to replace the system because of the higher efficiency (and lower gas & electric bills) and rebates available for newer equipment.

Finally, how well your system was installed plays a major role in how long it will last. Systems left with even small amounts of water vapor in the refrigerant lines or ones that have too little return air flow will often have serious malfunctions before they’re even five years old.


What is SEER?

This stands for Seasonal Energy Efficiency Rating. The “size” of an air conditioner is rated in BTUs (British Thermal Units) or tons; however the “efficiency” of a system is rated in SEER. SEER is like mpg (miles per gallon) in a car: the higher the mpg (or SEER) the lower the gasoline (electricity or gas) bill.


Shouldn’t I install the highest SEER air conditioner available?

In our climate, 13 SEER is considered “standard” efficiency (this is the minimum efficiency that Austin Energy supports with rebates) and 16 SEER is “high efficiency”. The initial investment is higher for a 16 SEER than a 13 SEER system, however, the electricity savings will usually pay for the difference in 4-6 years. Single speed high SEER equipment doesn’t remove humidity as well as older, lower SEER equipment, so it is important that the new air conditioner be sized properly so it runs long enough to remove humidity (so you don’t have a cool, but “sticky” home). New variable speed equipment runs longer typically at a lower fan speed so that it keeps air circulating in your home and removes more humidity. Equipment with SEER ratings of 17 and higher are available, but are quite expensive and not considered economical yet.


What is a heat pump? Is it better than an air conditioner?

In the summer, a heat pump works in exactly the same way as an air conditioner, i.e., cooling your home or office by moving heat from the inside to the outside. In the winter, a heat pump operates in “reverse”, moving heat from the outside to the inside of your home or office. Even though it feels “cold” outside during the winter, there is still plenty of heat in the air that can be captured by a heat pump. After all, Absolute Zero, or the total absence of heat energy, occurs at minus 459 degrees! Also, heat pumps have auxiliary electric or gas heating systems that automatically come on to provide more heat when the temperature outside falls below 40 degrees or when the thermostat temperature is increased more than 5 degrees at a time.

The initial investment for a heat pump is somewhat higher than for an air conditioner with a gas furnace, they have somewhat higher maintenance costs, and ductwork must be of good design and in proper repair for proper operation. One common complaint of a heat pump is that the air coming out of the registers is not hot enough (compared to a gas furnace), however, it is plenty warm to heat your home. Actually, because of this, heat pumps will keep your indoor temperature more constant than a gas furnace.
Even if you have natural gas, heat pumps are often the most economical and efficient way to heat and cool your home. With gas prices poised to rise dramatically this winter (2003/2004). the savings provided by a heat pump may be dramatic.


My home has a forced air furnace but no air conditioner. Can I add central air?

Yes. Air conditioners require more air flow than furnaces and it may be necessary to add more ductwork. Also, local codes require that your ductwork be insulated in attics and crawl spaces, and your electrical service may need to be upgraded. McCullough Heating & Air Conditioning can design a central air conditioning system for you and provide you with a fixed price quote to install it.


It’s winter and I need a new furnace and air conditioner. Should I wait until spring to buy a new air conditioner?

If you think you are going to need to install an air conditioner in the next 24 to 36 months, you probably want to have it installed with the furnace. In the Central Texas area, you may qualify for substantial cash rebates, low-interest financing, and extended warranties when you replace your whole central heating and air conditioning system at the same time. Also, if you do install only a furnace or only a condenser, it is important to have a reputable contractor that can properly match the new component to your existing equipment and install it properly. Generally, due to lower demand, the cost will be lower to have a new system installed during the winter.


It’s summer and I need a new air conditioner. Should I install a new furnace too?

Not necessarily, however there are many considerations here. Similar to the question above, if you think you are going to need to replace your furnace in the next 24 to 36 months, you should consider having it installed with the air conditioner, i.e., a complete system. With the new higher efficiency system you’ll probably qualify for cash rebates, low interest financing, and far better warranties than when you replace one component at a time. However, if you do install only a furnace or only a condenser, it is important to have a reputable contractor that can properly match the new component to your existing equipment and install it properly. A very important point: If your furnace is getting old, you should have the heat exchanger checked for “cracks”. If the heat exchanger is “cracked” you should have the heat exchanger replaced or replace the furnace because a cracked heat exchanger may allow dangerous carbon monoxide into your home or office.


Should I replace my furnace and air conditioner at the same time, or can they be installed separately?

It depends. If you plan to replace them within a few years of one another, special warranties, rebates, and financing that are often available with a complete system may make changing the complete system the best option. If they are installed at the same time, the coil cabinet (part of the air conditioner that sits on top of the furnace) will match the furnace in color & style. The system will operate OK whether they are installed at the same time or not, so it is comes down to a question of convenience and economics.


Is it OK to install a different brand of furnace (or air conditioner) to work with my existing air conditioner (or furnace)?

Yes, this is fine. It is important that the furnace have the proper size of blower to match the air conditioner, but McCullough can determine this easily.


How do you pour a new concrete pad that the air conditioner sits on?

We bring them in on a two-wheeler. They are pre-cast concrete (3″ thick).


Should I have a new programmable thermostat installed with my new system?

Programmable thermostats allow you to have the temperature raise and lower automatically at specific times each day. They will reduce your energy bills and increase your comfort (ie. get up to a “warm” bathroom during the winter). If your family follows a fairly regular schedule, a programmable thermostat will pay for itself in a few months.


What about a new humidifier?

Aprilaire humidifiers are great! They reduce dry skin and especially help with dry sinuses. They help reduce colds and allergies. They also help furniture from drying and eliminate shock from static electricity. We have several models available and the investment is surprisingly low.


How does McCullough determine what size of furnace and air conditioner to install?

McCullough’s comfort consultant can measure your home and calculate the actual heating & cooling load on the home (calculation using Manual J v8 that incorporates information about window size & direction, walls, ceiling, floor, appliances, insulation, etc). This can determine the proper size of equipment and duct work that is needed. This can be compared to your current equipment & duct work and can be adjusted based on your lifestyle, etc.


I want a “big” air conditioner. Someone told me this is not good – what are the advantages & disadvantages?

An “oversized” air conditioner will cool your house quicker, but it will use more electricity and will not remove humidity adequately. Contrary to popular belief – and intuition – long A/C system run cycles are far more desirable and energy efficient than short run cycles. You can think of this in terms of a car, where you’d prefer to buy a car that has mostly highway miles rather than city miles. The greatest amount of energy usage and wear and tear on your equipment occurs at system start up (it takes tremendous torque and, hence, amperage to get your compressor turning). Once started, it takes 10 to 15 minutes before your system is operating at peak efficiency and performance. Because an oversized system will often bring the temperature down to the thermostat setting in just a few minutes, your oversized system will never get to operate at peak performance and will end up “short-cycling” — starting and stopping over and over again – a fact which will cost you plenty in terms of comfort, utility bills and added repairs.

Another factor to consider with regard to system size is that comfort is a function of temperature and humidity. That is, you can have low humidity (relatively dry air) and be comfortable when the temperature is 77 degrees or be absolutely miserable when you have high humidity and a temperature of 72 degrees. One of the most important jobs your air conditioning systems performs is removing moisture from the air in your home or office. Removing moisture requires long run times so that enough moisture laden air has a chance to blow across the cold indoor coil and condense into water which then drains from your system. Today’s high-efficiency central air conditioners may remove as much as two gallons of water from the air in your home every hour, which makes you far more comfortable. If your system is oversized, it will cool the temperature down to the thermostat setting too rapidly and the system will shut off before proper dehumidification of the air can occur. Taken to the extreme, a severely oversized system will create “rain forest” like conditions in your home: you’ll have water dripping from your cold supply grills and, very soon, mold and mildew covering your ducts and walls.

Duct system sizing must be considered too. If your duct system is not big enough to handle the increased airflow required by an “oversized” air conditioner, the evaporator coil may freeze and the system won’t work at all. Even if the coil doesn’t freeze, reduced airflow will impact operating efficiency and effectiveness and cause premature failure of expense components such as the compressor.

Obviously the air conditioner must be sized big enough to cool your house, but too big is just as bad. We can measure the heating and cooling load on your particular home and then recommend a system that is properly sized to cool your home to 77 degrees when it is 100 degrees outside, then increase the size slightly, if needed, based on your temperature preferences.


Will a larger furnace work better than a smaller furnace?

An “oversized” furnace will warm up the house quicker, but it will use more fuel and there will be greater temperature swings in your home. A smaller furnace will maintain more even temperatures, use less fuel, but will take longer to raise the temperature. McCullough Heating & Air Conditioning will calculate the proper furnace size to maintain 80 degrees inside when it is zero degrees outside.


Why should I consider a new high-efficiency filter?

Filtration is an important – and often overlooked – aspect of a home comfort system. We spend an increasing amount of time in our homes. Filtration impacts not only the air you and your family breath but the air that travels through your heating and cooling system. When you allow dirty, dusty air to move through your system, you’ll soon have clogged components which will impact system operation and efficiency. Removing and cleaning a clogged and dirty evaporator coil can easily cost $400 – not to mention the lost efficiency you paid for while it was dirty! Beyond this, poorly filtered air will cause more dust for you to clean and can really impact pets or people with allergies and respiratory ailments.

So what kind of filter should you use? First of all, disposable fiberglass filters are only about 15% effective. That means 85% of particles get through the filter. We don’t recommend them. Instead of a fiberglass filter, at a minimum McCullough recommends using disposable pleated filters because they remove far more particles from the air. Better yet, if you are replacing your HVAC system, install an electronic air cleaner or a media filter. Both filters are very effective at removing even the tiniest particles from the air, so you and your family will breathe cleaner air, enjoy a less dusty environment, and you’ll keep your heating and cooling system in better operating condition. Added bonus: with an electronic air cleaner or media filter that is part of you’re heating and cooling system, you only need to change the filter ONCE a year (twice if there are heavy smokers in the home).

High-efficiency filters remove more of the smaller particles from the air. This will help us breathe better and reduce sinus problems, headaches and colds. Many people miss fewer days from school & work and use less allergy medication. The air is filtered before entering the furnace and air conditioning evaporator coil, which makes the equipment last longer and will reduce fuel consumption 10%-15% over the life of a new furnace and air conditioner. McCullough has several different filters available and can show you the differences in efficiency and installation cost.


My gas & electric bills are high. Will a new furnace and air conditioner lower my bills?

YES! A new 15 SEER air conditioner can usually cut the electricity used by the old air conditioner in half. Even a 12 SEER air conditioner (this is the minimum efficiency the federal government allows to be sold) will cut the electricity used by approximately 40%. A new 90% furnace can usually cut the gas used by the old furnace by as much as 30%, and a new 80% efficient furnace (minimum allowed by the federal government) will use approximately 20% less.