Atlanta AC Question: What Are Thermostatic Expansion Valves?

Monday, April 30th, 2012

The thermostatic expansion valve, sometimes known as a TEX, TEV or TXV, is a critical piece to influence the efficiency of  your Atlanta air conditioning system.  A tiny sensor controlling the evaporating phase of process, the valve can have a big effect.

Cool air is manufactured by a rapid movement of a refrigerant between liquid and gaseous states.  Compound chemicals that are able to do this at a low temperature are compressed and expanded, absorbing and releasing heat at different points along the way.  The TEV controls the flow of the refrigerant into the evaporator coils according to the temperatures of the various ingredients.

Cool Air 101

To condition air, the refrigerant, most often freon or another fast acting, low temp compound, evaporates into a gas that runs through a coil and absorbs heat.  Passing through a compressor, the freon condenses under pressure back into a liquid again and releases the heat, becoming cool enough to chill a party.

Too much freon in the evaporator tube and the pressure is not low enough to expand to gas and absorb heat, working inefficiently for no gain.  Too little freon and the conversion is also ineffective by not reaching the density needed to condense.

There are four types of valves with different benefits for different types of cooling environments.  With its ability to adjust minutely to changing conditions, the thermal expansion valve creates the perfect mixture of pressure and freon for more complicated systems.

At the Starting Gate

An interactive device, the valve senses the evaporator pressure and temperature and adjusts the flow of the refrigerant so as to maintain a given “superheat”, the differ­ence between the refrigerant vapor temperature and its sat­uration temperature.  By controlling superheat, the TEV keeps nearly the entire evaporator surface active while not permit­ting liquid refrigerant to return to the compressor.

Some valves operate on an electrical impulse from sensors that can measure the temperatures.  Others are open all the time.  The thermostatic expansion valve actually utilizes the pressure between the two sections to open or close itself, regulating flow based on the very same pressure it is designed to moderate.

Like the buildings they comfort, central air conditioning systems in Atlanta are varied and diverse.  There are nearly as many thermostatic expansion valves as there are units to receive them. For more information about your air conditioner or to schedule a service call, contact Cool Air Mechanical today!

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Is Your AC Unit in the Shade?

Friday, April 27th, 2012

Did you know that the placement of your outdoor unit can actually affect your heat pump’s energy efficiency? If you place your outdoor unit in the shade and sheltered from wind, it will work more effectively and efficiently. You should also remember that the fan and compressor on your heat pump out door unit do make some noise so it should be located away from your home’s windows.

Want more tips on air conditioning and your home comfort system? Need a tune up? Check out our promotions and specials!

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Tips to Make Your Atlanta HVAC System More Efficient

Monday, April 23rd, 2012

Considering the fact that up to half of the energy used in a home goes toward heating and cooling, it is smart to make sound decisions regarding the heating, ventilation, and air conditioning system.   Below are some tips to make your Atlanta HVAC system more efficient:

Regularly Maintain HVAC Equipment

Annual tune-ups of heating and cooling systems can easily improve HVAC system efficiency. Some of these steps a professional tech will do include:

  • Ensure outdoor unit has proper ventilation, is free of debris or foliage growth, and is located in the shade
  • Check thermostat settings for comfort while home and to save energy while away
  • Tighten electrical connections and measure voltage and currents on motors
  • Lubricate all moving parts
  • Inspect and clean out the condensate drain on central air conditioning units
  • Check controls of the system for proper operation

Change Air Filters

Many air filters should be changed every three months, but some as often as every month.  Follow the manufacturer’s recommendation as well as simple common sense by checking the filters frequently during high-usage times and replacing as necessary.

Seal All Household Ducts

Heating and cooling ducts can be huge energy wasters if they are improperly sealed.  These ducts can be in an attic, basement, crawlspace, or garage, and can be easily repaired with duct sealant, or metal-backed tape along seams and connections.  As well, wrapping the ducts in insulation will keep them from overheating in the summer or freezing in the winter.

Install a Programmable Thermostat

A programmable thermostat can control how hot or cold a home is every hour of every day within a week.  During the summer they can be set to higher settings while residents are away on vacation, and during winter they can be set to lower settings while residents are away at work or school.  This is a great way to save on energy costs throughout the year, as keeping a more consistent house temperature also helps the HVAC system to run more smoothly.

Install ENERGY STAR® Certified Equipment

When an HVAC system is more than ten years old, or if it no longer works properly it is probably time for a replacement.  Prior to replacing an entire HVAC system, it is prudent to check for air leaks in ducts, which can be a major cause for heating and cooling issues.  If it is determined that it is time for a professional to come in and install a new HVAC system, the savings in energy will be quite dramatic indeed.

Use any or all of the above tips will make your Atlanta heating and air conditioning system more efficient, while saving you money throughout the peak seasons of heating and cooling usage.

Give Cool Air Mechanical a call today if you need any help choosing upgrades for your home’s HVAC system!


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Atlanta Air Conditioning Tips: How to Troubleshoot a Failed AC Unit

Monday, April 16th, 2012

In most cases, a failed air conditioning system may be fixed by going through some troubleshooting guidelines. If you would like one of our Atlanta air conditioning technicians to help you get your AC unit running again, give Cool Air Mechanical a call for assistance. We can also send someone to your home if we can’t get your system working again.

Here are some basic steps to try before you call for a repair.

Check All Controls and Fuses

Atlanta Air Conditioning RepairWhen your air conditioner won’t cool your home properly, always check the thermostat to see if it is on “cool” and set for the right temperature. If the air conditioner has shut down, check to make sure that the unit is receiving power by looking in the fuse box for a flipped circuit breaker and also making sure it is plugged in properly. You can also inspect the visible wires and electrical components for obvious damages. Call an Atlanta air conditioning technician if you see physical damage to the electrical components. Never try to fix this yourself.

If the weather is very hot outside, your air conditioner’s high-pressure switch can get flipped and turn your unit off. On most air conditioners the high pressure limit switch can be found on the compressor’s access panel. If you can’t find the switch or you would like someone to make sure nothing more serious is wrong with your AC, give us a call.

Check for Refrigerant Problems or Condensate Pan Leaks

Refrigerant problems caused by the wrong amount of refrigerant can keep the AC unit from cooling your home properly, and you can usually tell if there’s a refrigerant issue by looking for frost or icing on the evaporator coil. When there’s excess coil icing, it means that there isn’t enough cool air being delivered to your home. If you see thick frost on the evaporator coil, a technician will most likely need to charge the refrigerant, or there could be a leak in the refrigerant line.

Condensate leaks into the condensate pan can also cause an air conditioner to fail. The condensate drip pan is installed underneath the air handler to catch condensate leaks if the drain system gets clogged. Most of the time, a small clog in the drain line can be easily cleared. Also check the condensate switch for issues; sometimes these can be defective and cause your air conditioner to shut down.

At Cool Air Mechanical, we want to be the only Atlanta air conditioning contractor you’ll ever need. Call us any time to get troubleshooting advice for your AC system.

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Atlanta HVAC Tip: Heat Pump Air Duct Requirements

Monday, April 9th, 2012

Heat Pump Technology

Among the systems getting a fresh look are Atlanta heat pumps, a device that transfers thermal energy from one location to another, usually in the direction of from a colder temperature to higher and generally the opposite of the natural flow.  While compressor-driven air conditioners and freezers are technically heat pumps, “heat pump” is the term that usually implies one of the less-common devices in the class that are not dedicated to refrigeration-only.

Heat pumps can provide both heating and cooling; they simply reverse the heat flow from inside to outside and vice versa depending on the season. Heat pumps use the thermal energy in the outdoor air, even when the temperature is near freezing they can still transfer the heat that is in the air into your home. Since heat pumps transfer heat instead of producing it through combustion, more and more people are seeing them as an energy efficient Atlanta heating and cooling option.

Atlanta HVAC  - Air DuctsChange of Use

In considering a change from an existing system to a heat pump, there are many details to compare to see if it makes any sense at all.

Since a heat pump typically moves conditioned air through ductwork, the advantages of the change are much more realistic with a system of pre-existing ducts such as a forced air furnace or central air-conditioning unit.  While a heat pump often requires a larger volume of ducts, the old network of metal tunnels was often over-sized for inefficient furnaces and should do fine in a conversion to a heat pump.

The Right Data

Since the required formulas are dependent upon variables such as size, distance, volume and oomph, the design is strategic and makes all the difference.  Consulting with a trained and experienced professional such as Cool Air Mechanical is critical to the success of the conversion.

Do the homework to get the best recommendation for your home.

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Atlanta Air Conditioning Repair Tip: Things to Check on Your Broken AC Before Calling a Professional

Monday, April 2nd, 2012

Atlanta Air Conditioning RepairA broken air conditioner is a stressful situation, especially since you’re considering whether you need an Atlanta air conditioning professional to come out. No one likes spending hundreds of dollars to have a professional take a look at their system, so before you call anyone, make sure to check these problems. You may be able to fix the problem on your own without spending a dime.


The thermostat is one of the most common problems you’ll have with an air conditioner.  Make sure the thermostat wasn’t knocked out of position and the sensors near your coils are in the right place. Often times, a bumped sensor or a slightly off thermostat can cause this kind of problem and as a result, you’ll be left without steady cooling.

 Check Your Filters

A clogged air filter is a common problem that many homeowners run into. In many cases, your air conditioner will not stop running, but its performance and energy efficiency will suffer. Signs of a clogged filter include a bad smell around your unit and icing on your outside line. Remember to replace your air filters on a monthly basis, and it definitely on of the first things you should check before calling a professional.

 Blower Belts

Your system’s blower belt can be damaged and develop cracks or excess slack. This can reduce air flow which will make it harder for your system to maintain a steady temperature and might cause ice build up. While very difficult for the average homeowner to replace themselves, this is a pretty simple repair for an H VAC technician.

 Check the Outdoor Unit

Check to make sure nothing is blocking the outdoor unit. Clean the condenser coils and remove any debris that might have built up around the outdoor unit. Often, slowed air flow is caused by nothing more than leaves piled in front of your condenser.

If none of these problems is the culprit or if you fix them all and your system continues to struggle, it is time to call an Atlanta air conditioning contractor.

If you have any problems with your air conditioning system this season, give Cool Air Mechanical a call!

Photo by +++CoolValley+++

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