25 May 2016
 Categories: , Articles

The average central air conditioning system consists of two halves -- the indoor unit containing the evaporator coil and blower fan and the outdoor unit containing the compressor and condenser coil. Both are designed to work in unison to keep your home cool and comfortable.

When one half of your A/C system breaks down, it's tempting to replace only that half with a newer and more energy-efficient component. However, doing just that could be the start of an expensive and ultimately fruitless journey. There are plenty of good reasons why your central air conditioning equipment must be perfectly matched for the best performance and efficiency.

Compatibility Issues

Imagine buying a new indoor unit for your aging central A/C system, only to run into one of these issues:

• The new unit doesn't use the same type of refrigerant as its older counterpart.
• The new unit's cooling capacity doesn't match that of the old unit.
• The old unit lacks certain features that the new unit offers.

Refrigerant incompatibility is one of the major pitfalls of mismatching a central A/C system. While older A/C units rely on R-22 refrigerant, newer units use a wide variety of environmentally friendly refrigerants such as R-410a and R-422d. Many of these refrigerants require higher operating pressures or use lubricating oils that are incompatible with older A/C units. This makes it nearly impossible to match both old and new units together without the risk of ruining both units.

By matching an older half of a central A/C system with a newer half, you might not be able to take advantage of the latest features offered by today's A/C systems. Features like multi-stage compressors, thermal expansion valves and high-efficiency coils may not work well with older equipment, resulting in noticeable losses in energy efficiency and cooling performance.

Unequal Systems Offer Unequal Performance

Another pitfall involves using a unit that has different cooling capacity and performance specifications than your old unit. Pairing a high-efficiency outdoor unit with an older, lower efficiency indoor unit could leave the latter struggling to perform at the same level as the former. This can also lead to a number of problems later on, including chronic coil icing and eventual compressor failure.

According to Joanna R. Turpin's interview with HVAC expert Pedro Portillo, some contractors may deliberately install an outdoor condenser unit that has slightly less capacity than the indoor evaporator unit in an attempt to reduce humidity and improve efficiency. However, the small gains in humidity control and energy efficiency are usually outweighed by the loss in overall comfort and added wear and tear on the A/C system.  

Mismatches Can Prove Expensive

It's not unusual for homeowners to install mismatched A/C systems under the mistaken belief that it's a cheaper option to a complete central A/C replacement. However, a mismatched system can prove to be a drain on your finances. According to HomeAdvisor, the average homeowner spends between $165 and $494 on A/C repairs. The increased stress and resulting wear and tear on your mismatched A/C system could result in more frequent HVAC service calls. In the end, you could end up spending far more than the average amount on keeping your mismatched A/C system alive.

Mismatched A/C systems can also prove costly in other ways. Not only can a mismatched A/C system consume more energy (and consequently increase your home's utility bills), but using mismatched equipment can put it at risk of having its warranty voided, which could result in steep out-of-pocket expenses if you have to replace your A/C equipment.

For these reasons, it's important to make sure the different parts of your A/C/ system match each other. To make sure you're making the right decisions when replacing your broken A/C system, work with an experienced HVAC company like Controlled Comfort.