HVAC Buying Guides & Advice

If you're replacing a gas furnace, you may quickly run into two common efficiency ratings: 80% AFUE and 95% AFUE. At first glance, comparing an 80 vs 95 furnace seems simple. The 95% model uses more of the fuel it consumes to heat the home.

That difference matters, but efficiency is only part of the buying decision.

An 80% and a 95% furnace can differ in how gases are vented, if drainage is required, and what changes may be needed during installation. Your existing furnace setup can have a major influence on which option makes sense for a replacement.

Replacing an air conditioner used to start with familiar questions about tonnage, efficiency, electrical requirements, and equipment compatibility. Now there is another specification that deserves attention before anything is ordered: refrigerant.

The transition from R-410A to lower-global-warming-potential refrigerants such as R-454B has created some understandable confusion. An existing R-410A system does not automatically need to be replaced just because newer equipment uses another refrigerant. At the same time, an R-454B condenser should not be treated as a direct substitute for an R-410A condenser.

Understanding R-454B vs R-410A is especially important when only one major HVAC component has failed.

Shopping for replacement HVAC equipment is much easier when you know exactly what is already installed. One of the best places to start is the equipment nameplate.

If you're trying to read an HVAC nameplate, you do not need to understand every number printed on it. Your first job is simply to find the plate, take clear pictures, and identify a few useful pieces of information such as the manufacturer, model number, refrigerant, electrical requirements, and capacity-related details.

Those details can help an HVAC professional or equipment supplier understand what you currently have. They can also reduce the risk of shopping for equipment based only on square footage, tonnage, or a partial model number.

Shopping for a new central air conditioning system can look straightforward at first. You need a certain tonnage, so you find a condenser with that capacity, pair it with an indoor coil of the same general size, and you should have a complete system.

Not necessarily.

Split HVAC equipment is made up of components that operate together. The fact that two pieces of equipment are both labeled 3 ton, for example, does not prove that they are a certified combination. An AHRI matched system gives buyers another piece of information. It identifies a specific combination of indoor and outdoor equipment whose performance has been certified together.

Understanding that distinction is useful before buying a condenser, coil, furnace, air handler, or complete matched AC system.

If your central air conditioner’s outdoor unit fails, replacing the entire cooling system may seem like the obvious next step. But that is not always necessary.

In some situations, you can replace the outside AC unit and continue using the existing indoor equipment. The important part is determining whether the new condenser can properly work with the evaporator coil, furnace or air handler, refrigerant, controls, and other components already in place.

That means a condenser-only replacement should not be based on tonnage alone. Before ordering equipment, the complete system needs to be evaluated.

If you're replacing an air conditioner or shopping for a new HVAC system, one of the first questions is usually, “What size HVAC system do I need?”

Square footage can help you begin narrowing your options, but it cannot give you the final answer by itself. The same is true of the tonnage printed on your existing air conditioner. Both are useful pieces of information, but neither tells the complete story.

For residential cooling, the amount of capacity a home needs depends on how much heat the home actually gains under expected conditions. Size, insulation, windows, air leakage, climate, orientation and several other characteristics can change that load.

Understanding that distinction can help you shop more intelligently before an HVAC professional confirms the final equipment selection.