Your HVAC coil is one of the most important pieces when it comes to controlling the temperature in your home throughout the year, so you want to make sure that it is always working properly.  While coils are meant to last, they can easily become worn down and become less efficient if not maintained properly. If you’re looking for replacement coils for your home, look no further than HVAC Parts Shop, your leading internet source for Lennox OEM repair parts. From stand-alone replacement coils & drain pans to full coil assemblies, we make it easy for you to get the parts you need at affordable price and with fast shipping right to your home.Apparently, I haven't written a single article this summer about oversized air conditioners. I've written several in previous summers, mostly about how HVAC contractors bypass the HVAC design process by using rules of thumb and how they mess up the Manual J load calculations when they do go the preferred route. I've never written an article focusing on the reasons to size an air conditioner properly, though, so here it is.

When an air conditioner runs, it does two jobs. It lowers the temperature of the air, and it removes moisture from the air. To do the second one, the AC has to run for a while. As the air passes over the evaporator coil, it encounters a very cold surface. Ideally, when the air passes over that cold surface, the air temperature drops about 20° F. how to determine seer rating on ac unitIn places where we have higher relative humidity in the summer, the other important process that happens when the air hits the coil is that the temperature of the coil is below the dew point of the air. ac unit throws breakerAs a result, water vapor condenses on the coil.freon for window ac unit Here's the thing, though. Water vapor condenses on coils in oversized air conditioners, too, but you have to get enough condensation on the coil for the water to start dripping down into the pan below the coil.

Even then, you're not there yet. You still have to get enough water in the pan for it drain to the outside. Until the water that condenses actually makes it to the outside, you haven't really dehumidified the air. Because that water on the coil can evaporate and get back into the air in the home. If you make the mistake of leaving your thermostat in the Fan-On position instead of Auto (Don't do that!), the water on the coil gets back into the air even quicker. Oversized air conditioners don't run for a long time because they satisfy the cooling load quickly and then shut off. Properly sized air conditioners run longer, so if you want your air conditioner to dehumidify your home as well as cool it, don't let the HVAC contractor oversize it. If you live in the desert, what I just said above doesn't matter to you. There's no water vapor to condense on the coil, and if there were, your dew point is probably close to absolute zero. (Well, OK, that might be a bit of an exaggeration.)

The second reason definitely should matter to you, however. The thing that wears equipment out is starting up and shutting down. The more it happens, the shorter the life of the equipment. When an air conditioner is oversized, it starts up and shuts down a lot more because it runs for only a short time to meet the thermostat setpoint. Then a few minutes later, it comes on again and runs for a short time. Over the course of a day, an oversized air conditioner can have a lot more start-ups and shut-downs than a properly sized air conditioner. That means you'll probably be repairing it more often and replacing it sooner. People in the industry used to think you'd save money on your air conditioning bills with a properly sized air conditioner, but that thinking has changed. John Proctor wrote an article for Home Energy Magazine that shows only a small savings for the homeowner (but the utilities benefit by lower peak loads). You should save money on the upfront cost, though, because you're putting in a smaller AC. (As Proctor points out in his article, oversizing isn't always the worst problem, though.

You have to be a subscriber to Home Energy Magazine to read the article, but it's well worth the read if you can get it.) For new homes, use the full HVAC design process, which starts with Manual J, the heating and cooling load calculation protocol from the Air Conditioning Contractors of America, the trade association for AC contractors. For existing homes, the best way to do it is to see how long your current air conditioner runs when it's at the design conditions. Of course, you want to do this while your AC is still in good shape, not when it's on its last legs. If it runs for only 5 to 10 minutes before shutting off, it's definitely oversized. If your runtimes are over half an hour at design conditions, it's probably sized close to the actual cooling load. If you're building a new home, remodeling an existing home, or just getting a new air conditioner in an existing home, ask your builder, remodeler, or HVAC contractor how they're planning to size the air conditioner. If they tell you they're basing it on the size of your house, don't let them do it.

There's a lot more to it than square footage of conditioned floor area, and of course, I haven't touched at all on the capabilities of different types of equipment (single speed, fixed capacity, multi-stage, mini-splits...). More on that in future articles. Oversized AC, Screwed-up Manual J, ENERGY STAR HVAC Tirade!Don't Assume It's Correct. We Are the 99% — Design Temperatures & Oversized HVAC Systems An Oversized Cooling System Isn't Always a Bad Thing up to 2 Tons up to 3 Tons up to 4 Tons up to 5 Tons Huge selection of used and discount evaporator coils. Product Name: A to Z Product Name: Z to AModel numbers: 1024A13, 1024A16 Replacement evaporator Coil Characteristic profile 3 row replacement A-coil that is available in 13" and 16" wide plastic drain pans that is 19½" deep. The nylon resin is UL 94, 5VFR and U.V. light safe. The Coil is left hand configured with pre-swaged 3/8 liquid, 3/4 suction line connections and shipped with a dry nitrogen holding charge. 

The coils are piston metered for a nominal 2 ton R-22 application and can be converted to a R-410A refrigerant by resizing the piston or installing a R-410A expansion valve. The face area of the coil is 2..22 sq. ft. and the internal refrigerant volume is 94.08 cu. in.  Please click on the appropriate PDF above for printable specifications. Model numbers: 1036A13, 1036A16 Replacement evaporator Coil Characteristics plastic drain pan that is 19½" deep. The nylon resin is UL 94, 5VFR and U.V. light safe.  The coils are piston metered for a nominal 3 ton R-22 refrigerant application and can be converted to R-410A refrigerant by resizing the piston or installing a R-410A expansion valve. The face area of the coil is 3.12 sq. ft. and the internal refrigerant volume is 131.71 cu. in. Please click on the appropriate PDF link above for the printable specifications. Model numbers: 1048A16, 1048A20 profile 3 row replacement A-coil that is available in 16" and 20" wide

plastic drain pan that is 19½" deep.  liquid,  7/8 suction line connections and shipped with a dry nitrogen holding charge.  The coils are piston metered for a nominal 4 ton R-22 application and can be converted to R-410A refrigerant by resizing the piston or installing a R-410A expansion valve. The face area of the coil is 4.00 sq. ft. and the internal refrigerant volume is 169.34 cu. in.  Please click on the appropriate PDF link above for printable specifications. Model numbers: 1060A20, 1060A23 profile 3 row replacement A-coil that is available in 20" and 23" wide liquid, 7/8 suction line connections and shipped with a dry nitrogen holding charge.  The coils are piston metered for a nominal 5 ton R-22 refrigerant application and can be converted to a R-410A refrigerant by resizing the piston or installing a R-410A expansion value. The face area of the coil is 4.89 sq. ft. and the internal refrigerant volume is 206.98 cu. in. above for printable specifications.