Air conditioners don't last forever. The good news, though, is that if you have an old air conditioning system, replacing it should save you money. Efficiency has improved a lot since that old hunk of metal and noise was installed in your back yard. Beyond just swapping out the old equipment for new, getting a new air conditioner really needs to involve some thought. Here are five things for you to think about and ask potential contractors. If possible, you should use an HVAC contractor who understands building science and will treat your air conditioning problem using a systems approach. An air conditioner is only one component of many that helps with the heating and cooling of your home. Insulation, air leakage, duct leakage, solar gain through windows, radiant heat problems in bonus rooms, and more all affect the comfort, healthfulness, durability, and energy efficiency of your home. To understand the basics, see our article on Building Science 101. If you ask an HVAC contractor how they're going to decide what size air conditioner to put in, there are some wrong answers that should have you yelling, "Next!"

Here are a few: The first answer is bad because they're assuming the original contractor sized the system properly—and that nothing has changed since. The second is bad because they're assuming that bigger is better. The third is bad because using a rule of thumb based on square footage doesn't work, and they should measure the house themselves rather than relying on your number. The proper way to size heating and cooling systems is to calculate the actual heating and cooling loads for your home. To do so, the contractor has to measure the house completely, get all the insulation R-values, window types, orientation, infiltration rate, duct leakage, and more. Then they put all that into their load calculation software and find out how many Btu's per hour your home needs. The most common way of doing this is to use the Manual J load calculation protocol. Proper sizing is important because an air conditioner does two jobs: (i) cools the air, and (ii) dehumidifies the air.

In a humid climate, an oversized air conditioner will cool just fine but won't dehumidify well. Also, oversized systems go on and off a lot, and all those start-ups and shut-downs will shorten the life of your air conditioner. What happens inside the cooling equipment is only part of making your home cool and comfortable. The distribution system plays a huge role, and the typical duct system has a lot of leakage in it. 4 ton ac unit for saleIf you're paying a lot of money each month to run your air conditioner, you don't want to waste that cooling through a lot of leaks in your ducts, do you? 12 ton ac unit for saleA duct leakage test will determine how bad your ducts are.central ac sizing chart Duct leakage isn't the only problem with getting cool air into your home.

Many duct systems don't move as much air as they should because of ducts that are too small, kinked, too long, or have other types of constrictions. At a minimum, your HVAC contractor should measure the total external static pressure and make sure it's within the limits specified for the equipment they're installing. Ideally, they'll also measure the air flow to each room to make sure your home will be heated and cooled uniformly. Remember, it's not all about the air conditioner. The overall performance depends a lot on how well the ducts move the conditioned air. If you're serious about getting a new air conditioner installed for peak performance, head over to the ACCA website and download their Quality HVAC Installation Checklist. Use it as a guide to choose the right contractor. In addition to the checklist, they have a nice page on their website on choosing the right HVAC contractor. Getting an air conditioner replaced is a big investment. It's also an opportunity to improve the comfort, healthfulness, durability, and energy efficiency of your home.

It won't happen without your involvement, though, because many HVAC contractors will be happy just to swap out old equipment for new without looking at the bigger picture. Find one who's willing and able to go beyond the box. Even better, get a full home energy assessment. How to Choose a Company to Do a Home Energy Audit Case Closed: Get Those Air Conditioning Ducts out of the Attic< 1 2 3456789 > 1 posts, read 151,253 times Originally Posted by ByteRider I have been in the industry for more than 15 years on the Gulf coast and i totally disagree. Not just anyone can replace a compressor. First how do you know it's the compressor? Second, what caused the failure? Was it a burnout? Why would I need to know if it was a burnout? What must I do if it was a burnout? Not to mention the possibility of electrocuting yourself. Next you use 15% silver solder not 50%. What are the dangers of soldering? What happens with oil residue in the refrigerant lines?

What happens when flame is introduced to freon and freon residue in the lines? Ever heard of phosgene gas? What about the Oxygen Depletion Potential of freon? What about how inhaling freon causes heart arrhythmia? What about refrigerant recovery and disposal? What about evacuating the system? A/C systems, are very susceptible to moisture and other non condensibles. How are you going to purchase replacement freon with no EPA certification? What about the life threatening dangers of freon? How much freon do you add? You just can't go by the factory charge on the nameplate. You have to take into account many factors and then calculate your super heat and subcooling in order to achieve a proper charge. There are so many things to consider before trying to tackle something like this. If injury or death doesn't deter you, then the fact that you did it yourself will probably void any warranty that come with your $1000 compressor should. I can look up how to do an appendectomy online and get step by step instructions but I'm pretty sure most people would agree to just get someone who has been properly schooled and trained to do it.

This is not like changing a fuse or the oil in your car. You could die or even possibly kill someone else many different ways if you don't know what you are doing and I would never recommend a compressor change out as a DIY project for a novice. 16,739 posts, read 46,615,361 times 1 posts, read 151,139 times 9,224 posts, read 34,826,474 times Originally Posted by archcolin By yesterday's standards, a 2ton unit would probably be OK. By today's standards there no telling without a physical inspection of the home. Calculating a house for A/C requires a Manual-J worksheet. There are a lot of factors that are used in the calculation- # of doors and windows. Wall construction and insulation. compass direction (solar gain), etc. Then there's the Manual-D for the duct system. and finish all your calculations with a Manual-S. Today, there is no reason to guesstimate. By doing a thorough calculation you will have a system that works at peak performance with minimal operating expense.

2,398 posts, read 4,448,953 times Actually a license is only required if your system uses R22 freon, which of course most old systems do. If you have or are replacing with system with a R410-A refrigerant, no license is required. So long as your not touching a R22 system, your fine. If your replacing a R22 system with a R410-A system you need a licensed HVAC contractor to recover the R22 refrigerant from the old system before removing it. Originally Posted by ComfortZone1971 If you haven't mastered the mysteries of the circuit broker or equipment disconnect, you probably shouldn't be doing anything yourself. Pretty much anything you touch now a days voids the warranty. I wouldn't mass with the R22, but I wouldn't let a little thing like voiding the warranty stop me from working on it. Originally Posted by TechGromit I know the EPA would love to talk to you! You are required to have an EPA Section 608 Type II or Universal certification license to handle R-410A but no license is legally necessary for purchase.