Buying a New AC or Furnace?

6 Pitfalls to Avoid

If your air conditioner or furnace just died, you’re facing some quick and tough decisions. Now is the time to take a deep breath and not rush to an uninformed decision.  The top mistakes people make when purchasing a new heating or cooling system are:

  1. Ignoring SEER – The higher the SEER (seasonal energy efficiency ratio) rating the more efficient the unit, which translates to less money spent each month heating or cooling your home. A 13 SEER rating is the minimum; 15 SEER is good; above 16 is high efficiency. A high efficiency system can cut your energy bills in half when compared to an old 8 SEER unit and also provides many comfort benefits.
  2. Missing rebate opportunities – Many states and manufacturers offer rebates to help offset the costs of some systems, particularly those that are higher efficiency.  In fact, some states offer as much as $1500 in rebates. Talk to your contractor or visit to learn more.
  3. Only getting one estimate – Prices and options will vary, as will service contracts, installation costs, and permits.  Shop around and compare apples to apples.
  4. Going for the lowest price – A low price does not always equal the best value. A higher efficiency system might cost an extra $800 up front, but could save you $300 per year in energy costs. Over the life of the system, typically 12-15 years, you would be saving significant dollars by paying a little more for the higher efficiency system.
  5. Not considering maintenance contracts – Maintenance is necessary to keep your system functioning in optimal conditions over the life of the unit.  Over time dirt, debris, and other foreign substances can cause build up in your system, erode electrical connections and cause other damage that is expensive to replace.  In addition, the buildup can cause a 14 SEER unit to perform like a 10 SEER one, making your system work harder and your utility bills higher. Ensuring your system is clean and maintained annually can extend the life of your system and help you avoid expensive and preventable repairs in the future.
  6. Not paying attention to refrigerant – R-22, which might be referred to by a brand name like Freon®, has been restricted from use in all new units produced after 2009. As an ozone-depleting gas, new R-22 refrigerant should not be used in  new systems.  If you’re buying a new system make sure it uses R-410A or a similar approved refrigerant. In some cases repairs can be made to existing systems using the R-22 refrigerant that is already in your old system or it can be repaired and recharged with “re-claimed” and recycled R-22 refrigerant from other old systems.

Buying a new air conditioner or furnace is a big decision.  Take the time to make it a good one.  Have you recently replaced your system?  Tell us what you learned before your purchase!

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65 thoughts on “Buying a New AC or Furnace?

  1. I need to replace a 18 year 3.5 ton heat pump system wich has a 10 SEER rating. If I buy a new high efficiency system 16-18 SEER would I still need 3.5 tons or does the size requirement go down with a more efficient system?

    • Hi Kevin – you would probably still need about the same capacity as the unit you are replacing. Efficiency ratings just indicate how much energy a unit uses for its rated capacity. It might also be a good idea to get several estimates from different contractors to check to make sure the load on your home has not changed due to things like room additions, new doors or windows, insulation, shade, etc. If you go with the higher efficiency, multi-stage models (16+ SEER or greater) as you indicated you should realize better comfort as well as save on your energy bills but you still need to get the max capacity right to size the unit for the hottest days in your area. A good contractor can help with that calculation. Good luck with your new system!

  2. I really like your tip for avoiding just getting one estimate. My husband and I have been thinking about getting a new AC unit for a while now so we will have to keep these tips in mind. Our current unit is costing us a lot of money so we definitely need something that is more efficient.

  3. I have a 17 year old gas furnace and electric AC system. The inducer motor needs to be replaced on the furnace. Because of the age of the system, the HVAC company will replace the motor, but is suggesting I consider replacing the furnace, and possibly the AC. They did not identify any other issues with either system, but they think the systems are past their prime. I can replace the inducer motor and keep the system running for a fraction of the cost of a new system. I’m going to be putting the house on the market in 12 to 24 months to downsize. Even if the systems do not break down before then, will I just wind up replacing the systems anyway when I go to sell?

    • Hi Joyce,

      Generally, most HVAC systems have a life of 14-16 years however replacing certain components may prolong the life of the overall system. The system may operate just fine with the repairs/replacements. Although it would not be a requirement to upgrade the system when you decide to sell, it could be an incentive to the buyer, or requested as a condition of sale given the age.

  4. I have gas fired blown warm air system for heating so the duct work is there and I was told by home inspector that when the furnace was recently installed, the inside work for central air was completed and that I needed the outdoor unit, connections and refrigerant and I would be good to go, saying half the work was done. How will the contractor determine what kind of condenser to install to pair with the existing setup? Anything else I should be looking out for or asking about when I’m getting my estimates?

    • Hi John,

      The contractor would use the model number of the indoor unit to select a compatible outdoor unit. We would suggest that you contact a qualified contractor for a quotation and encourage people to get at least 2-3 quotes from a few different contractors not only to get competitive prices but to also get different opinions on the installation project, equipment sizing, types and efficiency levels. The ACCA – which is a national contractor organization has a contractor locator tool which may also help you find a qualified contractor in your area.

      Here’s the link:

  5. I have a 31 year old split system. With the exception of 2 circuit breakers over the past 4 years, it has worked flawlessly for the 21 years we’ve owned the home. Seems to be doing just fine yet while we can afford it right now, my wife wants us to consider an energy efficient upgrade. SO, do I remove a perfectly good system for a new one. BTW…its a 4-ton trane

    • Hi Bill,

      It is a difficult decision to replace items that are not ‘broken’ and 31 years is great service life! A qualified contractor would be able to estimate the energy savings and explain the increased comfort advantages of a new unit. In general it is always a good idea to have a few quotes from different contractors before making any repair or replacement decisions. The ACCA – which is a national contractor organization has a contractor locator tool which may also help you find a qualified contractor in your area.

      Here’s the link:

  6. We have boiler heat and a dying A/C unit. We got a quote to repair our boiler at a cost of $750 and replace our A/C at a cost of $4,000 OR, we can replace our A/C AND add a forced heat for $4,500. Since I really like our boiler heat, I’m opting to repair it, but it just seems logical to go with the A/C and furnace combo since I’m replacing that unit anyway and it would be a good backup for heat if the boiler went out. The A/C is a 13 seer and we have the option of a single stage for $4,500 or a 2 stage for $5,000. What would your suggestion be to do? Also, if the heat is 2 stage, does that automatically make the A/C 2 stage as well?

    • Hi KM – I really like my boiler heat too so I would definitely keep that and have it repaired. You might look into an AC Heat pump instead of an AC with a gas furnace. Since you already have the boiler you could use the heat pump for the milder heating days and just use the boiler for the coldest periods – and you can use either the electric heat pump of the (gas or oil) boiler as the rates change. Dual stage gas furnace does not always imply that you have two stages of capacity on the AC. Two stages or variable speed on the heat pump systems means both have that staging capability. I hope this helps to answer some of your questions. Thanks for using our site!

  7. Need to replace old ac unit. We have a new heating system only 3 years old with a 13 seer rating. Does our new ac unit need to be 13 seers as well or can we go higher seer even though our heating system is only 13 seer.

    • Hi Doreen – you can go higher on the AC SEER. SEER is a rating used for AC and not for heating. Not sure what the rating is on your furnace but these do not have to match unless it is a heat pump.

    • Hi Daniel – most people do not replace their ductwork when they purchase a new HVAC system since it is usually fixed in place and does not typically wear out with use or over time. It is a good idea to have the contractor inspect the ductwork for leaks and see if it needs cleaning (there are companies who specialize in this). If you have easily accessible flex-duct or if you have some old sections that might be easily replaced you could just replace those sections rather than replacing the who duct network. Another thing you could do is talk to the contractors about adding some additional ducts into spaces that are not getting enough conditioned air with your old system or you can talk to them about setting up a zoning system where you can shut off certain sections from time to time. There are automated duct zoning technologies available as well. I hope this answers some of your questions.

  8. The article talks about the SEER rating which is good. It would have been wholesome if it would have talked about installing a new energy efficient A/C unit with an older furnace like 80% Furnace.
    Can someone please elaborate on the above match up? Is it ok to do it if the Furnace is good but the A/C unit is gone?

    • Hi KG – it is pretty common to just replace the AC system and keep the furnace and air handler if they are still in good shape. This happens often in parts of the country where the AC gets more run time than the furnace. One thing to watch is whether the new AC system’s indoor coil will fit in the space on the indoor unit. Since the minimum allowable efficiency was increased in 2006 and again this year, the new coils will probably be larger than the one you have.

      A few other things to consider would be keeping your furnace but upgrading your AC to be an AC-heat pump which can also efficiently heat your home in the winter using electric power. You can use your gas furnace to heat your home on the coldest days and nights when the heat pump is not as efficient and gas becomes more efficient and cost effective to operate. You should also consider upgrading to a two stage or variable speed high SEER system (16 SEER or greater) to realize improved comfort and humidity control. Look for two stage or two steps of capacity at a minimum to get this benefit. They cost a little more but it might be worth it depending on your location and usage pattern.

      I hope this helps to answer your questions.

      • Is there a concern to have the duct work enlarged at the furnance to accommodate the larger inside coil on an older furnace?

  9. Hello,
    My furnace just died! i live in a cluster home. The furnace is sitting on top of part of the a/c so I see the benefit of replacing both at the same time. However, I am reluctant to purchase a high efficiency furnace. The one I have is 80% efficient. I am fine with that. Is it ok to not go to the High efficient furnace? I really don’t have the money to invest right now. But I will if you think I will regret it down the line. What are the pros/cons of not getting the high efficient furnace?

    • Here are some things to consider. On average, HVAC systems in the U.S. are replaced after they are about 14 years old – but this varies by region and run time. For example, heat pumps that run year round have shorter lives and AC in the south has shorter lives, but AC lives in the north might be longer. If your system is older and/or has had a lot of hours it might be best to replace both the AC and furnace now to get them both done at the same time and avoid the extra labor expense of doing two, separate installation projects.

      The benefits from high efficiency (both AC and furnace) include lower energy costs and in some cases improved comfort due to having two or more stages of capacity – which provides better temperature and humidity control. Depending on where you live you might also want to consider a heat pump or a dual fuel system. These feature the combination of both a heat pump and a low efficiency gas furnace to use on the coldest periods. If you wanted to break up the purchases for financial reasons you could install a low efficiency gas furnace and air handler now and add the high efficiency heat pump to go with it later when your AC needs to be replaced. In any case, we recommend getting quotes from 2-3 good contractors before deciding. You can ask them about these questions and they can help you select the right equipment for your particular situation. I hope this helps to answer some of your questions.

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