When should you replace your central air conditioner units?

[dennis thompson]

My house was built in 2005 and still has its original 3 central air conditioning units, one for each floor. They work fine but I wonder, at what point would you think they should be replaced?

[Lee Schierer]

IMO, unless they fail or are requiring service excessively you will be hard pressed to gain enough efficiency improvement to justify new units.

[Nathan Johnson]

Mine was installed in 1994.
I cross my fingers every summer since we bought the house in 2011....so far so good!

[George Yetka]

If they get to a point where maintenance is an issue or its seer value is so low that the power savings would pay for the new equipment.

[Edward Weber]

All the units you guys have and mine are more than likely R-22 judging by their age. They can't even repair(add refrigerant) these units anymore. All new units contain R-410A, so when the time comes, it's an all new system. You can't replace a condenser, evaporator coil, or compressor to try and nurse it along for a few more seasons.
Back to the original question, usually15-20 years depending on all the usual variables, location, hours of use, etc.
Mine is 14 years old and I've already looked into it.

[John K Jordan]

My house was built in 2005 and still has its original 3 central air conditioning units, one for each floor. They work fine but I wonder, at what point would you think they should be replaced?

I replace it if it seriously breaks or when doing a major renovation if it has some age on it.

I had a new Trane put in a few years ago during a major remodeling. The old unit was well over 30 years old and still heating and cooling nicely. The HVAC guy was surprised the old one was a large commercial unit, perhaps a reason for it's long life. We replaced it with a similar commercial unit.

In the previous house I replaced the outside unit when the compressor failed, out of warranty.

JKJ

[Brian Elfert]

One of the issues with waiting is your A/C might go out during the hottest time of year when you can't even get an appointment for a couple of weeks. The OP has three units so they could probably get by with one dead unit for a while. This year there is a major issue even getting replacement A/C systems. It is taking upwards of a month to get equipment where it has usually been just drive over to the supply house and pick the equipment up.

I have told my parents they really should replace their 27 year old air conditioner before it fails. Me personally I probably wouldn't go more than 20 years max for myself. My furnace, A/C, and duct work was installed in 2014 so I should be good for a while yet.

[Kev Williams]

We replaced an 18 year old unit a few years ago, the cooling fan motor went out. It was still working okay otherwise but decided to change it out. The repair guy showed me one test he recommends for the do-it-yourselfer: Check the amperage draw... the old one was pulling over 12 amps, the new one was less than 8-

[Tom M King]

I think only if one needed a couple of major parts, in the same year, other than capacitors, or it used some old form of refrigerant that I don't mess with anymore.

[lowell holmes]

If you are concerned have a service company check it out.

[Larry Frank]

A few years ago we replaced our 20 year old gas furnace and AC. I tracked gas usage in the winter and kWh in the Summer. I was surprised to see a 15-20% reduction in energy use.

[Bruce Wrenn]

All the units you guys have and mine are more than likely R-22 judging by their age. They can't even repair(add refrigerant) these units anymore. WRONG ANSWER! Yes you can service older units, using "blends" to replace R-22. Google "Replacement for R-22" and see what pops up. Our old unit (Carrier heat pump,) replace two summers ago with a Goodman. Second HP (also Carrier) replaced last summer with another Goodman. Power bill has been cut in HALF, plus house is more comfortable. FYI, both HP's were about 40 years old. When bought, they were "top of the line" models.

[Brian Elfert]

A lot of HVAC contractors still have R22 in stock, although one guy charges $200 per pound. If you need refrigerant you almost always have a leak. It often isn’t worth it to fix a leak in an old system unless the leak is obvious and easy to fix.

[Mike Henderson]

All the units you guys have and mine are more than likely R-22 judging by their age. They can't even repair(add refrigerant) these units anymore. All new units contain R-410A, so when the time comes, it's an all new system. You can't replace a condenser, evaporator coil, or compressor to try and nurse it along for a few more seasons.
Back to the original question, usually15-20 years depending on all the usual variables, location, hours of use, etc.
Mine is 14 years old and I've already looked into it.

R-22 is not being manufactured any more and can't be imported (legally). But it can be recovered from old units and sold. The price is fairly high, however. So you can get your old unit serviced but eventually the cost of R-22 will be too high and you'll replace your unit.

@Dennis Thompson - air conditioners seem to fail during the hottest weather. But since you have three units, you can still stay cool. If you're going to keep three units when you replace, I'd probably choose the one you use the most and replace it in the off-season when you can get a better price. That way, you'll know you have one unit to keep you cool.

Air conditioners are rated in SEER (seasonal energy efficiency ratio) (https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_ratio). At one time a SEER 13 was considered pretty good. Today, you can get units up to maybe 20 but they're expensive, I'd go with one rated maybe 16.

Mike

[Tom M King]

I left out one factor. If I was worried about one being long in tooth enough to be close to losing its refrigerant to the atmosphere, I'd recover the refrigerant, and commit it to scrap metal. I wouldn't be running one with R22 this late.

[Roger Feeley]

My daughters house has one air handler in the attic. I have no idea how they got that thing up there. There’s a fold down stair and a big return that’s about 30” square. My guess is that they hoisted the AH through that return before putting in the duct.

That return in the upstairs hallway serves the whole house. We have it on a service contract and I asked the tech about it one day. He said it looked like a hack job. The main plenum should reduce in size as various branches take air. But it’s just this big box. When they replace that thing, it’s not going to be just plugging a new air handler in where the old one was. I think they are going to have to redo the ductwork.

[Erik Loza]

Funny timing: Our upstairs AC unit just died last week and crew should be replacing it today. It was an appropriately sized Bryant unit. Not sure cause of death but suddenly developed a leak and won't hold refrigerant. Unit was installed, new, in 2012, so almost 10 years old. Only other issue we had previous was the capacitors needing to be replaced. Also, I am not totally unconvinced that the Freezemaggeddon we had here in February didn't have something to do with it. Like, fatigued lines or something. We are having a Lennox unit installed instead of another Bryant.

Erik

[Stan Calow]

I've replaced AC units twice. Each time they were around 12 years old. The signs they needed replacing were (1) compressor running all the time even on not so hot days. (2) temperature drop (measured at a vent) was less than spec (I think 20º). (3) coils freezing over. (4) electric bill suddenly much higher than normal summer months.

[Mike Henderson]

I've replaced AC units twice. Each time they were around 12 years old. The signs they needed replacing were (1) compressor running all the time even on not so hot days. (2) temperature drop (measured at a vent) was less than spec (I think 20º). (3) coils freezing over. (4) electric bill suddenly much higher than normal summer months.

Those symptoms could be a sign of low refrigerant. Coils icing over is usually caused by loss of some of the refrigerant.

Mike

[Michael Weber]

Those symptoms could be a sign of low refrigerant. Coils icing over is usually caused by loss of some of the refrigerant.

MikeExactly. Low refrigerant or low air flow are about the only thing that will cause coils to freeze. I just replaced two condensers last month. The old units were beautiful two stage 18 SEER units given to me by my employer. Unfortunately, they were early high efficiency models with complex control boards and early ECM motors. Things are simpler now and hopefully more reliable. Because I was paying for them I bought 16 SEER single stage units. The price difference was significant. In hindsight, the SEER rating is fine but I miss the dual stages which really wrung the humidity out of the house much better that these do. Oh Well.

[dennis thompson]

Funny timing: Our upstairs AC unit just died last week and crew should be replacing it today. It was an appropriately sized Bryant unit. Not sure cause of death but suddenly developed a leak and won't hold refrigerant. Unit was installed, new, in 2012, so almost 10 years old. Only other issue we had previous was the capacitors needing to be replaced. Also, I am not totally unconvinced that the Freezemaggeddon we had here in February didn't have something to do with it. Like, fatigued lines or something. We are having a Lennox unit installed instead of another Bryant.

Erik

Erik
Just wondering why you choose Lennox?
Thanks

[Stan Calow]

Those symptoms could be a sign of low refrigerant. Coils icing over is usually caused by loss of some of the refrigerant.

Mike

Yes, that was true. I omitted saying that the cause of the leaks was unrepairable. Unit would not hold recharge.

[Erik Loza]

Erik
Just wondering why you choose Lennox?
Thanks


Well, we had a Lennox unit that was still going strong after 15+ years but got rid of it when we put the second story on our house in 2012. Went with two separate units. Both my wife and I felt Lennox was better quality than the Bryants but they were what we could afford when we did the remodel. It was a calculated move, I guess.

Erik

[Tom M King]

I have one tractor that is old enough to use R12 in the AC. It only needed a compressor, when I bought it cheap at an auction, years ago. I'm running R12a in it, which I really believe is pretty much only Butane. Butane makes a decent refrigerant, and is easier on the atmosphere than most of the others, but I guess hauling around a pound of Butane is a lot scarier than hauling a 20 gallon tank of gasoline.

[Scott T Smith]

I replaced my 1990 vintage Goodman unit three years ago when the compressor died. It's a good thing that I did, as I discovered that the gas furnace flues were starting to crack after almost 30 years of service.

Previously I had to replace the furnace blower motor (thank you to Graingers for opening up one Fathers Day so that I could source a replacement motor!) as well as some capacitors on the condenser fan. One thing that I have to do every two years or so is to remove the outer housing on the condenser and rinse off the condenser coils, as they will get clogged up with dirt, etc (we live on a farm).

The replacement unit was a Seer 16 Rudd and my power bill dropped by almost $100.00 per month during the summer. Gas usage remained about the same.

[Brian Elfert]

I have one tractor that is old enough to use R12 in the AC. It only needed a compressor, when I bought it cheap at an auction, years ago. I'm running R12a in it, which I really believe is pretty much only Butane. Butane makes a decent refrigerant, and is easier on the atmosphere than most of the others, but I guess hauling around a pound of Butane is a lot scarier than hauling a 20 gallon tank of gasoline.

One up and coming refrigerant is propane. I think it is more for commercial stuff right now. I couldn't imagine using it in a mobile application like a car.

[Ken Fitzgerald]

Our home was built in 1966 and had the original HVAC system, a Lennox, in it when we bought the place in 1982. That system lasted 21 years and I replaced it with another Lennox. 2 years ago that system gave out. Due to the Lennox factory fire in Iowa, the two local Lennox dealers switched brands. I chose to go with Bryant.

[Clifford McGuire]

Mine was installed in 1994.
I cross my fingers every summer since we bought the house in 2011....so far so good!

Similar for my old unit in my old farmhouse. Living in Wisconsin has it's advantages for air conditioner longevity. Now, about furnaces.....

[Kev Williams]

I dunno, I'm thinking butane or propane is just a wee bit too EXPLOSIVE for my taste ;)

So how/why does ammonia work in RV refrigerators? (something I've never researched)

[Brian Elfert]

RV refrigerators heat the ammonia which then somehow absorbs heat in the refrigerator. Big frozen food warehouses also use ammonia for cooling. Ammonia is extremely toxic if inhaled which is why it isn't used for air conditioners and home refrigerators. It is used in RV refrigerators because it works without electricity.

[Tom M King]

How about 15 gallons of gasoline? They use Butane in other countries.

[Mike Henderson]

I dunno, I'm thinking butane or propane is just a wee bit too EXPLOSIVE for my taste ;)

So how/why does ammonia work in RV refrigerators? (something I've never researched)

See here (https://en.wikipedia.org/wiki/Absorption_refrigerator)for an explanation of how those refrigerators work.

Mike

[Paul F Franklin]

We just had our approximately 25 year old furnace and A/C replaced, even though it was working fine and we haven't spent more than a couple hundred on repairs (which I did myself). My thinking: I wanted to replace them with equipment I picked (vs. what was readily available at the time of failure), on my schedule, and using the contractor I wanted, not one who was available on short notice. This also let me get multiple quotes and interview several contractors, all of which is hard to do when you are without heat in winter or A/C in a heat wave. Add on top of that knowing that equipment availability is variable and uncertain these days due to supply chain issues and high demand from the areas of the country that are getting boiled. I already had a 90% furnace, so don't expect much saving on heat bills going to a 96%, but should see some saving on cooling cost going from a 10 seer unit to an 18 seer unit. The most noticeable difference so far has been the improvement in comfort and reduction in noise, that's a bonus.

[Michael Weber]

Hard pass on any Ammonia systems. A father of a friend was burned severely all over his body when a leak happened while he was working on an industrial system. He was lucky to live.

[Jerome Stanek]

I worked for a crop service and my first job there was filling Ammonia tanks Think 1000 gallon propane tanks. after you fill them you have to bleed the fittings and they ice up also you don't want to get a splatter on you skin as it will burn you actually it freezes your skin

[Rick Potter]

Good timing for me too. Last evening about dinner time I got a call that the brand new AC in my rental stopped working. I went right over there and determined the thermostat was working, and the breaker and fuses were not popped, which reached the end of my AC repair ability.

I called the AC guy I have used a few times, and got lucky. He was on his way home and the repair was nearby, so he stopped there and found an unusual problem. He says the breaker was working, but not flowing enough juice (I forget the amps he mentioned) to start the compressor. Fortunately, there was a 40A 220 breaker in the panel that was no longer being used, so he hooked the AC up to that breaker, and that fixed it.

Next week he is coming back to replace all the breakers in the panel, just in case.

Getting back to the question of replacement....I only replace when they are not worth fixing. BUT..my policy is based on having an AC tech I trust, who is not trying to sell me a new unit before he even checks out the old. I am extremely fortunate in having two very good techs in my rolodex. This one has a bonus coming.

[Bill Dufour]

Hire an actuary to tell you to replace it one day before it fails.
Bill D

[Mike Henderson]

Hire an actuary to tell you to replace it one day before it fails.
Bill D

That guy is no longer available. Since he could predict the future, he went into investing in the market and is now rich and living in the Caribbean:)

Mike