Should I look into replacing the AC unit?

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The AC unit on the house is original, 28 years old. Reliable, blows cold and keeps the house comfortable without problem to any temp it's set at. Does not require any maintenance/repair. Had a tech out once years ago and he commented the unit was in great shape and it's blowing very cold and did not recommend replacement.

But when it’s hot, the unit just seems to run almost constantly (or at least cycles very often). Either it’s just because I’m paying attention more, it’s been very hot/humid lately or the unit is slowly getting more inefficient and working harder. If it’s 90 outside, the unit can get the house down to 72 no problem. It seems to work really well. I keep the unit at 72 at night, 77 during day when at work and 75 at normal times in the evening.

But I can’t help but think… Would it be worth it in the fall to consider a new unit to something more “energy efficient” or do I risk having a unit that performs worse and doesn’t save that much money on cooling bills? Would the payback for a more energy efficient unit be something like 4-5 years or something like 10-15 that won't really matter?

Just wanted to get some thoughts from those who are more experienced with this stuff. Seems like the unit has done it’s job well for the past 28 years or so, but wondering if it’s time to replace or just let it go until it breaks and then replace it. We do need to replace the upstairs windows as they are shot, so that doesn't help, but will be coming soon enough before next summer for sure. Other windows have been replaced already on the mid and lower level of the house.

Thoughts/suggestions?
 
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It sounds like the argument for a new, fuel efficient car over and older, less fuel efficient car. Only makes sense when you want a new car to drive.

If it is really humid, it is going to run all the time. I would put money into windows as they will help during the winter too. Nice windows are nice, makes you look like you actually care about the condition of your house.
 
Dollars and cents , compare you electric bill to what it would be with a high efficiency unit .

Also , you will fine parts for a high efficiency unit are likely to be $$$ !

It is normal for the A/C to run longer , the hotter it gets . A perfect design would run continually at the max temperature day . Running longer , I am told , also works better to remove humidity .

One big selling point is the very high price of R-22 refrigerant , if it develops a leak . Personally , I think many contractors over sell that point .

For better or worse , I do my own HVAC work .
 
I had to replace a unit in my mothers condo in FL and a large RUUD was 6700 incl labour which is a ripoff as the unit was only 3700 and the (2) guys were there only 3 hours AND IT DIDNT WORK ANY BETTER THAN THE OLD UNIT. - but my compressor was screaming and it had to be done. Also the air handler/evaporator in the closet was rusting out and the drip traty was leaking into the garage ceiling below. Sold the house 2 months later.

I would RESEARCH units and installers but wait till she gives up the ghost.

You may want to revisit that 72deg F setting at night to save some money; Seems too low for the summer.

Sleep naked with a VERY think light cotton sheet - or just a small towel.
Then NO AC will be best
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If it's running good, don't mess with it. As was mentioned, the biggest downside is the cost of refrigerant of the older models. But if yours doesn't leak, don't get caught up worrying about what you don't have to buy. My cheap builder grade unit that came with the house lasted 15 years out here in Phoenix. That is almost unheard of out here, because we put more wear and tear on a A/C unit in a year than the Midwest does in 5. Once the daytime temperatures get above 110F, the units run pretty much continually day and night.

When I finally replaced it, with what was supposed to be a "state of the art" modern, efficient unit, I ended up going through 3 complete refills of R-410 refrigerant in 3 years. Before they found the condenser was leaking. The part was covered under warranty. But the labor ended up costing me over $1,500.00. New doesn't always mean better. My cheap, inefficient builder grade unit never leaked a drop, or ever required a service call.
 
Our 1971 central air conditioning unit lasted 32 years. I cleaned the indoor and outdoor coils every year. When the compressor finally gave up, everything was replaced. Coil, tubing, electrical, compressor/condenser unit all highest efficiency. Our summer electric bill dropped about $100 per month. And, the house is more comfortable with better dehumidification. Worth the $ to me.
 
If it still works keep it. What brand is it? You do realize that a.c. systems nowadays only last 10-15 years max right? Plus they break down, need a capacitor every couple years. Every 6 months if your repair guy uses cheap capacitors.
 
If it ain't broke, don't fix it and in the mean time, start putting away some money so that when you do replace it, it won't break your bank.
 
Have the coils been cleaned inside (near the furnace unit) and how often to you spray the fins on the external unit?

Also how is the insulation in your attic and how well does it breath to get rid of the hot air? I added extra insulation in our attic, put in baffles for the soffits and added ridge vents to the front half of my house to keep the attic cooler in the summer months.

That makes a big difference as well to keep the house cooler.

If it's not killing your hydro bills, I would keep the old unit.
 
not an HVAC expert however if it runs constantly in extremes and cools/heats fine it means that is sized appropriately.

You may get better energy bills with modern system however the recovery cost you have to figure out.
 
Originally Posted By: billt460
If it's running good, don't mess with it. As was mentioned, the biggest downside is the cost of refrigerant of the older models. But if yours doesn't leak, don't get caught up worrying about what you don't have to buy. My cheap builder grade unit that came with the house lasted 15 years out here in Phoenix. That is almost unheard of out here, because we put more wear and tear on a A/C unit in a year than the Midwest does in 5. Once the daytime temperatures get above 110F, the units run pretty much continually day and night.

When I finally replaced it, with what was supposed to be a "state of the art" modern, efficient unit, I ended up going through 3 complete refills of R-410 refrigerant in 3 years. Before they found the condenser was leaking. The part was covered under warranty. But the labor ended up costing me over $1,500.00. New doesn't always mean better. My cheap, inefficient builder grade unit never leaked a drop, or ever required a service call.



A lot depends on the skill level of the installer & how much he / she cares . Especially when it comes to leaks . Of course , if you have a leaky piece of hardware , no amount of skill or dedication is going to offset it .

Seems like every time they change designs to cut cost , they have problems / growing pains . The old designs / materials worked OK . Then the bean counters get involved ! :-(

Consider mini split ductless units . They can be had with very high SEER ratings . Either straight A/C or heat pumps . We installed 2 with the help of family members .
 
Clean coils and fans inside and out and replace the filter regularly. A new unit probably won't pay for itself anytime soon, so replace the old one when it suffers a major failure equivalent to a good chunk of the cost of a new unit.

The unit running almost flat out on the hottest days of the year and still keeping the house comfortable means that it is properly sized for the house and climate and running most efficiently. As others have said, look into improving the sealing at windows and doors, which makes a big difference in how much humid outside air infiltrates the house.
 
Originally Posted By: madRiver
not an HVAC expert however if it runs constantly in extremes and cools/heats fine it means that is sized appropriately.


That is what I read .
 
Excellent advice/feedback everyone, thanks!

I do need to clean the unit (did it a few years back). Will get on that though this weekend. I will keep it around until a big repair causes me to think otherwise.

As far as the 72F at night, I am a very hot sleeper and need it to be cold or I wake up constantly. In winter, mid to low 60’s at night for me. I’ll pay an extra 100$ a month in AC to be comfortable and sleep better! Lol

Appreciate it again everyone. Have my mind at ease!
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Originally Posted By: motor_oil_madman
If it still works keep it. What brand is it? You do realize that a.c. systems nowadays only last 10-15 years max right? Plus they break down, need a capacitor every couple years. Every 6 months if your repair guy uses cheap capacitors.


DIY replacing capacitors is no big deal . Also look at the contactor . Both are relatively inexpensive parts . I buy both at Johnstone Supply or W. W. Granger .
 
Originally Posted By: Schmoe
If it ain't broke, don't fix it and in the mean time, start putting away some money so that when you do replace it, it won't break your bank.


Very good advice ! :)
 
If you replace a R-22 with an new R-410a , , the copper refrigerant lines need to be either replaced or flushed . The mineral oil used with R-22 does not play well with R-410a and the synthetic oil used with R-410a .
 
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