Replace Central Air Conditioning System?

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mur44
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Replace Central Air Conditioning System?

Post by mur44 »

Our house central air conditioning system gave us 22 years
of trouble free service. It is an Amana SEER (8) rated system.
It is still keeping us comfortable as our cooling needs are
rather modest (any thing below 78 is too cold for us).

Of late the air flow from the system dropped but the
we have been comfortable despite this years significantly
hot and humid weather we had in New Jersey.

One estimate for AC replacement came at $8,600
for a 5 ton (Trane) system. I am waiting for 2 more estimates.

Is it worth replacing now or wait for the system to
die? Any tidbits and advice would be appreciated.
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Tycoon
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Re: Replace Central Air Conditioning System?

Post by Tycoon »

The installation of your new system is more important than the brand you buy. Hire a reputable contractor who is willing to give recent references.

I was in your shoes a few years (4) ago. Ended up buying a Trane 16i system. The A-Coil developed a leak and had to be replaced almost exactly one year after installation. I discovered it was a common problem related to the 16i system - a factory defect if you will. So my recommendation is to take a little time and research the system you choose to purchase and find a quality installation team.

Good luck.
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Kenkat
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Re: Replace Central Air Conditioning System?

Post by Kenkat »

How much longer do you plan on staying in your current home? You might get another 5 years out of your existing unit but I doubt you will get another 10. If you plan for staying 10 or more, it might make sense to go ahead and replace as 1) you will eventually earn some payback in energy efficiency and 2) sooner or later, you are going to end up replacing it anyway. That said, I always have a hard time replacing anything still working.
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Macmungo
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Re: Replace Central Air Conditioning System?

Post by Macmungo »

The upper half of our dual 1989 Trane air-conditioning system died Monday and was replaced Thursday. The replacement is a Carrier STEER 13 system, cost $3100 (presumably the future lower half will cost the same).We took this because we needed it quickly for medical reasons and did not shop around because the company has served us well (in contrast to earlier ones). A STEER 16 would have been optimal, but (at least for the first two days) this one does the job. The system began to show problems in the late spring and I would have done better to have replaced it then, rather than wait for it to fail completely.
Mudpuppy
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Re: Replace Central Air Conditioning System?

Post by Mudpuppy »

Since the system is still working, it might be cheaper to wait until after summer to have it replaced. There is a bit of a seasonality to these things, although the magnitude of the difference will depend on factors specific to your location.
rotorhead
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Re: Replace Central Air Conditioning System?

Post by rotorhead »

22 years is a long time. Don't wait until it fails; when you will be at the mercy of the contractors and their schedules. Gather your estimates and do your research; and decide which unit and contractor you will choose. I did that (we choose Carrier); and since our unit was still limping along, I asked the contractor how long the estimate would be valid for. He said as long as the manufacturer did not increase prices. So I asked to be put on their "call list" in the event that was about to happen. In the end it was 8 months from the time we got the estimate until installation of the new system; and at the previously agreed price.

Another thing to consider is the energy cost savings you will realize with a new system. Considering the age of your present unit, It very likely will be substantial. We replaced our 10 year old 12 SEER Carrier system in April with a new 16 SEER Carrier unit, including the condenser, air handling unit; and a new digital, programmable thermostat. The first full month of service our electric bill was 24% less than the same period last year. Second month was less also, but not as much (we were away for 2 weeks during the period last year). Will see how it goes month to month; but I'm certain we will realize substantial savings.

Your electric utility company very likely offers a rebate for upgrading to a new and more efficient system; don't forget to ask about that. Our rebate was $900, which the contractor factored into his price; and handled the necessary paperwork, saving us the effort. That was nice.
Mingus
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Re: Replace Central Air Conditioning System?

Post by Mingus »

mur44 wrote:Our house central air conditioning system gave us 22 years
of trouble free service.

Of late the air flow from the system dropped but the
we have been comfortable despite this years significantly
hot and humid weather we had in New Jersey.

Is it worth replacing now or wait for the system to
die? Any tidbits and advice would be appreciated.
22 years is pretty good. That tells me the system was well built and installed well. If an air conditioner system has thick copper tubing, and quality solder joints there is very little that can go wrong.. Until the compressor dies. Maybe a capacitor or relay will wear out here and there, but those are inexpensive fixes. Until a contractor comes along and sells you a new system when a 30 dollar relay is all that is really wrong.

Air flow has dropped? That could be a few things. The most obvious is the filter might be overdue for replacement. Next on the list would be possibly the evaporator coil is dirty. And lastly, perhaps the whole duct system in the house needs vacuumed out. HVAC guys come out, cut a big whole in the plenum and attach a giant vacuum hose to it, and then blow compressed air into the individual registers in the house. Then the whole is patched up with a piece of sheet metal and some metal tape.

I would say it is not worth replacing now. What is being sold today has replaced the simple and generally reliable mechanical relays with expensive electronics. For some strange reason, the HVAC industry has not figured out how to implement reliable electronic controls such as the automobile industry has.

If I were in your shoes, I'd get some estimates and just keep those in your back pocket. As someone else has mentioned, the reliability of an HVAC is about 75% the quality of the installation.
Saving$
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Re: Replace Central Air Conditioning System?

Post by Saving$ »

You have received good advice, especially from kenschmidt above.

The only things I can add are:
1. There is another federal tax credit currently in effect. If you don't pay enough taxes to take advantage of the credit, wait until the credit expires to replace. HVAC contractors tend to increase their prices when the rebates are in effect.

2. If airflow is your issue, you got advice above, and a new condenser is not really going to help that - you have some other problem. However, if you get a new condenser, you will also need a new lineset and new coils. They are using a different refrigerant than was used 22 years ago, so all three need to be changed out because the new ones need larger line sizes.

3. If what you are trying to say is the air is not cold, then you might be able to solve for that by recharging your system. I had mine recharged 8 years ago, and the contractor swore it was only temporary and I needed a new system. 9 months later it needed recharging again. I called a buddy who had a friend working for an HVAC company. He came by at 9:30 one night, last call of the day. Could not believe how low it was, shot some leak plug stuff through it, recharged it and it has been working fine for 7 years.
travellight
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Re: Replace Central Air Conditioning System?

Post by travellight »

I just put in a new rheem 5 ton 14.5 seer for 3600$. In another house I replaced a 3 ton 14.5 seer for $2800.
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tibbitts
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Re: Replace Central Air Conditioning System?

Post by tibbitts »

travellight wrote:I just put in a new rheem 5 ton 14.5 seer for 3600$. In another house I replaced a 3 ton 14.5 seer for $2800.
How many bids did you get? Did you have any experience with the installer before? Did you have to run new lines? Any new ductwork?

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Monk53
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Re: Replace Central Air Conditioning System?

Post by Monk53 »

At 22 years, you are on borrowed time. I would certainly replace it before the next cooling system. Personally, if I could afford it, I would replace the system now. You will be replacing both the air handler and the outside condenser unit. I would be concerned about the loss of air flow. If you have been replacing your filter at reasonable intervals, your system should not be that dirty. You could have a multiple speed fan that is only working on slow speed, but you could also have a hole in the system and the system's trying to cool part of your attic or crawl space. If the reduced air flow is due to restrictions, it could be insulation inside the duct work coming apart. With flow restrictions the system will not be running as efficient as it should be, costing you money.
tomd37
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Re: Replace Central Air Conditioning System?

Post by tomd37 »

Mur44,

Do you really "need" a 5-ton unit or are you being "sold" a 5-ton unit. It may be that you need such a large unit but IMO, without knowing other information, that is rather large unit. Just make sure you are not being oversold. Based on my personal experience, the increase in SEER rating will make a big difference in your comfort and your pocketbook.
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walkabout
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Re: Replace Central Air Conditioning System?

Post by walkabout »

At 22 years old, your system is ancient. It is 8 SEER. You can easily get 13-16 SEER today, which will result in a significant improvement in efficiency and comfort. We just replaced our 22+ year old 10 SEER Lennox heat pump with a 19 SEER Carrier Infinity system (pretty high end in the Carrier line). Our old system was still running reasonably well, but we had had a few (minor) service calls recently, and I figured that we were probably on borrowed time. Better to replace it at a time and place of our choosing rather than HAVING to replace it when it fails in the middle of a summer heat wave or a a winter cold snap.

We love our new system. When it runs, it usually runs on low. We can barely hear it. It maintains are desired temp very well and, by running longer, removes more humidity, increasing our comfort.

Here are some features of our system (that I would recommend to anyone getting a new system):
1. Two stage condenser (outside unit). Runs at low most of the time (that it runs). Cranks up to high when a significant cooling demand is requested (drop thermostat down a few degrees) or if it is so hot that low cannot maintain the desired temp.
2. Variable speed air handler (required in order to get the most out of two stage condenser). Again, runs on low most of the time. Running for longer periods at low speed maintains desired temp better and removes more humidity from air. Controlling humidity better ctually allows one to run at a higher than expected temp and still maintain comfort.
3. Dehumidify on demand. Even if the current temp is at or below the desired temp, the system may still run at low speed for dehumidification. Again, less humidity, more comfort.

What would I recommend for you?
1. Require a Manual J calculation to ensure correct system size. Some might call it a load calculation. Your current system may or may not be correctly sized for your home. Manual J takes into account square footage, home orientation, windows, insulation, heat gain/loss, and more parameters. Do not rely on "rule of thumb" estimates like 1 ton per 500 sq feet. Do not assume that your original system was correctly sized.
2. Consider two stage condenser/variable speed air handler. This may up the price, but it will also increase efficiency and increase comfort. I suspect that there is not much point in getting either a two stage condenser or a variable speed handler but not both, but I'm not an expert.
3. When comparing estimates, make sure that the dealers are quoting comparable systems. If one dealer quotes a Carrier Infinity System, and another quotes a Goodman builder grade system, you can bet that the Goodman will be cheaper. It would be like comparing a Cadillac (or your favorite luxury car) to a Chevy Impala. The Impala might be a fine car that will get you where you want to go, but, feature for feature, it is probably not comparable. Generally, a brand will have "good, better, best" models. At the least, when comparing between brands, it is probably a good idea to compare similar tiers.
4. Someone upthread mentioned that quality install is as important as quality equipment. I agree. However, I do think that not all HVAC equipment is created equal, just like all cars are not created equal.
5. Do you have any accessible ductwork (like in an unfinished basement or garage) If so, consider having it checked to ensure that it is well sealed and insulated. About 40% of our ductwork was accessible (in garage). We had trunkline resealed (mastic and tape) and branch lines replaced with R8 insulated flex duct. The idea is to create air tight (to the extent possible) duct system to preserve your cooled air and to prevent air infiltration. I can tell a difference, if for no other reason than our garage seems to be hotter than it has been in the past.
6. Ensure that refrigerant lines are sized correctly for new system. What you currently have is probably sufficient, but you want to be sure. Your current system probably uses R22 (freon). Your new system will probably use R410A (puron). If the lines can be reused, ensure that they are flushed (I think they use nitrogen). You want to get all of the remnants of the old refrigerant/lubricant out of the lines so that it does not contaminate your new equipment (the two refrigerants and lubricants are not compatible).
7. Try to have some idea of a "good" installation. When our system was installed, we had a few punch list items that to be addressed afterwards: some ductwork not adequately sealed (could feel cold air coming out of a seam), condensate trap not installed correctly (easily determined simply by looking at installation instructions and comparing to our installation).
8. Consider getting a system with a "communicating" controller (thermostat). The controller will,optimize the operation of the condenser and air handler for efficiency and comfort. This is a higher end feature, but I think it is worth the cost.

I strongly recommend these two forums. You will find several helpful pros that will help assess your equipment needs and will help evaluate your quote (e.g. do competing quotes specify comparable equipment and work to be done).

http://ths.gardenweb.com/forums/hvac/ (I especially like "tigerdunes" here).
http://hvac-talk.com/vbb/forumdisplay.p ... ntial-HVAC

Spend some time reading these forums. Pay special attention to posts from people getting new systems. Take note of the responses of the pros. You will find that people are often quoted systems that are too large or are not based on a rigorous calculation (Manual J). People often post competing quotes that are not really comparable (two stage condenser/variable speed air handler vs single stage condenser/single speed air handler).

Do not be duped into buying more tonnage than you really need.

Be aware that a new, modern system might run longer than your current system. That is ok. It is supposed to work that way, especially if you go the two stage/variable speed route.

Educate yourself.

Good luck! I hope you like your new system (when it is installed) as much as we do.
Last edited by walkabout on Sat Jul 13, 2013 6:29 pm, edited 2 times in total.
tomd37
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Re: Replace Central Air Conditioning System?

Post by tomd37 »

The previous reply, by wageoghe, is excellent and should be very seriously considered.
Last edited by tomd37 on Sat Jul 13, 2013 6:19 pm, edited 1 time in total.
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Tycoon
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Re: Replace Central Air Conditioning System?

Post by Tycoon »

+1

I had a load analysis done on my home before replacing my unit and the analysis showed that I could go from a 5-ton to 4-ton unit. No more short cycling.
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obgraham
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Re: Replace Central Air Conditioning System?

Post by obgraham »

Agree, wageoghe's thorough analysis is topnotch.

I've run a/c in two quite hot environments over the past 30 years. I've developed opinions on various brands, and they seem to be in agreement with service folks in both communities. None of the service companies are dedicated to a single brand.

I've replaced virtually every part of every Carrier system I've had, sometimes twice over. They're at the bottom of my list.

I, and everyone I've known with a Trane unit, has been happy with it.

Goodman units are supposedly "basic builder quality", but seem to be extremely reliable, and outstanding value for dollars spent.

I do agree that choice of HVAC contractor, their reliability and longevity, is the most important issue.
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walkabout
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Re: Replace Central Air Conditioning System?

Post by walkabout »

I would also say that there is some value to using two more factors in picking a dealer:
1. Look up companies on Angie's List. Pay attention to high ratings AND the number of ratings (more is better). Read the reviews. Pay attention to new system installs. Often the reviewers will be commenting on service work, which can be helpful, but you are interested in a new system.
2. Go to the HVAC equipment manufacturer sites (Carrier, Trane, etc). Look for dealers in your area. I tried to pick dealers that had some sort of extra factory training. That is probably more important for more advanced systems (e.g. Carrier Infinity) than more mainstream systems. It is not always obvious what some of the manufacturer "certifications" mean. I think that some are training related (factory training) while others are apparently sales-oriented. I don't know that this necessarily will get you a "better" dealer, but I put some stock in factory training.
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Watty
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Re: Replace Central Air Conditioning System?

Post by Watty »

tomd37 wrote:The previous reply, by wageoghe, is excellent and should be very seriously considered.

+1

Would there be a good place in the Wiki for that post?


A few comments;

After having to have a failed water heater replaced and getting semi-gouged, I decided that doing pre-emptive replacements of critical systems that are at the end of their useful life was a good thing to do.

I have found September is a great time to buy HVAC systems in most areas. The summer cooling season is basically over and the heating season has not started so you may get some very good bids because they have little other work.

In my inexpert opinion if your furnace is getting pretty old too, then consider getting it replaced too since in many homes the systems are interconnected in the fans and air ducts and by getting matching units they will both work well with the air handing unit.

If your original AC was SEER 8 when it was new 22 years ago it is likely a lot less efficient now just with age.
Getting a new more efficient one should make a huge difference in your electric bill if you use the AC much.
rustymutt
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Re: Replace Central Air Conditioning System?

Post by rustymutt »

I replaced a Lennox furnace and AC in 2003. I went with Lennox top of the line system. Two stage compressor, and two variable fan on the blower. I went with their signature thermostat,and we saw our electric, and gas bill drop right away. I've had no issues with the system.
At the time we had it installed, I added about 50% more return air vents to various parts of our home, not previously well vented. As I recall, it was about a 5 ton outside ac unit. Can't go wrong with Lennox.
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Topic Author
mur44
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Re: Replace Central Air Conditioning System?

Post by mur44 »

Thank you all for the great tidbits and advice.

Our current system is a 5-ton unit and it served us
well - the house has 2700 sq. ft. living space.

Our heating and cooling systems are independent
as the heating is baseboard with hot water with separate
thermostat. AC uses flexible duct pipe with the ventilator
in the ceiling.
jebmke
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Re: Replace Central Air Conditioning System?

Post by jebmke »

We had a new Bryant 2-stage unit/VS blower installed last summer to replace a 30+ year old system. Because of our layout, we could not split the system into two so we installed a 4-ton unit. The installer told us they rarely go over 4 tons. For most larger loads they recommend splitting the home (not always possible) into zones since the larger units are not as efficient as the smaller ones (so they told us).

We heat/cool about 2,600 sf in Maryland. A lot of western exposure glass but we recently replaced most of it with low-E glass. We also added insulation to the attic space, sealed all the attic penetrations into the house and sealed all the ducts in the crawlspace.

The service tech said we are probably mostly running at the first stage of the compressor most of the time. The only time I have heard the blower run up to top speed was when they tested the system after installation.

The system runs longer at times than the old one but at very low speed. They told us that this was how 2-stage systems work and it helps make the space more comfortable in addition to being more efficient.
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Valuethinker
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Re: Replace Central Air Conditioning System?

Post by Valuethinker »

mur44 wrote:Thank you all for the great tidbits and advice.

Our current system is a 5-ton unit and it served us
well - the house has 2700 sq. ft. living space.

Our heating and cooling systems are independent
as the heating is baseboard with hot water with separate
thermostat. AC uses flexible duct pipe with the ventilator
in the ceiling.
Baseboard electric heating? In a New Jersey climate? Ouch

You might want to look into an Air Source Heat Pump (perhaps the predominant system in the southern states). Ie that would do your heating on the same system as the AC.

Baseboard heating has a coefficient of performance of 1.0. Ie 1kwhr electricity in = 1 kwhr of heat.

That's fine, except that electricity is typically in the US 8-22 cents/ kwhr (lower in the South, higher in places like Connecticut and California). A typical heating load for a house in the north eastern climate, unless a modern house well insulated, can be c. 20,000 kwhr pa (30,000 is possible).

COPs of ASHP are c. 3.0 times (they drop sharply down towards 1.0 when the air temperature drops below about 20 F, I believe-- one would have to check that number). Ie for every 1kwhr the ASHP uses, you get 3 kwhr of heat in your house.

It's really a call based on your electricity bills (and I am assuming gas is just not available, as natural gas is usually the cheapest solution available for home heating-- if you install a modern 90% efficiency gas furnace) but baseboard heaters are typically an expensive way to heat.
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Re: Replace Central Air Conditioning System?

Post by jebmke »

heating is baseboard with hot water
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mur44
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Re: Replace Central Air Conditioning System?

Post by mur44 »

Valuethinker,

Thanks for your comments.

As jebmke pointed out, our house heating is from baseboard
hot water from natural gas based furnace located
in the basement. It has no issues.

In New Jersey, no heat pumps are used as it is
cold 7 months of the year. By the by, I am not
fond of cold weather but we are close to our
children and grand children.
travellight
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Re: Replace Central Air Conditioning System?

Post by travellight »

How many bids did you get? Did you have any experience with the installer before? Did you have to run new lines? Any new ductwork?
I got 3 bids. I found this guy through internet research; did not have any experience with him. The 5 ton, 14.5 seer unit was a new install so they did run new lines; the price was $3500. It was in the middle of a heat wave and they were able to come out for the bid and do the install the next day.

The other unit was done by the same guy and no new lines or duct work was done. He did have to flush the system out and recharged another unit in the same house as well. Both were working fine but I just did these 2 weeks ago.
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smackboy1
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Re: Replace Central Air Conditioning System?

Post by smackboy1 »

FWIW we live in NJ and had a Carrier Infinity hybrid system (heat pump + natural gas furnace) installed about 3 years ago. We have multiple zoning and the house is very comfortable all 4 seasons in every room. It's been close to 100 F recently and the temp and humidity in the home is perfect. If you search, I've posted about it on this board before. Wageoghe and others have posted some very good information so far.

hvac-talk.com is a wealth of information. If you search under my name you'll find the advice I got.

It cannot be overstressed the importance of having a proper Manual J load calculation performed. I went so far as to download my own Manual J calculator so I could run through the options myself ($49 from http://www.hvac-calc.com/main.asp). Not surprisingly the 1996 original builder installed system was oversized and the contractors who bid using "rules of thumb" recommended oversized units. It takes at least 1-2 hours to perform properly, which is why many contractors won't put in the effort.

A good contractor will also perform a Manual D to assess the ducts.

I am guessing the home is older and hasn't had a recent energy audit. Consider getting one and improving the insulation and air sealing BEFORE installing a new HVAC. A new HVAC won't help discomfort caused by drafts inside the house. A well insulated and air tight house may require a smaller HVAC unit to cool/heat.

There may be state and federal energy efficiency tax incentives or rebates for both upgrading equipment and passive improvements.

I chose a heat pump in case NG prices spike or electricity become very cheap (we are considering solar). But with PSE&G pricing for the past few years it's not been cost effective to heat our home using electric.

Here are a few calculators that may help:

http://www.warmair.com/html/ac_efficiency.htm

http://sagoro.wrightsoft.com/Carrier/Default.aspx
Disclaimer: nothing written here should be taken as legal advice, but I did stay at a Holiday Inn Express last night.
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prudent
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Re: Replace Central Air Conditioning System?

Post by prudent »

How long are systems supposed to last? Ours is 10 years old and at the last routine maintenance check the tech said we should start thinking about a replacement. Only had one service call ever, about 5 years ago. Is it likely to work for 15 years? 20?
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Re: Replace Central Air Conditioning System?

Post by Rupert »

prudent wrote:How long are systems supposed to last? Ours is 10 years old and at the last routine maintenance check the tech said we should start thinking about a replacement. Only had one service call ever, about 5 years ago. Is it likely to work for 15 years? 20?
Depends on where you are. In the Deep South, an outside HVAC unit lasts, on average, 10-15 years. Climate kills it after that.
ted123
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Re: Replace Central Air Conditioning System?

Post by ted123 »

prudent wrote:How long are systems supposed to last? Ours is 10 years old and at the last routine maintenance check the tech said we should start thinking about a replacement. Only had one service call ever, about 5 years ago. Is it likely to work for 15 years? 20?
I think ten to fifteen years is the "expected life" but that's just an expectation on average. Plenty of units fail to last that long, and some last a great deal longer. During a recent renovation I replaced a unit that was approximately 30 years old, and the service technicians always told me that they had a few others they'd regularly service that just seemed to run forever without any problems. (Truth is, I'd have replaced mine a few years before, but for the planned renovation, but it never did fail in expensive way on me.)

I wouldn't replace a well-functioning unit solely because of age (well, maybe if it were exceptionally advanced in age), but I would be financially prepared to replace it if need be.
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mur44
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Re: Replace Central Air Conditioning System?

Post by mur44 »

Thanks all of you for the replies.

We decided to replace the unit with a Trane.
Do we need to tip the workers; If yes, how much?
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Re: Replace Central Air Conditioning System?

Post by tibbitts »

mur44 wrote:Thanks all of you for the replies.

We decided to replace the unit with a Trane.
Do we need to tip the workers; If yes, how much?
No, unless they perform out-of-scope services in addition to installing your hvac.

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Re: Replace Central Air Conditioning System?

Post by Sconie »

prudent wrote:How long are systems supposed to last? Ours is 10 years old and at the last routine maintenance check the tech said we should start thinking about a replacement. Only had one service call ever, about 5 years ago. Is it likely to work for 15 years? 20?
My Bryant system down in Green Valley Arizona provided 29 years of service before it was replaced----lots of regular service checks on it----a few part replacements----but otherwise, it ran (and up through the day it was replaced) ran like a champ. Energy efficiency is what finally sold me on a new unit-----went with a Bryant again. :D
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walkabout
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Re: Replace Central Air Conditioning System?

Post by walkabout »

Just out of curiousity, what model Trane?
Single stage? Two stage?
Variable speed blower/air handler? Any extra work like duct sealing/insulating?
Did they do a load calculation (Manual J) and did it yield the same tonnage as your existing system?
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