Air Conditioning Decision

[Woodboy]

On the cusp of ordering central air for a new home in Denver Metro area. Denver is not a high cooling day’s area, 3 – 4 months maximum. I am debating the merits of a five ton 13 SEER the new minimum, vs. 16 SEER and higher. Payback needs to be 5 years or less (my arbitrary rule). I have a high efficiency 94% Lennox furnace with a variable blower.

Also trying to decide the merits of American Standard unit vs. Lennox unit, etc. The contractors all seem to have a favorite manufacturer, but it seems more like a path of least resistance, or “what we’ve always carried”, choice on their parts.

Any suggestions to help me break the mental logjam?

[Tundra_Man]

I had to replace my A/C unit last summer. I also was considering the higher SEER unit, but the salesman talked me out of it. Our cooling season is similar in length, and the salesman said it wasn't worth the extra cost of the higher efficiency unit for our short cooling season. IIRC, the payback was somewhere in the 25 year range. I chose the 13 SEER model.

I figure if a commision-based salesman was working to convince me to go with a cheaper model, then the higher efficency unit must have been a real bad decision!

Also, I think there's one component manufacturer that makes the compressor units for most brands so there's not really a lot of difference between them. I based my decision on price and warranty.

[JimD]

My rule of thumb is to let the contractor put in what he recommends unless I have a strong preference. The issue with going against the recommendation is what happens if there are any issues. If it's your choice, you will probably hear about it. If you went with their recommendation, there should be less noise and you might even catch a break.

Jim

[Bruce Cohen]

All I can add it that I still have the original Lennox 3.5 ton central unit that the builder put in. It's 26 years old and the only thing I needed to do (up till now; I need to have the unit recharged-for the first time) is to change out the compressor cooling fan (75.00 from Graniger and that took about 15 min).

We have a 3-4 month cooling season and a house with cathedral (mulitple) celings. Something not very conducive to efficiient cooling, or heating.

Additionally, my wife likes it cool in the summer, so the unit gets mucho use.

If it lasted this long without any real maintenance or repairs, I would strongly suggest the Lennox unit.

Bruce

[maxparot]

I have a Lennox that is only 6 years old and up until last year was nothing but problems.

First thing was hard starting.
The problem started with the unit being 3 years old. Every other week it would blow the breaker. Repairman stated by replacing the breaker but ended up a few days later needing to add a hard start kit into the relatively new unit.

Next was a refrigerant leak that couldn't be found.
each season we'd need to call to have the unit checked and refigerant added after the 3rd or 4th go around the leak was finally found and repair last summer. Turn out to be the factory filling ports that are not used after the unit is assembled.

I've had York and Carrier units that had no problems but after talking with a few repairmen it seems that there are lemons in every brand.
I'd go with the best deal (with a free service contract) on a unit with a SEER of 14 or higher.

[gary]

I have 2 American Standard units here where we have a longer cooling season. One lost a compressor just before the 10 yr (free) extended warranty expired and the other is still running fine. See if the dealer will throw in an extra warranty for free as part of your negotiation.

[dedaddy]

I have been in the HVAC industry for over 37 years with York (which has been sold to Johnson Controls) as a design engineer. From that experience I can say that the quality of the installation is as important as the quality of the unit. All manufactuers use almost identical components. Failure analysis of units usually point to problems with contamination of the refrigerant, the oil or bad electrial components/connections. The installation by the dealer can cause very early failure if all air is not removed from the system before refrigerant is put in. Any contaminates in the system generates acid that causes valve failures, motor winding insulation failure or breakdown of the oil leading to compressor lockup. So if the installation tech or manufacturer does not take the time to properly evacutate and seal the system, it will lead to early compressor failure.
Electrical problems are usually caused by bad components and/or bad electrical connections. The good manufacturers use quality relays and contactors. There usually is some kind of computer control in the better systems to increase efficiency and functions. These can cause early failure if not designed properly. Good engineering and reliability costs money.
Another short cut that some installers take is to put in the minimum size wiring required. Low voltage situations during a high demand season will cause hard starting and high motor winding temperatures. I recommend the next higher guage power wiring than is recommended to avoid these problems.
Make sure the ducting is designed for cooling as well as heating. The return air for heating should be drawn somewhere near the floor on the lowest level that is heated. The return air for cooling should be drawn from the highest level near the ceiling. Also, if you are adding cooling to a forced air heating system, you may need to install a bigger indoor fan/motor to push the air through the added cooling coil.
As far as payback on higher efficiency units, please remember two things: Electric prices will only go up in the future. Higher efficiency units are more reliable as far as compressor failures are concerned because the system runs at lower pressure differentials because of the larger coils. This puts less strain on the compressor motor, lowering winding temperatures which reduces acid generation.
Sorry this turned out so long. PM me if you have other questions.

[Hellrazor]

Dedaddy, thanks for the confession that your design HVAC units. Now when I have to pull 200 things off one of our units at work because it wasn't designed to be serviced easily... I'll blame you

We had a bearing to replace in a unit and the factory rep said 'oh thats easy to get to". Famous last words. We started to rip into the unit and he looked puzzled. Then he checked the model number and went "Ohh revision 1, We are screwed". 5 hours later and the unit was back together for a "simple bearing replacement". We had to pull the whole unit out of the wall, take the whole front, back and top off. Remove half the units guts, find a bunch of the screws were in from the wrong side to get anything apart, etc. grrrrrrr

[Jeffrey Schronce]

Dedaddy,
This comes at an interesting time. Yesterday I replaced the outside blower fan on my 6 year old Carrier system. Last year the blower in the inside unit was replaced. The year before the electronic control panel for the dual zone system that controls everything was replaced. What could have gone wrong in the installation to cause those problems? Also, why are there so few residential systems with York in York?!?!!? (I live in Hellam/York/Wrightsville).
I hate Carrier. Supposedly one of the best in the industry, yet the year we had ours installed in our newly constructed house (2000) Carrier had chosen to have only a 1 year warrenty on all components other than the compressor. The prior years it was 5 years. The later years it was 5 years because a lot of dealers threatend to switch to other brands. So for 1 year Carrier only had 1 year warrenties. This of course was the year I bought mine. If I could find the person who made that decision I would kick him squarely in the nutz.
Stupid fan was $156 with tax. 1/4hp. Made in Mexico.

[dedaddy]

Hi, Neighbor!
You were probably in the end of the statistics that are termed "infant mortality" in the bathtub curve of failure analysys. Somebody has to be there and it was you.
All manufacturers buy from the lowest bidder on parts. They are under tremendous pressure to keep prices down. A $10 difference in a $800 unit can make or break a sale. The compressor makes up about 65-75% of the cost of the outdoor unit. All the other components make up the rest, including labor, packaging and shipping. Electrical components are the most fragile. Lightning, power surges and sags play havoc with their reliability. Most electronic failures are caused by lightning striking near the unit and a tremendous EMF pulse generating internal currents, even with the unit turned off.

But protection for those problems cost money which the consumer does not wish to pay for.

A small cost increase in manufacturing can cause wide price swings to the consumer. Back in the '70's we made almost all the automotive a/c compressors for a major American manufacturer. I remember one model had a manufacturing cost of $17.56. By the time it reached the consumer as a replacement part it was over $140. Everyone in between added their 40% margin. So saving every penny by the manufacturer is important. Of course, putting in really cheap parts can come back to bite them in warranty costs.

But, I repeat: The best insurance of having a reliable A/C-Heating system is having a well engineered installation. Manufacturers cannot control that.

Sorry for high-jacking this post.