Which AC make and model gives me the best reliability and efficiency?

[flash gordon]

I am a homeowner and I need to get a new central unit for my house. The house has about 3000 square feet with high ceilings. It has dual zone. I need to replace the upstair unit because it just can't cool the bedrooms during hot summer days. I want to get a unit that is very reliable and has very good efficiency ratings. There are just too many makes and model for me to choose from. Please suggest a couple of makes and models so I can approach my local dealers. Many thanks in advance.

[Senior Tech]

Best to let your local dealers come in and size the equipment. As far as efficiency they go as high as 19 seer...but hang on to your wallet.
I prefer Trane, but you are about to get alot of other brands recommended...so hang tight and hang on, your about to go for the ride of your life...and the main thing of course is, to a degree, most of the equipment is the same so concentrate on choosing a reputable company to install it, most failures are created by improper installation.

[docholiday]

Understand that going to a newer high efficiency system includes replacing both the indoor unit and outdoor unit and possibly the lineset. Exsisting ductwork should also be closely examined for size and integrity.

If you are offered just an outdoor unit, you can plan on not achieving any degree of efficiency or reliability. There are many contractors who sell on price so they will cut those corners in an effort to get the bids.

Are you looking at Cooling only, A heat pump, or is the a/c on a furnace of some sort?

No matter the brand, consider having a r-410A system installed as R-22 is being phased out. Any replacement system will likely last well into the next decade where the cost of R22 may be higher than you would like it to be.

[noimposters]

There is a subsystem that's often overlooked: the duckwork.

If the ductwork has a high static say 1" it will kill the efficiency of whatever unit you choose. It can quickly turn a 15 SEER unit into a 10 SEER or even less.

If you have high static duckwork I would choose a lower SEER unit since it will live longer and acutally be more efficient.

Most residential poor cooling conditions are due to poor duckwork design, and not system sizing.

The brand name is the least important issue when choosing equipment.

The ductwork is the most important part of the system.

[dash]

1.Load calculation for at least the the upstairs unit,as there is a problem there.Look at adding attic insulation ,with extra insulation the existing unit may be the right size.

2.If you increase the the size of the system,it's almost for sure that the duct system will be too small.Infact an undersized duct system,could be be the problem now.


3.Manual D to size the duct system,in addition to Man. J..
They are both from, http://www.acca.com ,any good contractor should be able to do this.However a lot can't or won't,so tell them that's what you want before making an appointment.


4.Brands??Look at the varios brands for the features you want or need.Be sure you are comparing ,comparable equipment within each brand ,when comapring .Each brand ,has a sort of,Good,Better ,best,with the best having the most features and benefits.

5.Features ,like variable speed indoor fan,high SEER,two stage/speed compressors,two stage gas heat,all have benefits for you.Other than SEER,most are for YOUR indoor comfort,so when you see the cost,decide how much your comfort is worth to you.assume a 15 year system life and divide the "extra comfort cost" by 15 years ,then 365 days ,and lokk at the cost per day.It'll be less than you think.

Good Luck,and remember,don't make an appointment if they can't do the calculations,it's a waste of their time ,and yours.

[flash gordon]

Many thanks for the input. I have already learned a lot here. I think my attic duct work may be an issue since they are the flexible type, not the sheet metal type compared to downstairs. I guess I need to change them also.