Central air

[TollandCT121699]

I am putting in central air in my house. It was roughed in when built. I am looking at two options.

1) American standard 13 Seer 3.5 ton with variable speed air handler , system SEER = 14

2) American Standard 3.5 ton 15 SEER with same handler as above, System SEER = 15.25.

The difference is $350.00 after the higher rebate for option 2.

My question is the company doing the install mounts the handler in the attic on the floor with vibration isolation. All other quotes I received said it would be mounted hanging from the rafters. The company said this would not be a problem. Will this be a problem with noise?

Also, the two different condenser have the exact same capacity (42,000) but the 15 SEER unit is said to be much quieter. I cfound out that the decibel levels are 76db for the 13 SEER and 73 for the 15 SEER. Does anybody know if three decibels is noticable?

Any opinions on whether option two is worth the extra $350.00?

 

[Doc]

Welcome TollandCT to Forums Forums. I'm glad you joined up and posted.

Tough question.
1st off. I am not a HVAC expert. Far from it.
I have heard of systems being mounted both ways. It seems it is common practice. Special attention should be given to where the drip pan is located so that it stays put.
Hanging from the rafters can be quieter and less vibration overall. But these days if you sandwich some foam between two sheets of plywood for a floor mount, that is close to as quiet. So, no obvious right or wrong answer from my point of view. Sorry.
For the $350 price difference, divided out over the life expectancy of the unit I'd guess it's pennies on the day. I would probably go for the more expensive unit. quieter is always good, but I could not find a good example of how much difference there would be between 76db and 73db.

 

[Erik]

I'd go with the 15.25 seer -- that's an electrical efficiency rating and you'll save more than the $350 in electric bills over the life of the unit. If you go up to 16 SEER, you start hitting TAX REBATE levels of efficiency under the recently extended energy efficiency laws. In answer to the opther half of your question: 3 decibels IS a noticable difference, but it's still going to be too loud for comfort if you're up in the attic with it for long. (80 dB (vacuum cleaner) is where long term exposure starts causing permanent hearing loss) 60dB is considered normal conversational levels. every 10 dB above that is a 10 time increase in sound level, so 70dB is 10 times louder than normal conversation - or about the intensity of heavy traffic, 73dB is 30 times, and 76dB is 60 times louder... for more technical discussion: http://www.glenbrook.k12.il.us/gbssci/Phys/Class/sound/u11l2b.html

 

[thcri]

The decibel rating he has more than likely is from the outdoor unit. As for hanging it versus setting on the floor, have it hung from the rafters and have a secondary drain pan installed under it. This way if you have any condensation on the unit or overflow of the drain pan your secondary will catch the water instead of running down your ceiling.

The more efficient unit more than likely will pay for itself depending on what part of the country your from. In Minnesota where we don't use them as much as the south it will take longer to pay off but still shorter than the life of the unit.


Murph

 

[urednecku]

The decibel rating he has more than likely is from the outdoor unit. As for hanging it versus setting on the floor, have it hung from the rafters and have a secondary drain pan installed under it. This way if you have any condensation on the unit or overflow of the drain pan your secondary will catch the water instead of running down your ceiling.

The more efficient unit more than likely will pay for itself depending on what part of the country your from. In Minnesota where we don't use them as much as the south it will take longer to pay off but still shorter than the life of the unit.


Murph

I would SERIOUSLY check on having the air handler on the outside for this reason. I am ALWAYS seeing a house, or business with a wet/ruined ceiling because the drip pan, or drain, stopped up and run over. The repair to the ceiling & wall would also be expensive. And if you are like me, it would happen on a weekend or holiday when the emergency call would cost twice as much to repair. With the whole unit on the outside, no worry about drain. It would also be easier to wash/clean during regular maintenance without worrying about getting the surrounding area wet.

BTW, the noise would also be outside the building, not inside.