2nd floor return for A/C?

[rgrimard]

I'm in the market for central air. I recently bought a 1,900 sq ft. colonial with forced hot air for heat. I'm speaking with two reputable local companies for the A/C service. Both have told me that my return air is not adequate. I already knew this beforehand because I have a single return duct running to the 1st floor (severely undersized) and no return duct running to the 2nd floor. My question deals with how each of these companies plans on remedying the situation.

Company A says they will branch off of the existing duct and add a new return vent in another room on the 1st floor.

Company B says it is necessary to run a new duct up to the 2nd floor in order to get a return on the 2nd floor. They say this is necessary for air flow and air quality reasons.

Is it common to have only 1st floor returns in a multi-floor home?

Thanks. Grim

[rgrimard]

Both companies are suggesting a 3-ton unit.

My heating system is currently all on one zone. Neither company suggested multiple zones as an option.

[AlanBown]

Here in AZ the second floors become really warm in the summer. All of the new homes that I looked at NOW have returns up and down. Problem is where do you put the stat? If it is up stairs it will cool the bottom floor to a lower temp than set. If on the bottom the top floor becomes slightly warmer.

I would want a return on the second floor. If your in a dusty dirty climate. I would consider asking for a larger than normal return. That way when you put in the super filters the static pressure is not so high as to lower the air output. I have been told that tube grills have less static resistance than the stamped ones.

Who ever does the job the closer the new return is to the unit the better air flow you will get.

[m Ransley]

Im a home owner on my AC add on I had no second foor return, several companies told me without the upstairs return it will not work well heat will pool at the ceilings. I added one with the AC it operates well. Whoever you get a load calculation needs to be done in writing , it is to easy for them to oversize you leaving you to humid in summer. I dont think the guy that wants a second first floor return is worth talking to.

[webmaster]

If the home is over 2000SF by code in most areas, its required to have two anyway....at 1900...its close enough to justify one anyway.

Without seeing your situation, and offering an opinion, this is the way to go. On ANY multi level home we install systems in, each floor gets at least ONE return, sized properly and ran to allow for proper circulation. If the home requires more than 2.5 tons of cooling, we normally suggest two sep systems as well, since that is the ultimate in comfort for most, and when sized correctly, can be cheaper to run long term than a single system.

Where do they plan on mounting the thermostat? Any zone controls?

Sadly...yes. Most builders want CHEAP, and they want it NOW. Most will go with the cheapest installers they can find, and many companies will lower their rates to get that work, and in order to do that, you lose something.

[webmaster]

Just checking about the zoning.

The company that suggested an upper level return is on the right track. Without seeing what you have, its impossible to tell you if 3 tons is enough. Have either, or both companies ran what is called a manual J? or in teh case of a heat pump, a manual T? If so, what about the manual D? A D must be ran to insure proper airflow, and duct sizing, for the supply and return side. It is possible, that company 1 hasnt done this..its possible company 2 hasnt either. insist on this being done, or keep shopping.

[webmaster]

Just a slight addition here...not a flame.

Even if the return is farther than one would like, sizing in this case can overcome that. Closer it is, to a point, you can use a smaller duct...TO A POINT. The farther is it is, velocity and flow will come into serious play, and here is where a manual D will save the day.