need an opinion on Luxaire configuration

[airberd]

I am in the market to replace my central air conditioning and and have been talking to various contractors. About 1800 sqft, need about 2.5 tons

One has recommended Luxaire LCJF30(2.5 ton) Condensor and AVL36(3 ton) Air handler. The second has recommended 2.5 ton matched American Standard. There will be some ductwork changes required - widening of ducts/ additional ducts/ additional return air duct

The questions I had:
1. Can a 2.5 ton condensor unit be matched with a 3 ton air handler? Any issues with that config?
2. Is luxaire a good value? The other option I have is American Standard(No specs yet, will post when i receive them)
3. I have read in some forums about noise concerns with Luxaire. Can anyone help in comparing the noise level with American Standard?

The main question I have.. and this is a long one.
The first contractor said my ducts need work and suggested widening both the existing intake and exit ducts, and an additional return air duct to properly feed air into the 3 ton air handler.

The second contractor, who suggested the American Standard 2.5 ton all around, said I need widening of intake and exit ducts, plus ADDITIONAL exit ducts to properly balance the air flow. In fact, he suggested that I have 2 exit ducts from the air handler, leading to different sub-ducts.

so I have 2 contradictory opinions - additional return air intake duct VS additional exit duct

Can anyone help in this? I have rudimentary knowledge of air conditioning systems and do not know which is the right approach. Reading the earlier posts, installation seems to be the most important item, so I am concerned.

Thanks for reading a long post.

[beenthere]

Luxaire commonly uses a larger rated indoor unit then the outdoor unit.

Hard to answer your quesion about the duct work.
Without knowing sizes and lenghts.

[airberd]

Right now, The return is 12". The primary exit or trunk is 10". There are 6 ducts running off the trunk. 6" to 8" in size.

First Contractor suggested 14" return PLUS adding another return. PLus expanding the 6" to 7". This is for the 3 ton air handler

Second suggested 14" return + TWO exit trunks of 10" with 8 flexible ducts coming off those. This is for the 2.5 ton air handler.

and that was my confusion. One is suggesting additional return + expansion and the other is suggesting additional exit ducts.

Thanks for all comments.

[beenthere]

A single 14" flex return is too small, unless it really short.
2-10 Supply trunks is small for 2.5 tons also.

The 3 ton Luxaire, would stillonly be set to move the same air as the 2.5 ton air handler that american standard will move.

You should get another estimate. From a company that will size teh duct properly.
Manual J for finding load of house.
Manual D for duct sizing.

[airberd]

The air handler is in the attic and the return is right below it. So the length is short, from the hole in the ceiling to the air handler - about 3 ft?

Question: does having 2 supply trunks have any effect on efficiency of the system? The contractor led me to think that this would be a more efficient setup.

If the 3 ton luxaire would only move the same air as a 2.5 ton AS, then why not have a 2.5 ton instead? why is there a mismatch in the Luxaire setup?

Thanks once again



A single 14" flex return is too small, unless it really short.
2-10 Supply trunks is small for 2.5 tons also.

The 3 ton Luxaire, would stillonly be set to move the same air as the 2.5 ton air handler that american standard will move.

You should get another estimate. From a company that will size teh duct properly.
Manual J for finding load of house.
Manual D for duct sizing.

[beenthere]

The 3 ton coil is larger. To gain some efficiency.

Its not the 2 supply ducts that will improve efficiency. Its the greater area for the air to move easier that will help.
The same could be done with 1 large duct.

That short 14" return will handle the air flow. But could become noisey after teh supply size is increased.

[Freezeking2000]

http://www.luxaire.com/PDFFiles/413452-LTG-D-0509.pdf

You will see the match-up on page 6 AV air handler which is the acclimate air handler. 16.25 seer.

Thanks,

Brian