I'm replacing my 20 yr old heat pump and air handler. The air handler is installed in an enclosed area under the stairs leading to my second floor. The return grates are located on either side of this enclosed area. My problem is that the new air handlers I am considering (Trane, Carrier, Amana) are taller than the old unit and will not fit under the stairs with the existing return ductwork. One contractor suggested moving the handler to the garage (at a significant price premium). The other suggested that the new handler would fit under the stairs if we elimlinated the return ductwork and converted the area under the stairs to a "free air space", in effect making the whole thing a return plenum. The space is fairly well sealed with only a few minor gaps in the stair treads. What's the advisability of going with this type of install?

 

Go free air. Have them put linner on the floor and walls to help with noise.

 

How about a Rheem air handler.

They are good units and they are more then half the size of Trane.

 

Thanks for the quick responses.

Rob61: I checked Rheem's website and all VS handlers were at least 42.5" high, only slightly shorter than the new Trane and Carrier units I'm looking at. The original Carrier was around 39". Better, but still not good enough. Thanks for the lead anyway.

airman.1994: any recommendations on the liner? Heavy mil plastic sheet or perhaps rigid foam insulation?

 

one inch duct liner!

 

I know they make a "Low Boy" furnace, check AH's

What do you have? Make Model? And what do you want to do?

Info, Info, Info, Info.

Chris

 

Jarredsdad,

I currently have a Carrier 40AQ024300EH which I'm told is a 30k BTU 2.5 ton unit. Trane makes a compact 39" (low boy) AH but it is only rated to 25k BTUs.

My three replacement options appear to be:
1) find a similar size (39" high) unit and transition to existing plenum
2) install a taller unit, eliminate the plenum and convert the enclosure to a free air space.
3) move the AH to the garage (which I would prefer not to do).

I have no problem with option 2 as long as it is a generally accepted industry practice.

 

First you have a 2 ton fan coil. The 024 in the model number means 24000 BTU or 2 ton (12000 BTU per ton). If it were a 2.5 ton it would be 030 not 024.

I bit of quick research here finds:

What you have (looing at the front) is 14 3/8 inches wide, 21 1/2 deep and 38 3/8 tall.

Looking at your option #2 Carrier makes a a Base Fan coil Model FF1E which is 22 1/8 wide, 15 3/16 deep, and 38 1/6 tall for both 024 and 030 models.

A couple more clicks at Carrier finds the coil in the 024 and 030 are the same part number.

Chris

 

Jarredsdad,

Sorry, I goofed! I gave you the specs on my second floor (attic-installed) AH which I also want to replace. The first floor unit is a 40AQ030310 which from the helpful info from your previous post tells me is a 30k BTU unit. It measures approx. 39 x 17.5 x 21.5, (three inches wider than the 25k.)

I know I’m getting picky for someone with few choices but I’m looking for a variable speed AH which I’m told will help with the high humidity problem we have in SE Virginia. The Carrier Base models you mentioned appear to all have fixed-speed fans.

I’m having a hard time finding the dimensional specs on the Carrier website. Are they on a contractor-only page?

 

Are you in VaBch? I moved from there to Central VA (Charlottesville area) in 11/05.

If you are in that area, let my tell you the best residential contractor there is is Hampton Roads HVAC. Dave, the owner, is a done once, done right type guy. He was the #1 on the mental "Do call list". Small company though, his wife answers the phone (or did).

And DO NOT UNDER ANY CIRCUMSTANCES EVEN THINK ABOUT CALLING .........!!!! #1 though #5 on the mental "Do not call list". Even if they are at the house next door, hide your wallet.

Now back to your post, the model I told you about is the same dimentions in 024 and 030 but not variable speed.

I looked at Carrier again and the smallest variable speed is 3 ton and 47 inches tall.

If your having humidity problems the original unit maybe incorrectly sized.

It works like this. When the A/C first comes on the first thing it has to is remove moisture (lower the humidity - called latent heat). Once it gets the moisture down it starts to work on actually cooling the air (sensible heat) to satisfy the tstat.

I'd say stop with the take out the old and put in new, have a load calc done.

You could also call Simmons or Quest Mechanical. Stay away from ..... , they charge too much.

Lastly, if you are where i think you are why not look into Geothermal? Plenty of water down there. It's more money because you'll need wells. But you'll be in the 17 - 20 SEER range and very low electric heat/cool costs. And you would probably have to add duct works for a packaged or split system. A split would be an airhandler 1/3 the size you have.

All the people I said too call also install Geothermal.

Again Dave would be my top pick. He's still my favorite "if you can't do it right on my time then you will on your time or find another place to work" stories.



Chris

 

Jarredsdad,

Yes, I'm in the Tidewater area and thanks for the tips on who to call and who not to call. I thought about geothermal: one of my neighbors recently had one installed and is quite pleased with the performance. However, I just can't justify the additional initial cost. I'm quite certain that I'll be out of this house well before I reach the additional cost payback point. Also, my energy costs are quite reasonable even with my 20 yr. old units.