Poor system design!

[desert_rider]

Hope you folks don't mind an "outsider" barging in on your party.

I need to change out my central air system, but it looks like I may have a hard time doing it without redesigning my ductwork. I'm hoping someone here can recommend something.

I have a 22 year old Carrier 4ton unit that is leaking freon right where the line set meets the compression fitting at the condenser unit. The HVAC tech who came out to recharge the system said it wouldn't be worth welding the lines, and for various reasons, I agree.

Here's the big problem, I only have 56" of vertical space to cram the new system into. The guy looked at our inside unit and said he could not do anything unless we redesigned the ducting on top of the furnace.

I can't afford to re-do my ducting, but I need air, it's way too hot right now.

I need to find a manufacturer that has a filter tray/blower/furnace/evaporator coil that can all fit into 56". It has to be a 4ton, 13SEER, R410 unit.

Here's a couple of pics....

http://i218.photobucket.com/albums/cc297/desertrider_bucket/pics72109081.jpg

http://i218.photobucket.com/albums/cc297/desertrider_bucket/pics72109083.jpg

Any recommendations?

Thanks for your time.

[jpb2]

You're screwed sorry

[spotts]

Yer gonna be gettin a loan I predict. I used to have that poster! [in 1983]

[desert_rider]

Tough room.

Not as bad as my first wife though.

Gonna have to see if the various manufacturers offer component dimensions on their websites.

Doesn't seem it should be impossible to find a 22" tall evap, 20" tall furnace, and maybe a 15" tall blower.

Since the ducting draws from the side instead of the top, the evap would just have to be rotated so the plate isn't obstructing the the flow.

Gotta be a way to get it done.

[jerryd_2008]

...

I can't afford to re-do my ducting, but I need air, it's way too hot right now.

I need to find a manufacturer that has a filter tray/blower/furnace/evaporator coil that can all fit into 56". It has to be a 4ton, 13SEER, R410 unit.

...
Any recommendations?

...

Don't know your feelings about York (just installed 4-ton York 18 SEER DFHP), but they have 33" high VS and modulating furnaces in either 80 or 90%+ AFUE. Not pushing Aspen, but just for a place to look at coil sizes here is a link with their coils (we got the 5-ton CC60E cased coil which is huge compared to the old 10 SEER coil): http://www.aspenmfg.com/products/evaporator-coils/list.asp

Don't see any filter tray in the pictures but I could be blind. Our 5" inch MERV 11 filter is 10" wide. That ain't good. Depending on the returns, can

Big questions are where do your returns feed and how. That can imply some rework. The furnace looks like it sits on a plywood plenum like mine. They may be able to cut it down to get height depending on the amount of rework due to you returns below (it is an upflow, right?). Can you set the furnace in front of the plenum and feed it from the plenum in back of it?

At the price point you are at, a bit of rework on the upper supply duct might seem like peanuts. Ask.

Don't forget your coil drain. Mine was in the wall and the bigger coil required the addition of a pump to get the condensate up to the drain.

Lots of gotchas. For no surprise expenses make sure the contractor does a good site survey and knows all of them before pricing and then hitting you with add-ons when he said that is an extra.

[jerryd_2008]

Whoops! Duplicate post.

[desert_rider]

Don't see any filter tray in the pictures but I could be blind.

Filter sits directly under the blower, no housing, just held in place against the return opening with a spring.

Big questions are where do your returns feed and how.

Return is under the unit and draws from a 14X24" vent behind the front door of the home.





Thanks for the input.

I'll look into the possibility of lowering the "floor" where the unit sits.

As far as the filter goes, I wonder if it's possible to stick a filter into the return vent?

[tinmandad]

Why is the draft hood on the water heater not installed?

[udarrell]

SHOW US A PIC OF WHERE THE LINE IS LEAKING. (Caps sorry!:()
If possible, I'd braze the line. There are usually options depending on what's available to work with there.

I got a bunch of work to do; will be waiting on the pic.

[mark beiser]

Wow, haven't seen one of those evaporator coils in a long time, old York/Borg Warner low profile evaporator coil.

Nothing like it is even remotely available anymore...

[DanW13]

Not sure what your budget is, but have you or anyone else thought about going with a horizontal install, and possibly going with a tankless HWH ? A slight down fall with a horizontal install is you will lose a few % in efficiency but nothing to lose any sleep over.

[Cold Feet]

Any way you can move the furnace down on the floor adjacent to the HWT? Feed return air through the side of the furnace rather than through the bottom.

That'd gain you a few feet of height.

[catmanacman]

what about installing a heat pump

[motoguy128]

I think carrier makes pretty short 80% furnaces. You might want ot have a load calculation done. Maybe you don't need 4 tons. Maybe 3.5 tons is adequate. It would help the situation. Most systems in the US are oversized.... expecially if you've had more insulation or new windows installed.

Just a thought.

I don't see why making a new plenum is a big deal? It's just sheetmetal work.

[Shophound]

I think carrier makes pretty short 80% furnaces. You might want ot have a load calculation done. Maybe you don't need 4 tons. Maybe 3.5 tons is adequate. It would help the situation. Most systems in the US are oversized.... expecially if you've had more insulation or new windows installed.

Just a thought.

I don't see why making a new plenum is a big deal? It's just sheetmetal work.


His present system is up against the wall, figuratively and literally speaking.

The furnace base can't be lowered to the floor...the furnace and the water heater are in a garage...base of both units must be at least 18" off the floor, IIRC.

New coils have considerably more surface area (that is, they're BIGGER) than their older equivalents. The pics show a flat horizontal coil, if I'm seeing it correctly, with a short plenum above dumping into a huge 90 degree elbow that apparently goes into the attic from there. Traditional closet installs in my area where the furnace sits on a plywood deck has the plenum going into the attic and the ducts spidering out from there.

Not sure why this was done differently...code may not allow plenum to penetrate garage ceiling other than how it did with elbow...or it was installer's choice and there's no actual prohibition for busting the ceiling above the plenum...or there may be. The elbow may feed a vertical chase that goes to a second story, and right above the furnace is the second floor of the house. Can't really call it from where I sit.