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fredm54 09-21-2010 11:48 PM

Upgrade old Rheem Split System
My 2 story Miami, Fl. home (1750 sq. ft) was built in 1983 and came with a 3.5 ton Rheem Split Sytem (10 SEER) During all these years I had a new evaporator coil installed in the air handler and a new condensing unit installed (about 2 years apart) The new coil was upsized to a 4 ton coil (they just had that size in stock) and 2 years later when the condensing unit was replaced a new 4 ton unit was installed (to match the coil)

Anyway, my system is still working though I recently heard about the Florida Energy Rebate program ($1500) which runs until the Dec 31 2010. (actually, it's in limbo due to politics in the legislature) Plus there the Federal Tax credit (30% up to $1500) plus an FPL Rebate (estimated at $780) To qualify I need to install a 16 SEER or better system.

But I have a problem, the home builder ran an undersized lineset. I have a 1/4" x 3/4" lineset! (measured OD) The condensing unit is on the ground and the air handler is on the 2nd floor. The lines run through the walls and between the 2 levels where there is no access at all. I can go outside the house to the upper attic and across but this will add an additional 20 feet over the original path.

The old system uses R22 and the new systems uses R410. If I select a new 16 SEER 3.5 ton system how detrimental will the small lineset be?

I think the recommended size is 3/8" x 7/8" but I've been running like this for 27+ years! If you compare an R22 installation with a R410 installation, with all things equal, which refrigerant will tolerate an undersized lineset better?

I had an estimate done yesterday, a Rheem 16 SEER 4 ton system. But he quoted a 14 SEER Condensing Unit with an 18 SEER air handler which he said would qualify as a 16 SEER system. Is that right?

I thought about running a new lineset myself to save a few dollars but I'm wondering how difficult is it to unwind the line set and to bend it without kinking it? (the 7/8" tubing already has the insulation on it)

Oh, the estimate was for a Rheem $4550 (includes $300 toward new lineset) Also, I can upgrade to a Trane system for $4850

Finally, to get the Florida rebate I need to get my ducts tested for leakage. That test costs an additional $399 which will reduce my effective rebate to $1100 (if I pass the test!)

thanks for reading all this!


beenthere 09-22-2010 04:38 AM

You don't have a choice between refrigerants. No new R22 equipment is made.

Running a line set 2 stories by yourself can be interesting. But its possible. However, if you kink it, your back to square one.

Technically. There is no such thing as an X SEER air handler.
It is common to match up a larger air handler with a 14 or 15 SEER outdoor unit to get a much higher SEER.

fredm54 09-22-2010 09:21 PM

I guess what I'm trying to ask... Is the undersized lineset more detrimental for a R22 system or for a R410 system?

Also, here are the 2 Rheem part numbers: 14AJM49 and RHLLHM4821 is this a good match and is it a 16 SEER set?

thanks again!

beenthere 09-23-2010 04:08 AM

Its just as bad for one as it is for the other.

fredm54 09-25-2010 07:11 AM

One more question, a little of topic... How much colder should the air be coming out of my vents when compared to the air return at the air handler?


fredm54 05-15-2012 10:19 AM

This is an old topic I started! Now that I'm in the middle of a kitchen remodeling project and I have some exposed ceiling areas I can see the old lineset! I also see a path where I could run a new lineset and have it in place when the old Rheem dies (it's still working!) I think back then I found out I needed a 3/8" x 7/8" lineset for a 4 ton R410 system.

Question, how easy or hard is it to bend a lineset like this and not kink it?


HVACDave 05-15-2012 11:51 AM

Depends on how quickly you want to make the bend take place and how you go about making the bend. You can use a bending spring to keep it from kinking, or you can get bending tools to do the same, but if the arc is large enough you can bend by hand without kinking it if you are carefull.

Good idea to think of getting the new lineset in there now. Someone will be happy you did in the future. Be sure to keep the ends sealed up till needed.

REP 05-15-2012 02:04 PM

OK,this is what is driving me crazy.All this time and energy and money spent with an aim toward getting a high effiency unit for your house for the next twenty years.All this and not one mention of properly sizing the equipment which is the single most important thing that needs to be done.
All this 3.5 mixing with 4 ,all this putting aq wet finger up in the air.Why not put a 5 ton unit in and hang raw meet in ther kitchen?
You need a manual "J" done AND,AND,AND a manual "D" done to properly size your equipmewnt.
Installing a/c equipment is not a guessing game,two houses of exactly the same square footage right next to each other can be vastly differant in whats needed. Its the only sane thing to do.

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