My brother's Central AC for a rental?

[ombre]

He wants the biggest and the best for everything---Just the way he is.

His theory is that a renter just wants to be cold under the worst 97 degree ambient------tired of renters complaining CAC not working cold enough in July and August. And that a renter could give a crap about proper sized systems and proper humidity control.

He just had changed out a 3.5 ton straight AC with oil furnace Rheem unit for a 5 ton Trane heat pump.

5 tons of AC/heat pump?

For a house that might be at most 1600 sq ft?

(although with a lot of heat loss through hurricane type windows all over and a large Floriduh room,--- almost solid glass area, Hurricane type windows on three sides, facing south---built in the mid 50's --that room was really never meant to be air conditioned. )---

-(Replaced a 3.5 ton unit whiched seemed to work fine, except for the Floriduh room.--which never cooled well--what would you expect?, was never designed for AC, just air flow off a lake for cooling effect was its original design)

He went for that 5 ton Trane with an seer of 18 because of the price ---left over from last year or something like that.

Now I tried to talk him out of so seriously oversizing a unit. The guy who sold that 18 seer 5 ton unit tried to talk him out of buying it.

He hasn't turned it on yet for the Florida summer---still pretty cool here.

What would you all expect to happen when he does turn that monster on?

And does an 18 seer 5 ton Trane have a good reputation? I know that the higher the seer the more likely for problems (bugs) to develop especially with a latest design. Were they just unloading 5 ton 18 seer Trane unit at a good price because there were problems?

Any input appreciated on this.

(I know that this coming summer I will get hit with all kinds of questions about the unit from my brother, if it does not perform well.---which I doubt it will)

The one nice thing about this all is that I got his old, relatively new 3 and 1/2 ton unit for free. Which will work very well in my house.



[Edited by ombre on 03-18-2005 at 05:09 PM]

[jpwiggs]

Oversized unit wont run long enough to take out the humidity.

[beenthere]

His renters will complain it doesn't feel right, they have to set the stat to 66 to make the place feel comfortable.

The electric bill is too high, because the a/c short cycles too much.

[Wild Leg]

Leave all the doors & windows open.
Turn on all of the lights.


It will have very short run times, high humidity, and a short unhappy life.

Go ahead & call the factory people so that they can deny warranty, due to abuse of the equipment.

[docholiday]

First off he was sold a bill of good suggesting he bought an 18 SEER Trane Heat Pump, there is no such beast. Especially at 5 tons. They got a 2.5 or 3 ton that can get to 17.9. The 19i on the unit is intentionally misleading. At best he's getting 15.9 SEER or 15.25 and HSPF's in the mid 8's. His sound rating is almost 79 dB. (80dB is equal to that of a Garbage disposal or freight train(at 15 meters) I'd say he bought a label.

Anyway back to your question....being potentially OK although not right. If he can move the air he might be somewhat ok since he is dealing with a 2 stage unit, just lock it out from going into second stage in cooling. Kind of an expensive single stager but hey he got one big ol unit to show off,

[Shophound]

I can just see how this cooling season's conversations will go:

RIght now:

"Heat load calc? Screw that, they're renters."

Middle of summer arrives:

"Aw man, stupid renters calling again sayin' a/c's cratered. Cheap ass Trane junk!"

[ombre]

Great responses.

Hard to tell my older brother anything. Guess he will have to learn on his own.
----------------------------------------------

I also wonder about the sound level of that moose when he finally starts running it.

79 db's eh? As loud as a garbage disposal eh?------assume of course you are talking about the condensing unit. But I wonder about the sound level of the blower too.

Massive blower unit is now inside in a hallway close to 3 bedrooms. (the old furnace blower and AC evap was out in the garage----couldn't even hear it run unless you listened very hard)

The massive Trane condensing unit now sits right outside the largest bedroom. (Old 3 and 1/2 ton condensing unit sat on the other side of the garage way away from living space---never heard it run either from inside the house.)

----By the way I did mean heat gain, not heat loss, in that first post----

[Edited by ombre on 03-19-2005 at 04:35 AM]

[AllTemp]

Thats going to be one humid rental in Florida...

Did your brother happen to mention if they added any duct work or reworked the return?

I see trouble brewing in the near future when that thing cycles off in heat mode if they didn't and a short life in cooling mode...

Just went thru the same thing here with a customer who in Dec had someone out to check heatpump 2.5 Goettl (Over/Under) diagnosis was it wasn't moving enough air because it was to small. Jack Ass installed a 4 ton system on undersized ducting. HO has complained since Dec 2004 no heat, just blowing cool air...

HO stuck with 4 ton system, added 2-10" trunk replaced all the duct work all 6" now equal 8" and so on and the 12" RA is now a 18" , more than they need. Thank goodness for dry summers here in Calfiornia, unlike Florida...

[ombre]

Never have had much luck telling my older brother anything at all. Although I do try.

I always told him the best way to go was to stick with the original set up---proper sized AC unit (3 and 1/2 ton) with gun fired oil furnace in the garage and condensing unit outside on the other side of the garage, where you couldn't hear it run.

And if he really wanted to be able to cool that all window Florida room to put a 15 to 18000 BTU wall unit in there to be used as necessary.

He had 2 problems with that.

1-----He hates wall units ---something about holes in walls he doesn't like (don't know why--I think they are excellent in their place)

2----He wanted the garage to be a true 2 car garage--the old original air handler and furnace in the garage made it impossible for a second car to fit in there.

He will just have to find out for himself. Spent $11,000 on that monster too.

I asked him if they had done anything to improve the ductwork. He said he thought so. For $11,000 I hope so.

[Edited by ombre on 03-20-2005 at 04:16 AM]

[Jultzya]

Big brothers, relatives, friends, etc...if, they don't want to listen to you, let them learn the hard way!

[ombre]

Agree with that one.

Sometimes you have to learn the hard way.

It is very helpful to find out that one good way to reduce the oversize problem is to disable one of the compressors.

The sound level, at least from the massive Trane condensing unit sitting right outside a bedroom, could be corrected by relocating it back to the other side of the garage, where the old condensing unit used to be. Would mean a line set of maybe 50-60 feet. Any problems with that besides adding a little refrigerant?

I think that the sound level of the now indoor blower, right next to all the bedrooms will end up being troublesome--------but maybe a little extra sound insulation will help enough.

You all might wonder about some of this. The house was originally built in about 1950---with a gun fired oil floor furnace in the hallway---no AC at all.

(That cubby hole in the hallway where the old original gun fired oil furnace used to be is now where the new Trane air handler is.)

The original floor furnace in the hallway was modified over the years for a gun fired oil furnace in the garage, and an added Chrysler central air. All of which have worked quite well for the past 40 years or so. (Only problem was that you no longer had a useable 2 car garage.)----

--and an extra problem--the Florida room, rather large with 3 sides facing south and mostly glass area would never cool with the old 3 and 1/2 tonner)--- That room is almost impossible to cool--too much heat gain. Why I always suggested to my brother a simple wall unit of maybe 15 to 18,000 BTU's to cool that room if desired and only when needed.

(Actually it is a great room to just open the damned windows and enjoy the off-lake breeze-----that was what it was always intended to do)

Interesting advantage is that, unusual for Florida nowadays with now prevalent slab construction------there are 2 duct systems. --the original return for the old floor furnace, underneath and in the crawl space under the house.------and an added duct discharge system in the attic. Added ductwork in the attic done in the mid 60's when the original Chrysler Air Temp unit was installed.

The condensing unit has been replaced at least a couple of times and the evap replaced once with an Addison. All 3 and 1/2 ton.--up until now.

So there is an awful bunch of ductwork. Much more ductwork than you usually see in modern day homes in Florida.

And whoever did the installation just recently might actually have improved the ductwork generally. For an $11,000 total cost for this new 5 ton Trane heat pump, I would think so. Of course you never know.

I live over 100 miles away from my brother and don't get over to Orlando all that much. ------but every time I do go over there--I always get all kinds of questions about anything and everything mechanical (my brother is a complete ding a ling when it comes to mechanical stuff)

I know I am going to get hit with all kinds of questions about this "poor working" and very noisy Trane monster he decided to have installed next time I visit.

So all input appreciated.

I do like my brother, even with all his stubborness. And I try to help him out when I can.

[Edited by ombre on 03-20-2005 at 02:42 PM]

[condenseddave]

Gonna be one big ol' moldy, sweating swampy mess real soon.

[tinknocker service tech]

the real shame here is next summer when it is arround 80 or 90 degrees and the people are sitting in a cold clammy damp house and still sweating amd the tech who knows what he is doing has to take the heat after he tells them its to big and there is nothing he can do about it
poor guy
so much for sizing a unit just take a guess from the curb

[Wild Leg]

I've got two brothers-in-law I'd swap.

Wanna trade?

[ombre]

Nope--

[pstu]

Allow me to ask a naive question, I am just a homeowner who tries to follow what the best pros are doing and understand it.

The Trane 5.0 ton system is a two-stage unit, is it not? And the 1st stage will be sort of equivalent to a 3-ton unit, is that about right? And the house was cooled OK when it had a 3.5 ton system installed?

It seems reasonable to speculate that most of the time, that Trane will run on 1st stage and do its regular job of humidity removal (yes I agree a 4 ton model would do it better). So will this necessarily be inferior to the older system which appears to have been properly sized?

I understand that without big ductwork improvement, that Trane will make extra noise on those few times it is in 2nd stage. And it seems that the only way to cool that sun room will be to add lots of ductwork to that load, and no doubt its own return. We *do* know it has a terrific heat load, even though we don't have it in numbers.

Does this sound reasonable to you all?

Thank you -- P.Student

[ombre]

Originally posted by perpetual_student
Allow me to ask a naive question, I am just a homeowner who tries to follow what the best pros are doing and understand it.

The Trane 5.0 ton system is a two-stage unit, is it not? And the 1st stage will be sort of equivalent to a 3-ton unit, is that about right? And the house was cooled OK when it had a 3.5 ton system installed?

It seems reasonable to speculate that most of the time, that Trane will run on 1st stage and do its regular job of humidity removal (yes I agree a 4 ton model would do it better). So will this necessarily be inferior to the older system which appears to have been properly sized?

I understand that without big ductwork improvement, that Trane will make extra noise on those few times it is in 2nd stage. And it seems that the only way to cool that sun room will be to add lots of ductwork to that load, and no doubt its own return. We *do* know it has a terrific heat load, even though we don't have it in numbers.

Does this sound reasonable to you all?

Thank you -- P.Student

A lot of good points. I am an old fart technician who has been out of the trade for over 12 years-----so I know very little about 2 stage compressors (did they ever actually do that--I know they were working on it?), or 2 separate compressors---and how they work exactly.

One reason I come onto this forum---is to try and keep up.

Again you make good points. If there are actually 2 compressors in that Trane monster-------I would assume with a light heat load, that only only one of the compressors would be working. No need to disable the second compressor at all.

That Florida room facing south with 3 sides of almost all hurricane windows was always impossible to cool. ------The best solution would have been to install a highly efficient 15-18000 BTU, and, if you want to spend the money, fairly quiet running, wall unit in that room--close it off and turn on the wall unit when you need it, leave the unit off when not necessary---Which would make everyone, especially renters--- HAPPY HAPPY HAPPY ---

---Which is exactly what I kept suggesting to my brother---Not that he ever listens to me. He has this horror of holes in a wall. (I think holes in a wall do have their place.)

And so now that 5 ton monster might even cool the Florida room, although, I think rather inefficiently---They did actually install 2 rather large discharge ducts into that room (there was just one teeny discharge before)--

-and the return is back through the rest of the house--through a very large sliding glass door, which can be easily closed.

The fact that that room can be so easily closed off from the rest of the house is the main reason I suggested an expensive, but highly efficient and very quiet wall unit specifically for that room.

Hell, my brother spent $11,000 for the oversized absurdity he has now---He could have bought one hell of a good wall unit for 1/20th of that price.

One possible problem I see, the way it is now is that-------the rest of the house will tend to overcool just to make up for that monster of heat gain in that silly Florida room.

And I think excessive noise from both the blower inside next to bedrooms and that monster of a condensing unit outside the main bedroom--Plus the serious possibility of a very damp house------will have renters seriously upset.

But we will all find out this summer.

I know there will be a problem when my brother calls me and says--- "Kenny---can you come over?"

[Edited by ombre on 03-22-2005 at 07:30 PM]

[Shophound]

A lot of good points. I am an old fart technician who has been out of the trade for over 12 years-----so I know very little about 2 stage compressors (did they ever actually do that--I know they were working on it?), or 2 separate compressors---and how they work exactly.

The Trane XL19i uses two compressors. Lennox has a new high SEER model out that uses a modulating scroll compressor, like the Copeland UltraTech Scroll shown here:

http://www.emersonclimatecontractor....ics&User=false

I saw one of these at a recent RSES conference. It uses an internal solenoid operated by DC current to move a plate that covers up or reveals a hole in the lower scroll to effect capacity control. It appears destined for two stage systems and to me would seem ideal for when the homeowner wants to use the A/C for dehumidification on cooler but muggy days.

P. Student:

The Trane 5.0 ton system is a two-stage unit, is it not? And the 1st stage will be sort of equivalent to a 3-ton unit, is that about right? And the house was cooled OK when it had a 3.5 ton system installed?

It seems reasonable to speculate that most of the time, that Trane will run on 1st stage and do its regular job of humidity removal (yes I agree a 4 ton model would do it better). So will this necessarily be inferior to the older system which appears to have been properly sized?

Good point, P. This may indeed work out to be the MO for this system. Only time will tell, since apparently it was just thrown together, hoping for the best. If it performs adequately it will be more from luck than engineering.

[docholiday]

Im not going to try to make heads or tails of the specs but for the most part this is not a good practice since generally you may find poor latent capacity when the unit is running at low stage and suggesting it will performt the same as a regular 3 ton system may not be as accurate when looking at latent sensible ratios.

[beenthere]

When its in first stage cool, you'll have a 3 ton compressor running with a 5 ton evap, giving you a warmer evap coil and not condensating like a 3 ton condenser, with a 3 ton evap.

So on mild temp days you still have short cycles with higher humidity then with the old straight 3.5 ton a/c.