Repair or replace? 5 ton residential unit - 12 years old

[Blazer406]

Sorry for the long post..... but I'm in a delima......

I have a 5 ton RUUD split system installed in my house. It is a 10 SEER with a scroll type compressor. I think my compressor is bad and that it has probably contaminated the rest of my system with acid from the burn out. Date on the unit is 3/99.

It was installed when the house was built in '99. I bought the house in '04. Since then, I have replaced the run capacitor twice, the outside fan motor, the contactor, and the inside fan motor. I had also put in a KS-1 hard start kit a couple years ago when I first had issues with the start capacitor.

OPTION 1:
Should I try and replace just the compressor? I would assume the tech would have to flush the rest of the system to get the contaminants out. I also assume I would probably want to put in suction and liquid line filters/driers at the same time.... as there are currently none installed.

I think I can still get the R22 compressor but it is around $1100. I assume it will cost $500 or so to have it installed along with the filters and flush the system out.

OPTION 2:
Replace the current system with a new 5-ton system. I would probably opt for a 2-stage unit with a variable speed fan. Looking at the current tax credits, I would shoot for a 16 SEER system and try and get the full $1500 tax credit on my taxes next year. If I do that, I need to reconfigure my system to have 3 zones. My current 5 ton system has 1 zone for a 2400 sq ft house with a 430 sq ft bonus room upstairs. It is a joke IMHO. To accomplish this I would need (the way my current ducting is set up) around 5 dampers, a bypass, a zone controller, and a programmable thermostat for each zone. I might also need to install a new return into one zone (Master bedroom) that currently has no return there.

OPTION 3:
Scrap the current 5-ton and replace with 2 smaller units. I would probably put my MBR and my upstairs (approx 830 sq ft) on a 2 ton system with two zones (one for the MBR and one for the bonus room upstairs). The rest of the house could possibly be on one zone on a 3 ton system. Obviously this is a more complicated and more expensive way to go.... but at the end of the day..... probably better suited.

The way my house is now.... with one 5 ton unit.... no separate zones.... if I have the downstairs at 72°.... the upstairs is probably 10 deg hotter. To band-aid this.... I put a 12,000 BTU 115v window unit in my bonus room so we can turn it on when we are up there. It make the space much more comfortable.

Any thoughts?

I live in MS where it is pretty hot during the summer months.

 

[Wareagl487]

IMHO, option No. 1 would be a no go. 12 years on anticipated 15 life cycle doesn't make since to repair. Three reasons for me come to mind, age, R-22 and the third, its a RUUD (not a huge fan of theirs).

While a zoned 5-ton system looks good on paper and would be cool to show off to your friends, I personally would go would two systems for the simplicity of operation. Tow speed compressors for both is a great idea too.

Andy W.

 

[IRstuff]

5 tons sounds like a lot for 2400 sf house. We have a 2200 sf house in the Los Angeles area running a 3 ton system. Since utility rates are continually increasing, getting a newer, more efficient system would seem to make sense. If you can drop the tonnage a bit, the system might run even more efficiently.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Blazer406]

I'm about 1950 ft downstairs and 430 ft upstairs.

My 5 ton takes hours to drop from a 76 deg setting to a 72 deg setting. Maybe my current system isn't doing what it is supposed to be doing?

My house is on a slab. No basement. Bonus room upstairs. It always seems HOT in that room in the summer.

 

[IRstuff]

Mine's only two story, no basement. There'll always be a delta between the topmost floor and the ones below due to solar loading on the roof. Your upstairs might also be extremely poorly insulated, particularly if the house is pretty old. It might be worthwhile looking at upgrading your insulation.

How cold is the air from the registers? A typical AC system should be putting out 55ºF-ish air into the ducts. My spouse was/is always complaining that the AC air is too cold, but that is as it should be, usually. I would think that a 4ºF drop should take less than an hour or so, at least, for the air temperature. Your walls might still be convecting heat back into the rooms, since their thermal masses are larger.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[imok2]

I would go with option 2 and install wireless zone control for the 2 upstairs rooms Go here:

http://jacksonsystems.com/search/category/251

 

[Blazer406]

Well, I got a "TRANE" guy that lives near come by and get me some pricing on several options.

1.) A new 5 ton 13 SEER Trane condenser unit.
2.) A new 5 ton 13 SEER Trane condenser unit and matching a-coil (keeping existing furnace and air handler)
3.) A new 2 ton unit to install for my upstairs that would allow me enough capacity excess capacity that if I put another room upstairs, I would just run a few supply ducts to the new room.

He also priced a Goodman condensing unit to replace the current (now dead) 5 ton RUUD unit I have.

He also priced me a 15 and 16 SEER 5 ton complete Trane split system.

I kind-of had sticker shock. Prior to me getting the prices mentioned above, I called a buddy that is in that business and he "offered" to get me some American Standard stuff.... or anything else at his cost and could hook me up with a guy that installs near where I live that would do it on the side.

He came back with pricing that appears to be pretty good. I am contemplating between the 13 and 15 SEER American Standard 2 ton and 5 ton systems. I am leaning on putting just the 13 SEER systems in knowing that they are way more efficient than my current 10 SEER system is.

I talked to the tech and he is supposed to come to my house tomorrow morning and look at what I am needing.

I think I can get some good quality stuff and get a good install done and I'd be tickled.

Thoughts?

 

[IRstuff]

Keep looking.

When I got my AC, I talked to 5 AC guys, 4 of which wanted to get me 4 ton or 5 ton systems. Only one guy came up with the 3 ton solution. I would guess that you could probably get by with a 3-ton downstairs and a 1-ton upstairs.


TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[KiwiMace]

Replace the lot, don't muck around patching a new A coil into the old existing indoor unit. They will stiff you on any warranty work and it will always be some problem with the sa fan. Does this thing have a furnace?

Return air path restrictions are common with residential systems, as well as basic balancing as everyone dicks with the dampers. Have your guy run through the whole system.

 

[msquared48]

blazer406:

Sounds like it could be an inefficient ducting delivery and/or return air problem to me too.

Have the same problem in my house and it would take bookoo bucks to fix. Was a bad design from the beginning. I just have to live with it.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[berkshire]

When the tech comes to your house, get him to go room by room, and check supply and return duct sizes,also under door gaps for rooms with no return grille. Spec out the entire house from scratch totaly ignoring what you have now. Then figure your zones and air handler sizes for heat, then air. If you need to add ducts or increase duct sizes do it now
You are already into a major replacement anyway. A few extra bucks spent now will save thousands over the life of the operating system.
B.E.

 

[Blazer406]

IRstuff,

I agree for the most part. I am a mechanical engineer. They make us do plenty of HVAC calcs. I do understand an appreciate the importance of not oversizing too......

My "Trane" guys answer when I question him about why I shouldn't downsize the unit once I take the upstairs "load" off the unit...... he said, well.... it has been cooling it well as of now.... you might need that little extra capacity for one of those 100° summer days when a 4 ton unit would not maintain 80°......

I can't exactly say he doesn't have a point. It does routinely get near triple digits here every summer..... with very high humidity..... feels like a sauna.

I surely don't want to spend thousdands of dollars and come the middle of this summer....... wish..........I had another 1/2 a ton of cooling.......

 

[berkshire]

My "Trane" guys answer when I question him about why I shouldn't downsize the unit once I take the upstairs "load" off the unit...... he said, well.... it has been cooling it well as of now.... you might need that little extra capacity for one of those 100° summer days when a 4 ton unit would not maintain 80°......

It sounds like a better solution would be a multispeed unit.
B.E.

 

[Blazer406]

berkshire,

I am assuming you mean 2-stage or 2-step compressors?

I am already wanting to make sure I get the variable speed blower in the air handler.

The 2 ton and 5 ton AS 15 SEER systems my buddy quoted me have the variable speed blower but I think just single stage cooling. I have asked him for clarification. I have asked at what SEER level I need to get to get the 2-stage compressor.....

 

[IRstuff]

And don't be too surprised by the utility bill...

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[317069]

replace the unit but:
You said "My 5 ton takes hours to drop from a 76 deg setting to a 72 deg setting"
That tell me that your unit is overzised.
I think it is better to hire an engineer to recalculate your load and redesign your system.
Happy Easter for everyone

 

[berkshire]

Blazer
Yes,
I meant two stage compressors, that way you get the dehumidification with the first stage and you get the capacity when you really need it.
B.E.

 

[willard3]

RE system size:

Remember, your family will not thank you when they are too warm.

 

[msquared48]

I guess what I am saying is that it makes no economical sense to me to upgrade only the Unit if at least part of the problem is with the delivery system. The problem will still persist.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Blazer406]

Well.... The 2nd HVAC guy came and looked and agrees that I need to stay with the 5 ton for my downstairs. I have 9 and 10 ft ceilings throughout and a huge vaulted ceiling in my living room that is close to 20 ft at the top. I also have no conditioned space above any of my current downstairs.

I am probably going with the AS 5 ton with the variable speed air handler 13 SEER. Then a 2 ton for the bonus room over the garage also 13 SEER. MY budget is driving me to stay with the 13 SEER in stead of the 15 SEER. I just can't afford to do the 15 SEER right now.

The 2 ton is slightly overkill but I am planning an expansion upstairs that will need any excess capacity I will have from the current bonus room. I'm actually tempted to dump a new duct or two off this 2 ton back down in my master BR.