Right-sizing Replacement HVAC System(s)

[WayDownSouth]

The time has come to replace my home HVAC systems. I currently have three separate Comfortmaker systems that are all 21-years old as follows:

First floor (~1,700 sq. feet) - 8 SEER 2.5 ton unit
Second floor (~800 sq. feet) - 8 SERR 1.5 ton unit
Enclosed & Finished garage (~550 sq. feet) - 8 SEER 1.5 ton unit

The house has 8-foot ceilings throughout.

I have had 5 local companies’ present proposals. All but one company strongly recommended with the new upgraded systems that I upgrade both the first and second floor units by 1/2 ton. They claim this is an industry-wide recommendation. Only the Carrier rep suggested I stay with the same size units I currently have.

That said, I have narrowed down my selection to two finalists as follows:

Carrier proposal (Comfort Series):
First floor - 2.5 ton 13 SEER 25HBA330 heat pump & FX4CNF036 air handler
Second floor - 1.5 ton 13 SEER 25HBA318 heat pump & FX4CNF024 air handler
Enclosed & Finished garage - 1.5 ton system same as above

Trane proposal:
First floor - 3 ton 13 SEER XR13 heat pump & 2/4TEE air handler
Second floor - 2 ton 13 SEER XR13 heat pump & 2/4TEE air handler
Enclosed & Finished garage - 1.5 ton 13 SEER XR13 heat pump & 2/4TEE air handler

Now my comments and questions:
• Both dealers are reputable and come highly recommended.
• Both dealers advised the above heat pump and air handler combinations would give me the equivalent of a 14 SEER system due to the dual-speed air handlers.
• The Carrier system uses R-410A.
• Trane said they would install either R22 or R-410A (the price is exactly the same for either system); however, they would recommend that I stay with R22 at this time.
• All other dealers I spoke with sell both R22 and R-410A systems, and all advised they would highly recommend that I stay with R22 as well.
• The Trane proposal is exactly $50 higher than Carrier.
• Is there an industry-wide recommendation to bump the size of the unit by 1/2 ton?
• I live in South Georgia where he have hot and humid summers and mild winters

All comments and suggestions are welcome. Thanks in advance!

[subcooled_]

An industry wide recommendation would be to have a heat load calculation done to see what size equipment you need. Did they do this? Or just say, well we should bump it a 1/2 ton. If the equipment is over sized, it won't remove enough humidity and you can have a cool but uncomfortably humid house.

[BigJon3475]

• Trane said they would install either R22 or R-410A (the price is exactly the same for either system); however, they would recommend that I stay with R22 at this time.

Nothing wrong with R410a it is installed in almost all of the highest SEER rated equipment that should speak for itself. R-22 can be installed also it's efficiency are very close with r410a being slightly higher. R-22 is a little easier to work with so that is probably why they recommended it. You may need new line sets if the sizes are different.



• The Trane proposal is exactly $50 higher than Carrier.

Then you need to compare features like warranty and items that you might want specifically for yourself and your needs or at least this is my suggestion.



• Is there an industry-wide recommendation to bump the size of the unit by 1/2 ton?

The industry wide standard for residential if you want to assure your comfort:

• Manual RS for system concept
• Manual J for load calculations
• Manual T for air distribution
• Manual S for equipment selection
• Manual D for duct size calculations

At least according to the ACCA (Air Conditioning Contractors of America)



• I live in South Georgia where he have hot and humid summers and mild winters

Specific area or city? near Waycross, Moultrie, Albany?

[WayDownSouth]

Specific area or city? near Waycross, Moultrie, Albany?

Valdosta

[BigJon3475]

Voldesta Moody AFB:

elevation: 233 ft
latitude 31º N
heating 99% db = 34º
cooling 1% db = 94º
coincident wb = 77º


It does seem you have a high humidity load in the summer time. It's real important not to oversize when humidity is an issue. How well did your previous system keep up with humidity?

[dash]

I would not add the 1/2 ton,without a load calc(Man.J).

If you needed it ,you'd likely know so,due to lack of cooling.

Adding 1/2 ton,usually requires largerer ducts,as most are barely large enough for the original system.

In your humid climate I want a Carrier model FV air handler(variable speed indoor fan) and a Thermidistat ,for dehumidification control,as a minimum,or the Trane equivalent.

Carrier Infinty system is tops for dehumidification,but the the price goes up even more then a Thermidistat.

[WayDownSouth]

Voldesta Moody AFB:

It does seem you have a high humidity load in the summer time. It's real important not to oversize when humidity is an issue. How well did your previous system keep up with humidity?

I have lived in the house for four years and have not had a problem with humidity - no mold or mildew anywhere that I am aware of. The current system(s) seem to cool the house okay too, except I have had to add Freon every year for the past three years, hence I am shopping for a new system.

Additionally, no one lives upstairs except 4-6 weeks a year when the kids are home visiting. When not in use I keep that system turned off, which is most of the time.

[WayDownSouth]

I would not add the 1/2 ton,without a load calc(Man.J).

If you needed it ,you'd likely know so,due to lack of cooling.

Adding 1/2 ton,usually requires largerer ducts,as most are barely large enough for the original system.

In your humid climate I want a Carrier model FV air handler(variable speed indoor fan) and a Thermidistat ,for dehumidification control,as a minimum,or the Trane equivalent.

Carrier Infinty system is tops for dehumidification,but the the price goes up even more then a Thermidistat.

Can I mix and match Carrier products, e.g., a Comfort Series Heat Pump (25HBA) with a Performance Series Fan Coil (FV4)?

[dash]

Yes,for the most part,FV definaely with base or comfort.

[RyanHughes]

None of them recommended, since you have THREE relatively small tonnage units, to possibly go with TWO units? A dedicated unit for a GARAGE? :eek: I'd go for the Trane XR13 units with R410a (or R22) and variable speed air handlers. Just my .02. I find it surprising that nobody recommended going down to two units, but of course that may require some ductwork to be done which some companies probably don't want to do, so at the same time, I'm not too surprised... it might mean more money on their end. :)

[WayDownSouth]

None of them recommended, since you have THREE relatively small tonnage units, to possibly go with TWO units? A dedicated unit for a GARAGE? :eek: I'd go for the Trane XR13 units with R410a (or R22) and variable speed air handlers. Just my .02. I find it surprising that nobody recommended going down to two units, but of course that may require some ductwork to be done which some companies probably don't want to do, so at the same time, I'm not too surprised... it might mean more money on their end. :)

Quite the opposite, I asked about this and everyone looked into the option and they all advised against it. I was told it is impossible to bring a larger enough duct over to the garage area from the main unit due to the fact the second floor is in the way, and tapping into the current ducts off the main unit in that area would degradate the existing service. Bottom line -- I have to stay with three $y$tem$.

[RyanHughes]

I see. I still like the Trane equipment I suggested in my previous post, but 2 tons for ~ 550 sq. ft. = a big no in my opinion. Good luck. :)

[WayDownSouth]

I see. I still like the Trane equipment I suggested in my previous post, but 2 tons for ~ 550 sq. ft. = a big no in my opinion. Good luck. :)

Thank you for your opinion. The Trane guy has recommended we stay with the 1.5 ton for the ~550 sq ft. garage conversion, but upgrade to a 2.0 ton for the rarely used upstairs area (which is ~800 sq ft currently on a 1.5 ton unit). And for the record, there are only four windows upstairs -- each 32x36 inches, double pane glass with wood frames and sashes.

[RyanHughes]

Alright. Well, I like Trane so I'm biased, but there are many members on this forum who really like Trane equipment. I've just found that it is durable and reliable for the most part. I don't like the idea of a 2 ton unit for 800 sq. ft. still, especially with only 4 windows. He may have reasons behind this that I cannot see from this forum, though, i.e. warm/humid upstairs during the summer. You should not be disappointed at all with the XR13 heat pumps. I'd look into getting variable speed air handlers with them as well for improved comfort. I was amazed at how quiet the XR13 was that I saw recently. As always, good luck in your decision. It looks like you're taking a wise approach to this.

[RyanHughes]

I don't think you'd be disappointed with the Carrier equipment either. The FX4 air handlers have a fixed speed; they aren't variable speed, so I'm unaware as to why the Carrier guy said you could get 14 SEER. The Trane air handlers proposed are variable speed. You may want to double check with the Carrier guy to see how you'd be getting 14 SEER with a fixed-speed air handler.

Edit: I now see that Carrier says on their website: "Improve system efficiency by 2 SEER" by using their Comfort fixed-speed air handler, thus giving you 15 SEER with a Comfort heat pump. Does anyone agree with this? I don't really believe that, so if I were to use a Performance 15 SEER heat pump with a Comfort air handler I'd get 17 SEER? That doesn't go over well with me.

Reference:

http://www.residential.carrier.com/products/coils/fan/comfortdeluxe.shtml

http://trane.com/residential/products/AirHandlers/VariableSpeed.aspx

[beenthere]

Since the Trane guy want to over size 2 of your systems, I'd advise you to use the Carrier company.

Trane is no better then any other brand.