Carrier 24AAA5 and Coil to replace 30 plus year old system

[dylanmitchell]

A Factory Authorized Carrier Dealer that's N.A.T.E certified is recommending the following to replace a 30 plus year old evap coil that's leaking and a low quality R22 fill on site compressor installed by the prior owner. We're in San Diego and fortunate to have a mild climate and it's a two story 1200 sq foot town home. My question is if it's worth upgrading to an energy star rated unit for example Carrier 24AAA6. And any problem with using the existing gas furnace that's in good condition (other than a little loss in efficiency from the single speed fan)?

Carrier Comfort Series 24AAA (536A003) (3 ton)
Evap coil high efficiency up flow
Existing basic Bryant furnace stays
Condensation drain system and float switch safety
Carrier pad, fuse disconnect/ safety switch, whip
Vacuum clean/ leak test existing line

We knew the prior owner used an existing coil and low dollar fill on site compressor when we purchased the condo. We planned to use it until it failed and the coil now appears to be rusted out and dripping water into the wall cavity below. The compressor is still working but we think it's a good idea to replace it so we can change over to Puron/ R410A. We're expecting a balanced system with a 410A compressor and 410A coil versus keeping the existing coil and installing a new R22A coil is a better choice for long term ownership. R22A is becoming very expensive and replacing the compressor and evap coil at the same time while more costly will give us more efficiency and future proofing for when R22A becomes even more expensive and harder to source



And how is Carrier vs Trane for the installers/ dealers? I've heard both are great quality but that Carrier may be more tech friendly.

Thanks for the help!

[hedrash]

First of all, the contractor should do several load calculations starting with a Manual J load calculation. There's a manual S calculation also but that's for areas with extreme weather conditions. This will tell you if your unit is properly sized for the house. Under or Oversized equipment can cause several issues. Then after the proper equipment size is determined a manual D & manual T should be done to determine proper duct size & "throw." Throw refers to the air that leaves the supply diffusers in each room. Proper throw allows the air to stratify properly & mix through the room evenly.
That's the first step. Consult Google, Facebook, Yelp & Better Business Bureau reviews to see if a company is reliable & competent. If they don't know what a Manuals J, D & T are.... DON'T USE THEM.
The dealer and brand is important, to a point. Each company has it's ups & downs. Avoid lower end products of their lines. Bryant is Carrier's "value" brand, Rheem's "value" brand is Ruud. Basically they're going to look the same but their lifespans & make up are significantly different. Trane is known for durability & Carrier is certainly the oldest company around but I'm not a big fan of their newer equipment. 30yrs ago, they were fantastic. They were primarily out of Syracuse in NY but shut down factory operations & relocated, leaving many people jobless in their mid-fifties. I personally think their equipment is substantially lacking in quality & they're in it to make money.

Lennox is another high end manufacturer whose most efficient equipment is solar ready. YES. SOLAR READY. You live in San Diego & the last time I was there I didn't see too much in the way of clouds, but constant sunlight. Basically you can use the abundance of sunshine to power you're equipment. Their XP25 is a variable speed heat pump that can be matched with a variable speed Air handler. They have amazing rebate programs & other perks. There's also the iHarmony zoning system & iComfort zone sensor control system. Zoning means you can run different parts of your house at different temperatures. Do you use your bedroom during the day or just at night when you sleep? If it's not being used, why condition it?? It's also rated around 23.5 SEER & carries a ten year warranty. You can also hook it up to an app on your phone to control/monitor everything remotely. I actually put one into my own home & amazed at how efficient it is, plus it lowered my electric bill by nearly 45%. I used a CBX40UHV Air handler with indoor air quality filtration, the Lennox Pure Air system & a Reme Halo in the supply duct. Additionally I use the iComfort S30 thermostat which communicates with all of my equipment. So if I have only one zone running (like the living area) the fan runs at a slower speed & the outside compressor does too. The filtration take about 99.9% of the dust, pollen, smells, etc out of the air & the REME Halo adds hydro peroxides to the air (not hydrogen peroxide) which kills pathogens, bonds molecules together like bad smells, dust, etc. & allows the filter to pick it up easier. I actually have three filters, poly disposables in the return grilles, the Pure Air, the HEPA that comes with the Air handler plus the REME Halo. The poly's are cheap & pick up 90% of the stuff in the air because of the REME. The really small stuff that gets by gets picked up by the Pure Air & I've NEVER seen anything on the HEPA in the air handler.
It's NOT a cheap system, but if installed correctly will pay for itself in 5.5 years just by saving on utilities. Also, I dunno how to explain it, but the air smells fresh all of the time. Like being outside on a perfect day. I've also found that I don't suffer from allergies & sinus issues anymore as well as getting sick.
Most of these brands are really good. Personally I would go with Trane or Lennox & skip Carrier.
Most importantly, make sure they do a proper load calculation. It will surprise you how much of a difference it will make in the comfort of your home. Also, GO HEAT PUMP. It's WELL WORTH replacing the existing gas furnace. A heat pump works by basically reversing the A/C system, taking the heat in the air outside & mechanical energy of the compressor to warm your house. Dollar for dollar it's the most efficient way to heat your house. You can install a heat pump & a new Lennox SLP98V furnace which will modulate gas & fan speed. Most likely in San Diego you'll NEVER need gas heat. You might be better off installing the CBX40UHV with an electric heat strips or two for "defrost" mode, but honestly, these newer high end equipment are really worth it. I'm extremely pleased that I can basically turn off part of my house (through the zone control) & the system adjusts for that. I live in Dallas so I don't need anything more than a heat pump & the occasional defrost during winter. This past winter my electric bills were $27 during the winter down from $78 the year before & gas bills down $50. Right now, it's been a 100°+ the last month & my electric bills came out to be $63 for July. Gas was practically nothing, $28, because it runs a new high efficiency hot water heater & stove.
The Lennox equipment is freaky big though (unfortunately due
to the efficiency requirements) & quiet as HELL!!! I find myself out gardening & putting my hand on the unit to see if it's really running. It's something like 38 decibels on full speed.
Anyway, avoid Carrier, go with a company who will provide a Manual J, D & T report for free & go with a Trane or Lennox system. Lennox covers everything for ten years with a $1500+ rebate, so ask about Trane's rebate & warranty programs.
Important thing is to research the company as I explained before. I would also suggest having the ductwork redone or cleaned since it's an existing system. Don't be afraid to ask questions and spend the extra money, it'll pan out in the long run. Insist on insulating & sealing the duckwork with mastic. Insulate the ductwork with all new 2.5" wrap. These trivial things really add up quickly and the additional price tag sucks, but financing is available. Sell your old gas furnace online too!

Sorry for the long post but I hope I helped.

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[dylanmitchell]

Thanks, that is very helpful. I'll look for a quote from a Trane dealer and a load calc to determine the correct compressor size.

Also, I have room for a very large foot print compressor on the concrete pad by the equipment/ utility room where the AC compressors for our town homes sits. Is there a 3 ton (or other if the load calc comes back different) Trane or Carrier model that takes advantage of a large foot print? For example since I'm fortunate to have a large concrete area is there a compressor that would take advantage of the large space (don't know if making components fit in smaller footprint decreases efficiency).
We have a half or really 3/4 stucco wall around a large concrete area where our AC compressors sit, gas lines go into the walls, and the closet for electrical and coax and phone enter the property from the street. And the compressors have lots of room between and in front of them so a large compressor will easily fit while maintaining plenty of breathing room on three sides and six or more inches from the wall on the fourth side. The Carrier contractor included a vibration pad in his quote which may or may not be needed but it's cost is nominal. And the are where the compressor will sit is about 4 to 6 inches above grade so it's doesn't get standing water or run off going by it.

[hedrash]

ALL of the new units are HUGE. The higher the efficiency the bigger the unit.

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[dylanmitchell]

Thanks!