Please help with new HVAC system decision?

Question

I am so confused. I have done due diligence by checking BBB and all 4 companies have AAA+ ratings. The prices quoted include tax and all. Our House is 1200 square feet and 8 total vents.

Here is the main difference between the companies:

Two companies (within $300 of each other) basically offer the following for $6500 + 1000 if i get new duct work
Trane 3-ton upflow xr15. 16 seer/13 eer, condenser, pad
XT 80 furnace, 4txcb004 high eff evap coil, 1” filter rack
10 year parts/labor included
My duct work is in good shape according to both companies but company 1 recommends changing all 5” to 8” and they will hang it up vs. having it lay across the attic floor as it does now. They want $1000 for the duct work and dampers. He said having 3-tons pushing through small ducts makes the system work harder. What confuses me is that company 2 said the opposite, increasing duct size will cause the house to not cool as quickly.

Companies 3 and 4 are within $600 of each other ($8100)
American Standard 3-ton 16 seer
Gold package (new lines, pad, condenser, aluminum coil, digital thermostat, 4” filter)
80% efficient furnace and add baffles/adjust existing ductwork

One gave me the option for 13 seer with 95% furnace for $7500

I appreciate any suggestions, I can’t understand how some companies go in the attic other don’t. Totally opposite explanations about the ductwork (straw blowing demos??) All of these offers supposedly qualify for $1500 tax break

Answer 1

My thoughs are that too small of a duct work system won't allow enough air to flow over the evaporator coils. That can lead to freeze-ups (frost build up on the evap coils). Now whether 5" or 8" is large enough for your system, I can't say. But I think 5" is too small and maybe 8" also.. Most systems I've seen start with a large feed and taper down to smaller diameters the further they get away from the evaporator. My 3-ton unit started with a 15" duct and tapered down from there (960 sq ft home). This helps to maintain back pressure so that you get the volume of the air out of the ducts that are far away from the AC unit. It's much like a long, long water line. The further away from the source, the less water pressure you have at the end because upstream, you are taking off water pressure from the taps.



I would start with 12"-15" at the AC unit (if that's the size of the duct connection at the AC unit) then taper down to 8"-10" then down to 5"-6" at those points furthest from the AC unit. You also have to consider the size of the room. If the room furthest from the AC unit is a large living room or master bedroom, maybe 5"-6" is too small, you may need two vents.

Answer 2

Well heres my take for optimal system performance and 8" run would be ideal. Will the 5" runs I cant say because I dont know what the supply plenum is and the return plenum . The key factory one would need to know is what ton system do you have now? Lets assume you have a 2 ton. If you go from a 2 ton to a 3 ton you wont have enough return. And may, lack supply flow. That would be determined by load calculations your home. So the return would need to be increase to handle the extra tonnage. And possible the supple feeds would need to go to 8". A 1000 bucks if you ask me is robbery, the stuff is cheap and its not rocket science to change it out.

If you ask me there all out of wack with there prices you should be around the 5K-6k mark. They all qualify for the tax break except the 13 seer unit but the furnace would. Anything 14seer or above, and the furnace depends on too many things, that they dont tell you. Best thing woudl be to check mfg web site to see if that furnace model qualifies.

Heres the thing when you increase the seer rating the cost factor goes up. Same would apply to the furnace, and require a new flue to be ran. So, again more cost factor and labor.

If I were you I would call 2 more companies. I know your looking at the tax break thing but your paying more for the equipment so the tax thing really is a wash for you, the end user. If it we me and I were you I would have the quote you the following: None of this qualifies for the tax credit

13Seer Condensing unit

80% AFUE 2 stage furnace (they can reuse existing flue, plus to this is it has low and high fire mode so it does not use near as much gas no special gizmos it does it on its own. )

Cased Coil (evaporator coil)

Line Set

Power Whip (fat wire from box below that feeds power wires to unit)

Disconnect Box (power box on outside of house)

Digital Thermostat (programmable or non programmable you pick)

Condensing Pad

They all come with a 10 year warranty and 20yr or lifetime on the heat exchanger. So, they bank roll the labor thing into the price to cover there behind, should a major component fail IE the compressor. So toss out the labor thing and knock off somewhere from 400-600 bucks.

I think you'll be shocked as the numbers you get back it should shave a good 3K off what your getting quoted from the 8K number. Where im at they sell all day long for about 5500 or less with what I suggesting. If you going for the high efficiency stuff it will take you 20 years to get your investment back, not to mention with the higher efficiency unit and furnace when they are out of warranty they are expensive to repair. So, you have to ask youself how long are you going to be in this house?

The reason most dont go in the attic if the furnace is not in there the generally tend not to go up there. And no offense some of these salesmen they send out cant even turn a screw driver. Its all preset pricing. So, they go, look whip out a price based on what you have bingo bango. Then try and up sell you on 4 inch filter media, electronic air cleaners, UV lights, a programmable thermostat that could run the space shuttle, ect.

Try and find a smaller company that gives the personal attention to detail, and explains every thing. If they listen to what your needs are and there not out to give you a one over. I guess I;ve run into this way to much over the years, where the homeowners is so freekin confused they don;t know what too do or what to choose. Sure is the high efficiency stuff nice, but I always have to look at it from there perspective and what make sense. To say as just to make a quick buck.

Lastly the correct way to go what ever seer rating you get or furnace is to have the parts that I listed replaced.If the equipment is install correctly you should see many years of trouble free service.

Lastly, I would suggest, if you exclude the labor warranty, use the money for a Preventative maintenance program . That the real key to equipment longevity. Plus make sure you change the furnace filter at least 4 times a year and use a good pleated filter. Not the mesh style ones that are 3 bucks. Hope this helps for some food for thought. Good luck !

Answer 3

First thing is not to automatically go with the low bidder.



My recommendation is to ask a lot of questions before selecting a contractor. See who is on the top of their game. Don't be afraid to challenge the contractor responsible for your comfort. Remember, that's what they are there for. From the information you provided they all seemed competitive. Your final decision should be to consider the most professional and thorough company of the bunch.



The good thing is that all four of these companies are quoting you reputable products. American Standard is the top of the line for quality equipment these days, but Trane is not that far behind. As far as I know, Trane aquired American Standard HVAC as of about 2 years ago.



As far as the equipment, I see the companies that quoted American Standard included new lines with their number. With the new refrigerant (R-410a) that has replaced the old (R-22), the need for new refrigerant lines is very important. The oils from the two refrigerants do not mix well and will cause a freeze up if the do not properly evacuate the oil during installation. If you opt out of new lines just be sure that the old lines are thoroughly flushed, that nitrogen is added to the pipes during brazing and a good vacuum (between 800-500 microns) is achieved before charging. Also make sure that the company performs sub-cooling calculations when the A/C is tested. The desired subcooling should be provided by the manufacturer. American Standard will list the desired subcooling directly on the outdoor unit. This last step is very important for the new units that use R-410a.



Ask for a start up sheet with the calculations upon completion. Make sure that they note all the proceedure performed and that you are happy with their work before issuing the final payment.

Answer 4

i would reccomend keeping the same duct work. if it works properly now then it will work with the new system. the 95% furnace is the way to go. it will save 15-20% on your gas bill.