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Thread: Quality A/C and Heating Brands

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    Default Quality A/C and Heating Brands

    Our central A/C and gas heating systems are the original for our home;now 19 years old. I know they have lasted beyond their life expectancy so I am obtaining quotes from different contractors.My question is what are the better brands and what are the ones to avoid?
    The first contractor came by yesterday and they install Carrier. When I asked why his answers made sense but I don't really know.
    Next week I'll have another contractor come by that installs for the Costco program and they install Lennox and I don't know much about it.
    Any opinions are appreciated.
    thanks

  2. #2
    DIY Senior Member BobL43's Avatar
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    Quote Originally Posted by vaman77 View Post
    Our central A/C and gas heating systems are the original for our home;now 19 years old. I know they have lasted beyond their life expectancy so I am obtaining quotes from different contractors.My question is what are the better brands and what are the ones to avoid?
    The first contractor came by yesterday and they install Carrier. When I asked why his answers made sense but I don't really know.
    Next week I'll have another contractor come by that installs for the Costco program and they install Lennox and I don't know much about it.
    Any opinions are appreciated.
    thanks
    You will need to consider more than just which brand is the one for you. Even more important than manufacturer, is the quality of the installing company and their technicians. Hacks can take the very best equipment, do a crappy installation, and give you lots of grief. On the other hand, finding and getting a good company to do the work can make the lower end equipment perform great and last a long time.

    The really hard part for the consumer is finding a good company; they are out there, but I personally believe they are out numbered by the hacks out there. I started out by first looking at the BBB web site, which I'm not sure is reliable any more, but it has info on companies and customer complaints, and if they have been resolved. Then I checked with the my county's department of consumer affairs. I am not a member of Angie's list, so I did not check there. I found a good company, but far from perfect. To their credit, they did have one of their service tech's come out and address and clean up any issues I complained about, which were mostly cosmetic. It is mind boggling to have to go through this and having to spend SO much money. I just got a new central AC system installed last month. I chose Trane equipment, as this company sells Trane and York, but the Trane had a higher SEER rating and gets a much bigger rebate from our local power company here.
    Make sure whoever comes out does a manual J and Manual D to measure all the room sizes, heights, number, size and types of windows, doors and their exposure directions. The Salesman that got my order spent more than 2 hours at my house, and most of that was spent going through my house with me and taking all these measurements to plug into the computer and determing the heating and cooling losses to decide which size and system and ducting was correct for my house.

    Good luck
    I am definitely not a pro plumber, but I am a pro crastinator

  3. #3
    In the trades Dana's Avatar
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    What BobL43 said.

    At 19 years they're still within the projected 20-25 year service life for gas-fired furnaces, and many AC systems will last that long too. But almost all ~20 year old systems were oversized for the actual heating & cooling loads, often by 3x or more, to the detriment of both efficiency & comfort.

    Old-schooler rules of thumb such as "a ton of cooling for every 500 square feet " or "25-35 BTU of heating per square foot" are literally GUARANTEED to oversize the equipment, which leads to shorter (and sometimes more frequent) on-cycles. Real heating & cooling loads are usually a fraction of that. It's common to see 4, 5, even 6 tons of central AC in homes with only 2 tons of actual peak cooling load. While that allows you to cool the place off more quickly when you come home after work, it often doesn't run enough during the less-warm days to handle the humidity, and you end up alternating between sticky and clammy. It's better to used right-sized equipment and programmable thermostats with not-so-deep set-backs. Similarly when the heating is 2-3x oversized you often end up having to settle with either wide swings in room temp, or short-cycling of the equipment if the hysteresis in the thermostat is set too low. Right-sizing the equipment is always more comfortable, and delivers efficient, comfortable, long on-cycles even with low T-stat hysteresis.

    Every good HVAC design starts with a room-by-room and whole-house load calculation (Manual-J or similar). Contractors that offer to do this without prompting (even if it's for a fee) move to the top of your list. A good load-calculation actually takes some time, so getting some compensation for that effort is reasonable. But look out for thumbs on the scale in their calculations, such as using too low a heating design temp or too high a cooling design temp, incorrect window or insulation values, etc. The 99% heating and 1% cooling outside design temps compiled by the ACCA are based on 25 year weather data for those location, and are plenty good enough. Lowering the heating design temp by 10F or increasing the cooling design temp only adds size & cost to the system.

    There is inherent margin built in to a Manual-J calculation, so try to avoid upsizing the equipment by more than 15% from those numbers should be avoided, even if it means going 10% lower than the calculated number due to incremental sizing within a manufacturer's line. For VERY well insulated modestly sized houses even the smallest hot air furnaces are oversized. If the heat load calc comes in under 20KBTU/hr at the 99% outside design temp (unlikely, unless it's a small very-tight house) it might be better to go with a different solution, of which there are several.

    In any ducted air system the system efficiency depends on the duct design (compliant with Manual-D) and good air sealing. If the ducts aren't sealed with mastic or FSK tape (2" aluminum) at every seam and joint, it's worth sealing as much as you can after the fact. If the ducts run outside of conditioned space (as in an attic, above the insulation) it's worth paying to test the duct leakage and remediate, since any duct leakage outside the pressure boundary of the house inevitably leads to driving pressure differences that drive outdoor air infiltration to levels many times the mere stack-effect or wind-washing drives, adding to the heating & cooling loads.

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    Plumber jimbo's Avatar
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    Excellent summary by Dana. Covers all the key points, and in terms which are very informative even for the layman/consumer.

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by jimbo View Post
    Excellent summary by Dana. Covers all the key points, and in terms which are very informative even for the layman/consumer.
    That was nice.

    I would have recommend Montgomery Ward.
    Theory only works perfect in a vacuum.

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    DIY Senior Member Runs with bison's Avatar
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    Oversizing the furnace seems to be the most common sin. Most are already vastly oversized, and when a 95+% unit is compared to an 80% or 65% unit the input Btu ratings that you typically will receive for quotes mean little, unless you do the math to put them on the same output basis (which is all that matters for sizing.) If a contractor wants to replace an 80 kbtu/hr 80% unit with an 80 kbtu/hr 95% unit then he has introduced ~19% overdesign...and chances are the old 80% unit was already 25-50% over designed. Result will be a unit that runs infrequently and inefficiently during normal winters.

    One thing to remember though is than other than southern climates the minimum furnace size is set by the air handler frame size, which is in turn set by the AC size...not the furnace. (Frame size is tied to standard blower sizing increments and throughputs.) So to minimize furnace over design, outside of the warmest regions, one must minimize/nail the AC sizing. If your AC can already keep up in even the most extreme heat (such as the 117 year record summer we are easily breaking) then it is already oversized. If someone wants to go larger, they have missed the design. If your system is keeping up and they want to go marginally smaller to get to a lower frame size and smaller furnace that is within reason, then they probably have it nailed down. And if you are wondering, if your AC isn't running full out on the hottest day for hours, nonstop, and barely holding set point...then it is oversized.

    Most decades old ductwork is already below what is considered good design sizing for today. Going with higher capacity equipment is probably not feasible anyway. But going with lower capacity equipment could end up being substantially more efficient/quieter.

    Multi stage AC and furnaces will provide better comfort as they will run about twice as frequently (and more quietly) on all but the most extreme days. I have both now and they are a huge comfort improvement over the old single stage units they replace. Temps here have topped out at around 108 F in recent summers, and bottomed out at about -14 F in winter. My 2nd stage AC doesn't kick on until about 95 F sustained, and has no trouble at 108 F...indicating about 25% overdesign based on set point and offsets I've observed. The furnace rarely runs in 2nd stage since 1st stage is about 60% of max. When it kicks on the extra burners it is very cold outside, mostly sub-zero. I had the min. size furnace put in for the AC required air handler. The size choices I had for blower/furnace sizing worked out to either 4 ton AC for my present unit, or 3 ton AC for the next increment of blower. I went conservative with the 4 ton, but from what I see now, 3 ton would have worked...but very close. Since I have dual stage units, that is more than close enough. With single stage, comfort would suffer.

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