My experience says nothing today holds up that well, in the first year or down the road. It also says OEM parts are very pricey, especially with the 2 brands mentioned, and labor costs are getting pricey too. Many dealers are selling extended warranties quite reasonably as a marketing plan to keep their customers. Really, all it takes is 1 major component going out in 10 years to pay for the extended warranty. And odds are very great that it will happen.
A/C systems are the most reliable though repairs are STEEP. Indoor or outdoor coil changes or even in-warranty compressor changes cost a bundle.
As far as which of the two brands are better, i can only give you my opinion on the Lennox G61V since that is what i have in my home along with the Lennox XC21 air conditioning system. Efficiency is huge in todays world, and between the furnace and ac, i dont think i could possibly have a more energy and gas efficient package. The biggest plus of the variable speed furnace is your ability, or my ability as a technician to control the airflow the furnace provides with quick and simple dip switch changes. Noise? The only complaint I could say about the furnace is that the blower sounds a little like a jet when it is ramping up to speed and when it is comming down from its full rpm. The ac unit, all i can say is it is so quiet i can hear my neighbors on both sides of me ac running over mine, and the two stages of ac is great because of the dehumidifying ability without dropping the temp in the house. I would sware that the Lennox G61V is the best furnace for total home comfort, the only downside is efficiency and total home comfort are a little pricey!!!
As a dealer that handles both Lennox and Bryant (which is the same as Carrier) my vote is for the Bryant 90i hands down.
The Bryant furnace is better designed, quieter and easier to maintain. I have been standing next to a Bryant 90i and not been able to ascertain whether the unit was operating (based on sound). I know Lennox markets their unit as "the quiestest furnace" but that is only in the smallest size they offer.
On either of these furnaces please know that replacement parts can be extremely expensive out of warranty. The variable speed motors can cost almost half the price of the furnace. Getting 10 years parts coverage is ideal, and Bryant offers this for a minimal cost without investing in 10 years labor to go along with the package.
The decision of whether or not to match the furnace with an Evolution thermostat and/or a two-stage air conditioner should be based on your climate and your personal preferences. But comparing the furnaces side by side I would vote Bryant 9 times out of 10 (depending on the application). Unless of course is was my mother-in-laws house, then I vote Goodman.
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