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  1. #1

    Modulating furnaces, are they all the same?

    I see that Rheem, York, and Lennox have modulating furnaces. Rheem has 5% steps and York/Lennox have 1% steps. Are they all the same or what makes them different. Is one better than the other? Just curious.

  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
    Everyone has their own opinion.

    Rheem/Ruud and Nordyne have special thermostats that tell the furnace what firing rate to be in based on difference in temp between setpoint and room temp plus based on what the difference is doing, how long, how fast etc.

    York's is run by a single stage thermostat based on past cycles and supply & return temps.

    Lennox's is run by a 2 stage stat. One thing I don't like, unless they changed it, is once it stages up it won't drop back.

  3. #3
    Join Date
    May 2008
    Baker City, OR
    TO be honest a staging furnace is savings....whether a percent of 5 percent intervals of staging is irrelevant. I personally have found that staging units are decided basically on cost and problems. Research the equipment online and it there are web sites that rate these Units...If it was me I would only buy Bryant or Lennox. That is just me. The other factor is find the company with the best service not price in your area. Let that be the deciding factor in which one to use....Cause one company is different from the me!

  4. #4
    Join Date
    Sep 2002
    I don't know
    TO be honest a staging furnace is savings....whether a percent of 5 percent intervals of staging is irrelevant
    Staging is for comfort - it has nothing to do with saving energy.

    Energy used = instantaneous input x time. If you reduce the input, you must increase the runtime to compensate.
    I've discovered a natural law - everything gets progressively worse. Things only break down and become depleted. Life isn't worth living and everything is going to hell.

    Death is the messiah. Everything else is irrelevant and arbitrary.

  5. #5
    Join Date
    Jun 2009
    Would a staged furnace not help prolong the life of the heat exchanger due to fewer and possibly shallower heat cycles?

  6. #6
    Join Date
    Apr 2004
    Generally, they still have the same temperature rise regardless of the firing rate because the blower adjusts with it. Besides, they probably all have lifetime HX warranties.

  7. #7
    Join Date
    Jan 2004
    Brand means nothing.

    If the installing company doesn't set it up right.
    Contractor locator map


    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Jul 2006
    Ive always looked at the mod furnaces this way regarding reducing utility usage.
    A single stage furnace is like drag racing your car from stop sign to stop sign. Using a mod or even multi stage furnace has to affect how much you use. They have a greta deal to do with personal comfort as well.
    I have installed Rheem and i like their design but im really a fan of Westinghouse.
    You sure are cocky for a starving pilgrim.

  9. #9
    Join Date
    Jun 2009
    Good point, although there will be fewer heat cycles with the modulating furnace.

    Generally, they still have the same temperature rise regardless of the firing rate because the blower adjusts with it. Besides, they probably all have lifetime HX warranties.

  10. #10
    I have a new York modulating furnace.

    The control board is Made by Varidigm

    "Minneapolis, MN., February 9, 2001 — When you look inside the furnace of tomorrow its unassuming appearance may not impress you. However, its performance will. That’s because hidden within is breakthrough technology that stands to single-handedly reshape much of the home comfort systems industry. As a result, millions of consumers will enjoy a new level of comfort, energy efficiency and quiet operation from their furnaces, air conditioning systems and heat pumps.

    The company driving this shift is Varidigm Corporation, formed in 1999 as a supplier to leading manufacturers of heating, ventilation and air conditioning (HVAC) equipment for home and light commercial use. Armed with 20 patents and 10 years of research and development at the Gas Research Institute (now the Gas Technology Institute), Varidigm has “unlocked the power and promise of fully modulating furnace technology”—the ability to efficiently, affordably and quietly move conditioned air throughout the home, said Chuck Kovac, Varidigm CEO. The company offers variable speed electrical motors and controllers, premix burners and closed loop combustion controls.

    Estimated at $650 million in the NAFTA region today, the market for motors in HVAC air-moving applications is expected to swell to $2 billion by 2005 as this low-cost, high-performance technology takes hold. According to research conducted by Gas Research Institute, 35 percent of consumers report uncomfortable cool spots or drafts, further highlighting the opportunity for heating systems that deliver improved comfort.

    The furnace that works like a car
    Imagine driving your car only at high speed or with the brake on. That's what today's typical furnace works like—ON or OFF. In a car, the driver decides when to accelerate, soft pedal or brake to match driving conditions. Fully modulating furnaces—finally, made simple and affordable thanks to Varidigm technology—work much like the car’s driver matching the heating load under varying conditions in the home to improve comfort. "

    I would not be surprised if they don't supply similar systems to other companies.

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