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  1. #1
    Join Date
    Feb 2007
    Posts
    999

    My (continuing) Rheem Mod saga

    Still trying to find Mr. Right (contractor, that is).

    Now that the weather has moderated, I thought it was time to renew my efforts to have my system changed-out.

    Having changed my strategy over time (DIY manual J & static pressure tests [still working on the latter]), I thought I'd save some time and frustration by having an in-depth interview over the phone.

    I spoke to a representative of probably the last 'Top Team' contractor in the area. After mentioning that I was interested in a Mod, the response was along these lines:

    "I would strongly recommend against it. Customers are complaining that they use more gas because they run all the time. You know, they have 65 (yes, 65) stages. You'll get your maximum efficiency with a 2 stage unit." The conversation lasted about a minute or two.

    One of you guys mentioned that dealers are required to take training on the Mod. What ever happened with that?

    I just looked at the listing for Rheem contractors. It seems that they just added a bunch and deleted some. Many list residential addresses (or P.O. Boxes); one in my old neighborhood, and some who haven't been in business very long.

    I may need to be thinking about alternatives. But, just for information's sake, must a contractor be listed on the Rheem website in order to sell the mfg's 10 year warranty and accept it for pament?

    AM

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,923
    Don't know the answer to that question.

    But have that last guy install a York mod, then he'll be right about the number of steps.
    Contractor locator map

    How-to-apply-for-Professional

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

  3. #3
    Join Date
    Apr 2004
    Posts
    7,680
    Where are you at? What's your zip code?

  4. #4
    Join Date
    Feb 2007
    Posts
    999
    Quote Originally Posted by docholiday View Post
    Where are you at? What's your zip code?
    I'm in Camden County, NJ (080xx).

    AM

  5. #5
    Join Date
    Apr 2004
    Posts
    7,680
    Well that doesnt help without all the numbers, But anyway.

    The guy you spoke to fly's by the seat of his pants. I dont appologize for this response.

    Your home requires X btuh's over the course of an hour, day, week or month. All furnaces will deliver those btuh's over the course of the timeframe. The mod deilvers the same but in a long low fire output. IE 30,000 btuhs is 30,000 btuhs regardless if it's fired at a full 90,000 btuhs for 20 minutes out of an hour or 30,000 btuhs continuously over the course of an hour. There is no difference when it comes to the amount of gas burned but there is and can be a significant difference in comfort.

    I would have cut the conversation to less than a minute. He probably doesnt recommend a mod because he either has not been trained, is afraid of it for some reason or something else other than what he is presenting you.

    Fact is, you save gas by using cruise control over stomping and releasing the gas pedal. That is not to say that the mod will save you on gas, but the ride will be a heck of alot nicer. That said, the blower on the mod when in the 40% firing range (the vast majority) draws the same energy as a light bulb. Min is a 90k mod and at low fire the entire furnace pulls all of 80 watts of electricity. Ask this knucklehead how his PSC blower will be benificial to you.

    Ask him how you are going to control humidity in mild weather? Does his two stage furnace have On Demand Dehumidification?

    Ask him what the difference is between a lifetime HX warranty and a Furnace with a Lifetime furnace replacement warranty. Ask what the difference in price for labor warranty is between the two.

    Better yet, hang up on him and call someone who has the ability to think, has integrity, and actually knows what he is doing.

  6. #6
    Join Date
    Feb 2007
    Posts
    999
    Quote Originally Posted by docholiday View Post
    Well that doesnt help without all the numbers, But anyway.
    I'm kind of central. You can get from one end to the other in about a half hour. All the zips end in xx. I need to use some discretion.

    The guy you spoke to fly's by the seat of his pants. I dont appologize for this response.

    Your home requires X btuh's over the course of an hour, day, week or month. All furnaces will deliver those btuh's over the course of the timeframe. The mod deilvers the same but in a long low fire output. IE 30,000 btuhs is 30,000 btuhs regardless if it's fired at a full 90,000 btuhs for 20 minutes out of an hour or 30,000 btuhs continuously over the course of an hour. There is no difference when it comes to the amount of gas burned but there is and can be a significant difference in comfort.
    Yes, I've gotten some BS statements from quite a few contractors, which I was able to dispell, thanks to you, Baldie, and some others (sorry guys, if I forgot you)

    I would have cut the conversation to less than a minute. He probably doesnt recommend a mod because he either has not been trained, is afraid of it for some reason or something else other than what he is presenting you.
    I might have exagerated it (the duration, that is).

    Fact is, you save gas by using cruise control over stomping and releasing the gas pedal. That is not to say that the mod will save you on gas, but the ride will be a heck of alot nicer. That said, the blower on the mod when in the 40% firing range (the vast majority) draws the same energy as a light bulb. Min is a 90k mod and at low fire the entire furnace pulls all of 80 watts of electricity. Ask this knucklehead how his PSC blower will be benificial to you.
    I won't be asking him anything.

    [quote]Ask him how you are going to control humidity in mild weather? Does his two stage furnace have On Demand Dehumidification?{/quote]

    I've already come across several Rheem TT contractors who didn't know about DOD.

    Ask him what the difference is between a lifetime HX warranty and a Furnace with a Lifetime furnace replacement warranty. Ask what the difference in price for labor warranty is between the two.
    Do you mean difference between $ to replace HX vs. new furnace?

    Better yet, hang up on him and call someone who has the ability to think, has integrity, and actually knows what he is doing.
    He's long gone. Unfortunately, I don't seem to be able to find that guy.

    Thanks again.

    AM

  7. #7
    Join Date
    Jan 2008
    Posts
    85
    Quote Originally Posted by docholiday View Post
    Well that doesnt help without all the numbers, But anyway.

    The guy you spoke to fly's by the seat of his pants. I dont appologize for this response.

    Your home requires X btuh's over the course of an hour, day, week or month. All furnaces will deliver those btuh's over the course of the timeframe. The mod deilvers the same but in a long low fire output. IE 30,000 btuhs is 30,000 btuhs regardless if it's fired at a full 90,000 btuhs for 20 minutes out of an hour or 30,000 btuhs continuously over the course of an hour. There is no difference when it comes to the amount of gas burned but there is and can be a significant difference in comfort.

    I would have cut the conversation to less than a minute. He probably doesnt recommend a mod because he either has not been trained, is afraid of it for some reason or something else other than what he is presenting you.

    Fact is, you save gas by using cruise control over stomping and releasing the gas pedal. That is not to say that the mod will save you on gas, but the ride will be a heck of alot nicer. That said, the blower on the mod when in the 40% firing range (the vast majority) draws the same energy as a light bulb. Min is a 90k mod and at low fire the entire furnace pulls all of 80 watts of electricity. Ask this knucklehead how his PSC blower will be benificial to you.

    Ask him how you are going to control humidity in mild weather? Does his two stage furnace have On Demand Dehumidification?

    Ask him what the difference is between a lifetime HX warranty and a Furnace with a Lifetime furnace replacement warranty. Ask what the difference in price for labor warranty is between the two.

    Better yet, hang up on him and call someone who has the ability to think, has integrity, and actually knows what he is doing.

    Doc,

    Wouldn't there be more heat loss associated with longer run cycles of a
    furnace running in low fire mode when there's supply ducts running through
    unconditioned spaces and/or are leaky(as compared to a high fire short
    cycle) ?

    Not trying to stir up a hornet's nest here.....

  8. #8
    Join Date
    Feb 2007
    Posts
    999
    Quote Originally Posted by House View Post
    Doc,

    Wouldn't there be more heat loss associated with longer run cycles of a
    furnace running in low fire mode when there's supply ducts running through
    unconditioned spaces and/or are leaky(as compared to a high fire short
    cycle) ?

    Not trying to stir up a hornet's nest here.....
    Nor I. I'll take a guess on that. Your ductwork has a leak rate. Higher fire = more CFMs = more leakage.

    Might the longer run heat up the ductwork more and possibly reduce leakage (less expansion and contraction)?

    AM

  9. #9
    Join Date
    Mar 2008
    Location
    Baltimore MD and Ridgebury PA
    Posts
    542
    Quote Originally Posted by House View Post
    Doc,

    Wouldn't there be more heat loss associated with longer run cycles of a
    furnace running in low fire mode when there's supply ducts running through
    unconditioned spaces and/or are leaky(as compared to a high fire short
    cycle) ?

    Not trying to stir up a hornet's nest here.....
    I know I'm not Doc, but it seems to me that you'd have a heat loss with short run cycles at a higher firing rate because the supply ducts running through unconditioned spaces would cool off between cycles and would have to be heated once again at the beginning of each cycle.

  10. #10
    Join Date
    Jan 2008
    Posts
    85
    Quote Originally Posted by ampulman View Post
    Nor I. I'll take a guess on that. Your ductwork has a leak rate. Higher fire = more CFMs = more leakage.

    Might the longer run heat up the ductwork more and possibly reduce leakage (less expansion and contraction)?

    AM
    After thinking about it for awhile, I believe leakage loss is similar when comparing
    high CFM during high fire short cycles to low CFM low fire long cycles.
    Prolly could have worded that better.

  11. #11
    Join Date
    Nov 2007
    Posts
    25
    Best advice I can give you after having a Rheem mod installed is that be very sure that the installer has been trained and has the proper tools specifically for the mod. Ask for references from other mod installs they have done.

    I found out the hard way and am still working out the bugs on a mod install were the installer assumed they are just like any other 90+ single or 2 stage Rheem, and they just aren't.

    Did I see a huge decrease in gas costs, no (some of that could be contributed to the wife running the gas fireplace nonstop for days at a time). Electricity cost, yes, much lower in the winter with the fan running on low most of the time. Comfort level, much nicer, many less hot/cold spots in the house. No more banging ducts either as I had with the old furnace when they would heat and cool quickly.

  12. #12
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Quote Originally Posted by House View Post
    After thinking about it for awhile, I believe leakage loss is similar when comparing
    high CFM during high fire short cycles to low CFM low fire long cycles.
    Prolly could have worded that better.
    Leak losses will be higher for the higher CFM.

    Theoretical consideration...
    • Losses due to transfer through the duct surface will be higher. At lower CFM, there is a lower velocity. An air molecule will have longer contact with the duct. Therefore, heat transfer will increase.
    • Although, it may be that the lower discharge temperature of the furnace at lower fire rates will offset the slower CFM. Remember, lower temperature differential equals lower heat transfer rate.

    It would need to be tested. I haven't seen any studies.
    Perhaps you should have read the instructions before calling.

  13. #13
    Join Date
    Feb 2006
    Posts
    96
    what is so hard about installing a mod compared to any other 90+ furnace?
    maybe a few more tstat wires and a supply sensor?

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