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  1. #1
    Join Date
    Jun 2009
    Posts
    146

    Question on Rheem RGRL 2 stage Gas Furnace

    On the Rheem RGRL, does the blower speed change with each stage as well as the btu or is it only the btu? I have medium low (yellow) on heat and low (red) on fan.

    On first stage, will it run the blower on low or does it run both on the medium low and just the btu goes up?

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,398
    On 1st stage, it blows on fan speed. When 2nd stage calls and fire cranks up, it switches to heat speed.

  3. #3
    Join Date
    Feb 2007
    Posts
    999
    Quote Originally Posted by david8370 View Post
    On the Rheem RGRL, does the blower speed change with each stage as well as the btu or is it only the btu? I have medium low (yellow) on heat and low (red) on fan.

    On first stage, will it run the blower on low or does it run both on the medium low and just the btu goes up?
    The furnace has a 2 stage gas valve, which operates at 70% and 100% input. The speed of the blower will change from a lower (first stage) to a higher (2nd stage) speed.

    From your post, do I take it that the furnace is already installed? You don't want to be adjusting blower speeds without the requisite knowledge and equipment.

    Whether it is low, medium low, medium, etc., is dependent on your duct system and will be adjusted by the contractor during installation, so that the unit's temperature rise (difference in temperature of return and supply air) is in specification for each stage. He may also set the fan's 'on' speed.

    I tried to view the mfg's specs, but were unable to retrieve them for better information.

    Amp

  4. #4
    Join Date
    Jun 2009
    Posts
    146
    Thanks guys. I'm going to have my contractor come out before heating season to make sure the blower settings are appropriate.

  5. #5
    Join Date
    Jun 2009
    Posts
    146
    One more question... my contractor refers to my furnace as a 4 ton. Does he mean that it has the capability of moving 4 tons of air, i.e., 1600 cfm?

    When I look at the spec document, it actually shows it can deliver up to 2100 cfm on the high blower speed, so wouldn't it really be capable of 5 tons of blowing?

  6. #6
    Join Date
    May 2009
    Posts
    6
    The furnace is capable of being matched up to a 5ton AC unit that would need about 2100CFM, but it sounds like your AC and duct system is a 4ton that needs about 1600 CFM.

  7. #7
    Join Date
    Jun 2009
    Posts
    146
    Quote Originally Posted by freeflow View Post
    The furnace is capable of being matched up to a 5ton AC unit that would need about 2100CFM, but it sounds like your AC and duct system is a 4ton that needs about 1600 CFM.
    Actually, my condenser is a 3 ton. The blower setting is currently on med-low and producing around 1255 - 1490 CFM (depending on static pressure). I don't think my contractor ever measured the actual static, but he initially left the factory settings with blower on high for cool which was producing between 1745 - 2100 CFM. Needless to say, it was VERY noisy before it was changed it to med-low.

    Incidentally, my inside coil is a 4 ton.

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,398
    I bet 95% of the furnaces installed are left on high from the factory even though low or medium low is appropriate!

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