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  1. #1
    Join Date
    Aug 2011
    Posts
    12

    Rheem output temp

    I have a brand new Rheem RGRM07EMAES that's outputting tops, 100 degree heat here in Minnesota. Installer has been spending the last couple of days playing around dip switches, messing with the default rise temp of 55. Aside from the amount of air being pushed out, he has been unsuccessful in getting the heat output above 100 degrees.

    We measured return and supply temps and it's averaging around 30+ for rise. Because of this, he adjusted the heat rise so it was closer to that number. However, we got temp readings in the mid 90's with this and of course, it didn't blow as hard.

    My question is, should I be expecting higher temperature output, as I'm being told it should be around 125? I have an older model American Standard in another portion of the house that's the same size and is blowing out around 120. Please let me know your thoughts and if I can provide any more info.

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,386
    tell us a little more about the installation...

    Where is the air handler? What are the temp readings return and supply?

    More information from you will help us to form a better picture of your installation, and then to give you better answers.

    I'm not familiar with Rheem model nomenclature. Is it a fuel burning appliance or an electric furnace?

  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,386
    Thermojohn,

    This is the Ask Our Pro's forum. In order to post advice here, you must have verified qualifications and have been approved by the AOP Committee.

    You can find the rules for posting and qualifications here.

  4. #4
    Join Date
    Aug 2011
    Posts
    12
    Return: 67
    Supply: 98

    Furnace is in the basement, directly below the two floors it heats. Gas heat. This is the furnace: No links of to direct sale sites allowed please I'm posting this to help my hvac installer. He's not much of an internet guy if you know what I mean.



    Quote Originally Posted by jpsmith1cm View Post
    tell us a little more about the installation...

    Where is the air handler? What are the temp readings return and supply?

    More information from you will help us to form a better picture of your installation, and then to give you better answers.

    I'm not familiar with Rheem model nomenclature. Is it a fuel burning appliance or an electric furnace?
    Last edited by k-fridge; 11-19-2011 at 11:16 PM.

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,889
    The default temp rise on a Rheem 95 isn't that hot. To get the AFUE, they run a lower rise though that is rather low. Is he sure it is going into high fire? Is he using a 2 stage stat or the #$#& timer? Hopefully he's smart enough to "clock the meter" and take a manifold pressure.

    Now, where is he taking his supply temp? We had a furnace that the HO complained it wasn't putting out warm air. Tech took a reading in a dead zone and the supply temp was pretty cool. The tech rep pointed out that to have that low of a rise due to airflow would be impossible, the blower didn't move that much air!

  6. #6
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,386
    larnot,

    This is the Ask Our Pro's forum. In order to post advice here, you must have verified qualifications and have been approved by the AOP Committee.

    You can find the rules for posting and qualifications here.

  7. #7
    Join Date
    Aug 2011
    Posts
    12
    Supply temp is being taken directly from the supply plenum, right above the unit. The 98 degree reading is being taken while the unit is in 2nd stage. I'll mention to him about clocking the meter and read the manifold pressure.

    In your experience, is a temp of >100 degree output something you would question? Or is it quite possible that's what this Rheem usually puts out?

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,889
    Something is fishy. High fire temp rise should be minimum 40.

    A/C isn't coming on with the furnace is it?

  9. #9
    Join Date
    Aug 2011
    Posts
    12
    Just an update on this. We're using a 3M Filtrete 3M22 state that's correctly set into 2 stage mode. The stat needed to be set into the correct stage mode to allow for 2 stage heating/cooling. Funny thing is, however, that this still hasn't solved the problem. The furnace will ramp up in low, however when it switches to high there's no flame and it blows for a minute that starts the cycle again going back into low. Will keep sniffing around here...

  10. #10
    Join Date
    Dec 2007
    Location
    houston, texas
    Posts
    3,787
    Your tech need to spend a little more time diagnosing the problem and leave the dip switches alone. Sounds like your only running in low, should be easy to figure out. Gas pressure in and manifold pressure should have been the first things he checked.
    I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.

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  11. #11
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,829
    There are many variables that can affect the actual temperature outlet form the furnace. For example, if your indoor temperature is 68F but your return air ducts run through a cold crawl space, leak like a seive and are non-insulated, the actual return air to the furnace could be 50F or less. If the furnace has a rather normal 45F temperature rise, then clearly the output would only be 95F. But if the return air is 67 and you add a 45 temperature rise, the result is an output of 112F.

    The second case is more in the norm of system operation. Your installer should already have checked the return air temp, the supply air temp and should therefore know what the temperature rise is through the furnace. The manufacturer's data plate clearly states the minimum and maximum temperature rise and changing the blower speeds to adjust between those two temperatures will only work when you're already operating within that range. If the return air is too cold, you may never get there. That's bad for your comfort and for the system operation on a continuing basis.

    It sounds a little like the installer is guessing. He needs to start using accumulated data obtained on site. 99% of the time that data will reveal the cause of the problem and once the cause is known, a remedy can be prescribed.

  12. #12
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,889
    Furnace or install issue. We had an RGRM that wouldn't heat the house. Found a sag in the flue pipe causing the pressure switch to cut out. Fixed that, no further problems. That cycling explains the cool air. Make sure it is vented on 3" PVC and that the pipe has a clear fall from where it leaves the house back to the furnace. If you see nothing visually with the flue, the installer should be able to figure out why the fire is going out.

  13. #13
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,422
    I agree with Bald, he needs to check his flue size and number of elbows. Sounds like a flue problem keeping the unit from going to high fire. We had a similiar problem with another brand when the manufacturer changed the design of the flue motor, and of course our installers never read the newer install manuals!!

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