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  1. #14
    Join Date
    Nov 2007
    Thanks to all of you for your guidence, much appreciated.

    The yellow wire is now good to go, and a bit shorter

    Dont regret that you spent a couple hours familiarizing yourself with your system, I am pletny familiar with the Mod and still play with it just for fun.
    Good point.

    I'm looking at the Rheem myself. How is the noise level?
    As of now, the difference between the Rheem and my old furnace is noticable but subtle at best. Not as big of a difference as I made myself believe based on what I read. Although the noise when heating is far different than my old furnace. For kicks I may use my spl meter to measure the db.

    However, I'm pretty convinced the unit isn't fully modulating. I decided to call my dealer and a tech will be comming out early next week.

    The furnace appears to run the fan during the heat cycle no different than when it does not call for heat.

    I have stuck my nose in the manual and learned of the various dip switches, and they are all at factory default. It doesn't appear that this should be the case. So, I believe this should certainly be an installer fix, especially the SW3 set.

    Hopefully in a few days all will be good. I'll chime in then and give my impressions. The temps haven't moved much past the mid 40's for a high, so I will have ample time to play with my new toy after the installer works his magic.

    Thanks again boys.


  2. #15
    Join Date
    Oct 2007
    Southern California
    I'm sure you've seen this.

    47 db at 40% should be pretty quiet.

  3. #16
    I have more or less the same setup , I have a Rheem 70k BTU modulating furnace matched with a modulating t-stat. I have my fan on for 24/7 and set it on heat right now. And I matched it with a Trane xb13 for my aircon. Before the install I have a old GE furnace and an 15 yr old Rheem aircon ( no idea what model) and the first thing I notice is that the cold spots on my house (1650 sf ranch) GONE!! I'm happy with the Rheem modulating furnace.

  4. #17
    Join Date
    Apr 2004
    The switches in SW3 are for fine tuning if needed, barring a weird duct system, you probably dont need to set them. The important switches are in the SW1 bank as to where you set your cooling size and speed, and whether or not you have a 2 speed AC or single speed.

    If you set your thermostat up one degree, your furnace will probably jump to near 100% so you really can't "force" it to modulate without using one of the test modes, it will do that on it's own. You can look in the window on the blower door (look down if upflow) and look at the Code. If you see a capital H, it's modulating, if it's a lower case h, it's not.

  5. #18
    Join Date
    Nov 2007
    My installer came back and corrected a few things. All appears to be good.

    Although a couple issues I'm not certain of....

    He moved the wire on the Thermo (pics are on page 1) from Y to Y2, not sure why?

    After correcting previous issues, he found the furnace to click often (a couple dozen times within a couple minutes) before running full blast before shutting down the heat. He made adjustments to the SW3 switches to compensate for ducts which were found to be on the small side for this furnace.

    Apparantly, the furnace was throwing code 22 which, if I remember correctly, tells the furnace to shut down because the heat exchanger was not cooling properly.

    I do notice upon shutting the furnace off, then back on, that the furnace has two codes, 11 and 22. I believe this means the codes are stored and doesn't reflect a current problem?

    Am I correct in saying that if the furnace throws a code when the furnace is operating, or cycling on or off, then there is a problem? But if I'm only seeing codes upon manually flipping the switch off/on then it is simply a stored code?

    If so, shouldn't the stored codes be cleared out? I looked in the manual but didn't see how to clear them out.

    Do I need to place another call to my dealer?

    Thanks again,


  6. #19
    Join Date
    Nov 2002
    The yellow wire on the thermostat should be on Y. The yellow wire on the furnace should be on YH/Y2.

    11 is four failed ignitons. Could be someone left the gas valve shut off.

    22 is a failed limit. Not a good thing. Usually comes from dirty filters if no other code is present . Based on the clues of your dealer saying the ductwork is too small I'd suspect this could be a re-occuring thing. Why didn't you have the ductwork fixed? If the dealer suggested to fix and you refused -shame on you. If the dealer didn't suggest to fix prior to install - shame on him.

    basically a code 22 means that you do not have enough air going across the heater tubes to cool them down. The safety switch is tripping to keep your unit from harm (and your house). If there was a 66, 67 or a 68 code also I'd say motor problem causing your code 22 (limit problem).

    Not knowing how to wire single stage AC to the Mod is not a sign of a competent installer.

    On the Mod thermostat Y is the first to come on to meet normal cooling loads, Y2 comes on if the house temperature continues to rise. On the furnace, Y is low speed cooling fan YH (Y2) is high speed cooling fan. So, on a single stage AC Thermostat Y comes on first and if it is wired to YH (Y2) on the furnace it will turn on high blower speed.

  7. #20
    Join Date
    Nov 2007

    Thanks for the info. Actually, this was the first the ductwork was mentioned.

    The sales rep visited my home and nothing was mentioned, three installers visited my home and installed the units and nothing was mentioned. Then after some headscratching while attempting to find why error code 22 would not go away, they discovered the ductwork issue. They were talking about installing a register above the ac coil to help with the issue, but the SW3 switches appeared to help. They didn't think a register was in the furnace room, but I noticed it after they left as it is in a hard to see area.

    This is a little upsetting to hear as I don't know what I should do at this point.

    Had I known there could be additional expenses, I would have done things much differently. My ac unit was ok, just old, I could have skipped the install of a new unit. I also could have simply paid to have my old Rheem repaired or purchased a less expensive alternative as I don't think I'll be in my current home for more than three years. I thought I was going about things the correct way.

    Should I just keep an eye out and see if the code is thrown again? If so, is a code valid only durring operation and not upon turning the furnace off/on at the switch, would this simply be a stored code?


  8. #21
    Join Date
    Nov 2002
    I need to re-state that the 22 code is an open limit. When the limit opens it will shut off the gas and keep the blower on until it re-sets. I would only expect to see it during a gas heat call and only if there is an issue like a failed blower or a extremely diry filter.

    If you are having airflow issues with the heating it will be as bad with AC. Roughly, your AC will blow 1000 CFM and your heating will be 1080 cfm. It could have been worse if your AC was 3 tons then the AC blower would call for 1200 CFM cooling!
    I would simply stand my ground that I want the unit to not flash any codes during any call for cooling or heating (look in the window when it is running). Bad ductwork will cause the furnace to flash a 66 only when it's running as the 22 code takes presedence and can bump it out if both are present simultainiously.
    Playing with the switches is an effort to boost airflow so the unit won't trip the limit (22). If it works it will only work with a clean filter and it will cost more electricity to keep the blower running on that much back pressure (static).

    Hopefully the installers will step up and correctly fix.

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