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  1. #1
    What is the difference in effiency with a Ruud UBHC21J18SHG to a UBHK21J18SHG?Both have a thermal expansion valves,w coils..What makes the UBHK more efficiant than the UBHC?
    I've talked to several Ruud dealers because i want a 14 seer unit and they recommend a 12 seer unit...Someone please help me understand...

  2. #2
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    the UBHK has a Varible speed blower. Runs on DC voltage. Uses a lot less electricity than a PSC motor that the UBHC has.

    Do a search on this site for better info.
    Karst means cave. So, I search for caves.

  3. #3
    Join Date
    Apr 2004
    Posts
    7,680
    The UBHK does indeed have the ECM motor, a great option. Adds a SEER point generally speaking over the BHC. It will alsoprovide the airflow you need even when conditions change such as filter accumulating or brnch ducts being shut off.

    I gotta tell you this. Its worth the difference, and not in efficiency alone. With the BHK, I would install a 2-stage cooling thermostat. Have it configured for On Demand Dehumidification. When 1st stage calls in cooling the airflow will be reduced by 15% which will lower the sensible capacity and increase the latent. This will comfort your home 2 ways. It will increase run time which removes more moisture, and of course the higher latent capacity will also. Then in the event 2nd stage is required the airflow returns to nominal which gives you the sensible cooling you need for the temperature. Its like getting a 2 stage condenser that operates at about 80% and 100% for the price of a single stage.

    I tell you this, if you are not using a 2-stage stat or a humidistat with the BHK you are not doing your customers justice. Its a shame this is a unknown secret it seems.

    BTW, just to clarify, it runs on AC votage but the module in the motor end, rectifies the votage to DC and therefore uses less current for standard operation.

  4. #4
    Join Date
    Jul 2003
    Posts
    51
    Doc,
    I have the rheem version of this airhandler - installed last year, and wanted to talk to my contractor about upgrading my stat. I currently have a honeywell programmable, which works fine, but wanted to take better advantage of the A/H's humidity control ability. Do you use a humidity sensing stat, like a thermidistat, or what do you recommend? I have my spring clean and check coming up and want to run this by him...
    Thanks.
    JM
    Originally posted by docholiday
    The UBHK does indeed have the ECM motor, a great option. Adds a SEER point generally speaking over the BHC. It will alsoprovide the airflow you need even when conditions change such as filter accumulating or brnch ducts being shut off.

    I gotta tell you this. Its worth the difference, and not in efficiency alone. With the BHK, I would install a 2-stage cooling thermostat. Have it configured for On Demand Dehumidification. When 1st stage calls in cooling the airflow will be reduced by 15% which will lower the sensible capacity and increase the latent. This will comfort your home 2 ways. It will increase run time which removes more moisture, and of course the higher latent capacity will also. Then in the event 2nd stage is required the airflow returns to nominal which gives you the sensible cooling you need for the temperature. Its like getting a 2 stage condenser that operates at about 80% and 100% for the price of a single stage.

    I tell you this, if you are not using a 2-stage stat or a humidistat with the BHK you are not doing your customers justice. Its a shame this is a unknown secret it seems.

    BTW, just to clarify, it runs on AC votage but the module in the motor end, rectifies the votage to DC and therefore uses less current for standard operation.

  5. #5

    RUUD AIR HANDLERS

    Will a 14 SEER Ruud Condenser work well with the UBHC Air Handler besides not getting the full 14 out of it?

  6. #6
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Yes it will work, as long as it has a TXV in the coil. I think it is a 13 seer with the R/UBHC airhandler.
    Karst means cave. So, I search for caves.

  7. #7

    RUUD AIR HANDLERS

    My other question is,would bumping up a 1/2 ton make much difference?I have a 4 ton air handler with a 3.5 ton condenser,..I was wondering if it would make much difference with a 4 ton condenser..The condenser is 26 years old and I think the compresser is on its way out,the light dim when it kicks on and back to normal once it gets going...

  8. #8
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Click the bullseye at the top of the page and see what size unit you need. Too big of a unit is worse than too small.
    Karst means cave. So, I search for caves.

  9. #9
    Join Date
    Apr 2004
    Posts
    420

    Re: RUUD AIR HANDLERS

    Originally posted by rebelchevyz71
    My other question is,would bumping up a 1/2 ton make much difference?I have a 4 ton air handler with a 3.5 ton condenser,..I was wondering if it would make much difference with a 4 ton condenser..The condenser is 26 years old and I think the compresser is on its way out,the light dim when it kicks on and back to normal once it gets going...
    Resdential RUUD AH's come in four sizes, with 7 total blower speed possibilities throughout. If you currently have a 4 ton condensing unit, have a tech change the blower speed to put out 14oo CFM, or 3.5 tons, IOW no such thing as a "4 ton air handler."

    Lay out about 50 bucks for the program at the top and you will find your money well spent. Bumping this or that up is merely guessing. You won't be sorry for being conscientious now.

  10. #10
    Join Date
    Apr 2004
    Posts
    420
    Originally posted by docholiday
    The UBHK does indeed have the ECM motor, a great option. Adds a SEER point generally speaking over the BHC. It will alsoprovide the airflow you need even when conditions change such as filter accumulating or brnch ducts being shut off.

    I gotta tell you this. Its worth the difference, and not in efficiency alone. With the BHK, I would install a 2-stage cooling thermostat. Have it configured for On Demand Dehumidification. When 1st stage calls in cooling the airflow will be reduced by 15% which will lower the sensible capacity and increase the latent. This will comfort your home 2 ways. It will increase run time which removes more moisture, and of course the higher latent capacity will also. Then in the event 2nd stage is required the airflow returns to nominal which gives you the sensible cooling you need for the temperature. Its like getting a 2 stage condenser that operates at about 80% and 100% for the price of a single stage.

    I tell you this, if you are not using a 2-stage stat or a humidistat with the BHK you are not doing your customers justice. Its a shame this is a unknown secret it seems.

    BTW, just to clarify, it runs on AC votage but the module in the motor end, rectifies the votage to DC and therefore uses less current for standard operation.
    That is an awesome tip and I can't wait to try this.

  11. #11
    Join Date
    Apr 2004
    Posts
    7,680
    Remember Y2 goes to the ODD terminal and both dips 5 and 6 go to off.

    Be sure too charge the unit with both Y1 and Y2 calling.

    Also I think you'll need at least 7 conductors to the thermostat (unless no C is used).


    Another free tip from the good doctor.

  12. #12
    Join Date
    Nov 2001
    Location
    East Texas
    Posts
    883
    I installed 2 UBHK in the house I built 2 years ago. I installed 2 stage stats but have never hooked up the Dehum. On demand feature.

    How much would that effect my utility bill?

    How much longer would the comp run?

    Should I hook it up?

  13. #13
    Join Date
    Apr 2004
    Posts
    7,680
    Its a comfort thing, not an efficiency thing. It will be more comfortable but it wont reduce your power bill, and it will increase your runtimes during non-peak loads to better dehumidify. There is no magic, just a matter of what is the priority for you. I believe that with a lower humidity, you can run the temperature higher. If you like 74 and humid you will much better like 76 and dry.

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