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  1. #1

    Bryant heat pump using too much aux. heat

    I just had a new Bryant 265 heat pump with FE4 Evolution fan coil installed a month ago. I live just outside of Washington DC. The A/C seemed to work great. Now that it is getting cooler in the evenings, I have the heat turned on and I've noticed what seems to be a problem to me and I wanted to get some other opinions. I first noticed the issue when I got up in the mornings. I have the system programmed to bring the heat up from 67 to 72 15 minutes before my alarm goes off. The house has not ever cooled down below 69 so it has not had to bring the temperature up more than 3 degrees. What happens is that the heat pump comes on as scheduled, but at a very low fan speed, so it does not push enough heat to warm the house. After 15 minutes the auxillary heat kicks in and the fan speed increases, with the house warming up very quickly. Last night I did a test where it was 70 in the house and I kicked the thermostat up to 71. The outside air temperature was 49 degrees. The same thing happened. The heat pump ran for 15 minutes. The air felt warm at the vent, but there was very low air pressure. After 15 minutes the auxillary kicked in and the house temperature went up to 71 in about 5 minutes. I have the fan setting to AUTO in all of my schedule entries and also set to AUTO on the thermostat. Does this operation sound normal? I didn't think the auxillary heat should come on at all when it's 49 outside. Is there some way to boost the fan speed without having to force the programming into a fixed speed setting? Thanks for your advice.

  2. #2
    Join Date
    Jun 2007
    Location
    The Twilight Zone
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    2,964
    What brand/model# thermostat do you have?

  3. #3
    I have the Evolution control. Don't know what the model number is. Is there more than one Evolution model? If so, I'll check this evening and post it tonight.

  4. #4
    Join Date
    Jun 2007
    Location
    Metro St. Louis
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    181
    http://www.docs.hvacpartners.com/idc...iuid01-0-1.pdf

    One of the options that can be set is Electric Heat Lockout. The installer probably left it blank (default) - which is no lockout. You'll want this to be set rather low (25-30*).

    In fact, you will probably want to review all of the settings. Just don't change anything unless you are comfortable with doing so. Otherwise, just note what things seem "weird" and call your installer to come and reprogram it if necessary.

  5. #5
    Thanks for the link waterloo. I am pretty sure that the dealer left all of the setting at the default settings. I turned off the smart recovery, but that is all so far. I will try setting the electric heat lockout as you suggested. What do you think about changing the fan coil airflow from comfort to efficiency? Since it seems like the airflow is so low now, will that give me more heat from the heat pump? Do you know how this would differ from setting the fan speed to medium in the scheduling program?

  6. #6
    Join Date
    Jun 2007
    Location
    The Twilight Zone
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    2,964
    Quote Originally Posted by robinhood View Post
    I turned off the smart recovery
    Why??

  7. #7
    According to the manual, with smart recovery on, the heat will come on 90 minutes before the time set in the schedule. In the mornings, which is the only time the heat has to raise the temperature significantly, I only need it to come on 15 minutes before I get up, so I programmed the wake time to be 15 minutes before I get up.

  8. #8
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    I don't know much about the Evolution controls - I'm just going by what I read while I was making my decision...

    Does it show the correct size information for the HP and the electric heat sizes?

    Efficiency should increase airflow. I don't know what the two speeds are exactly. Do you have a bypass humdifier installed? If so, it looks like you need to hit the low heat rise option.

    Turn the auto recovery back on. It will start the heating process earlier (and slower) to get it up to temperature at the desired time.

  9. #9
    The size information is showing correctly. I do not have a humidifier on the system. I will have to experiment with the smart recovery setting, but first I want to set the electric heat lockout to see how well the heat pump works by itself. If smart recovery works without turning on the auxillary heat it might be more economical, but it depends on how long the heat pump runs and that depends on the outside temperature. I don't know the electricity demands of the heat pump vs. the aux. heat. For example, is it more economical for the heat pump to run for an hour as compared to the aux. heat running for 10 minutes?

  10. #10
    Join Date
    Aug 2002
    Posts
    1,651
    Robin,

    I would turn the smart recovery back on.. The control will slowly bring the temp back up in the house by using the heatpump and very little aux heat even if the aux heat is left on default.. When you disable the smart recovery a heat pump is designed to maintain temperature and has a hard time recovering from a set-back with out the use of aux heat..However with the smart recovery on the control slowly raises the temperature which will primarily be with the heat pump heat..

    I would also lock out the aux heat, the lock-out set point may be able to be set low 25-30 or higher/lower depending on sizing and house.. This depends on an accurate load calculation to give you an exact number to set it at..

    J

    Also it is cheaper to run a heat pump for an hour than running aux heat for 10 mins in most cases...

  11. #11
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,040
    I think you may be missing the point of using a heatpump in the first place. The 286 unit with air handler is approximately 15 SEER. The evolution system (if programmed properly) will use the best option/least expensive mode to heat your home. That's what you paid for, and that ability is probably what sold you on it.

    Your heatpump should be sized for air conditioning load in the summer time, not the heat load when it's cold. The electric heat is there to make up the difference between these two amounts.

    Your home needs X amount of btu's of heat to heat it at any given outdoor temperature. The "speed" at which you put that amount of heat into it coming out of setback dictates how long it will take. Trust the evolution system to figure this out correctly.

    Adjustment of the fan speed is limited to what the options are on the interface. The evolution system will assure correct air flow for the heat pump operation and will give you the range in the form of the comfort, efficiency options. The air flow that you are sensing is what can be supplied by the air handler to allow the heatpump to run correctly.

    I run my heatpump down to 15 degrees outside temperature because I've done the math and know at that temperature the heat pump will put out the required amount of heat to replace what the house is loosing plus enough to bring it out of night setback. If you don't know how to do the math, experiment with it. Lock out the electric heat at the lowest temperature you feel comfortable with and see how the system responds. Enable the smart recovery and set the time you get up and let the system do what you paid it to do. If the system decides that it requires the electric heat to come on it might be that the heatpump has gone into defrost on the outside unit. If the electric didn't come on at this point you'd be getting air conditioning air out of your registers.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  12. #12
    Thank you to everyone for their advice. I will turn back on the smart recovery. Yesterday I changed the setting on the air handler from comfort to efficiency and it did boost the airflow coming out of the vents. Today the auxillary heat did not come on.

    One question I have - last night I went into the install/service menus on the thermostat and tried to go into the heat pump settings under Setup Heatpump, to turn on the electric heat lockout as several of you suggested, but the option did not appear on my menu. To clarify, the Setup Heatpump menu appears, but that specific option for electric heat lockout is not there. It is shown in the manual they gave me with the system (the is for an Evolution SYSTXBBUID01-B thermostat). Any ideas on why it's not showing? I tried to go through the other menus, but I did not see it anywhere else.

  13. #13
    Join Date
    Oct 2003
    Location
    Haymarket, Northern Virginia
    Posts
    72
    Looks like you have the same issue I have. JRBenny posted in my thread on Carrier Installation Issues that this part of the menu got dropped in the software version you and I have, v.13. Look on your controller and see if that's what you have under the setup menu I think. He says v.14 should be coming out soon, but that means a change out of controllers.

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