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Thread: Please Help. Ecobees Smart Si. Heatpump, w/ electric furnace backup.

  1. #1
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    Please Help. Ecobees Smart Si. Heatpump, w/ electric furnace backup.

    I installed my ecobee a little over 2 months ago, and all was working wonderfully until this recent cold front came in.

    I have a power meter on my house so I am able to see instantaneous usage and i noticed that while it is too cold in the house for the heatpump, and ecobee should be running aux only.. I am only using half the amount of power that it should be using. As if it is only utilizing half of the thermal strips.



    Can anyone please help?

  2. #2
    HVAC Thermostat Specialist

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    Do you have seperate W1 and W2 connections at the air handler? Are both energized? If both have power on both, your thermostat is OK.

    Sequencers are a high failure item inside the air handler, and have one bad would cause the problem you are having. To troubleshoot requires working with high amperage 240v circuitry, don't touch if you don't know exactly what you are doing.

  3. #3
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    Quote Originally Posted by Servicetech View Post
    Do you have seperate W1 and W2 connections at the air handler? Are both energized? If both have power on both, your thermostat is OK.

    Sequencers are a high failure item inside the air handler, and have one bad would cause the problem you are having. To troubleshoot requires working with high amperage 240v circuitry, don't touch if you don't know exactly what you are doing.
    Thank you for the response. Please bare with me as this will be a longer response.

    Little history: The furnace is question is 13months old, and was installed by a bank hired contractor while I was in closing on the house.It appears to have 3 heating elements (although the schematic refers to 4). The thermostat initially installed was unsupported for the system this house has (see previous threads on this forum for details) so I bought the Ecobee at the start of winter.


    Last night I opened the panel** and began reviewing the schematic inside.. internally the system is wired to have 2 stages of heat, done through two relays, W1 (BLK) and W2 (WHT) being the controls. W1 and W2 are then tied together with the thermostat control W wire, which should mean all heater elements come on at once.

    I checked connections inside and all felt solid, and seemed to match up with the schematic. So i began measuring the 24v signal. I adjusted the thermostat to 50* in order to test that the W wire is switching properly, and it was. When I switched the setting back to 70* I saw a 10kw usage on my meter which means a second of the heater elements came on this time. ( i changed no wiring, only checked connections)

    This setup allowed the system to overtake the cold weather and get my house back to temperature, but it is still not the full power of the furnace.

    **I am an electrical engineer with experience with 460-600v systems, So I am comfortable investigating within the furnace, and even have the proper equipment.

  4. #4
    HVAC Thermostat Specialist

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    W1 and W2 should each control a sequencer. On a 3 element system each element is typically about 5KW. The 1st 2 elements are typically controlled by the 1st sequencer, and W2 picks up the 3rd element. Most newer air handlers have 2 breakers, 1 for the blower and W1 element(s), the 2nd for W2 element(s) Be sure the 2nd breaker is is getting power. Considering the history of the house it's entirely possible it was hacked and there is no power being fed to the 2nd breaker. If power is good, check the 3rd element for voltage. If no voltage just trace the circuit and see where it's dropping the power.

    I think Ecobee is capable of staging W1 and W2, this could keep some of the elements off until they are needed.

  5. #5
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    Quote Originally Posted by Servicetech View Post
    W1 and W2 should each control a sequencer. On a 3 element system each element is typically about 5KW. The 1st 2 elements are typically controlled by the 1st sequencer, and W2 picks up the 3rd element. Most newer air handlers have 2 breakers, 1 for the blower and W1 element(s), the 2nd for W2 element(s) Be sure the 2nd breaker is is getting power. Considering the history of the house it's entirely possible it was hacked and there is no power being fed to the 2nd breaker. If power is good, check the 3rd element for voltage. If no voltage just trace the circuit and see where it's dropping the power.

    I think Ecobee is capable of staging W1 and W2, this could keep some of the elements off until they are needed.
    This is exactly how my system is set up. Breaker 1 is 60A, and controls the fan and seq1. Breaker 2 is 30A and Controls the seq2. Although W1 and W2 are both connected to the thermostat wire W so all should come on at once, and not be staged as mentioned.

    Last night I tested jumpering W1 and W2 separately to the red 24v directly (i also jumpered the fan so not to overheat the elements) doing this I was able to confirm on my power meter that each sequencer was indeed working separately and added up to the full power of the furnace.

    I then tested a switch inline with the W2 and the thermostat control wire, using this I am able to select if the thermostat can activate only sequencer1 or both. When I did testing with this the power meter showed 2 elements on with the W2 disabled, and the full power 3 elements with W2 enabled. Somehow adding this switch allows the furnace to function properly?!?!?! Any ideas why that would be?

  6. #6
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    Quote Originally Posted by micro2112 View Post
    This is exactly how my system is set up. Breaker 1 is 60A, and controls the fan and seq1. Breaker 2 is 30A and Controls the seq2. Although W1 and W2 are both connected to the thermostat wire W so all should come on at once, and not be staged as mentioned.

    Last night I tested jumpering W1 and W2 separately to the red 24v directly (i also jumpered the fan so not to overheat the elements) doing this I was able to confirm on my power meter that each sequencer was indeed working separately and added up to the full power of the furnace.

    I then tested a switch inline with the W2 and the thermostat control wire, using this I am able to select if the thermostat can activate only sequencer1 or both. When I did testing with this the power meter showed 2 elements on with the W2 disabled, and the full power 3 elements with W2 enabled. Somehow adding this switch allows the furnace to function properly?!?!?! Any ideas why that would be?
    Sounds like you may have just had a bad connection somewhere. Try putting it back like it was and verify both sequencers are coming on and providing power to the elements. Also verify all elements are in fact 5KW and are drawing thier rated amperage.

    The blower shoudl be interlocked with the sequencers. If a sequencer comes on it should force the blower to run with the elements.

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