Maryland 7 Series Aux Heat Energy Monitor

Discussion in 'Maintenance and Troubleshooting' started by dmj2359, Feb 11, 2016.

  1. dmj2359

    dmj2359 New Member

    I've had a 7 series unit running in our new home for 3.5 years now, and I'm pretty happy with it. This morning I noticed that the aux heat had kicked in, which as far as I've noticed is the first time ever. I wandered over to the thermostat to check, and noticed that the system said 0 Watts for the Aux Heat. After a quick internet search I saw that there are CT sensors for the compressor and aux heat - after popping the front cover off the unit I noticed one CT at the top of the wire bundle has no wires through it.

    So problem solved - almost. When I look at the compressor CT, the wire is not routed straight through it as I would expect, it's doubled back on itself in a way (I will try to get a photo if needed). For the Aux Heat CT can I just route the two black wires the head to the heater strips through the sensor, or is it more complicated than that?
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Plug the existing power blower power 5-pin connector (brown, orange and green wires) into receptacle from the
    auxiliary heat control panel with the brown, orange, and green wires. The ground wire from the original blower power is
    no longer used and should be clipped or tied to prevent interference with other components.
    • Plug the 5-pin connector (blue, violet, and green wires) hanging from the auxiliary heat control panel into the variable speed
    ECM motor receptacle P11. Connect the green ground wire to the blower housing using the previously removed screw.
    • Units that have the Aurora Advanced Control option are shipped from the factory with a current transducer already connected
    to the variable speed ECM blower motor brown power wire. On these units the brown wire that is routed twice through the
    Current Transducer will need to be replaced with the blue wire that is connected to the auxiliary heat power block.
    the brown wire from the PB2 power block in the unit’s control box. Route wire into the blower section and remove the current
    transducer. Reroute the wire back into the control box and reconnect it back to its original location on the PB2 power block.
    Remove the blue wire from the quick connect terminal on the auxiliary heat power block. Route this wire through the current
    transducer twice and reconnect it back to its original location on the auxiliary heat power block.

    • Reconnect the 16-pin connector from the main control board to the variable speed ECM motor receptacle P12.
    • Proceed to the Energy Monitoring Connections table for instructions on connecting the auxiliary heat kit to the auxiliary
    heat current transducer.
    • Proceed to step 15.
  3. dmj2359

    dmj2359 New Member

    I'm not sure it's any clearer after reading all that. Summarized:

    1. Remove the brown wire (ECM blower) that is wrapped twice through the CT.
    2. Replace that with the blue wire (Aux Heat) wrapped twice through that same CT.
    3. Proceed to instructions for connecting the auxiliary heat to the aux heat CT.

    In the top cabinet of the unit there are two CT's - one has the brown wire through it twice (lower) and the upper one has no wires through it. I have previously confirmed that the total power reported by the thermostat (compressor + blower + pump) is pretty accurate using current clamps on the feed wires in the panel. Doc - where did that write up come from - I couldn't find it in the 7 Series Install Manual.
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    sorry, my mistake, this was for the blower wire, not the compressor, which is the one coming not installed. Do you see the fan wattage? how about if you go online? not the thermostat.
  5. dmj2359

    dmj2359 New Member

    Yes, I see the fan wattage on both the thermostat and the AID tool. I have previously confirmed that the total Fan + Compressor + Pump reported by the AID tool and thermostat are within +/- 10 Watts of a multi-meter current clamp reading.
    geoxne likes this.
  6. geoxne

    geoxne Active Member Forum Leader

    Your summary is incorrect, depending if your installer followed factory wiring instructions for aux heat and CT placement. Based on what your ability to read blower amps now with blower CT on the Brown wire, he did not.

    WaterFurnace factory wiring diagrams with aux heat (on site installed) provide power for blower and control board through the Aux Heat circuit (this also requires removal of jumpers between cc and powerblock). The reasoning here is if the compressor supply circuit breaker tripped, the unit would still operate blower and aux heat.

    This is not a big issue. The instructions are shipped with the aux heat pack and get complicated depending on the equipment installed. Instructions must be followed explicitly with Power OFF. If you do not understand the instructions don't do it. Make the original installer do it.
  7. geoxne

    geoxne Active Member Forum Leader

    Also, I just realized the installer may have pulled out and tossed the violet, blue and green blower power connector needed power blower from aux heater. Check to see if you have it.

    Edit- Some installers do not follow factory instructions for particular reasons. One case includes when HO wants to leave Aux Heat breaker off until they determine it is needed. Of course automatic redundancy is lost in this case.
    Last edited: Feb 12, 2016
  8. geoxne

    geoxne Active Member Forum Leader

    You can just leave all wiring as is and feed AUX Heat L2 supply leg once through currently empty Aux heat CT. If you have more than one circuit feeding Aux heat you will have to check phase between both circuits to make sure both circuit legs of the same phase are routed through the Aux heat CT (if you don't they will cancel each other out).

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