WF Series 5 Open Loop/Power Consumption Not Making Sense

Discussion in 'General Discussions' started by batman71, Mar 2, 2013.

  1. batman71

    batman71 New Member

    I have a new home with a WaterFurnace 3 ton Series 5 open loop system. The well pump is a 1.5 HP constant pressure set at about 120 ft. Since the house is not yet complete, I am running the system with NOTHING else drawing any power.

    I have the thermostat model that displays the power usage which includes the compressor as well as the fan. Yesterday when I left the house, I checked the readings on the thermostat as well as the power company's electric meter and then checked again today. As noted above, nothing else was left on (no lights or anything). Over the intervening 18.5 hour period, the thermostat reported 15.9 KWh consumption while the electric meter showed usage of 36 KWh. All of the compressor run time was in stage 1. This means that the well pump was apparently responsible for a little over 20 KWh of power consumption.

    The run time of the heating system during the 18.5 hour period was 10.5 hours. If the well pump was running at full capacity during the 10.5 hours, then it would have used a little under 12 KWh (1.5 HP x .746 KW/HP x 10.5 Hours). That leaves at least 8 KWh unaccounted for. If we assume that the well pump was pumping about 6 GPM as compared to full capacity of about 18 GPM, then the power used by the pump would be significantly less than the 12 KWh mentioned above and the power that I can't account for would be significantly greater than the 8 KWh figure.

    What am I missing here?
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Is the well pump shutting off?
     
  3. Calladrilling

    Calladrilling Member Industry Professional Forum Leader

    What kinda of constant pressure pump is it?
    Is it a true variable speed motor or a CSV on a constant speed pump?
    is it capable of running low volume of water without cycling?
     
  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    You may have failed to account for the inefficiency of the well pump. A nominal 1.5 HP pump routinely consumes 1800-2000 Watts. That your system needs 6 GPM and the pump can move 18 GPM have no useful bearing on pump duty cycle unless you know actual pressures and flows.

    Put another way, the pump could easily account for the power consumption you believe unaccountable. Consider applying a clamp amp meter to one of the pump hot leads. Consider also observing pump cycling and measuring delivered pressure and flow. Results will likely suprise you.
     
  5. batman71

    batman71 New Member

    To urthbuoy....yes, the pump is shutting off.

    To Calladrilling....I have a Goulds 18GPO715 Propak Kit which also includes an Aquavar Solo contoller
    My understanding is that this is a TRUE variable speed pump and is capable of running low volume of water without cycling

    To engineer.....I had considered that there may be some inefficiencies in the well pump. However, I admit that I assumed they would not be significant enough to account for the 20 KWh mentioned. Although I am a degreed M.E. I have forgotten everything I ever learned that would have helped me evaluate what is going on.

    I had been considering the purchase of a TED monitoring devide (or similar). I assume that would tell me specifically how much power the well pump is consuming.

    If I confirm that the pump is in fact using that much power, are there any adjustments or modifications I could make that would not comprimise the performance of the geothermal system or domestic water pressure/flow? I noticed a posting on another message board (not here) that suggested reducing the pressure to the geo unit.

    When I decided on the open loop system, I recognized that the power to operate the well pump would be considerably greater than the power used by the recirc pump in a closed loop system. However, I never imagined that the power consumption of the well pump might be significantly greater than that of the compressor and fan. That being said, I can pay for the cost of pumping a lot of water before it equals what would have been my incremental cost to go closed loop.

    Thanks everyone for your feedback.

    Batman71
     
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    You have stumbled upon an essential truth of open loop systems operating off a domestic water well...pumping large quantities (1000-3000 gallons per day) of water up to 50 psig and then using it in a geo heat pump that needs just 5 psig consumes a large amount of energy, a significant fraction of that used by the system's compressor.
     
  7. OH_Bueller

    OH_Bueller New Member

    I am curious if this may be related to something I have noticed, I have a 4-ton closed loop system. About a month ago I started having compressor faults. My installer and Waterfurnace have been working on the problem- have updated thermostat software, replaced AXB board, and last week took Intellistart off-line - which seems to be have fixed it (I hope) - they should be installing a new Intellistart soon.

    Anyway - in the course of all of this, I had photos of my instant energy use screen on the thermostat because a coworker and I were comparing our Climatemaster and WF systems. It appears (according to thermostat) that something has caused my 240V items in the cabinet to double in consumption (most likely was just reading incorrectly originally). I don't know if this is due to the thermostat update or the wiring in the cabinet, but I'm wondering if your thermostat is only reporting 1/2 the power consumption. Here are the values from my thermostat:

    H1 mode......................Before Repairs.....................After Repairs
    Fan...............................18W....................................40W
    Compressor...................789W.................................1672W
    Pump............................236W.................................236W

    H2 mode......................Before Repairs.....................After Repairs
    Fan...............................18W....................................40W
    Compressor...................922W.................................1968W
    Pump............................236W.................................236W

    Also - if anyone could report back their instant energy use values for fan and compressor I would appreciate it -wondering which of my reported values were correct - Thanks.
     
  8. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Stage 2 now running when it couldn't before, could explain this.
     

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