How much generation do I actually need to run my WF 5-series?

Discussion in 'Maintenance and Troubleshooting' started by JFLame, Nov 22, 2013.

  1. JFLame

    JFLame Member

    I have a 4 ton NDV049 5-Series Waterfurnace with Intellistart.

    The sheet referenced here:

    Says that my NDV049 requires:

    Starting Amps: 33.6
    Starting Power (kw): 4.4

    That part I can believe. What I'm wondering about is this:

    Normal operation with accessory pumps (A): 16.3
    Continuous power: (kw): 5.3

    My thermostat says that my average running watts in stage one for heating/cooling is 2.2kW, with the pumping costs included. Is the 5.3 kw continuous power rating due to spikes during normal operation?
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Is the 5.3 kw continuous power rating due to spikes during normal operation?

    No. It will be a safety factor. But your thermostat in stage 1 doesn't reflect much useful information to generator sizing unless you are planning on eliminating stages of operation.
  3. JFLame

    JFLame Member

    Stage 2 takes about 200w more, so 2.4kw. Stage 3 is a non-factor and can be eliminated from this inquiry.
  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Just 200 Watts more for stage 2 with a 4 ton system? Color me skeptical.

    That said, it could be perfectly reasonable (and very easy) to lock out stage 2 (and higher) whenever utility power is not present.
  5. JFLame

    JFLame Member

    That's what my fancy energy monitoring/reporting thermostat tells me. Are you saying you think it's incorrect? What are your observations on the energy use of a comparable 4-ton system? FYI, 472W of my reported totals is pumping wattage. 39W is supposedly the fan. The rest is compressor wattage.
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Stage two power (blower + compressor) should be approximately 50% more than stage one. 39 Watts seems very very low for a 4 ton system blower
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    4 ton waterfurnace 5-series on a external monitoring system.

    right now is it drawing 2370 watts in stage 1, including blower and circulation pumps, although it is only a 1 pump flowcenter. EWT is 44F.
  8. JFLame

    JFLame Member

    Any idea how many watts the desuperheater draws when it's running? I'm betting the WF stat isn't reporting the DSH wattage.

    What is the wattage for the single pump flowcenter?
  9. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    DSH draw no watts, but is a passive heat exchanger, but steals about 10% of the heat from the heatpump. However, there is a small circulation pump, I think 1/25 horseposwer, to circulate the water through the DSH. Should use less than 50 watts.

    Single 26-99 pump in the flowcenter uses about 230 watts.
  10. JFLame

    JFLame Member

    I went back to my Geolink report and made some calculations:

    Est. Heating Run time: 2352 hours
    High speed runtime: 5%
    Heating electrical use: 6316 kwh

    So 6,316,000w/2352 = 2,685w

    Given I have a dual pump flowcenter this seems to coincide with the number posted by docjenser with a single flowcenter:

    2370 + 230 = 2600

    If you figure that the 5% of the number is high speed, the 2,685 would be a bit high, so this seems to match very well with the real world observed number.

    HOWEVER, what's also interesting is the Geolink report breaks out the DSH costs separately! This part I can't seem to make a sensible number out of.

    Combined cooling and heating run time: 3411 hours
    DSH Electrical use: 675kwh
    DSH Costs / year: $101 (estimated $0.15kw rate)

    675,000 / 3411 = 198w

    So I'd expect the DSH to be taking almost 200w to run based on this, not 50 w like docjenser is thinking. Keeping in mind the 2,685 w number I calculated would have whatever DSH wattage is added to it, so I guess the actual stage 1 power draw is somewhere between 2,600w and 2,800w. Close enough for horseshoes and hand grenades.

    Doc, have you ever seen the stage 2 running wattage on the WEL report?

    I'm curious on some thoughts on his analysis.
    Last edited: Dec 5, 2013
  11. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    The DSH pump is an itty-bitty affair operating at 50 or so Watts as DJ noted.

    The attribution of 200 Watts to its operation may be in recognition of the heat diversion effect; that is the burden it imposes on the system while it heats the home, somewhat lengthening calls for heat.
  12. mkutch

    mkutch New Member

    Yes I know this is a really old thread....but am doing this for the benefit of others in the future, much like myself when searching the 'net for some "answers"....

    In my 2008 home have a 4-ton NDV049 WF unit (previously no Intellistart, wasn't aware of it until now) with desuperheater, and this fall I had been searching the 'net to see if/how I could power it with something less than a whole-house XXkw standby generator in the event of a winter power-outage... From the learnings in this thread and others of similar nature, I just recently purchased and installed an Intellistart module..... This past weekend I trialed it with my Generac GP6500 portable generator (my version GP6500 is 8000w peak / 6500w continuous). My theoretical calcs said it was going to be close, expecting the Geo w/ Intellistart to need about 7800-8000w which is/was right on the limit of my portable-generator's peak/spike output. And since I do not have the means to monitor startup loads, I had to rely on a bunch of hope and the ballpark calcs pertaining to the approximate LRA reduction the Intellistart provides in order to finally "gamble" and purchase/install the Intellistart.

    The Generac had no issues at all starting the Geo unit in heat-mode, both first and second stages. Note I did not even bother to try the emergency strip heat (10kw), because obviously there's not enough juice to power that.... BUT, aside from that very minor issue whcih I knew upfront, I am very glad that my GP6500 8000w-peak genny showed no signs at all of a struggle when I fired the Geo. Just kept on purring....

    So to those in the cyberfuture -- NDV049 works just fine Stage-1 and Stage-2 with just a "little" GP6500 and an Intellistart module....

    And a big thank-you to those that contributed in threads such as this one.
    Stickman and Deuce like this.
  13. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Thank you for reporting on the results of your experiment with a 6500 Watt genny. Though Intellistart is said to reduce starting amps by 2/3 compared to locked rotor amps, I would not have bet on a 6500 Watt portable genny starting a 4 ton heat pump.
  14. ChrisJ

    ChrisJ Active Member Forum Leader

    Well that's good news for me, I have an 8500 I need to start a 3 ton Comfort Aire (Climate Master). Just need to find the correct soft-start kit.
  15. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    ChrisJ likes this.
  16. arkie6

    arkie6 Active Member Forum Leader

    FYI - I was quoted $383 from Ingrams Water and Air for a Copeland SecureStart, Climatemaster part number 13B0045N01, for a 3 ton Climatemaster TEV038 unit.
    ChrisJ likes this.
  17. Stickman

    Stickman Active Member Forum Leader

    ChrisJ likes this.
  18. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Last edited: Nov 15, 2016
  19. Stickman

    Stickman Active Member Forum Leader

    Could you please elaborate? I'm not sure how to apply what you're saying here.
  20. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Just disregard this comment, I was under the impression that the LRA is less in a dual stage unit starting up in 1st stage versus a single stage unit. But that is not correct.

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