Texas POWER USAGE & PERFORMANCE? BOSCH SM060 - need input?

Discussion in 'Maintenance and Troubleshooting' started by KJW, Oct 14, 2015.

  1. KJW

    KJW Member

    Guys --

    I have had my unit online since January 2015. I have analog gauges to monitor entering / exiting water temps. see below stats... I am curious what you the experts think about my system and what it is doing. I think the power bills are a little high, but maybe I am off on my thoughts. I wanted to provide some info and see what you all think about my system and how it is performing. 2 adults and 3 dogs -- ;)-

    -- House is just around 4100 sq ft located near Montgomery, TX (northwest of Houston about 1.3 hours) - so, hot, and humid. Full depth spray foam insulation, energy effencient windows, led lighting, gas used for cooking only and backup water heating. See manual j attached
    -- System is a Bosch SM060 - closed loop, 5 vertical wells at 300 feet deep each
    -- De-super heater with a marathon holding tank with on demand Navien condensing water heater as backup
    -- Zoned to 4 zones using Honeywell equipment.
    -- Wife is home all day in her home office which is part of a zone that cools one area, all other zones raise and lower as scheduled.
    -- exiting water temps around 91F and entering around 85F - as shown on images attached running in stage 2 4 zones calling... usually see a 7 degree spread on ENTER/EXIT temps
    -- power usage below - last month was 2508 KWH and $270.97 - sounds a little high to me...
    -- 4.25 hp well pumps for irrigation and potable water (just starting watering heavily with new landscaping installed)
    01971015dbe55062a5e5aed936190516d0fa045a5f.jpg 0185b7b4252fee462574db1f143280c93ebb9295fc.jpg 01e29524e4f13f5038d4b78343113e0f99d2a93027.jpg 01dd2fce828be8e7df8d28c61bac340f469cea03e5.jpg
     
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It appears that you base load of your house is around 1250 KWH/month, and that A/C via the geo system adds about the same amount during the hottest months. I would think that $135 for the A/C portion in Texas during August appears to be very low for a 4100 sqf house.
     
  3. It seems as if you are inline. You have to understand that the zoning system does add a slightly different dynamic as it can add a little more run time and does waste more energy running that size machine when you might have one smaller zone calling. So all in all looks close.
     
  4. KJW

    KJW Member

    Guys,

    My energy audit states that I should have utility bills around 150.00 a month, not 270.00 to 280.00. Here are the temps today on the loops with all zones calling... I have a very efficiently built home and the other nervy consultant is also scratching his head, as his numbers are all off...
     

    Attached Files:

  5. KJW

    KJW Member

    See attached
     

    Attached Files:

  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Difference between theory and practice, something a software does not compute.

    You are supposed to have $289 annual cooling costs for a 4100 sqf house in Texas? who did that math?

    Your loop water is kind of warm, at 84F EWT your heat pump will perform (EER) about 8-10% worse than rated in 2nd stage.

    Describe you system more. What model of circulation pump(s) do you have?
    4.25 hp irrigation pumps can consume some serious electricity
     
  7. KJW

    KJW Member

    Doc,

    I know this does not make sense to me either -- he is very confident in his numbers though with only 2 homes in the last 30 years not meeting expectations on calculations. The 4.25 HP of pumps was not used until August for irrigation except for normal water usage in the home with only 2 adults present.
     
    Last edited: Oct 18, 2015
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    84 / 90 EWT / LWT suggests maybe a tad overpumped

    HZ432 board has a bad habit with 4 zones, depending upon how set up, of kicking system into high gear (y2) if only 2 of 4 zones are calling. If possible, configure so that only largest zone can command Y2. Finding a zone board able to contain its enthusiasm for Y2 is harder than one would think. Exasperated with HZ432's weakness in that area I put a few WF Intellizone Ones on 4 zone dual stage air source heat pumps. WF's zone and call weighting is unique and ingenious.

    Doc - I have about $200 annual cooling costs on a 3300 SF home near Jax, FL (similar climate to Houston), so $289 for 4100 SF home near Houston is theoretically doable, though not likely with an over-pumped 5 ton Bosch.

    Closed loop EWT of 84 during summer is actually pretty good, given our deep ground temps of low 70s
     
  9. KJW

    KJW Member

    Engineer,


    What do you mean by over pumped? Can you expand? We are really digging into this heavily and have built a great building envelope. I am just digging into this and breaking out the spreadsheet and calculators!
     
  10. arkie6

    arkie6 Active Member Forum Leader

    What is your overall wall construction? 2x4 or 2x6 studs? Stud spacing? What type of foam? Open cell or closed cell? Is there any rigid foam on the exterior of the studs? What about your ceiling/attic? How is it insulated?
     
  11. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    What kind of pumps do you use for your loop field? How many and what is the model number? Your delta T between incoming and outgoing is not high enough, although I would not trust the gauges. Get a needle thermometer and remeasure.
     
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Yeah, but you know all the tricks, keeping your 3 ton unit in low stage, effectively using it as a 2 ton. KJW has a 5 ton running, with 5 ton pumping running all the time. The other thing is the zone controller. KJK, do you have a bypass damper installed for the ductwork, when only one zone is calling?
     
  13. KJW

    KJW Member


    Icynene full depth spray foam with 2x6 exterior walls on 16 centers with plywood outer wrapping for wind ratings and the attic has a spray foamed attic on the roof deck with full depth and no wood showing - all foam. Data is not making sense to us, as the bills are a higher than expected or forecasted!
     
  14. KJW

    KJW Member

    Doc,

    Yes I do... So, I am learning a lot here. It appears over pumping is the term used above for too much horsepower here and full on all the time, when I should be in stage 1 more than not. I do notice that the system is in stage 2 more than not! the pumps are Bosch 2 pump flo-link center Grundfos 116...
     
  15. arkie6

    arkie6 Active Member Forum Leader

    There are several different types of Icynene foam. Since you said the stud walls are full depth, I'll assume this is open cell foam at R3.7/inch. For a 5.5" stud cavity, this gives R20.5 in the cavity. But when you figure in the thermal bridging from the much lower R value of the studs on 16" centers, double top plates, bottom plate, and window and door headers, you are left with approximately R15 for the wall. Not bad, but not great either. Do you have 2x6 rafters? If so, and assuming you have ~1" of spray foam cover over the rafters, you are only looking at ~R20 when you factor in the low R value wood rafters for 5.5" depth of the insulation. That is way less insulation than the 2015 energy code minimum ceiling R value of R38 for South Texas (Climate Zone 2). This is a likely a contributor to your higher than expected energy usage.

    Have you ventured into your attic during the heat of the day to see what the temperature is up there?

    Where is your duct work located? In the attic? Is it insulated? If so, with what?
     
  16. KJW

    KJW Member

    The attic is always cool. The ducts are insulated and in the attic. Did you look are attached energy audit? The attic is double deep on the roof deck - they applied two applications and flashed the beams and rafters all 2x8 and larger. I am no thinking this is the issue, as the house down from me is the same insulation and principles but his over 5100 sf and has air to air and is over 100.00 a month lower! We are looking at zoning (4 zones) and Honeywell zoning panel using too much stage 2 and not taking advantage of stage 1 cooling... There are known issues from what I am gathering...
     
  17. KJW

    KJW Member

    The attic is always cool. The ducts are insulated and in the attic. Did you look are attached energy audit? The attic is double deep on the roof deck - they applied two applications and flashed the beams and rafters all 2x8 and larger. I am now thinking this is the issue, as the house down from me is the same insulation and principles but his over 5100 sf and has air to air and is over 100.00 a month lower! We are looking at zoning (4 zones) and Honeywell zoning panel using too much stage 2 and not taking advantage of stage 1 cooling... There are known issues from what I am gathering...
     
  18. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    What is the second number on the pumps?
     
  19. O.k is the attic a conditioned attic?
    If so are there supplies and returns in your attic.
    Can you arrange for a local contractor to come over to do a blower door test to see whats going on with the envelope?
    I am interested to see what your ACH is?
    Do you have any ERV's
    Bath fans or exhaust fans with backdraft dampers / Humidistats?
    Yes R values for foam are important but there are other factors that do help foam versus the other insulations. As you can have the same insulations side by side with the same r value but the foam insulation outperforms the others by not allowing direct energy to transfer threw it. We call this the performance factors for the SPF as it outperforms by slowing down air movement and moisture penetration depending on product selection.
    I have a few 16,000 sq' homes we did under new construction using open cell foam and geothermal HVAC systems with utility bills under $220 per month here in Virginia. These homes are 10 years old and have already reimbursed our customers for the additional expense of the HVAC and Foam.
    All of these have a dramatic affect on the envelope as one system which in turn you will see in your monthly bill.
    If you truly want to see whats going on I would suggest a blower door test to see if something got missed under construction. As I don't disagree with the statements of prescriptive R values of insulation, but really with SPF they are kind of irrelevant once you add the performance factor. And yes it would be nice to know the exact product we are talking about.
     
  20. KJW

    KJW Member

    See energy audit - already did all this while building - had an independent auditor throughout the building processes. File attached. HERS rating kicked butt! Just not happy with power usages! Seems a little high but maybe not! Getting all kind of conflicting data and opinions - attached is a picture of the flow center and the audit report... Also include manual j again too. image.jpeg
     

    Attached Files:

    Last edited: Oct 19, 2015

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