Pennsylvania Higher than expected electric use

Discussion in 'Maintenance and Troubleshooting' started by AndrewL, Jan 22, 2015.

  1. heatoldhome

    heatoldhome Geo Student Forum Leader

    OK if your looking to size a single ecm pump find the ft of head in all 4 systems.
    Take the highest ft hd and used that number.

    Now you need a pump that will do 52-60 gpm at that amount of ft hd. Make sure you size the manifolds and headers so it doesn't add much ft hd. If your going to run a delta p ecm pump you can over size it a little I think to be safe.
  2. AndrewL

    AndrewL Member

    The last HP, #4, had a same delta p (5 psi or 11.5 ft-head).
  3. heatoldhome

    heatoldhome Geo Student Forum Leader

    I might have confused you. Or maybe you do get it. But 5 psi drop across the heat pump exchanger is 11.5 ft head but that is only the exchanger not the whole loop field.

    So of the 45 ft head total 11.5 is the heat pump itself and the rest is the loop.

    But all we care about is total ft head. So you can find a single pump to serve all 4 units correct?

    Once you find this pump you can find how many watts it draws and then calculate estimated savings, then see if it's worth the money to redo everything.

    This is what your trying to figure out correct?
  4. AndrewL

    AndrewL Member

    Yes, i get it, thanks. I was just confirming that #4 was within the range of 1 through 3. Thanks!
    I have a total of four FC2-GL flow centers that consume 492 watts. I typically am running 2 at at time for 984 Watts vs 150 for the Wilo Stratus 1.5 x 3-40. So (834 watts less) (23 hrs/day) / (1000 w/Kw) ( 0.11 $/kWh) ( 300 days) = $633/yr savings.
  5. heatoldhome

    heatoldhome Geo Student Forum Leader

    Well the wilo will very in power consumption depending on number of units running. The chart I looked at showed 25-470 watts depending on load.

    Your 150 watts is probably close if you only average 2 units running at a time.
  6. heatoldhome

    heatoldhome Geo Student Forum Leader

    The first place I Googled showed it would take you 2 years just to pay for the pump itself with your estimated electric savings.

    But you will have more cost then that to get it installed.

    The load side might be more attractive in savings to do first.
  7. AndrewL

    AndrewL Member

    Combining the loops raises the EWT, so that will increase efficiency, which makes payback shorter.
  8. heatoldhome

    heatoldhome Geo Student Forum Leader

    Very true. I wonder how much higher the COP would be on average.
  9. AndrewL

    AndrewL Member

    I just took the following data. The Delta p at the HPs are now up to 6 psi. This equates to slightly higher flow at the HP of 16.5 GPM which equates to about 40 ft-head on the flow center chart. I suppose that makes sense. The higher the flow rate, the less ft-head given the same circulator.

    2/15/15. 0635. 8F outside
    HP1. 50/56 psi, 30.6/35.6F
    HP2. 55/60 psi, 28.3/33.8F
    HP3. 62/68 psi, 27.0/32.0F
    HP4. 48/54 psi, 24.5/29.7F
    Last edited: Feb 16, 2015
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It is not just the pump. You need the flow center and the headers made. You are talking 50-60 gpm your system needs. If you are 40 ft hd at 16.5 gpm, then you would be at 22.5 ft hd at 12.5 gpm per circuit, 50 gpm for all 4 hp minimum. The GV 15 does 27.5ft hd at 50 gpm, it should do he job nicely.

    Phoenix energy supply can also build you the headers. You need an installer. They will unlikely sell to a DIYer.
  11. AndrewL

    AndrewL Member

    Phoenix recommended the CV15z-CA-2 after analyzing my loops. Also recommends that the output from the HPs go directly to the load and T to the top of the buffer tank. Add in a Stratos 1.25x3-30 circulator and zone valves. With this plan, I'm pretty sure I could use most of the existing plumbing. In addition, I'd ditch the desuperjeaters and add 3-way valves and a solar dual heat exchanger storage tank for domestic HW so I can eliminate the electric water heater. Seems like a pretty solid approach. This design would not include any lower temp water--all the same. Phoenix says 120F water under subfloor is safe.

  12. heatoldhome

    heatoldhome Geo Student Forum Leader

    Sounds good to me. You going to do it?
  13. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    And make sure you have some check valves on any of those parallel configurations - like the source plumbing. You can, in theory, get reverse flow though a 2nd unit coming online.
  14. AndrewL

    AndrewL Member

    Thanks. I think all of the HPs already have them between the Load Out and the circulators. Would I need them on the zones? Each will have a valve, so it seems unnecessary.
  15. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Did you talk to John Manning at Phoenix?
    He is recommending a stacked flow center, that is interesting.
    Diagram looks good.
    I use the solar tank in all our hydronic applications, it is really an elegant solution for hot water. But it comes at a price.
  16. AndrewL

    AndrewL Member

    Yes, I spoke with him. He was concerned about the total head. I've also determined that the pipe that connects to the twisters is 1-1/4, not 1-1/2. This adds a little, too.

    Besides the obvious price in dollars, what else should i be concerned with regarding the hot water configuration?

    What do you think about not having two water temps on the system (1 lower for the hardwood radiant)?

    I do not have any floor temperature sensors--only air units on the wall (all Tekmar). Do you recommend adding floor sensors? It seems that it would be quite nice in the bathroom and the Tekmar thermostats are designed for it.
  17. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Well, he is one of the best in the business.

    No, the hot water configuration is one of the best one out there. The tank is pricey, and it requires some motorized 3 way valve which have a low pressure drop, John and I prefer the belimos. Also pricey.

    But my father always said: Life is too short to drink cheep wine. I'll enjoy the quality long after you have forgotten the price.

    I am usually not too crazy about floor sensors when you have an outdoor reset, since it down regulates the supply temperature and increases your runtime for the floors anyway.
    Not sure if your Tekmar are setup to do an outdoor reset.
  18. AndrewL

    AndrewL Member

    Thank you. I do have an outdoor reset. Does Tekmar have a way of adjusting the target RH using the outdoor reset?
  19. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Yes it does.
  20. AndrewL

    AndrewL Member

    Can you point me to instructions on how to implement it?

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