Pennsylvania Higher than expected electric use

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

  1. AndrewL

    AndrewL Member

    I just checked that PDF and it worked for me, but here are images of the pages of it. Let me know if this isn't what you were looking for.
    HVAV Load 1.PNG HVAV Load 2.PNG HVAV Load 3.PNG
    thermostats are Tekmar U527, U557, U530 and D161. Air Handlers are using Intellizone controls.
  2. dgbair

    dgbair Just a hobby Forum Leader

    Assuming you have the 9 gallon models and running 20hours/day:

    (120V)(10A)(20hours/day)(31days)/(1000)($.127/kwh)(2 units) = $189 per month... or about 12% of the bill.
  3. dgbair

    dgbair Just a hobby Forum Leader

    Looking at your load and the runtime on HP#2 I would be tempted to turn the breaker off for that unit until your problems get solved.
  4. AndrewL

    AndrewL Member

    I was thinking the same thing; will do.
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Sounds like you are about 6 tons overkilled.
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    3 main ways ways to transfer heat:

    Conduction: That what the plates are for to heat up the subfloors. The R-value is a measure of resistance how poor a medium transfers the heat.
    Convection: also playing a part, heating up the air, warm air raises, is usually trapped between the joist bays, and usually finds its way up to the floor above via cracks etc.
    Radiation: via rays, can be blocked or redirected by reflecting material, for example mirrors in solar power plants. The r-value of the material does not matter for the radiant part of the energy transfer, it matters only for the conduction part.
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader


    adding buffer tanks will not improve your energy usage. Buffer tanks are there to disconnect the flow requirements of the heatpump from the flow requirements of individual zones, especially when only 1 zone is calling. Any size buffer tank can serve that goal, as long as you get enough flow into the tank, enough flow for all your 4 heat pumps running altogether.
    Another reason may be that one wants to increase the thermal mass of the radiant system, in order to prevent short cycling of a heatpump. Your heat pumps are not short cycling due to the fact that you essentially have 4 stages due to 4 heat pumps, look at at your graphs, they are not short cycling.

    No radiant system with heatpumps should be designed for 20F delta T. In your case you would send in 110F water and get out 90F, meaning an average temp of 100F in the radiant. If you design for 6F delta T, you can send in 103 F and get 97F back. Sending in 7F lower water temps means your heat pumps operate 8-9% more efficient, plus it makes your floors more evenly warm.

    If you have a central system, your supply temps are the are dictated by the zone which needs the highest supply temps, likely your zones which have carpets. Again, it is like wrapping your radiator in blankets. You interfere with heat transfer.

    Your loop fields get utilized unevenly, you would benefit from combining the loop fields with a common header, feeding all the hat pumps.

    Even if you have too much capacity, that does not mean your individual heat pump, when running, runs less efficient. Shutting off the one which comes rarely on will not do anything to improve your bills.

    Your core problem is that your lift is too high, meaning that your do not utilize your whole loop fields oversize in order to increase your entering water temperature, which you paid for, but mainly also that your radiant system with carpets on top in parts of it, is running at a too high of a temperature, rendering it less efficient. In order to get 110F in your buffer tank, your heatpump must discharge 120F water, and you don;t have an outdoor reset which lowers your water temp on warmer days, which would increase efficiency.
    Same with air handlers.
    The other main problem are your many pumps, which you pay electricity for when they all run. And yes, having your steam humidifiers run so much also increases your consumption. Is your house so dry?

    It all adds up...
  8. AndrewL

    AndrewL Member

    Good point about the humidity. I assumed that the system was adjusting the min level based on the outside temperature, but it appears that it does not. I just lowered it from 40% to 30% on all thermostats and the humidifiers finally took a break.

    What is the definition of Short Cycling for our purposes here? Regarding the duty cycle, how long should / can a heat pump run at a time? Do they need a break?

    If the ground loops are combined, would they operate in parallel? I assume there is some easy way of balancing them...? Also, should the loops have air bleeders on them? Mine do not. Coolant is Propylene Glycol, not Ethanol.

    Another assumption that I had is that the 406 is modulating the tank set point based on the outside temperature. The Tekmar does have an external temperature sensor. Does this model not do that?

    Are you saying that 100F is too high? or that that is too low for the Air handlers and radiant under the carpet and tile?

    I set HP SOURCE to AIR so it wouldn't make both HP1 and HP2 shut down at the same time; are there any other ramifications of this?

    Here are the current settings on the 406:


    Thank you!
  9. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    No radiant system with heatpumps should be designed for 20F delta T.

    If that is directed at my suggestion, I don't think you understand the purpose of the primary loop when dealing with fan coils and radiant.
  10. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Why is the 406 not switched to geothermal? I would still like to see the piping used. If the piping is not correct the 406 is clueless.


    I did not say a radiant system should be doing a 20* delta T. Re-read. I said "if".


    I get it.
  11. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader


    I missed the whole context obviously. Just ignore my statement.

    I'm not even sure what AIR on the 406 triggers...but the other parameters look good.
  12. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Hey I only have one out there running, but remember geo being an option. That job has been on going for six plus years. The file is 4" thick on just the controls. Just trying to get more data.

    BTW I think I like the HBX systems.
  13. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    The thing I like about the HBX is they can work with standard thermostats - non communicating ones. You do lose some flexibility with that though.

    I had a system that I had to convert to a Tekmar 406 to control the units. There were 12 existing thermostats and zones and it was too cost-prohibitive to switch that all out. We ended up using one of Tekmar's boiler controls just to take those thermostat calls and turn it in to a zone call for the 406. It was a workaround.

    I have a new Tekmar 485 internet gateway I'm trying out on a site this week. The old remote communication system setup was pretty bad. Hopefully this streamlines things.
  14. AndrewL

    AndrewL Member

    On page 36 of the 406 d document, "When two heat pumps or a two-stage heat pump is being used (HP TYPE = 2STG or ROT), the staging method of the 406 changes depending on the HPSOURCE setting: AIR or GEO. With an air source heat pump selected, the 406 will stage on sequentially and off sequentially. This allows the supply water temperature to be kept close to the target. AIR Source Staging Stage 2 ON (Y2) Stage 1 ON (Y1) With a geo source heat pump selected, the 406 will stage on sequentially, but turns off both stages at once. This allows the ground to naturally recover better since there are longer periods of time between the heat pump transferring heat to or from the ground source. "

    I did not see any other mentions of this setting, and since my HPs have their own loops, it seemed the better choice.

    I'll change it back to GEO.
  15. dgbair

    dgbair Just a hobby Forum Leader

    Yes, the need to be in parallel and they need to be somewhat balanced. You want to keep head pressure down so you do not waste alot of power pumping. Not sure of the best way to balance them... but I sure a full port ball value would do the trick. Then figure if you want to move to zone values/variable speed/pressure-regulated circulator or try and re-purpose some of the circulators your have. The Section 9 takes you though some options.

    If you do a good job purging the loops, in theory you don't need air bleeders. (But if you add air bleeders, then you better add water make-up.) I've read enough on this forum to know that Mark puts them in.. I'm not sure about others. My 'simple' system does not have them. During the first year I had to add some water to the loops to rise the pressure back up to target (loop expansion??), but after that they seemed to find a happy spot.
  16. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    To Chris,

    no the comment was not in regards to you. However, I indeed started to question wether a primary/secondary configuration is ideal in geo applications. I don't question the purpose of the primary, I am just saying that there can be better ways to achieve the goal.

    To Mark, you did not say "if". Nor did you say at what flow rate, on which the heat transfer depends on.

    A 20F delta T is not desirable in geothermal radiant applications, it significantly reduces the efficiency of the heat pump.

    To Andrew, I don't have a good definition of short cycling. In my book less than 10 minutes. Some of my heat pumps run for 5 months during winter season. No harm. They do not need a rest.
    Yes, the 406 should have an outdoor reset built in, what I am missing is the setting for the indoor temp to help with the starting point of the curve. Also their notion in the manual that the loop needs a rest is silly. The amount of heat the house needs is the same, that means the amount of BTUs you have to extract from the ground is the same. If you let the loop rest, you just need to extract more later on, running less efficient.
    You need a way to remove air out of the loop, usually done today with air separators or non-pressrized flow centers.

    Keep in mind that the temperature it is set for does not mean that it is the actual temperature in the tank.

    Here is a church we built, not our newest design, but same idea. 4 Heat pumps on one loop field, and 4 radiant zones. The only reason I have 2 buffer tanks was the 100 gallon per minute of flow on the load side, so I needed 2 ports instead of 1. Otherwise I would have used 1 tank. You should have half the flow on the load side, one tank with a 2" port should be fine.

    I don't know how far you can take down the supply temp at the 406, it depends on your house and the efficiency of your radiant, carpets etc. New houses without carpet we run with 90-95 supply temperature, that way the heatpump is very efficient.
    I'll look up your 406 controller and the settings, I am not too familiar with it.

    Given the amount of energy you pay for the pumps, your 17 pumps should be replaced by 3. One for the source, and 2 for the load. 2 of them would have to be variable speed.

    To Dgbair, in pressurized loops you will always have gases participating out of the water. Non pressurized flow center are called the "call back eliminator" for that reason.
    Also no need to balance the flow in 4 similar loop fields, you just need more pumping power. A loop field can balance itself. See John Manning's write up below.
    Don't take any offense with the dumber than rocks analogy, he explains nicely the math behind this.
  17. dgbair

    dgbair Just a hobby Forum Leader

    No offense taken... guess if this was my day job I might be a bit offended if not even embarrassed. I was 'concerned' with that extra 400' of pipe on the horizontal loops compared to the vertical loop... but I guess it doesn't really matter.

    So on the source side, sounds like you would have did a variable speed Wilo pump capable of a 60-70 GPM flow with motorized values at the heatpump.
  18. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    • 200’ bore = 3.4 gpm and the 100’ bore = 4.42 gpm at a pressure drop = 12.4 Feet
    Yes, the 400' pipe sees 77% of the flow the 200' sees, simply meaning that the water flows slower though the longer pipe. Chances are that the returning water temp is the same, you are simply pumping 30% more fluids through the shorter pipe. Not a big deal. So the notion that the loop field must be balanced within 10% is an old IGSHPA rumor, don't know why they were telling this to people. The same applies to radiant systems. Open everything up and let it flow! Don't restrict flow.

    Yes, one Wilo pump would do it. These are constant pressure D.C. inverter driven pumps, extremely efficient, if the customer would pay for it I would put them in every system. They are set to a constant pressure, and as soon as a a heatpump come online, the motorized valves opens up, creating a drop in pressure, and the pump revs up slightly to keep the set pressure constant.

    Here is an example of two Wilos (one would do it, but there are 2 for redundancy, both running at less than 50 %, in case one ever fails, the other one automatically picks up) serving 29 heat pumps all on a common loop field. Both pumps use a max of 310 watts each, when serving all 29 heat heat pumps at full capacity. In comparison, Andrew's 8 source pumps use 1,840 watts when all 4 heat pumps are running, not to mention the 9 circulation pumps on the load side. The first time I put an amp meter on a Wilo stratos, I thought they are cheating the physics. They are really that good.
  19. dgbair

    dgbair Just a hobby Forum Leader

    Really 12 of them in all on the source side. 8 for the loops and another 4 next to the HP.
    Edit: ops you are right... only 8 on the source side.

    Interesting pump, I never really looked at them until now, but I've seen you mention them before. A bit pricey if you only have one or two 26-99... but if you 'needed' 12 - 26-99, that would be a really good deal.... and all for just 310 watts.... sweet.
    Last edited: Feb 2, 2015
  20. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    310 Watt each, running at 50% each = 620 W total
    That is for 2 pumps serving 29 heat pumps.

    The smaller one for up to 10 tons is in the link below:

    3300 annual hours run time x (2) 26-99 = 3300 hours x 460 watts = 1,518 KWH
    1,519 KWH x 13 cents/kwh = $197/year

    The Wilo is doing the same thing for $40, you save about $150 per year. We sell the GV06 flow center for $1300 premium over 2 pump flow center. Tax credits take it down to $910 premium. Payback about 6 years. No brainer.

    But we use a single 26-99 on pretty much every 2-5 ton heatpump, so that is harder to justify.

    But combine it with a delta T controller, which throttles the pump back in lower stage, then you are really rocking!

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