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

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

  1. geoxne

    geoxne Active Member Forum Leader

    Looks like we scared another OP away. No reply in over a week, in spite of many requests for operation data (EAT, LAT, DeltaP with one pump). We also need to know what your normal thermostat setpoints are.

    KJW, if you are still there.
    I direct you, if you are still inclined, to the Trouble Shooting Check List here-
    We are still missing the data required for a proper evaluation of your system. Responses from would be helpers are all over the place ie. ACH, insulation, zone panel, stage control, energy audits, stud size, gauge accuracy, etc. Although, these are all relevant, I would direct your attention to your pumping and your bypass damper as major culprits contributing to your suspected inefficiencies.

    The good news is I believe your loopfield is performing as predicted or better based on your GeoSolutions Report with a Max Temp of 86F this late in your cooling season.
  2. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I agree, the bypass damper and the pumps themselves could easily reduce the efficiency by 30-50%.
  3. KJW

    KJW Member

    Guys, I am still here. The factory repa are here. Engineer from Bosch is coming in January. Flow meters were used today and I have a lot more data using precise equipment that I will get on here soon and I appreciate everyone's help. doc, I am in no way blowing you off or ignoring you. The zoning was put in at my request for convience, we wanted it...m the installer actually recommends only two,zones for up and downstairs... We requested it. We did find some interesting issues with the Honeywell zone controllers - not very friendly with staging and was forcing the unit into stage 2 all the time based on some sort of mathematical algorithm and we changed the programs to use stage 1 unless the zones are calling for a greater than 3.5 degree offset. Also, today's flow meter readings with one pump is 13.5 gpm and 19.4 with two pumps. As it turns out, Bosch recommends two pumps for 5 tons. Our loop field has very few plumbing restrictions and is close to the house. We van very little friction loss. Back to the zoning, this was something we requested as a way to control the temps in different areas of the home, a option like item, not something he recommended. We like to sleep cooler than maybe a guest or vs versus... We know it is not the most efficient. The loop field is running at about 76 in and 86 out. The data is being gathered by one source now and not several and using Bosch calibrated instruments were as before several people were using different instruments and we had some margins of error that were off the chart... What i am concerned with is Bosch wants 15 gpm and we are at 13.5 now with one pump... They didn't like the almost 20 gpm with two pumps so they took one out. The one that was running very hot. They are going to warranty it and replace it but are recommending it stay out of the flow center and in storage as a backup...
    Last edited: Nov 11, 2015
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I would expect your installer to be the guardian of reality and advise you that by following your request for 4 zones you make your system inherently inefficient. If you requested it, and you were made aware of the resulting inefficiency, then you should not complain about the high bills.
    I question that Bosch actually recommends 2 pumps for 5 tons, also do I question that they recommend to use much less efficient 26-116 pumps. They might recommend a certain flow, but how one gets there is up to the designer/installer. Bosch does not know the flow resistance in your specific loop field, thus manufacturers stay away from recommending a certain universal pumping solution ("2 pumps for 5 tons"), they just recommend a certain flow, how they get there is up to the installer/designer.

    Being at 13.5 gpm would increase the leaving water temperature by 1 degree right now, with maybe a max 1 % impact on efficiency, but that's about it. It probably will save you at least 7-8% in pumping power, if not more like 10%, to have the one pump removed. Bosch publishes performance data for 7.5, 10 and 15 gpm flow for the 5 ton at 90F EWT.
    It appears that you continued to be told a lot of BS, I continue to believe that your installer is un-evolved. he should know better.
  5. KJW

    KJW Member


    Thank you but I requested this zoning. He doesn't care for it except for use in on two different floors. It is like buying a fairly efficient diesel 4x4 truck and dumping the factory tires and installing large off road type tires, reducing fuel mileage by a large percent! Why? It gives better control, more options, but yes, it loses some efficiency! We all get that!

    Now, let's look at the pumps: what do you recommend? Bosch's very own design software and yes, Bosch, yes, really Bosch, recommend two pumps and this make and model! I was on the conference call and have the design reports. As a matter of fact, they are posted on this thread in this forum. My pumps or pump, as it stands now, uses 377 watts. The software has another number in it from Bosch of I believe 540 watts. I questioned this and was told it was due to an older model of pump being in the software and this particular model's data has not been updated in the design software.
    The zoning will stay - I am asking what can be done or needs to be done to help the situation. I appreciate your knowledge and all but can we just move along and provide your technological expertise? I do appreciate your input, truly! I know about zoning and bypass dampers now and get it! What else can I do here? I have fixed the staging call thanks to the poster engineer. I have removed one pump after verifying the loop field flows with a flow meter. Your input is greatly appreciated!
    Last edited: Nov 11, 2015
  6. KJW

    KJW Member

    Thanks for your inputs! Great information! Removed one pump after using an inline flow meter to see the actual flows in the loop fields. Shouldn't be over pumped now. Also reprogrammed all thermostats to only go to stage 2 with a greater than 3.5 degree split. Before this, we were in the Honeywell comfort setting and the unit was running in stage 2 all the time! You provided me some really great info! We have a lot more data and should get it soon in a report. I was with the installer and Bosch on conference calls. They are coming down in January to take a look at it all. Any other ideas?
  7. KJW

    KJW Member

    By the way - if I ever build again, I would use the WF 7 series with their variable speed blower and compressor! That would solve a lot of this stuff with zoning and staging. ROI is just there yet though!
    Last edited: Nov 11, 2015
  8. geoxne

    geoxne Active Member Forum Leader

    Listen to Engineer. Don't throw the HZ432 under the bus just yet. It has many configuration options for staging. Some are under Advanced Configuration. See install manual here-

    I usually set staging options to "TSTAT" and program my individual zone thermostats according to what they may need. Main and large zones setup for 2 stage and small zones setup as single stage only. The TSTAT staging option puts the thermostats back in charge of staging and passes the call through the zone panel. A small zone setup this way will never upstage the HP. You can fine tune with droop or timer settings at the thermostat as required. Or look at Advanced Option for other staging schemes.
  9. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Your point of inquiry here was why your electricity bill is so high, well, you own a very efficient diesel with big off road tires on it.I do agree here with the 7 series from Waterfurnace, the WF zoning controllers are taking advantage of the variable speed capabilities, we run up to 6 zones on them with no bypass dampers.

    The pump(s):

    Heat pump manufacturers usually do not understand geo system design very well, nor is total system efficiency including parasitic pumping loss on their radar screen. Most of them care about the rated COP and EER. Then it is up to the designer/installer to ensure that this heatpump system run with an EER of 25 , or 10.

    As evident in your case, their design software is far off! There are 2 standard constant speed pumps used by most manufacturers, both from Grundfos, one is the 26-99, the other one is the 26-116. Traditionally the 116 uses a constant 385 watts, versus 230 of the 99, but produces only about 10% more pressure at lets say 14 gpm. So again, whenever I see 116 pumps on a system, it tells me that people have not understood the concept of pumping water around efficiently. If I see (2) 116s in series on a system with low friction loss, like yours, it doubles down.
    Putting in a 26-99 in your system would have further lowered the pumping power, and reduced the flow probably to 12.5-13 gpm.

    Now, a dual stage likely spends 80% of its time in 1st stage, in your case needing about 9-10 gpm ideally. So you are still over-pumped. For the rare case where the manufacturer recommends 15 gpm in second stage, the heatpump can easily live with 12.5 gpm.

    Not sure if it is worth it to exchange the pump to a 99, to save 150 watts when running. 3000 hours x 0.150 kw x 12 cents/kwh = $54 annually. Your call. You already took one out, which was the right thing to do, and you wanted off road tires....

    Another thing with the variable speed technology such as the 7 series is that it comes with a variable sped circulation pump, which uses anywhere between 16 -160 watts, although it has much longer runtimes since it cycles through the stages, instead of turning on and off.
  10. KJW

    KJW Member

    Awesome. Thanks!
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Ducks under his desk and covers his head.

    Not all that glitters is gold.

    I like zoning.

    Honeywell is not my favorite.

    Arzel is my favorite.

  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I like zoning too. As you know so well, air is not water. The inherent problem is that a dual stage HP can only throttle back to 2/3 (66%) capacity, it needs to get rid of the heat, or the cool. With 4 zones, the maximum size of the smallest zone by definition is 25%. What happens if that zone calls? Now 66% of the air and heat capacity goes into a 25% zone. Yes you can be tricky, slowing the blower down, allowing the other zones to bleed to take some capacity all the time when the heatpump is running.
    But worst thing is to put a bypass damper in and feed the return with heated air, for the above reasons. A geo installer should know that.

    KJW, discuss the slowdown of the blower, and other zone damper not fully closing. That way they might be able to block the bypass damper, and your heatpump might work much more efficient.
    Last edited: Feb 9, 2016
  13. tekmiester

    tekmiester New Member

    I realize it has been fairly mild this winter, but how is your system running now?

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