[Equest-users] VFD Pumping

[Julien Marrec]

All,

I looked briefly at Mike's input file.

*Paul,*

It's two-way, so that's ok. For those who may be wondering why you need
two-way valves, that is in order to have a pressure change (as they close)
going back to the VFD for modulation. That's true in real life too.

*Joe,*

Bingo on your 1) point. (see extract of warnings below).

*Mike,*

I suggest you also investigate your tons of warning about insufficient
heating capability, because you do have 1851 hours below heating throttling
range...

-------------------------------------------------------------------------------------------


Here are an extract of the warnings

 **WARNING**********************************************************************
             Pump: Chlr1 (ElCentHerm) Pump          has a total
user-specified flow
             of      1300. gpm, but the loop flow is      2325. gpm.

 **WARNING**********************************************************************
             Pump: Chlr2 (ElCentHerm) Pump          has a total
user-specified flow
             of      1300. gpm, but the loop flow is      2325. gpm.

 **WARNING**********************************************************************
             Pump: CW Loop Pump                     has a total
user-specified flow
             of      1500. gpm, but the loop flow is      5649. gpm.

 **WARNING**********************************************************************
             Pump: CW Loop Pump                     cannot match the system
             flow at the minimum required head.
             Required system flow = 2824.3 gpm at head =  47.2
             Pump balance point = 2665.2 gpm at head of  43.5
             If the pump was sized by default, most likely this
             is caused by a primary equipment unit operating at
             greater than its design flow, and causing a pressure
             drop greater than design.  Try increasing the pump
             head or head ratio to compensate.
             First occurrence is on  1/ 1, hour  9

 **WARNING**********************************************************************
             Pump: Chlr1 (ElCentHerm) Pump          cannot match the system
             flow at the minimum required head.
             Required system flow = 2325.4 gpm at head =  42.6
             Pump balance point = 2314.3 gpm at head of  42.3
             If the pump was sized by default, most likely this
             is caused by a primary equipment unit operating at
             greater than its design flow, and causing a pressure
             drop greater than design.  Try increasing the pump
             head or head ratio to compensate.
             First occurrence is on  4/27, hour 15

 **WARNING**********************************************************************
             Pump: Chlr2 (ElCentHerm) Pump          cannot match the system
             flow at the minimum required head.
             Required system flow = 2325.4 gpm at head =  48.6
             Pump balance point = 2289.5 gpm at head of  47.3
             If the pump was sized by default, most likely this
             is caused by a primary equipment unit operating at
             greater than its design flow, and causing a pressure
             drop greater than design.  Try increasing the pump
             head or head ratio to compensate.
             First occurrence is on  4/29, hour 10

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en) : www.linkedin.com/in/julienmarrec
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
<http://www.linkedin.com/in/julienmarrec>

2015-06-18 21:28 GMT+02:00 Joe Fleming <joe at thespinnakergroupinc.com>:

> Hi Michael,
>
>
>
> To add to what Paul mentioned about 2-way valves;
>
>
>
> What are your building loads looking like in the eQuest output reports?
> There are 2 potential scenarios that may lead to limited savings from a
> properly modeled VFD installation;
>
> 1.       If the pump is under sized for the loads input
>
> 2.       If the loads are constant and mostly internal
>
>
>
> Kind Regards
>
>
>
>
>
> *Joe Fleming *|*  PE, *LEED AP BD+C, BEMP
>
> *Commissioning Agent & Energy Consultant *| *The Spinnaker Group*
>
> *joe at thespinnakergroupinc.com <joe at thespinnakergroupinc.com>*
>
> *Cell*  561-602-3132  |  *Office*  754-800-3100
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Mike Schaefer
> *Sent:* Thursday, June 18, 2015 2:49 PM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] VFD Pumping
>
>
>
> I’ve performing an energy model to compare VFD Chiller pumping and
> Constant Volume Chiller pumping for a multi-story office building using
> eQUEST v 3.65. Although I expect to save pump energy utilizing VFD pumping
> I’m not seeing a savings and I believe this is due to my “Pump Properties
> Inputs”.
>
>
>
> For both the VFD and constant volume pump scenarios I’ve input the
> scheduled pump flow (1,300 gpm) and head (200 ft) and the other pump inputs
> are default values. The energy difference between the two pumping scenarios
> is negligible, however, if I set the pump gpm to a default, which inputs a
> 1.00 Flow Ratio, the energy savings is significant in the VFD pumping
> model.
>
>
>
> Am I over defining the pumps by inputting the scheduled pump gpm? Should
> the pump gpm always be set to default?
>
>
>
> Thanks,
>
>
>
> *Michael*
>
>
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