[BLDG-SIM] eQUEST warning messages: HSUPPLY, DHW Loop Pump, CURINV

[Andy McNamara]

Thanks to those who responded, I found a solution to the "Pump Head" and
"CURINV" errors listed below.  I wanted to post the solution to the list, to
add to our knowledge-base.

Best,
Andy


*Error:*

 **WARNING**********************************************************************
             Pump: DHW Loop Pump                    has a user-specified
head
             of         1. feet, but the loop head is       6. feet.
CURINV: No real root for CURVE:
 1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000
CURINV: No real root for CURVE:
 1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000
CURINV: No real root for CURVE:
 1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000

…repeats for hundreds of pages



*Solution:*

Directly editing the INP file:

$ ---------------------------------------------------------

$              Pumps

$ ---------------------------------------------------------



"DHW Loop Pump" = PUMP

   HEAD             = 7

   MOTOR-CLASS      = HI-EFF

   ..



*Comments:*

By increasing HEAD from "0.5" to "7", the error disappeared.  Impact on
simulated energy consumption was minimal, there was an increase in pump
consumption of 0.4 kWh/yr.




-----Original Message-----
> *From:* BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] *On Behalf Of *Andy
> McNamara
> *Sent:* Tuesday, July 17, 2007 12:18 PM
> *To:* BLDG-SIM at gard.com
> *Subject:* [BLDG-SIM] eQUEST warning messages: HSUPPLY, DHW Loop Pump,
> CURINV
>
> I am modeling a building in eQUEST with the following HVAC system types:
> PTAC, UVT, MZS, PMZS.  The building is situated in New York City, where code
> ventilation requirements for the baseline model require exhaust rates
> roughly triple ASHRAE 62 guidelines (those requirements will be changing
> shortly).  It is a 15 story multifamily building comprised of 5 shells due
> to different floor shapes and zoning patterns.  I am having difficulty
> understanding three of the warning messages and thought I would see if other
> have experienced/solved these problems before.  Thanks in advance!
>
> 1)  I am pretty sure this warning message pertains to the MZS or PMZS
> because they are the only two air-side systems with HSUPPLY specified in the
> INP file.
>
> **WARNING**********************************************************************
>
>              User-specified HSUPPLY-CFM is larger than
>              available return air.  Heating capacity may
>              be inadequate.
> I checked the BEPS report and it shows that
> "PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE = 86.0
> PERCENT OF HOURS ANY PLANT LOAD NOT SATISFIED                =  0.0"
>
> 2)  I tried increasing the "Pump Head" under "Domestic Water
> Heater/Attachments" in the DDI from the default of 1 to several other
> values, but the warning message always spits back a number that is 5 ft
> greater than whatever I enter under "Pump Head".  E.g., I enter Pump Head
> = 100, it spits back a loop head of 105 in the warning message.
>
>  **WARNING**********************************************************************
>              Pump: DHW Loop Pump                    has a user-specified
> head
>              of         1. feet, but the loop head is       6. feet.
>
> 3)  Per a recommendation from Mike Tillou on the BLDG-SIM archive, I tried
> changing all curves in the model to "default", but that did not remove the
> following error message (which repeats for literally hundreds of pages).
> CURINV: No real root for CURVE:
>  1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000
> CURINV: No real root for CURVE:
>  1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000
> CURINV: No real root for CURVE:
>  1  1.353483  0.015932 -0.369414  0.000000  0.000000  0.000000
>
>
> (Background):
> Even though I think I've figured out the source of this warning message, I
> thought I'd include it in case it's relevant to understanding the warning
> messages above.
>
> This warning is coming from the exhaust rates being specified higher than
> outdoor air intake rates.
>
> **WARNING**********************************************************************
>              ZONE EL1 ESE Perim Zn ( G.ESE1)        in SYSTEM EL1 Sys1
> (PTAC) (G.ESE1)
>              has unused EXHAUST-CFM specified.
>              This has been converted to outside air.
>
> Thank you so much!  Looking forward to hearing back from those with
> thoughts/insights/experiences on this.
>
> Best,
> Andy
>
>


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