[Equest-users] Adding DOAS workaround to simple (SD wizard generated) building causing hard crash

Brian Fountain bfountain at greensim.com
Mon Mar 26 05:46:57 PDT 2012


It crashed for me too. I made 3 changes to the file -- one of which 
fixed it:

- in the dummy zone the OA was forced to 0 -- I reset this to default 
(OA must pass through the dummy zone -- sort of.)
- the DOAS type was PVVT -- I set the fan minimum flow rate to 1.

but the one that fixed it:
- the DOAS fan does not have a flow rate -- give it an initial value, 
even something low like 5000cfm and it will increase it up to the OA 
required (~69,000 cfm). -- check the SV-A report.  Once it runs once you 
can set the actual OA value in the fan volume.



On 3/26/2012 4:45 AM, Jason Quinn wrote:
> I'm running a baseline case to compare to my more complicated model.
> This model is completely generated in the SD wizard - now I've added a
> DOAS supply per the "standard" workaround: add a dummy space, dummy
> zone and system for that dummy zone Pak Var vol Var temp. Edit the inp
> to put the DOAS first and then change the 4pipe FC to use the DOAS to
> supply OA. This baseline case runs just fine through the loads and
> then locks up my windows 7 machine - have to power-cycle it. I've
> added it twice and the problem is repeatable. When I implement this
> same work around in a much more complicated model it doesn't crash so
> I think I've done it correctly but I'm not sure what to do at this
> point. .pd2 and .inp attached - Any suggestions would be welcome.
>
> Thank you,
> Jason
>
> Warnings at the end of the .sim file are:
>
> **WARNING**********************************************************************
>               ZONE dummy zone
>               might have insufficient heating capability.
>               Check that the SYSTEM or ZONE HEATING-CAPACITY plus this
>               ZONEs BASEBOARD-RATING is adequate to maintain the ZONE
>               specified DESIGN-HEAT-T for the calculated peak ZONE load
>               (see LS-A or LS-B for the ZONE peak load.)
>
>               SYSTEM DOAS
>               which supplies the above listed ZONE, has a design heating
>               coil exit temperature, HEAT-SET-T,(plus any zone reheat)
>               below its MAX-SUPPLY-T or the ZONE DESIGN-HEAT-T, which
>               might account for the insufficient heating capability.
>
>               ZONE dummy zone                       has a THERMOSTAT-TYPE
>               of REVERSE-ACTION, which, when added to the issues listed
>               in the messages above, will cause excessive underheating.
>
>   **WARNING**********************************************************************
>               DOAS                             defined as an OA-FROM-SYSTEM
>               has OA flow requirement of    69286. CFM
>               But its calculated/specified SUPPLY-FLOW is only        10. CFM
>               Its SUPPLY-CFM has been reset to meet requirement, however it is
>               strongly recommended you re-run with this SUPPLY-FLOW specified.
>
>   **WARNING**********************************************************************
>               DOAS                             defined as an OA-FROM-SYSTEM
>               has OA flow requirement of    69286. CFM
>               But its calculated/specified minimum SUPPLY-FLOW  is only
>         10. CFM
>               Its MIN-FLOW-RATIO has been reset to meet requirement, however it
>               is strongly recommended you re-run with this
> MIN-FLOW-RATIO specified.
>
>   **WARNING**********************************************************************
>               In the Southern hemisphere, the daylight savings start date
>               should be later than the end date. If the latitude is taken
>               from the weather file, you must manually specify the
>               daylight savings interval in the SITE-PARAMETERS component.
>
>   **CAUTION**********************************************************************
>               In curve: DX-Bypass-Factor-fAirFlow        the dependent value
>               is exceeding the limits.
>               Value/Min/Max/First time:    1735581.875   -1000000.000
>   1000000.000   1/ 1/ 1
>
>   **WARNING**********************************************************************
>               Energy-recovery ventilator: DOAS                             has
>               frost on the exhaust outlet.  First occurrence:  1  1  4
>               OA T&W:  52.0  0.0051   Return T&W: *****  0.0000
>
>   **WARNING**********************************************************************
>               Energy-recovery ventilator: DOAS                             has
>               frost on the OA outlet.  First occurrence:  1  1  4
>               OA T&W:  52.0  0.0051   Return T&W: *****  0.0000
>
>
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