[Equest-users] PVAVS heating and OSA

Chris Jones cj at enersave.ca
Thu Jun 7 17:52:26 PDT 2012


Note that the supply air temperature is the mixed 
air temperature which depends on the mix of OA 
and return air streams.  If the mixed air 
temperature is at 55 then there will be no central heating.

Set up some hourly reports to monitor the OA T, 
the supply air T, and the central heating coil 
output.  That will give some insight to how the system is working.

If the mixed air temperature is below 55 and cool 
control is set to CONSTANT you will see central 
heating.  If cool control is set to WARMEST then 
the PVAV system likely won't provide supply air at a minimum of 55.

Changing the heat control to CONSTANT or COLDEST 
may also make some difference in how the central heating coil operates.


>eQuest experts,
>I received some excellent support on an earlier 
>issue from folks here and have come across 
>another item that I haven’t found info for while searching this forum.
>
>Description of pertinent part of model:
>
>·         PVAVS system
>
>·         OSA requirements defined at zone level 
>as hardcoded CFM values (OUTSIDE-AIR-FLOW)
>
>
>
>What I intend to have modeled is the unit 
>providing 55degF tempered RA/OA to the boxes, 
>which will take the rest of the load.
>
>
>
>Issues I’ve run into:
>
>·         Heating coils in central units have 
>capacities of zero (per SS-P) but there is a 
>load to the system (per SS-J). It seems I need 
>to use HEAT-SET-T to enable a central coil, but 
>putting that value at 55 doesn’t do anything (if 
>I make it larger the central coil sees some load 
>but I don’t want the SAT to be above 55 nominally).
>
>
>How does one go about specifying the supply air 
>temp from a the central unit in PVAVS system?
>
>While trying to troubleshoot I was trying to 
>output the outside airflows in hourly reports. 
>Only applicable data I saw to output was under 
>thermal zone “Hourly zone OA/total flow for DCV 
>calculation” Is this  only used if you have DCV? 
>How do you check your OA flows to zones if you are not using DCV?
>
>Thank you!
>
>Erik
>
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 >>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca




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