[Equest-users] eQuest Model problems

[Edward Allen]

Jamie,

I recommend that you check you space temperature schedules to make sure that the throttling ranges around your heating and cooling setpoints do not overlap.  Have a throttling range of 6 (very wide!) will exacerbate this problem.  Keep in mind that the space temperature setpoint is in the middle of the throttling range. So if you have a heating setpoint of 68 and a cooling setpoint of 73, you overlap between 70 and 71 degrees, which will contribute to unmet load hours.  Ideally you should have one degree between your throttling ranges (sometimes you can get away with 0.5 degrees).  So in the example above, your maximum throttling range would be 3 or 3.5.

Good Luck,

Edward M. Allen, PE, CEM
LONG Energy Solutions
720-217-1356
________________________________
From: equest-users-bounces at lists.onebuilding.org [equest-users-bounces at lists.onebuilding.org] on behalf of Armstrong, Jamie [JArmstrong at dbrinc.com]
Sent: Tuesday, May 29, 2012 4:06 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] eQuest Model problems

Im still having problems with this model.  I think most of the problems are that I ran my loads in Trane Trace and am running the model in eQuest.  Another problem I think I’m having is that the design case system is a single zone packaged rooftop unit with natural gas reheat at the RTU level.  I’ve got the zones modeled and grouped according to orientation and occupancy to try to alleviate some of the problems but I still have around 1400 unmet hours.

Here is a list of some things I have done to fix unmet hours so far:

1.       Deleted % of OA at PSZ since the supply air that I input at the RTU level was not what eQuest was using

2.       Moved the total PSZ OA to the zone level, I put all the outside air in to the control zone.

3.       Set the heat and cooling schedules on all zones that weren’t a room with a thermostat to undefined – so those rooms didn’t add to unmet hours.

4.       Set Throttling range to 6

5.       Set thermostat type to reverse action on all zones.

6.       Checked schedules to make sure they are coordinated with other schedules.

7.       I stepped down the temperature when the unit first starts up in the morning to step down the space temp 2 degrees an hour to help reduce unmet hours at morning startup.
I’ve attached the baseline and design case files.  I also attached some of the simulation reports.

I’m having trouble modeling the gas domestic tankless water heater and a 9 kw electric tankless water heater.  My gas usage seems real high.

Thanks in advance for your help!!

Jamie Armstrong P.E.
Mechanical Engineer

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v. 210.546.0200 | www.dbrinc.com

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