It improved 25% from 3500 to 2600 hours by changing central heating supply temp equal to the set-point manager (OA reset). I can see few zones still have no reheat coil capacities whereas some reheat coil capacities kicked in and hence unmet hours are improved.ÂThanks youOn Fri, Mar 16, 2018 at 1:18 AM, Weili Xu weilix88@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com > wrote:Ah, this is for ASHRAE baseline. I don't recall there is any method in the document on how to calculate the nominal capacity of terminal reheat coil... If that is the problem, I normally will do trial and error on a particular day or week...But since this is baseline, I assume you are doing it for certification? Then it might be a good idea to change the "Central Heating Design Supply Air" under the sizing:system class and make sure the value is the same as your actual control temperature, which you can find in the setpointmanager:outdoorairreset class. Try it out and see if the unmet hour improved?WeiliBuildSim.ioOn Thursday, March 15, 2018, 3:34:02 PM EDT, Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com > wrote:ÂThank you Weili. I appreciate your feedback. Since this is ASHRAE 90.1-2010 Baseline Case, is there a way/methodology to do some nominal capacities calculations to hard-size Reheat coil?Regards,On Fri, Mar 16, 2018 at 12:56 AM, Weili Xu weilix88@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com > wrote:ÂHi Javed,You might want to update the "Central Heating Design Supply Air Temperature" in the 'Sizing:System' from 30+C to the lowest reset temperature setpoint defined in setpoint manager.Your sizing value mismatches with the actual control value. so When reheat coil sees the central design supply air temp is over 30C, it will assume there is no need heat up the supply air at the terminal, therefore, results in 0 heating load.However, in the actual control (defined in the setpoint manager), the central design supply air temp is between 12-15, which is much lower than 30C. With 0 heating capacity, the reheat coil won't be able to bring the 15 C supply air to 30+C.You can also hard set the reheat coil capacity (I remember it should be the nominal capacity field?), this will also improve the unmet hours.WeiliBuildSim.ioOn Thursday, March 15, 2018, 2:10:02 PM EDT, Germán Campos ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com> wrote:ÂCentral heating design supply aire temperature does not affect system design supply airflow but the temperature at the supply outlet which will affect how AHU coils and reheat coils are sized. You should use the maximum temperature from your setpoint manager at the heating coil outlet node. If you are using a reset as per G3.1.3.12 it would be Summer SP-11.1+2.77 (something as 16ºC).If you set a central heating supply of 32.1 and do the same at zone level, the reheat coil sees the same temperature at its inlet and outlet, resulting in zero capacity..
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Germán CamposAurea Consulting Â
www.ecoeficiente.es2018-03-15 12:32 GMT+01:00 Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com>:ÂThat is as per G3.1.2.9..1, sized supply-air-to-room-air temperature difference of 20degF (11.1degC) . All the Spaces winter set-point is 21degC so central heating design supply air tempretaire is 32.1 degC.On Thu, Mar 15, 2018 at 4:55 PM, Germán Campos ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com> wrote:ÂWhich are heating design supply temperatures in system and zone sizing?
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Germán CamposAurea Consulting Â
www.ecoeficiente.es2018-03-15 11:53 GMT+01:00 Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroup s.com>:ÂDear All,I assigned a typical VAV system (Baseline System 5) with reheat but there are many heating unmet hours in the zones served by the system. I did most of the quality checks (correct OA, zone setpoints, zone and system sizing etc.) to see where the problem lies. And i found ' AirTerminal:SingleDuct:VAV:Reh eat' is NOT active or sizing is zero in HTML report. To further ascertain the cause of the problem, I plotted temperatures [ see attachment] at all the nodes to see the temperature regime. This also shows that reheat coil doesn't raise the air temperature to meet the room set-point. ÂThis is being simulated for CZ5A.I also tried to look out for some solutions discussed here [ LINK LINK ] but unfortunately nothing works for me...ÂI would appreciate any help in this regard..Thank you, Â--Javed Iqbal, LEED AP, CEASr. Energy AnalystÂ--Javed Iqbal, LEED AP, CEASr. Energy AnalystÂ--Javed Iqbal, LEED AP, CEASr. Energy AnalystÂ--Javed Iqbal, LEED AP, CEASr. Energy AnalystÂ--Javed Iqbal, LEED AP, CEASr. Energy AnalystÂ
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