RE: [EnergyPlus_Support] Re: Heating and Cooling Coil Control

Matthew,

Here are some comments, in no order and without prioritization:

· Sizing:System for all AirLoops shows 50F heating design air temp. For the fan coils zones, that should be OK, but AHA, B &G have no other source of heat, so I suspect that will cause a problem. (Related: SetpointManager:SingleZone:Heating objects call for minimum 85F, but Sizing:System never lets it get above 50F)

· Fan efficiency of 70% is unrealistic for a small fan – 40-50% is more like it. (But that won’t cause a sim error.)

· Economizer changeover at 75F seems too high for Nebraska

· The “Always 20” schedule is really 21, “Always 25” is really 23

· Blow-through AHUs are not very common. For the future, double-check the actual configuration, and if it’s draw-through, you probably want the SetpointManager:MixedAir to reference a NodeList that picks up all of the looks something like:

NodeList,

MANodeLIST_Base3-1,

NodeOut_MA_Base3-1,

NodeOut_ClgCoilAir_Base3-1,

NodeOut_HtgCoil1Air_Base3-1;

· I find that adding a LOT of Output:Variables assists diagnosis of problems greatly. I report the node temps at each air branch node, air flow for outdoor and discharge air, zone temps and air flow, and water loop node temps and flow. In your case, some fan coil variables will probably help, too. If you see all of the nitty-gritty details, you can normally see what’s going wrong and investigate more efficiently. In addition, an .rvi file is very helpful so as to organize the presentation with like variables together. As you know, it’s VERY difficult to make sense of the messy representation in the un-organized .CSV. It’s a longer story, but I’ve made a spreadsheet with helpful macros to create the variables, export them and then import CSV results back in a neat, readable format. It looks like this:

You need not go to the same trouble, but having the data organized is a huge benefit.

· Notice in your CSV that various water node Setpoint Temps are “-999”. That means that E+ hasn’t got a setpoint for that node. In some cases, the node is identified as an inlet, whereas the setpoint is normally assigned to an outlet. AHB has 82C / 72C inlet / outlet water temp, despite showing “-999” for the setpoint – I’m not sure what that means.

· That’s all for now.

I hope that helps!

James V Dirkes II, PE, BEMP, LEED AP
BuildingPerformanceTeam.com

Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Matthew Anderson
Sent: Friday, August 17, 2012 5:26 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Re: Heating and Cooling Coil Control

Attached is a copy of the IDF, I got the setpoints working on the Air Handlers but I am having issues with runaway temperatures in hot water and chilled water loops. I would love some assistance with this.

Also, I realize the surfaces are not convex. I adjusted the Building -> Solar Distribution -> Full Exterior to compensate. According to the I/O manual this will allow for an accurate model but if anybody objects and has good reasons I can work on the geometry to get the building surfaces convex.

So I obviously have something very wrong here but I would appreciate any help that can be given.

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of YuanLu Li
Sent: Friday, August 17, 2012 1:10 PM
To: EnergyPlus_Support
Subject: RE: [EnergyPlus_Support] Re: Heating and Cooling Coil Control

Your questions are very good. See if anyone will respoond. I cannot answer them, as there is not enough information on the system.

If you place the control at the wrong point or at a point already used by another setpoint manager, I do not know what will happen. Once the supply air is set to 14°C say, it cannot be changed.

The reheat heater can be controlled by the zone thermostat. The VAV system overcool the zone at the minimum damper position, and then turn on the zone reheat heater to heat the zone to the required temperature. I suppose, you can re-associate the zone to the setpoint manager:reheat and not to use the zone thermostat directly. More controller, schedules are required to implement this mode.

I have said many times that I will never use this system control mode without a full computerised control for the building. I have not read the ASHRAE document and guidelines.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: matthew.sverre.anderson@xxxxxxxxx
Date: Fri, 17 Aug 2012 17:29:37 +0000
Subject: [EnergyPlus_Support] Re: Heating and Cooling Coil Control

So in reading thru the I/O Manual the difference between the

(1) SetpointManager:SingleZone:Reheat
(2) SetpointManager:SingleZone:Heating
(3) SetpointManager:SingleZone:Cooling

Are as follows:

(1) The reheat setpoint manager determines the supply air temperature (with upper and lower boundaries) required to meet zone load

(2) The heating setpoint manager only determines the supply air temp that will satisfy the heating load

(3) The cooling setpoint manager only determines the supply air temp
that will satisfy the cooling load

Now lets say I put a reheat setpoint at the zone inlet for supply air so that it will be able to generate a supply air temperature to meet either the heating or cooling load required. Presumably I wouldn't want to put it at the Air Loop Outlet because the Air Loop Outlet is the Cooling Coil Outlet How do I tie this into controlling the Coil:Cooling:Water and the Coil:Heating:Water?

The Controller:WaterCoil is meant to sense the temperature at the Air Outlet of the coil and adjust the flow of the fluid thru the coil correct? So if we put a setpoint at the outlet of the coil the coil flow will increase or decrease to reach that setpoint correct?

Is this correct logic?

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jim Dirkes <jim@...> wrote:
>
> How about SetPointManager:SingleZone:Reheat? I use it frequently for packaged rooftop (single zone) systems. No reheat is actually required.
>
> James V Dirkes II, PE, BEMP, LEED AP
> The Building Performance Team Inc
> 1631 Acacia Drive, Grand Rapids, MI 49504
> 616 450 8653
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of ntraughpee
> Sent: Friday, August 17, 2012 9:30 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Heating and Cooling Coil Control
>
>
>
> It is an air system with many diffusers and a single zone.
>
> Does my question about how to setup the Setpoint:Manager make sense?
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> Right now my model is simultaneously cooling and heating and I know I can fix a lot of this by just shutting off the heating coil in the summer and the cooling coil in the winter but I'd prefer to figure out how to make it work in E+ without that work around.
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> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>, YuanLu Li <yli006@<mailto:yli006@>> wrote:
> >
> >
> > Whether you call it a AHU or a zone fan coil unit depends on the capacity. If you have a gym with many people, it will be an air system with many diffusers, although there are no seperate zones. The old fashioned thermostat master zone controlled AHU is what you need. I think there is example file for this, although I am not very sure now, as many of the 5Zone examples have been converted to setpoint control of the AHU. The system should have Type 4 theremostat with economiser function at the OA controller. OA flow rate can be linked to the people occupancy schedule and the minimum air valuevalue. So, no people, low air flow, or shut down altogether.. Dr. Li
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>
> > From: matthew.sverre.anderson@<mailto:matthew.sverre.anderson@>...
> > Date: Thu, 16 Aug 2012 22:07:38 +0000
> > Subject: [EnergyPlus_Support] Heating and Cooling Coil Control
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> > Hey Everybody,
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> > So I currently have a zone which is controlled by a single air handler. The physical mechanics of the system are this:
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> > (Economizer) -> Fan -> Heating Coil -> Cooling Coil -> Zone
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> > Both the Heating Coil and Cooling Coil are on district plants. The system itself is a single zone CAV system.
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> > What would be the best way to go about modeling/organizing this?
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> > The HVACTemplate:System:VAV does not have the ability to list the coil as anything but electric/gas (for obvious reasons) or I could list it as a reheat coil and attempt to reorganize the nodes later. My first attempt was to list it as a reheat coil then reorganize the nodes, but it led to this question.
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> > How would I organize the controls, without using a schedule, so that the heating coil water massflow rates drop to zero when no heating is required and the chilled water mass flow rates drop to zero when no cooling is required?
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> > I currently have a mixed air set point scheduled at the fan outlet to control the economizer (is there a better way to do this to get maximum cooling out of the economizer?) but where can I put a setpoint in the SetpointManager(and what kind) combined with the ThermostatSetpoint:DualSetpoint (which is what the HVACTemplate expands to in the expidf) to add intelligence to the control layout. Currently I have the VAV airflow % set to 100% so it is a CAV system but I need to model the coil flow like what you would get with control valves on there that shut down when they are not needed and I seem to be spinning my wheels with this particular layout.
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> > The big problem with this building is that it is a gym so during cooling months we will always need to cool but during heating months we might need to heat and we might need to cool depending on the occupancy.
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