Sir:
Here is what the eQuest DOE2 Help Menu shows. Try to follow their guidelines.
John R. Aulbach, PE
Two-Pipe Fan Coil System (FC)
The two-pipe FC system provides both heating and cooling to individually controlled zones. However, all zones served by the system must be operating in the same mode (i.e., either heating or cooling) at any given time. A fan coil unit consists of a filter (not shown), combination heating/cooling coil, and fan. The coil is connected to a CIRCULATION-LOOP with TYPE=PIPE2 that provides either hot or cold water according to the prevailing mode of operation as defined by the HEATING-SCHEDULE and COOLING-SCHEDULE. The unit provides a fixed quantity of outside air ventilation or merely recirculates conditioned air. Exhaust fans are optional for any or all zones. Temperature control is achieved by throttling the flow of water through the heating/cooling coil. The control thermostat commonly used for this type of system has separate heating and cooling setpoints. The fan coil units, particularly the smaller direct-drive units, may not be available with a fan capacity that matches the calculated value. Therefore, assignment of the fan capacity for a specific, commercially available unit is recommended for improved simulation accuracy.
Figure 25? Two-pipe fan coil system (FC)Suggested minimal input for two-pipe FC system:Note that the input for a two-pipe FC system requires that you specify a CIRCULATION-LOOP of TYPE=PIPE-2 to which the fan-coil units, chiller, and boiler are attached. In the following, this loop is called FCLOOP-1. The fan-coil unit's cooling coil is attached to this loop by entering CHW-LOOP=FCLOOP-1 under SYSTEM. Similarly, the fan-coil unit's heating coil is attached to source loop by entering HW-LOOP-FCLOOP-1 under SYSTEM. On the PLANT side, the BOILER, called HW-GEN, is attached to this loop by entering HW-LOOP-FCLOOP-1; and the chiller is attached by entering CHW-LOOP-FCLOOP-1.SYSTEMS-REPORT
SUMMARY??????????? = (SS-A,SS-O) ..$ SYSTEMS SCHEDULESFANS-ON = SCHEDULE
TYPE?????????????? = ON/OFF
THRU DEC 31??????? (WD) (1,7) (0) (8,18) (1) (19,24) (0)
?????????????????? (WEH) (1,24) (0)? ..COOLSETPT = SCHEDULE
TYPE?????????????? = TEMPERATURE
THRU DEC 31??????? (WD) (1,7) (99) (8,18) (76) (19,24) (99)
?????????????????? (WEH) (1,24) (99)? ..HEATSETPT = SCHEDULE
TYPE?????????????? = TEMPERATURE
THRU DEC 31??????? (WD) (1,7) (55) (8,18) (72) (19,24) (55)
?????????????????? (WEH) (1,24) (55)? ..DHW-1 = SCHEDULE
TYPE?????????????? = MULTIPLIER
THRU DEC 31??????? (WD) (1,7) (0) (8,18) (1.0) (19,24) (0)
?????????????????? (WEH) (1,24) (0)? ..HEAT-ON = SCHEDULE
TYPE?????????????? = ON/OFF/TEMP
THRU MAY 15??????? (ALL) (1,24) (1)?????? [1]
THRU SEP 15??????? (ALL) (1,24) (0)
THRU DEC 31??????? (ALL) (1,24) (1) ..COOL-ON = SCHEDULE
TYPE?????????????? = ON/OFF/TEMP
THRU MAY 15??????? (ALL) (1,24) (1)?????? [2]
THRU SEP 15??????? (ALL) (1,24) (0)
THRU DEC 31??????? (ALL) (1,24) (1) ..DHW-PUMP-1 = PUMP ..? $ basic domestic hot water recirc pumpFCLOOP-PUMP-1 = PUMP? $ basic chilled and hot water pump
?????????????????? $ for fan coilsDHW-LOOP-1 = CIRCULATION-LOOP
TYPE?????????????? = DHW
PROCESS-FLOW?????? = 0.25???????????????? $gpm$
PROCESS-SCH??????? = DHW-1
HEAT-SETPT-T?????? = 120 ..
LOOP-PUMP????????? = DHW-PUMP-1? ..FCLOOP-1 = CIRCULATION-LOOP
TYPE?????????????? = PIPE-2
LOOP-PUMP????????? = FCLOOP-PUMP-1
LOOP-OPERATION???? = SCHEDULED
HEATING-SCHEDULE?? = HEAT-ON
COOLING-SCHEDULE?? = COOL-ON? ..CHILLER-1 = CHILLER-1
TYPE?????????????? = ELEC-HERM-REC
CONDENSER-TYPE???? = AIR-COOLED
CHW-LOOP?????????? = FCLOOP-1 ..HWGEN-1 = BOILER
TYPE?????????????? = HW-BOILER
HW-LOOP??????????? = FCLOOP-1 ..DHW-HEATER = DW-HEATER
TYPE?????????????? = GAS
DHW-LOOP?????????? = DHW-LOOP-1 ..AC-SYST = SYSTEM
TYPE?????????????? = FC
MAX-SUPPLY-T?????? = 110 ???????????????? [5]
MIN-SUPPLY-T?????? = 55 ????????????????? [6]
NIGHT-CYCLE-CTRL?? = CYCLE-ON-ANY???????? [7]
FAN-SCHEDULE?????? = FANS-ON????????????? [8]
CHW-LOOP?????????? = FCLOOP-1???????????? [10]
HW-LOOP??????????? = FCLOOP-1 ..????????? [10]OFFICE = ZONE
TYPE?????????????? = CONDITIONED
DESIGN-HEAT-T????? = 72
DESIGN-COOL-T????? = 74
HEAT-TEMP-SCH????? = HEATSETPT? ????????? [3]
COOL-TEMP-SCH????? = COOLSETPT? ????????? [3]
OA-FLOW/PER??????? = 15 .. ?????????????? [4]$ THIS MAY BE FOLLOWED BY AN ECON INPUT$END ..COMPUTE ..STOP ..Subtopic help for this Topic:Additional capability for two-pipe FC system:
Hi everyone I'm trying to model an existing building in eQuest 3.65. The building has a chilled water loop and a hot water loop (the same pumps changeover to pump HW in winter and CHW in summer). All apartments have a non-ducted 2-pipe Fan Coil Unit. Nothing controls the coil (there's no 2-way valve), there's just a fan selector (LOW-SPEED/HI-SPEED/OFF), and there is no outside air being supplied to the apartments. I'm struggling to understand how to properly model this in eQuest: ?????????Should I create one HVAC SYSTEM (type FCU) per zone? Or one FCU system serving all of my zones? (Both seem to work, but I'm guessing there could be a drawback to using one versus the other) ?????????What is the easiest way to ensure the outside air is zero? ?????????How should I configure the FCU to mimic as closely as possible the (lack of) controls I have? Thanks for any insight you can provide! ?
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The loop description sounds more like a "two-pipe changeover" system, which will be one of the choices in eQUEST....I see you've got a reply from John A. already with the details on that which should be helpful.
You'll have one FCU system per zone, although you may combine similar zones into one. (i.e. opposite faces of the building should be separate zones, at a minimum) OA quantity can be set to zero in the FCU dialog boxes, no problem there. The zones probably still have infiltration, and you might bump that up if there are operable windows. After simulating your can view the "summary" tab while viewing the air-side systems and you'll get a spreadsheet of all the AHUs, and a listing of capacities and outside air rates for verification purposes.
Your other obstacle is a little bit trickier. I think eQUEST must assume that there is some control valve - using three-way instead of two-way will give you the equivalent amount of pumping energy - i.e. constant flow.
However, one of the issues you may face is that if the coils are "wild" (no control valves, water flows all of the time when pumps are on) then there will be heat transfer with the room even when the FCU fans may have cycled off and eQUEST thinks the space temperature is met. In real life this might result in two circumstances depending on how much infiltration is taking place - actual temperatures go higher than desired, and/or occupants open their windows even in the winter.
You'll have to decide if those effects are important for your building, and if so you might have to adjust the eQUEST setpoints and infiltration rates to reflect what is actually happening in order to set a baseline. If the main concern is pumping energy instead of boiler energy and thermal comfort, then you should be fine using the three-way valves.
David
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates
Hi everyone I'm trying to model an existing building in eQuest 3.65.
The building has a chilled water loop and a hot water loop (the same pumps changeover to pump HW in winter and CHW in summer).
All apartments have a non-ducted 2-pipe Fan Coil Unit. Nothing controls the coil (there's no 2-way valve), there's just a fan selector (LOW-SPEED/HI-SPEED/OFF), and there is no outside air being supplied to the apartments.
I'm struggling to understand how to properly model this in eQuest:
* Should I create one HVAC SYSTEM (type FCU) per zone? Or one FCU system serving all of my zones? (Both seem to work, but I'm guessing there could be a drawback to using one versus the other)
* What is the easiest way to ensure the outside air is zero?
* How should I configure the FCU to mimic as closely as possible the (lack of) controls I have?
Thanks for any insight you can provide!