April Lutheran
Overview
This template generates a central DOAS air handling unit that provides a constant volume of conditioned outside air to all zones. It also generates a package terminal heat pump in each zone.
Application
This template system only applies to package terminal heat pump air conditioners. These are often also known as reverse-cycle split systems.
Air Handling Unit (AHU) – Return Air
The table below describes the key properties of the AHU for this system where there is return air:
|
AHU Feature |
Default |
Extent of user-control |
|
Airflow Rate |
Constant area-weighted rate for all zones |
Can change constant |
|
Supply Air dry bulb Temperature |
Constant with defaults as follows: |
Can change constant value |
|
Supply Air Temperature Reset Controls |
None |
No control |
|
Supply Air Dew Point Controls |
Constant with defaults as follows: Min: -5 C or 23 F Max: 13 C or 55.4 F |
None |
|
Supply Air Humidification Controls |
Via Min Supply Air Dew Point Control |
No Control |
|
Peak Fan Power |
3.5 W/(L/s) or 1.65 W/cfm |
Can control peak load |
|
Fan Curve |
Standard ASHRAE. Click to see fan curve. |
No control |
|
Outside air configuration |
100% outside air |
No control |
|
Return Air Rate |
100% of air assumed to be returned for heat recovery |
No control |
|
Heat Recovery Efficiency |
Sensible and Latent effectiveness available. Default is 50% sensible and 0% Latent. |
User can change sensible and latent effectiveness |
|
Cooling |
Direct Expansion coil post heat recovery |
None |
|
Heating Coil |
Hot water coil post chilled water coil |
Can change to electric coil or direct gas |
|
Frost Coil |
Electric coil pre-heat recovery |
Can change to hot water |
|
Frost Coil Setpoint |
Setpoint for coil – default is 2C |
Can Change default |
Zone PTHP Units
PTHP units are self-contained fan coil units incorporating an internal heat pump unit that are attached to the external wall of the zone.
Heat pump system provides both cooling and heating with supplemental heat source.
The table below describes the key properties of the zone level PTHP units for this system:
|
Fan Coil Unit Feature |
Default |
Extent of user-control |
|
Heating Type |
Heat pump |
No control |
|
Heating Efficiency Curve |
No control |
|
|
Supplemental Heating Source |
Hot water |
Can change to electric or gas coil |
|
Cooling Type |
Direct Expansion |
No control |
|
Cooling Efficiency |
COP with a default of 3 |
Control over COP |
|
Cooling Efficiency Curve |
No control |
|
|
Fan Coil Motor Type |
On/Off |
No control |
|
Peak Fan Power |
0.64 W/(L/s) or 0.3 W/cfm |
Can control peak load |
|
Fan Curve |
Constant Volume Fan |
No control |
|
Supply Air Temperature - Heating |
Constant for all zones (35C / 95F) |
User can change constant |
|
Supply Air Temperature - Cooling |
Constant for all zones (13C / 55.4F) |
User can change constant |
|
Demand Control Ventilation |
None |
None |
|
Dehumidification Load |
Air dehumidified to achieve the cooling setpoint at 60% Relative Humidity in the zone |
None |
The base case option is assumed to have a central plant that provides heating hot water to the AHU and zone.
|
Central Plant Feature |
Default |
Extent of user-control |
|
Heating Hot Water Source |
Natural Gas |
Can change to electric boiler |
|
Boiler Peak Efficiency |
Assumed to be 0.9 |
Value can be changed |
|
Boiler Performance Curve |
No Control |
|
|
Supply and Return Temperatures – hot water |
80/70 C or 176/158 F |
User can control |
|
System losses |
Constant loss of 15% |
User can control loss rate only. |
|
Peak Pumping Energy |
1.32 W/(L/s) or 21 W/gpm |
No control |
|
Pump Efficiency Controls |
Variable Speed Drives |
No control |
|
Efficiency Curve for Variable Pumping |
No control |
|
|
Pumping Configuration |
Primary Only |
No Control |
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