The chilled water loop is has a chiller and a variable speed pump to supply chilled water. As an option, the chiller may be water-cooled, in which case it is attached to a condenser loop.
Required Objects
The chilled water loop must have the following property.
- It must have at least 1 cooling coil attached to a the loop.
Design Assumptions
- The chilled water loop can operate in two modes: high-temp chilled water and low temp chilled water.
- The chilled water loop will operate as a high-temp chilled water loop only if all components on that loop typically operate at a higher temperature. In this domain, it is limited to the following objects:
- Active chilled beam
- Passive chilled beam
- Radiant panel
- If any of the following objects are on the chilled water loop, it will operate as a low-temp chilled water loop.
- Air system chilled water cooling coil
- Four pipe fan coil
- Unit ventilator chilled water cooling coil
- The chilled water loop will operate as a high-temp chilled water loop only if all components on that loop typically operate at a higher temperature. In this domain, it is limited to the following objects:
- The chilled water loop has the following default temperature assumptions.
| Property | Value | Notes |
|---|---|---|
| High temperature loop supply temperature | 15°C | Determined by the air system (typically 12.7778°C). |
| High temperature loop return temperature | 18.333°C | Determined by the air system (typically between 12.7778°C and 18.3333°C by default). |
| Low temperature loop supply temperature | 6.6667°C | |
| Low temperature loop return temperature | 15.5556°C | Set by hot water loop if hot water coil is included in the system. |
Configuration
- Chiller
- Pump
The chilled water loop is comprised of 2 main components.
Chiller
The chiller can be air-or water-cooled, and has the following assumptions.
| Property | Value | Notes |
|---|---|---|
| Leaving water temperature | N/A | Determined by the loop design stated above. |
| Minimum part load ratio | 0.15 | |
| Flow control | Variable | Modulates flow to meet set point. |
| COP | 5.5 | |
| Condenser entering water temperature | N/A | Determined by the condenser loop (typically 29.44°C). |
Pump
The pump in the default chiller configuration has the following assumptions.
| Property | Value | Notes |
|---|---|---|
| Pressure rise | 179344.014 Pa | |
| Flow type | Variable Speed | |
| Flow control | Intermittent | Only runs when there is demand. |