Issue:
Condenser water control for RTHD and RTWD
Resolution:
RTHD: The following guidelines must be met in order to ensure adequate oil circulation throughout the system.
1. The RTHD must maintain a 23 psid system pressure differential (condenser pressure - evaporator pressure) at all load conditions in order to ensure adequate oil circulation. (NOTE: RTWD pressure differential is slightly different, however, RTHD pressure references will be sufficient).
2. The entering condenser water temperature must be above 55F or between 45F and 55F with a 1F degree temperature rise per minute to 55F.
3. Condenser leaving water temperature must be 17F degrees higher than evaporator leaving water temperature within 2 minutes of start up. A 25F differential must be maintained thereafter.
The RTHD has an optional Condenser Head Pressure Control Module (1A13) which has the ability to output a 0 to 10 DC volt output to a valve actuator. Below is a table with recommended starting points for setting up the output. These values have been successful in many applications. To gain access to the setup, a laptop will need to be connected to the chiller, connect to the Main Processor (Dynaview) and do a local connection. Select Setpoint View and then Condenser Head Pressure tab.
| Off State Output Command | Output voltage at desired minimum flow | Desired Minimum Flow | Output Voltage at Desired Maximum Flow | Actuator Stroke Time | Damping Coefficient |
| 0V | 2Vdc | 15% | 10Vdc | Match stroke time of valve, if unknown use 30 sec. | 0.5 |
The CH530 control also has the ability to pre-start the condenser pump. Doing this will help in the event a long condenser loop exists such that it will give time for the building pipe water to mix with the colder tower water. Additionally, if the evaporator is full of liquid, pre-starting the pump may migrate the refrigerant to the condenser dropping the temperature in the evaporator. To access the the menu, go into Setpoint View, select Chiller Tab, and scroll down to Condenser pump prestart time. Start with 1 minute, however, this setting will depend on the size of the loop. Also, keep in mind that prior to the chiller starting after satisfying setpoint or being commanded off, the condenser pump will run for the duration of the pre-start timer before starting the chiller start routine.
Refer to RTHD and RTWD engineering bulletin RLC-PRC017*-EN & RLC-PRB021*-EN for more information. Current literature can be found in Pueblo Literature.
Note: If not present, adding the 1A13, Condenser Control and % RLA Output Module will give you the ability to do tower water control.
See bulletin RLC-SVB32A-EN to help with settings for chillers with 1A13
TECHTV Videos:
Condenser Water Regulating Valve Theory
Condenser Water Regulating Valve: Setting Minimum Flow
Other Question/Problem/Cause Statements:
- Condenser Water Control
- Condenser water regulating valve setup
- Head pressure control
- No differential refrigerant pressure
Facts:
- Water-Cooled Chiller (Pueblo) RTHD
- Water-Cooled Chiller (Pueblo) RTWD
Original HUB Document : DOC-83283
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.