Issue:
Water Regulating Valve?
Resolution:
RTWA Water Regulating Valve sizing and configuration:
When setting up a condenser water regulating valve, it is recommended that two valves be used, one per circuit, and that they should be piped in parallel. Refer to Water Regulating Valve? for information on sizing the valves offered by Trane.
The optimum system operating differential pressure is 70 psid. If working with a differential pressure valve controller, use this as the setting for the controllers. If working with controlling discharge pressure only, the valves should be set up to achieve this differential.
It is important to take the condenser and evaporator approach temperatures into consideration when back calculating to determine what the control head pressure setting should be. For example, if the leaving chilled water setpoint is 44 degrees F and, if you assume that there will be a 5 degree approach, then the saturated evaporator refrigerant temperature will be 39 degrees F (approximately 67 psig).
Next add 70 psid to the saturated evaporator pressure to get the approximate saturated condenser refrigerant pressure. In this example, that would be approximately 137 psig (77 deg F). Accounting for a 5 degree approach temperature, the leaving condenser water should then be 72 degrees F.
Depending on the type of control used, it would then be set up to maintain either 137 psig refrigerant discharge pressure or 72 deg leaving condenser water temperature.
RTWA, CGWF, CGWE, CGWD Water Regulating Valve sizing:
The RTWA has similar system pressure differential requirements as the RTHB. It must have 35 psid differential within 15 minutes of startup, along with a 25 deg F difference between the condenser leaving water temperature and the evaporator leaving water temperature. If this is not possible, some form of condenser water control must be provided and often the simplest method of accomplishing this is a two way water regulating valve downstream of the condenser.
Trane recommends piping two water regulating valves in parallel (see RTWA & CGWF IOMs). The water regulating valve options (V46) provided in Lynx for the RTWA and CGWF chillers are for applications with constant cold condenser water (well water, return water from chilled water loop, etc...). The valves are too small for the full flow needed during hot summer day operation and will need to be bypassed during this time or larger valves will need to be selected from a third party vendor (V43 valve).
The following provides several files to aide in the sizing of these valves.
This excel file helps calculate the necessary outputs for selecting the correct valve.
Use the sizing charts located in these Product/Technical Bulletins in conjunction with the outputs from the excel sizing file to select the correct size V46 or V43 Johnson valve. Note: Lynx only offers the V46 valve
Notes:
Changes:
Other Question/Problem/Cause Statements:
- Water Regulating Valve?
- RTWA Water Regulating Valve?
- RTWA Water Regulating Valve Sizing?
- How do I select the correct water Regulating Valve for a RTWA Chiller?
- CGWF Water Regulating Valve Sizing?
- How do I select the correct water Regulating Valve for a CGWF Chiller?
- CGWD, CGWE Water Regulating Valve Sizing?
- Sizing Condenser Water Regulating Valve
- What are the condenser water side requirements?
- How do you size and set up a condenser water regulating valve?
Facts:
- Water-Cooled Chiller (Pueblo) (RTWA)
- Water-Cooled Chiller (Pueblo) (CGWF)
- Water-Cooled Chiller (PBL) (CGWD, CGWE)
Original HUB Documents Combined: DOC-73803 and DOC-81594
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.