Issue:
- Start Inhibited by Low Condensing Temperature
- Chiller locking out at 25F ambient temperature
Resolution:
- Disable the Freeze Avoidance Start Inhibit setting
- This setting is in the Setpoint View of the TechView service tool
- To change this setting TechView/KestrelView must be in Access Level 4
- Ensure Low Ambient Lockout is not causing the problem
Low Ambient Lockout
Range: Enable, Disable
Default Setting: ENABLE ( For this issue, change the setting to DISABLE )
Description: Allow freeze avoidance algorithm to run.
Help Information: Due to the susceptibility of the RTAC to have an evaporator freeze up, it is necessary to prevent the unit from starting below 25F unless the chiller has appropriate freeze abatement applied.
Some of the measures that the customer would need to take to minimize/avoid the evaporator freeze risk include:
1. Adding glycol to the waterside system to bring the freeze point below the lowest ambient to be expected.
2. Install heaters (this option does rely on continued availability of power; however will not protect against a migrational freeze)
3. Provide for power backup to allow continued operation of the evaporator water pump and evaporator heaters for a minimum of 90 minutes after power loss
4. Drain the evaporator and blow tubes out with nitrogen or air
Operational mode: "Start Inhibited by Low Condensing Temperature" was implemented to prevent a migrational freeze at temperatures below 25°F:
- Heaters will protect the chiller from ambient freeze, however they will NOT prevent migration freeze at any temperature.
- Glycol at the incorrect concentration for the ambient conditions present will NOT prevent migrational freeze.
- Solution Flow WILL prevent migrational freeze at all but very extremely low ambient temperatures....below -10.0°F.
Notes:
- See Current IOM for information regarding evaporator freeze protection.
- This mode may also be present if a circuit has lost refrigerant and experiencing low pressure/temperature readings.
- Validate each circuit is properly charged.
- In this case, the affected circuit can be locked out to allow second circuit to run until repairs can be completed.
Other Question/Problem/Cause Statements:
- Chiller locking out at 25F ambient temperature
- Start Inhibited by Low Condenser Temperature
- Air-Cooled Chiller (Pueblo) (RTAC)
Document Identifier: DOC-81601
Document Identifier: 81601
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.