Issue:
Balanced compressor starts and hours
Resolution:
RTAA, RTWA, RTUA...Compressor Balanced Starts & Hours.
The control action when balanced starts and hours is enabled is to start the compressor with the least amount of starts and stop the compressor with the most hours.
Compressor with the most run time (hours) will shut off first.
The UCM shall provide the following two choices on units.
1. When balanced starts/hours is 'Disabled' the UCM will always start circuit #1 (compressor A) assuming all refrigerant circuits are operable. If circuit #1 is non-operable, circuit #2 will be started and so on. On two compressor units (two circuits) after compressor A is started, compressor B will be started; compressors will be stopped in reverse order. On three and four compressor units, after compressor A is started compressors C, B, & D will start in ascending order and stopped in reverse order.
2. When balance starts/hours is 'Enabled' the UCM will start the compressor with the fewest starts and stop the compressor with greatest hours. If the lead circuit is non-operable , the lag circuit will be started and so on. This requirement is modified for three and four compressor units to allow for the starting of the second circuit as soon as possible (for increased efficiency), even if the non-running manifolded compressor of the first circuit started has less starts.
There is a nuance to the counter that can cause unbalanced starts and hours under certain load conditions. If the cooling load is such that it is too much for just one compressor and not enough to cause the female stepper on the second compressor to energize, then the start on the second compressor will not be counted. The start is counted only when the female stepper has energized during a run cycle.
Under these conditions, it is possible for the starts and hours not to balance.
Notes:
This input shall be either factory or field selectable.
Changes:
Other Question/Problem/Cause Statements:
- Balanced compressor starts and hours?
- Compressor B is always starting?
- Compressor A is always starting?
- Compressor lead/lag function?
- Balanced starts and hours on the compressors does not seem to be working?
Facts:
- Air-Cooled Chiller (Pueblo) (RTAA 130-400 Ton)
- Air-Cooled Chiller (Pueblo) (RTAA 70-125 Ton)
- Compressor Chiller (Pueblo) (RTUA)
- Water-Cooled Chiller (Pueblo) (RTWA)
- Service Settings: Balanced Compressor Start & Hours Enabled.
- RTAA 70-125 TON (PUEBLO)
- Balanced starts and hours is enabled.
- Compressor A has 509 starts and 3785 hours.
- Compressor B has 128 starts and 6367 hours.
Document Identifier: DOC-74302
Document Identifier: 74302
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.