Issue:
Heating High Temp Limit Open diagnostic reported to CCP from Precedent
Resolution:
Possible solutions:
1. Lower the supply air heating setpoint at the CCP panel down from default of 120 degrees to 110 or 105 to prevent overheating at the rooftop.
2. Is the supply air sensor located directly in the supply air stream to properly sense air from the RTU?
3. Replace the supply air sensor with a low-mass, fast-response Supply Air Sensor (part number 4190 1129) at the Communicating bypass assembly. This will help the CCPÂ respond to supply heat more quickly. The standard sensor on the communicating bypass assembly has a mass that delays the response as the temperature rises in the supply duct, especially on larger or oversized rooftops.
4. Upgrade CCP to SP3 (image V4.200.338 or higher). The image upgrade adds a fixed heating high limit and cooling low limit that applies to the supply air sensed temperature. The image upgrade improves the temperature prediction logic to provide a faster response time when approaching a limit. The image upgrade revised the heat gain and deadband values used for gas/electric heat rooftop units to improve staging response.
5. Voyager high limit switches (TC02) may be tripping prematurely and need to be replaced. The High heat cutout sensor on the Voyager can only be tripped a finite number of times, if they have been tripping hundreds or thousands of times, this switch may be worn out and will trip too easily. This can cause nuisance trips. Replace it with the new and much improved High Heat limit switch.
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Other Question/Problem/Cause Statements:
- Diagnostic "Heating High Temp Limit Open" reported to CCP from Precedent with Reliatel controls.
- What are the fixes for the High Temp diagnostic trips on Voyagers connected to CCP III?
Facts:
- Varitrac CCP III
- VariTrac III Central Control Panel (CCP)
- I am getting high heat trips on the CCP III/Voyagers system.
- Voyager/Precedent-LCI-R
Original wave: wave2661
Document Identifier: DOC-80286
Document Identifier: 80286