How does morning warm-up work in CCP delivered VAV system when the RTU is cool only

Issue:

How does morning warm-up work in CCP delivered VAV system when the RTU is cool only

Resolution:

A cool only RTU really defeats the functionality of morning warm-up and prevents it from doing its intended job. If the system is cool only, I believe that the CCP will turn on the fan, close the economizer, and blow as much air through the system as possible. In order to bring the temperature up using local heat, it will probably be necessary to bring the system on early and allow the building to heat up slowly. To a certain extent, this will be assisted by closing down the source of outside air (closing the outside air damper) and by circulating as much air as possible in order to distribute heat from the local zones (turn on the fan). Depending on the amount of local heat and the geometry of the system this might be slow, or it might be ok.

 

Notes:

Reference VariTrac Controller Operator Guide VAV-SVU01A-EN.

https://tranesupport.zendesk.com/hc/en-us/articles/11744522945677-VariTrac-III-CCP-literature

 

Other Question/Problem/Cause Statements:

• How does morning warm-up work in CCP delivered VAV system when the RTU is cool only

Facts:

• VARITRAC III CENTRAL CONTROL PANEL (CCP)
• VariTrac III Central Control Panel (CCP)

Original wave: wave1805