BCI-R / BCI2-R RTU Modulating Heat (VAV, SZVAV, CV) - Occupied Heat, Supply Air Tempering
Summary:
Modulating heat refers to the ability of the RTU to vary the heat output based on the heating needs of the space. This is done by adjusting the fuel or energy input to the heating system. This feature ensures the the space is maintained at a comfortable temperature while optimizing energy efficiency
- How does heat work on BCI-R RTU with Modulating Heat?
-BCI-R VAV RTU will not heat
There are 4 types of heating sequences on BCI-R VAV RTUs with mod heat. Only Occupied heat can be commanded. The other 3 are only triggered when the configuration is correct and the necessary operational/space conditions have been met.
Assuming you already set up your unit per Table 1 in BCI-R / BCI2-R Point Configuration for Control with Automation System / 3rd Party (Voyager / Precedent / Odyssey), then follow these steps to set your unit up for heating.
In Occupied Heat, duct static pressure is controlled and the discharge air temp (DAT) is controlled to the DAT heating setpoint.
In Supply air tempering, duct static pressure is controlled and the DAT is controlled to the DAT cool setpoint - 3.5 degrees F.
The rooftop will never run occupied heat on its own.
The rooftop has to be commanded to occupied heat to run the occupied heat sequence.
Morning Warmup (MWU) and Daytime Warmup (DWU)
Use MWU/DWU if you desire full fan while heating
To setup, initiate and/or troubleshoot MWU and DWU sequences, refer to BCI-R / BCI2-R VAV RTU Heating - Max Heat, Morning Warmup (MWU), Daytime Warmup (DWU)
Occupied Heat
Occupancy Request = 1-Occupied
Heat Cool Mode Request BAS = 2-Heat
Supply Air Tempering
Supply Air Tempering from RT-SVD03K-EN page 39
RTOM J3-1 to J3-2 jumper to enable/disable supply air tempering when using a mechanical zone sensor module.
No jumper = open = supply air tempering is enabled
Jumper = closed = supply air tempering is disabled
The BAYSENS119 (communicating programmable zone sensor) can also enable and disable supply air tempering.
Supply air tempering can also be enabled and disabled over the comm. link.
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.