DXR2 applications permit control of electric heating coils, in addition to control of water heating valves and/or heating/chilled water valves. They are then operated as reheaters and only enabled if the water heating valve is fully open.
Plant diagram
Figure: Example for a 2-pipe system VAV application with electric reheater
Key:
DXR2… | Automation station |
| R1 | Room operator unit |
YS | Supply air VAV |
| D1 | Presence |
YHC | Heating/cooling coils |
| D2 | Window contact |
YR | Electric reheater |
| T | Over temperature contact |
Sequences
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Y | Output signal |
| TR | Room temperature |
YR | First stage electric reheater |
| SpH | Effective heating setpoint |
YH | Hot water heating coils |
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Figure: 1-stage electric reheater
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Y | Output signal |
| TR | Room temperature |
YH1 | First stage electric reheater |
| SpH | Effective heating setpoint |
YH2 | Second stage electric reheater |
| YH | Hot water heating coils |
Figure: 2-stage electric reheater
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Y | Output signal |
| TR | Room temperature |
YH1 | First stage electric reheater |
| SpH | Effective heating setpoint |
YH2 | Second stage electric reheater |
| YH | Hot water heating coils |
YH3 | Third stage electric reheater |
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Figure: 3-stage electric reheater
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Y | Output signal |
| TR | Room temperature |
YR | Modulating electric heating coils |
| SpH | Effective heating setpoint |
YH | Hot water heating coils |
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Figure: Modulating electric reheater
Actuators
Electric heating coils, controlled via an analog output on the DXR2 room automation station, can receive an enable via a relay or triac on the DXR2.
Safety thermostat
A binary overtemperature (open contact) protection can be connected on the DXR2 for all versions of the electric reheating application. The application switches off the electric reheater at device protection priority if overtemperature protection is enabled.
Description | Name | Default value |
|---|---|---|
Enable overtemperature detector input 0:No | EnOvrTDetIn | 0:No |
WARNING
Improper installation of electric heating coils can result in fire and cause destruction of life and property.
- Install a high temperature cut-out switch on all electric heating elements.
- Ensure that all wiring and installation conform to applicable safety codes and regulations.