15
RSM-DEV1 Technical Guide
SEQUENCE OF OPERATIONS
Staging
Stage 4 to 1 (VFD is on; Two-Step stages off)
• VFD was at minimum speed.
• Stage delay has been met.
• Controlling temperature is below the staging window for
cooling or above the staging window for heating.
• VFD resets to recommended start speed (3,600 RPM
Copeland; 3,000 RPM Danfoss).
Stage 1 to 0 (VFD stages off; two-step is off)
• VFD was at minimum speed.
• VFD minimum run time met.
• Stage delay has been met.
• Controlling temperature is below the staging window for
cooling or above the staging window for heating.
•
If Dehumidification Mode, VFD is not allowed to stage
off.
Reheat only on second circuit in Dehumidification Mode
Stage 2 (VFD is off; two-step stages on at low speed)
• Two-Step on immediately, no conditions needed.
Stage 2 to 3 (VFD is off; two-step transitions to high speed)
•
Set Two-Step to high speed if flush cycle is active. This
may make system go to stage 3 quickly if starting flush
is enabled.
• Set two-step to high speed if cooling or heating
controlling temperature is above the staging window for
cooling or below the staging window for heating.
• Set two-step to high speed if reheat valve is 100% and
supply air temperature is at least two degrees below
setpoint.
Stage 3 to 5 (VFD stages on; two-step remains at high speed)
• Stage delay has been met.
• Controlling temperature is above the staging window for
cooling or below the staging window for heating.
Stage 5 to 4 (VFD is on; two-step transitions to low speed)
• If VFD is 50% or less and reheat valve is 50% or less,
VFD resets to recommended start speed (3,600 RPM
Copeland; 3,000 RPM Danfoss).
Stage 4 to 3 (VFD stages off; two-step transitions to high speed)
Stage 5 to 3 (VFD stages off; two-step is on at high speed)
• VFD was at minimum speed.
• Stage delay has been met.
• Controlling temperature is below the staging window for
cooling or above the staging window for heating.
Stage 3 to 2 (VFD is off; two-step transitions to low speed)
• Stage delay has been met
• Controlling temperature is below the staging window for
cooling or above the staging window for heating.
•
Two-Step not allowed to stage off in Dehumidification
Mode
Transitioning
To Dehumidification Mode
•
Stage 1 is not a valid dehumidification stage
• If in stage 1, go directly to stage 2
To Cool/Heat Mode
• Stages 2 and 3 are not valid cool/heat stages
• If in stage 2 or 3, go directly to stage 4
Stage Type 4 - VFD Plus Tandem On/Off
Units affected
• RND 31 Ton
Modules
• Module 1(A): VFD
• Module 2(B):
On/Off (B1)
On/Off (B2)
Stages for all modes
•
Stage 0: All are off
•
Stage 1: VFD is on; B1 and B2 are off
•
Stage 2: VFD and B2 are off; B1 is on
•
Stage 3: VFD is off; B1 and B2 are on
•
Stage 4: VFD and B1 are on; B2 is off
• Stage 5: All are on
Cooling, Heating, and regular Dehumidification Mode
Stage 0 to 1 (VFD stages on; B1 and B2 are off)
• No stage delay.
•
Minimum off time has been met.
• Controlling temperature is above the staging window for
cooling or below the staging window for heating.
• VFD turns on at recommended start speed (3,600 RPM
Copeland; 3,000 RPM Danfoss).
•
Dehumidification Mode, VFD turns on immediately. No
conditions needed.
Stage 1 to 4 (VFD is on; B1 stages on; B2 is off)
• VFD was at maximum speed.
• Stage delay has been met.
• Controlling temperature is above the staging window for
cooling or below the staging window for heating.
• VFD resets to recommended start speed (3,600 RPM
Copeland; 3,000 RPM Danfoss).
Stage 4 to 5 (VFD and B1 are on; B2 stages on)
• VFD was at maximum speed.
• Stage delay has been met.
• Controlling temperature is above the staging window for
cooling or below the staging window for heating.
• VFD resets to recommended start speed (3,600 RPM
Copeland; 3,000 RPM Danfoss).
