Tracer TU has added a new ECM fan balancing tool starting in Tracer TU V12, please see this article: Tracer TU Balancing Tool: Calibrate ECM Fan Speed - Water Source Heat Pump (For Test and Balance Contractors)
Issue:
How do I adjust the ECM fan speed on a staged WSHP?
1 stage 1 compressor WSHP
2 stage 1 compressor WSHP
How to adjust WSHP ECM fan speed?
Resolution:
This Article only applies to a 1 stage 1 compressor WSHP or a 2 stage 1 compressor WSHP with ECM fan (CFM).
For units with torque controlled ECM fans, see article below.
How do I adjust the ECM Fan Speed Configured for Torque Controlled On Staged WSHP?
There is no ECM Engine Module in this WSHP.
The UC400 controls the fan speed directly through an analog output configured as pulse width modulation.
Note: To temporarily override the fan speed to high, override mv/12, Manual Test Sequence to Fan High.
The fan will not run less than 73%.
The factory sets the motor min and max RPMs at 400 cfm/ton.
Analog output configuration should look like this.
Type = Pulse Width Modulation
Dimensionality = Percentage
Reliquish Default = 0%
Minimum Value = -1000%
Maximum Value = 1000%
Peak Voltage = 17 VDC
Total Pulse Width = period = 12.5 milliseconds.
Total Ramp Time = 15 seconds
Output Ramp Rate = 6.667 %/second
These are the BACnet points to control the fan speed range.
AV64, Fan Capacity Low Limit
default = 73, min = 0, max = 100
This is the fan speed low limit.
The fan will never run slower than this.
AV20, Supply Fan Speed Ventilation
default = 73, min = 33, max = 100
This the fan speed when no cooling or heating capacity is running.
Make sure this value is equal to or higher than AV64.
And less than or equal to AV17.
AV19, Supply Fan Speed First Stage Minimum
default = 73, min = 33, max = 100
This is the initial fan speed for a 1 stage 1 compressor WSHP if heating or cooling is running. The fan will ramp up when capacity has been at 100% for 10 minutes.
This is the minimum fan speed for a 2 stage 1 compressor WSHP if heating or cooling is running.
Make sure this value is equal to or higher than AV64.
And less than or equal to AV17.
For 1 stage 1 compressor units, this may be set to 73%, but can be adjusted up to 91% if you want the fan to ramp to high speed as soon as the compressor starts.
For 2 stage 2 compressor units, it can be left at 73% or adjusted as desired.
From Waco, lowering the min fan speed to less than 73% can cause a lack of air flow and the evaporator to freeze up.
AV17, Supply Fan Speed Maximum Heat Cool Capacity
default = 91, min = 73, max = 100
This is the fan speed high limit.
The fan will never run faster than this.
When the 2 stage 1 compressor WSHP is heating or cooling, the ECM fan speed will modulate between AV19 and AV17.
There are no calibration factors.
If you are not getting the desired air flow, then adjust the percentage.
Analog Output 1 VDC
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Analog points for ECM fan speed
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Notes:
Changes:
Other Question/Problem/Cause Statements:
- How do I adjust the ECM fan speed on a staged WSHP?
- Why won't my fan ramp to high speed on a UC400 staged WSHP?