YORK SSE RTU Quick Start Guide

by cfm Distributors, Inc

⚡ Pre-startup and Startup notes:

• Check all electrical connections and tighten as necessary, as these may have become loose during transit
• Verify main incoming power, both voltage and phase
• Check and tighten fan set screws. This is IMPORTANT as set screws may come loose during transit
• Verify airflow — see the Pressure Drop chart in the installation manual. Measure Delta-P across a DRY evaporator (cooling turned off) and adjust the blower until the correct cfm is achieved. This is one of the most important startup steps! (see example chart below)
• Check voltage and amp draw for:
  • Each compressor
  • Supply fan / return fan motors
  • Condenser fan motors
• If economizer hoods are missing, check all unit compartments and these are typically shipped loose inside the RTU

Note: There are many more startup steps that are NOT included in this quick start guide. Please consult the manufacturer's installation manual for the full startup procedure.

Example chart to verify airflow

⚙ SSE Controls Overview

You can adjust settings and parameters using the LCD display and joystick on the Simplicity Smart Equipment (SSE) board. However, it's much easier to use the YORK CWa mobile app.

📱 YORK CWa Service Tool App Download

• Apple App Store → YORK CWa
• Google Play → YORK CWa

🔌 Connecting to the SSE Board

There are two ways get connected to the SSE board with your mobile device

1. Comm Card

YORK offers a small circuit board that mounts on the SSE board. This can be factory or field installed. This is the same board that must be installed to connect to a BACnet MS/TP bus.

Connection tip: In the SSE board, navigate to the "PIN" menu to reveal the PIN code to enter into your phone. This is located under Controller > Bluetooth > PIN

Comm card outlined in RED above

2. CWCVT Service Tool (Map Gateway Replacement)

This service tool plugs into the Ethernet port on the SSE board. Once plugged in, your phone can connect via Bluetooth.

Connection tip: Once the CWCVT is plugged in to the SSE board, press the "A" button a couple times to reveal the "PIN" code that your phone needs to connect (the Pin code is not shown on the picture, but if you press the A button again it will show up).

CWCVT pictured above

⚙ Common Setup Parameters

The SSE board should arrive factory-programmed for the correct number of stages, fan type, fresh air option, reheat option, etc. However, it is good practice to verify these before startup.

🌀 Fan Control Type

3 options to choose from:

1. Single Speed - VFD at a fixed speed regardless of number of stages being called
2. Fixed Variable (Identical to IntelliSpeed^TM) - User selects different VFD speeds for different calls. For example, Y1 = 50% of max air flow, Y2 = 100% of max air flow, G = 75% of max air flow. You can also select different minimum position for economizer (minimum position for low-speed fan, minimum position for high-speed fan).
   1. NOTE: Factory setting is Y1=70%, Y2=100%, G=50% (more on adjusting these setpoints below)
3. Variable - Used for True-VAV or Single-Zone VAV (SZ-VAV). The unit modulates fan speed based on temperature or duct static.
   1. SZ-VAV: Requires a space sensor (not common). This mode modulates supply fan speed to maintain an adjustable leaving air temperature (similar to true-vav), and cycles compressors to maintain an adjustable space temperature.
   2. True-VAV: Supply fan VFD controlled off duct static

Fixed Variable (IntelliSpeed^TM) is the most common setup, so we'll cover some common settings to look at first. First confirm that the fan is set up as Fixed Variable as noted in the previous section.

Thermostat-Only Control Setting

For Single speed or Fixed Variable, "Thermostat only control" must be set to "YES". This should already be set up if your unit was ordered as IntelliSpeed^TM.

💡 Troubleshooting Tip: If thermostat inputs aren't energizing heating/cooling/fan, check this setting first!

⚙ Supply Fan VFD Speed Options

In fixed variable, you have the option of selecting different VFD speeds depending on how many cooling or heating stages are being called.

⚠ Caution: Before adjusting speeds for Y and W, make sure that the RTU has been balanced to the correct airflow, so that 100% VFD speed corresponds to the design max airflow.

Note: These settings are ignored by the SSE board if the unit is programmed for Variable fan (VAV)

• Occupied: No Heat or Cool % Command: Select desired fan speed for occupied mode without cooling or heating calls
• Occupied: One Stage of Cool % Command: Select desired fan speed for occupied mode with Y1 call (70% default for 2 stage cooling unit)
• Occupied: Two Stage of Cool % Command: Select desired fan speed for occupied mode with Y2 call
  • If your unit has 3 or 4 stages, you can adjust these as well
• Occupied: One Stage of Heat % Command: Select desired fan speed for occupied mode with W1 call
• Occupied: Two Stage of Heat % Command: Select desired fan speed for occupied mode with W2 call

General Setup for True-VAV or SZ-VAV

Here is how to set the leaving air temperature setpoint and return temperature reset points:

Parameter Descriptions

• VAV Cooling Supply Air Temperature Lower Setpoint = Example 55°F
• VAV Cooling Supply Air Temperature Upper Setpoint = Example 60°F
• VAV Supply Air Temperature Reset Setpoint = Example 72°F

Logic: If the return temperature is above 72°F, the unit targets the VAV Lower setpoint. If the return air temperature is below 72°F, the unit targets the Upper setpoint.

For True-VAV Only

After confirming the fan control type is set to "variable", make sure to set the duct static setpoint.

For SZ-VAV Only

If your unit will be operating in SZ-VAV mode, make sure to set the occupied cooling and heating set points

• Set "SZ VAV Occupied Cooling Setpoint". Example: 72°F
• Set "SZ VAV Occupied Heating Setpoint". Example: 68°F

🕐 VAV Scheduling

For True-VAV or SZ-VAV, a schedule must be set up by either a 3rd party controls contractor (BACnet MS/TP), or a schedule can be programmed in the SSE board.

🌿 Economizer Settings

Economizer Minimum Position: When the RTU is occupied, regardless of heating or cooling calls, the economizer will be at this minimum position (%)

Dry Bulb Economizer Control

For Dry bulb, go to "Economizer Outdoor Air Temperature Enable Setpoint". We typically recommend setting this to 55°F.

Enthalpy Economizer Control

For Enthalpy control, go to "Economizer Outdoor Air Enthalpy Enable Setpoint". We typically recommend setting between 23-25 btu/lb. The lower the number, the less free cooling will be achieved, but also fewer "no cooling" call backs. Note: must have an enthalpy sensor installed to use enthalpy control

❄ Low Ambient Settings

If you have an aftermarket low ambient kit (head pressure controller)

If you don't want to lock out mechanical cooling at any ambient temperature, set this point to NO. This will prevent the unit from locking out the compressor in cold temperatures.

Parameter: Set the OAT Cooling Cutout Enabled = NO

If you don't have an aftermarket low ambient kit

If you would like to enable "poor man's" mechanical cooling in low ambient temperatures, enable this point. This feature will cycle the compressors on and off during low ambient temperatures to keep your space cool and the evaporator coil from freezing. This is typically not required if there is an economizer installed.

We call this the "poor man's" low ambient because A) there is no extra cost to add this feature and B) it should only be used in rare occasions when you need some cooling in a comfort cooling application. This shouldn't be used in a process application where cooling is needed most of the year.

• Parameter: Low Ambient Cooling Stages = 10 on / 5 off
• Setpoint = 45°F (adjustable)

🔒 Compressor Lock Out

If you'd like to lock out the compressor below a certain ambient temperature, you can achieve that here:

• Point: OAT Cooling Cutout Enabled = YES

AND

• Point: OAT Cooling Setpoint = 50°F (adjustable)

🔥 Hot Gas Reheat Settings

Relative Humidity Sensor Options

In most applications, the equipment will arrive with either a return or space mount relative humidity (RH) sensor that sends an analog signal (communicating) to the SSE board to report the RH. Then, a user would set the desired space/return RH setpoint. The unit would then operate in dehum mode depending on which option is selected below.

Using a Dry Contact RH Sensor

If a relative humidity sensor with a dry contact is preferred, this can be accomplished by updating the point "Use DFS for Dehum = yes." The unit cannot be using the dirty filter switch already.

Reheat RH (%) Setpoint

Here is where you select a space or return RH setpoint. If you plan to use the dry contact, your RH setpoint will be adjusted on the dry contact RH sensor.

3 Hot Gas Reheat Modes

Normal / Standard Mode

NOTE: This is the default mode

• Dehum call without a cooling call: unit runs in dehum mode, 1st stage only
• Dehum call with Y1 call: unit turns off dehum, enables first stage cooling
• Dehum call with Y2 call: unit runs full cooling mode

Alternate Mode

The only difference between Normal and Alternate mode is when there is a dehum call and a Y1 call.

• Dehum call with no cooling call: dehum mode, 1st stage only
• Dehum call with Y1 call: remains in dehum mode, 1st stage only
• Dehum call with Y2 call: dehum turned off, full cooling operates

Alternate AUX / Hybrid

Hybrid mode enables a second stage of cooling with a dehumidification call. This adds capacity to remove humidity from the air, but it may also lead to over cooling if there is a light sensible load. Hybrid mode combines Alternate mode and Normal mode and selects the appropriate mode in relation to the cooling staged percent command value.

Note: To enable hybrid mode, Alternate Mode must be turned on first.