Neptronic Pressurized Condensate Return System (PCR)

Foreword and Safety Instructions

Overview

Product Description

The objective of the Neptronic patent-pending pressurized condensate return (PCR) system is to return condensate generated within the steam dispersion tubes of a direct steam humidifier back to the boiler for the following reasons:

• Eliminate the need for a drain
• Reuse condensate and avoid waste
• Increase energy efficiency

By design, the PCR system eliminates the need for a heat exchanger, making inspections and de-scaling work unnecessary. It requires no specific maintenance regimen as it is an empty vessel.

With the PCR system, no maintenance means no downtime. All critical components are externally located and easily accessible. Critical functions are monitored and controlled in real-time by the independent PCR Electronic Controller. The controller can be stand-alone or integrated into a Building Automation System via BACnet MS/TP or Modbus.

PCR Means Maintenance Free

• Real-time status and monitoring.
• No systematic verification required.
• No de-scaling required.
• No downtime.
• No flooding of header.

This innovative, patent-pending Neptronic technology simplifies installation, provides maintenance-free and energy-efficient operation, and enables system monitoring for direct steam applications.

Principle of Operation

• The header's integrated slope forces accumulated condensate to the drain port (1), which then flows into the PCR tank (2).
• When the tank level setpoint is attained, the ESC controller opens the Steam supply valve (3) to empty the PCR tank (2) into the Condensate return (5) system.
• The check valve (4) prevents steam pressure from reversing into the header.
• The ESC controller continues to monitor the tank's condensate level and temperature.
• When the PCR tank (2) is empty, the ESC controller closes the Steam supply valve (3) and opens the Relief valve (6) to partially relieve pressure in the PCR tank (2) and allow the flow of condensate from the header to the PCR tank(2).
• With the Relief valve (6) open, the check valve (7) prevents backflow from the Condensate return (5) to the PCR tank (2).

Specifications

Handling and Lifting

⚠️ The Pressurized Condensate Return System MUST always be handled and lifted with care and must remain in its original packaging for as long as possible prior to installation.

Unpacking

The Pressurized Condensate Return System is shipped inside carton boxes or in a wooden crate. Remove packing and skids prior to commissioning.

Equipment Included

Dimensions

PCR Capacity

The PCR capacity is obtained based on the system differential pressure (ΔP), which is defined as:

ΔP = P_supply – P_recovery

P_supply: Steam supply pressure to the humidifier. Steam supply pressure may decrease after opening steam supply valve. Size piping and pressure relief valve accordingly.

❗ Important: Ensure that the steam supply pressure does not exceed 15 psi (103 kPa).

P_recovery: Pressure from condensate recovery system. For vented systems, this pressure is equivalent to 1 psi (7 kPa) for every 27” (686mm) of condensate rise. It is not recommended to connect the PCR and steam trap outlets together. Additional design considerations must be taken into account for pressurized returns.

Once the system differential pressure (ΔP) is obtained, the PCR capacity can be obtained using the following table:

❗ Important: It is not recommended to connect the PCR system to the condensate return line if the differential pressure (ΔP) is below 4 psi (28 kPa).

Installation Overview

⚠️ All installation work must comply with local regulations.

⚠️ All work related to the installation of the Pressurized Condensate Return System MUST only be performed by skilled and qualified technical personnel such as plumbers or technicians with appropriate training. The customer is responsible for ensuring their suitability.

For the installation of the Pressurized Condensate Return System and associated components, there are no specific tooling requirements.

Installation Method Statement

The installation involves the following steps:

• Step 1 - Install SKD Humidifier
• Step 2 - Secure PCR Tank
• Step 3 - Connect PCR Tank to Drain Port
• Step 4 - Install Steam Relief Valve (VT000)
• Step 5 - Install Steam Supply Valve (BM000F)
• Step 6 - Connect PCR Tank to Condensate Return
• Step 7 - Strainer Installation

Electronic Steam Controller (SKDESC)

Models

• SKDESC-MP
• SKDESC-MBP with BACnet Communication
• SKDESC-MDP with Modbus Communication

Description

The Electronic Steam Controller SKDESC is made specifically for Neptronic SKD-M (Multi-Steam) Humidifiers.

Features

• Conserves energy and eliminates condensate (dry operation)
• Manages isolating and modulating valves
• Pre-heats tube channel jackets only on demand for humidity
• Automatic temperature sensor adjustment
• On/Off or Modulating control
• Selectable internal or external control
• Configurable proportional control band & dead band
• Selectable Fahrenheit or Celsius scale
• BACnet or Modbus models available
• 24 Vac power supply (by others)
• Easy start up and troubleshooting
• Backlit LCD with simple icon and text driven menus

Technical Specifications

Wiring

Neptronic strongly recommends that all Neptronic products be wired to a separate grounded transformer and that transformer shall service only Neptronic products. This precaution will prevent interference with, and/or possible damage to incompatible equipment.

Terminal Block Usage

Symbols Used in this Manual

• Humidity: ?
• Temperature: ?️
• Communication/Network: ?
• Air Flow: ?
• Timer/Clock: ⏰

Controls Menu (637)

Entering Programming Mode

To enter the Programming Mode, perform the following steps:

1. Press * to start and enter password.
2. Enter the password 637 within 1 minute. After entering the correct password, press * to proceed. If you enter the wrong password, the controller returns to normal operation mode.
3. Use the arrow buttons ▲ or ▼ to navigate the menu.
4. Press * to enter edit mode of the displayed value.
5. Once in edit mode, use the arrow buttons ▲ or ▼ to change values. Changed values are automatically saved.
6. Press * to exit edit mode of the displayed value.
7. Return to step 3 or press ESC to exit the mode. Auto exits after 5 minutes without any action.

Menu Options

1. "LANGUAG"
   Default: ENG (English)
   Range: ENG (English)
   Only English available at the moment.
2. "METRIC DISPLAY UNITS"
   Default: ON
   Range: ON (metric units - °C, kg H2O/Hr), OFF (imperial units - °F, lbs H2O/Hr)
   Select the desired measurement system.

Configuration Options

General Settings

1. "WORKING CAPACIT IN PCT"
   Default: 100%
   Range: 10 to 100%
   Increment: 5%

   This option enables adjustment of the maximum demand capacity of the full system capacity in %. This is a factory setting; consult Neptronic before changing.

2. "SEPARAT TEMPER OFFSET"
   Default: 0
   Range: -10 to 10°C [-18 to 18°F]
   Increment: 0.1°C [0.1°F]

   Compare displayed temperature with a known value. Use arrow buttons to offset or calibrate the sensor.

3. "PCR TEMPER OFFSET"
   Default: 0
   Range: -10 to 10°C [-18 to 18°F]
   Increment: 0.1°C [0.1°F]

   Compare the displayed temperature of the sensor in the PCR tank with a known value. Use arrow buttons to offset or calibrate the sensor.

Control Modes

1. "CONTROL MODE"
   Default: Extern
   Range: Intern, Extern, Net

   Select the desired control mode:

   • Intern: Humidifier controlled by the SKDESC controller.
   • Extern: Humidifier controlled by an external signal (AI, DI).
   • Net: Humidifier controlled over the network (SKDESC-MBP and SKDESC-MDP models only).
2. "DEMAND SIGNAL RANGE"
   Default: 2-10 Vdc
   Range: 0-10 Vdc, 2-10 Vdc

   Appears only if "Extern" is selected. Select the desired relative humidity sensor signal at input AI1.

3. "NETWORK ROOM HUMIDTY”
   Default: OFF
   Range: OFF, ON

   Available only on SKDESC-MBP and SKDESC-MDP models. Select ON to control humidity over the network.

4. "ROOM HUMIDTY OFFSET IN PCT"
   Default: 0% RH
   Range: -10 to 10% RH
   Increment: 0.1% RH

   Appears only if "Network room Humidity" is OFF. Compare displayed humidity with a known value to offset or calibrate the sensor.

5. "ROOM HUMIDTY SIGNAL RANGE"
   Default: 2-10 Vdc
   Range: 0-10 Vdc, 2-10 Vdc

   Appears only if "Network room Humidity" is OFF. Select the desired signal range.

6. "EXTERN HUMIDTY SETPNT”
   Default: OFF
   Range: OFF, ON

   Appears only if "Net" or "Intern" is selected. Select ON to use an external setpoint for humidity.

7. "SETPNT SIGNAL RANGE"
   Default: 2-10 Vdc
   Range: 0-10 Vdc, 2-10 Vdc

   Appears only if "Net" or "Intern" is selected and "Extern Humidity Setpoint" is ON. Select the desired relative humidity sensor signal.

8. "INTERN HUMIDTY SETPNT IN PCT"
   Default: 40% RH
   Range: 10% to 90% RH
   Increment: 1% RH

   Appears only if "Net" or "Intern" is selected and "Extern Humidity Setpoint" is OFF. Set the desired humidity setpoint in % RH.

9. "CONTROL DEAD BAND IN PCT"
   Default: 2.0% RH
   Range: 0% to 5% RH
   Increment: 0.1% RH

   Appears only if "Intern" is selected. The deadband is the interval where no action occurs to prevent repeated activation-deactivation cycles.

10. "CONTROL PROP RAMP IN PCT"
    Default: 5.0%
    Range: 1% to 10%
    Increment: 0.1%

    Appears only if "Intern" is selected. Proportional control applies effort based on proximity to setpoint. Example: 100% demand at start of ramp, decreasing as setpoint is approached.

11. "CONTROL INTEGRA TIME IN SEC"
    Default: 0 seconds
    Range: 0 to 600 sec
    Increment: 1 sec

    Appears only if "Intern" is selected. Set the integral time for the humidity ramp. Cumulates difference between setpoint and actual reading for additional push.

12. "CONTROL DERIVAT TIME IN SEC"
    Default: 0 seconds
    Range: 0 to 25.5 sec
    Increment: 0.1 sec

    Appears only if "Intern" is selected. Set the derivative time for the humidity ramp. Dampens or predicts control effort to minimize overshoot.

Duct High Limit Sensor Settings

1. "DUCT HIGH LIMIT SENSOR"
   Default: Digital (On/Off)
   Range: Disable, Analog, Digital (On/Off), Network

   Appears only if "Intern" is selected. Select the desired type of high limit sensor. Analog option refers to AI3 input.

2. "DUCT MIN SETPNT IN PCT"
   Default: 15% RH
   Range: 0 to MAX SETPNT
   Increment: 1% RH

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the minimum duct humidity setpoint.

3. "DUCT MAX SETPNT IN PCT"
   Default: 65% RH
   Range: MIN SETPNT to 100% RH
   Increment: 1% RH

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the maximum duct humidity setpoint.

4. "DUCT PROP RAMP IN PCT"
   Default: 5.0%
   Range: 1% to 10%
   Increment: 0.1%

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the proportional ramp for control.

5. "DUCT INTEGRA TIME IN SEC"
   Default: 0 seconds
   Range: 0 to 600 sec
   Increment: 0.1

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the integral time for the humidity ramp.

6. "DUCT DERIVAT TIME IN SEC"
   Default: 0 seconds
   Range: 0 to 25.5 sec
   Increment: 0.1 sec

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the derivative time for the humidity ramp.

7. "HIGH LIMIT SETPNT IN PCT"
   Default: 80% RH
   Range: 10% to 90% RH
   Increment: 1% RH

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the high limit relative humidity setpoint.

8. "HIGH LIMIT PROP RAMP IN PCT"
   Default: 10.0 %
   Range: 0% to 20%
   Increment: 0.1%

   Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Sets the high limit proportional ramp.

9. "HIGH LIMIT HUMIDTY OFFSET IN PCT"
   Default: 0% RH
   Range: -10% RH to 10% RH
   Increment: 0.1% RH

   Appears only if "Analog" is selected for Duct High Limit Sensor. Adjusts the relative humidity reading of the high limit sensor.

10. "HIGH LIMIT SIGNAL RANGE"
    Default: 2-10 Vdc
    Range: 0-10 Vdc, 2-10 Vdc

    Appears only if "Analog" or "Network" is selected for Duct High Limit Sensor. Selects the high limit signal range.

11. "HIGH LIMIT MAX DEMAND IN PCT"
    Default: No default (information display only)
    

    Appears only if the Duct High Limit Sensor type is not disabled. Displays the actual reading of the high limit sensor.

Service and Delay Settings

1. "END OF SEASON DELAY IN HR"
   Default: 100 hours
   Range: 100 to 250 hours
   Increment: 5 hours

   Indicates that the isolation valve will be turned off after 100 hours if there is no demand.

2. "SERVICE DELAY IN HR"
   Default: 5000 hours
   Range: 1000 to 5000 hours
   Increment: 500 hours

   Set the number of hours running at 100% capacity before servicing is due.

3. "SERVICE RUNTIME IN HR"
   Default: No default (information display only)
   

   Displays the running time in hours at 100% capacity since the last service. To reset, press edit and hold ▲ and ▼ keys.

4. "RUNS WHILE SERVICE ALARM"
   Default: ACt (active)
   Range: INACT (Inactive), ACt (active)
   

   Select ACt to run even when servicing is due. Select INACt to turn off the system when servicing is due.

5. "TOTAL RUNTIME IN HR"
   Default: No default (information display only)
   

   Displays the running time in hours at 100% capacity.

Fallback and Network Settings

1. "PCR FALLBACK"
   Default: Off
   Range: Off, On
   

   Determines PCR system operation during water level or temperature sensor failure. OFF stops the system; ON allows continued function based on internal timers.

2. "NETWORK AUTO BAUD RATE"
   Default: ON
   Range: ON, OFF

   Available on SKDESC-MBP and SKDESC-MDP models. Enable or disable Auto Baud Rate detection. If enabled, baud rate is auto-configured. If disabled, select manually (Step 36).

3. "NETWORK BAUD RATE"
   Default: No default (information display only)
   Range: BACnet: 9.6k, 19.2k, 38.4k, 76.8k; Modbus: 9.6k, 19.2k, 38.4k, 57.6k

   Available on SKDESC-MBP and SKDESC-MDP models. Select baud rate if "Network auto baud rate" is OFF.

4. "NETWORK ADDRESS"
   BACnet Default: 0 (Range: 0 to 254)
   Modbus Default: 1 (Range: 1 to 246)
   

   Available on SKDESC-MBP and SKDESC-MDP models. Select the desired address.

5. "DEVICE INSTANCE"
   Default: 0153001
   Range: No, Yes
   

   Select Yes to change the device instance; No modifies it automatically per MAC address.

6. "NETWORK PARITY"
   Default: None
   Range: None, Odd, Even

   Available on Modbus models (SKDESC-MDP). Select parity control.

7. "NETWORK STOP BITS"
   Default: 1
   Range: 1, 2

   Available on Modbus models (SKDESC-MDP). Select network stop bits.

8. "NETWORK FALLBACK TIMEOUT"
   Default: 0 sec
   Range: 0 to 900 sec
   Increment: 1 sec

   Appears if "Net" is selected for Control Mode. Sets network fallback timeout. Alarm generated if no communication occurs for this period.

9. "NETWORK FALLBACK SETPOINT"
   Default: 0.0%
   Range: 0% to 100%
   Increment: 0.1%

   Appears if "Net" is selected for Control Mode. Determines humidifier function during network communication failure. Example: 20% means constant 20% demand.

10. "NETWORK FALLBACK COUNTER"
    Default: No default (information display only)
    Range: 0 to 900 sec
    

    Appears if "Net" is selected for Control Mode. Displays time remaining before fallback alarm.

Signal and Output States

1. "CONTROL OUTPUT SIGNAL IN MV"
   Default: No default (information display only)
   

   Displays humidifier steam control valve output in mV.

2. "PCR SUPPLY SIGNAL IN MV"
   Default: No default (information display only)
   

   Displays the PCR steam supply valve output in mV.

3. "ISOLAT VALVE OUTPUT STATE"
   Default: No default (information display only)
   Range: INACT (closed), ACt (open)
   

   Displays whether the isolating valve is open or closed.

4. "PCR RELIEF VALVE OUTPUT STATE"
   Default: No default (information display only)
   

   Displays whether the PCR relief valve is open or closed.

5. "ALARM RELAY OUTPUT STATE"
   Default: No default (information display only)
   Range: INACt (closed), ACt (open)
   

   Displays whether the alarm relay is open or closed.

6. "STEAM ON OUTPUT RELAY OUTPUT STATE"
   Default: No default (information display only)
   Range: INACt (closed), ACt (open)
   

   Displays whether the steam output relay is open or closed.

7. "SEPARAT TEMPER INPUT SIGNAL IN MV"
   Default: No default (information display only)
   

   Displays the separator temperature sensor reading in mV.

8. "DEMAND INPUT SIGNAL IN MV"
   Default: No default (information display only)
   

   Appears only if "Extern" is selected for Control Mode. Displays the demand reading in mV.

9. "ROOM HUMIDITY INPUT SIGNAL IN MV"
   Default: No default (information display only)
   

   Does not appear if "Network room Humidty" is OFF. Displays the relative humidity reading of the room in mV.

10. "SETPNT INPUT SIGNAL IN MV"
    Default: No default (information display only)
    

    Appears only if "Extern Humidty Setpnt" is ON. Displays the setpoint reading in mV.

11. "HIGH LIMIT INPUT SIGNAL IN MV"
    Default: No default (information display only)
    

    Appears only if "Analog" is selected for Duct High Limit Sensor. Displays the high limit sensor reading in mV.

12. "WATER LEVEL INPUT SIGNAL IN MV"
    Default: No default (information display only)
    

    Displays the reading in mV of the water level sensor inside the PCR tank.

13. "EXTERN DEMAND INPUT STATE"
    Default: No default (information display only)
    Range: INACt (closed), ACt (open)
    

    Appears only if "Extern" is selected for Control Mode. Displays if the demand is open or closed.

14. "AIR FLOW INPUT STATE"
    Default: No default (information display only)
    Range: INACt (closed), ACt (open)
    

    Displays if the air flow switch is open or closed.

15. "HIGH LIMIT SWITCH INPUT STATE"
    Default: No default (information display only)
    Range: INACT (closed), ACt (open)
    

    Appears only if "Digital" is selected for Duct High Limit Sensor. Displays if the high limit switch is open or closed.

16. "INTRLCK INPUT STATE"
    Default: No default (information display only)
    Range: INACt (closed), ACt (open)
    

    Displays if the interlock is open or closed.

17. "MICRO TEMPER"
    Default: No default (information display only)
    

    Displays whether the microcontroller temperature is in °C or °F mode.

18. "PCB TEMPER"
    Default: No default (information display only)
    

    Displays whether the PCB temperature is in °C or °F mode.

Alarms and Notifications

The following is a list of alarms and notifications displayed by the Steam Controller under different conditions. The alarm symbol, ⚠️, is displayed along with all alarms and notifications.

Operating Menu Display

Power Up

Upon power up, the LCD illuminates and all segments appear for 2 seconds. The thermostat then displays its serial number, model, and revision for 2 seconds. In the Operation Mode, the information is displayed automatically in a sequence. If you wish to scroll the information quickly, use the ▲, ▼ arrow keys.

Humidity Levels

The following humidity levels are displayed:

• Humidity Setpnt in pct - Humidity setpoint in % RH
• Room Humidty in pct - Room humidity reading in % RH
• High limit Humidty in pct - Duct sensor reading in % RH

Control Parameters

The following control parameters are displayed:

• control demand in pct - Current demand of the total system capacity measured in %
• control output in pct - Current output of the total system capacity measured in %
• control demand - Current demand measured in kg/hr or lbs/hr
• control output - Current output measured in kg/hr or lbs/hr

Temperature Levels

The following temperature level is displayed:

• separat temper - Separator temperature measured in °C or °F
• PCR temper - PCR tank temperature measured in °C or °F

Initial Verification

⚠️ Any installation work must be carried out by suitably qualified personnel.

Installation

• Ensure that the humidifier is installed properly according to the installation manual.
• Check that steam distributors are properly installed into the ventilation duct.
• Ensure that there is no leakage on the Pressurized Condensate Return System piping.

Electrical

• Confirm that 24Vac is present between tab 1&4 of terminal block TB5 on the SKDESC Steam Controller.

Drain if Required

• If there is a steam trap on the header, confirm that the drain piping is properly connected with a pitch of at least 1¼" (6.5mm) per foot (300mm). There is no header on the single tube channel configuration and therefore there is no steam trap on the header.

Steam Supply

• Ensure that the steam supply is on.
• Ensure that there is no leakage on the steam piping when the steam supply is on.

Controls

• Ensure that a high limit duct humidistat is installed, properly connected to the SKDESC and the setpoint is properly adjusted.
• Verify that the room humidistat or returned air duct humidistat is installed, properly connected to the SKDESC, and the setpoint is properly adjusted.
• Turn on the power at the disconnect switch.
• Confirm the control setup of the humidifier. The humidifier is factory set with EXTERNAL control setup, which means that the humidity demand is controlled by the room or duct humidistat.
• Ensure that the type of signal (0-10 Vdc, 2-10 Vdc or 4-20 mA) of the humidistat corresponds to the type set in the humidifier control set-up.

Start-Up Procedure

Start-up

Proceed to start-up the humidifier as follows:

• Make sure that the steam is supplied to the Pressurized Condensate Return System.
• Switch on the SKDESC.
• Make sure that there is no alarm. If the A6 alarm stays on, it means that the steam does not reach the separator or there is a problem with evacuating the condensate from the separator steam trap.
• Wait for a call for humidity or create it by setting the SKDESC "CONTROL MODE" to Internal (step #6), and the "EXTERN HUMIDTY SETPNT" to OFF (step #11). Then, adjust the setpoint to a higher value than the room humidity reading (operation mode B).
• Once the temperature is high enough, the control valve will open slowly.
• The start-up is complete and the humidifier is now functional.

Safety Test

• Check for steam or condensate leakage while the humidifier is in operation.
• Check the location of the airflow switch in the system and its operation by stopping the fan or by disconnecting the air pressure connection. With no air movement in the duct, SKDESC will automatically stop the humidifier by closing the control valve.

Reset the Setpoint and Control Mode

• If the humidity setpoint is controlled by the SKDESC, reset the setpoint to the desired relative humidity % (set #20) as suits the room.
• If the humidity setpoint is controlled by another device than the SKDESC (typically by the BMS), set the internal control signal to OFF.

End

• The humidifier is ready for normal operation.

Notes

(Blank section for notes as per PDF)