COMFORTSTEAM 259940-002 Electronic Humidistat Instruction Manual

: July 27, 2024
: COMFORTSTEAM

Table of Contents

259940-002 Electronic Humidistat
Specifications:
Product Usage Instructions:
Installing and Connecting the COMFORTSTEAM Humidistat and the
- Frequently Asked Questions (FAQ):
Q: Can I use a duct mount humidistat instead of a wall mount
Q: What does the outdoor sensor do?

259940-002 Electronic Humidistat

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Specifications:

Model: TRION 259940-002
Product: COMFORTSTEAM HUMIDIFICATION SYSTEM
Release Date: August 2009
Features: Electronic Humidistat with Outdoor Reset

Product Usage Instructions:

Installing and Connecting the COMFORTSTEAM Humidistat and the

Outdoor Sensor:

Location of Humidity Sensor: The wall mount
and duct mount humidistats have different humidity sensor locations
and are not interchangeable. Refer to Fig.1a and Fig.1b for
details.
Connecting Control Cable: Use a three-wire
control cable to connect the humidistat to the humidifier
electronic board. Connect GND to GND, 24V to 24V, and ST1 to
IN.
Outdoor Sensor Installation: Install the
outdoor sensor on an outside wall facing North. The sensor adjusts
humidity settings based on outdoor temperature automatically.
Connecting Outdoor Sensor: Use a two-wire
control cable to connect the outdoor sensor to the terminals COM
& ODR on the electronic humidistat. No wiring polarity needs to
be followed.

Frequently Asked Questions (FAQ):

Q: Can I use a duct mount humidistat instead of a wall mount

humidistat?

A: Yes, you can use a duct mount humidistat,
but it should be installed on the return duct. Refer to the
provided drilling template for proper installation.

Q: What does the outdoor sensor do?

A: The outdoor sensor adjusts the humidistat
settings based on outdoor temperature to prevent condensation on
windows during cold days and maintains comfort during mild days
without manual adjustments.

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COMFORTSTEAM TM
HUMIDIFICATION SYSTEM COMFORTSTEAM TM
HUMIDIFICATION SYSTEM
COMFORTSTEAM TM
HUMIDIFICATION SYSTEM
Aug. 2009

COMFORTSTEAM TM ELECTRONIC HUMIDISTAT

Features
· State of Art digital RH sensor · ROOM or DUCT mounting · Reprogrammable Microcontroller · Potentiometer Set-point setting · Out-door temperature sensor for Set-point Reset · Green (ON/OFF) and Red (warning) status LEDs
Specifications
Set-point range. . . . . . . . . . . . . . . 20% to 50% Relative Humidity Accuracy. . . . . . . . . . . . . . . . . . . . ±4.5%, without calibration Linearity . . . . . . . . . . . . . . . . . . . . ±1% in the Set-point range Differential % RH. . . . . . . . . . . . . ±2% Outdoor Temp. Reset Range between -9 °F (-23 °C) to 27 °F (-3 °C)

Outdoor reset Temperature vs.
28 °F (-2 °C) and warmer 27 °F (-3 °C) to 23 °F (-5 °C) 22 °F (-6 °C) to 18 °F (-8 °C) 17 °F (-9 °C) to 12 °F (-11 °C) 11 °F (-12 °C) to 5 °F (-15 °C) 4 °F (-16 °C) to -2 °F (-19 °C) -3 °F (-20 °C) to -9 °F (-23 °C) -9 °F (-23°C) and colder

Set point change
No change 42% max, 38% max, 34% max, 30% max, 26% max, 22% max, 20% max.

NOTE: these ranges can vary by ±2 %.

The Outdoor Temperature sets the maximum set point of RH internally. If the Dial position is higher, the actual set point will be limited as above.

Installing and Connecting the COMFORTSTEAMTM Humidistat and the Outdoor Sensor
1.1 The humidity sensor is not located at the same place in a wall mount or in a duct mount humidistat and therefore the two models of humidistats are not interchangeable. Please see Fig.1a and Fig.1b.

Terminal Block

GND 24VST1 COM ODR

Jumper

Red LED Green LED

Humidity sensor

Fig. 1a Wall Mount Humidistat

Fig. 1b Back View of a Duct Mount Humidistat

1.2 A three wire control cable (not supplied) has to be connected between the wall (or duct) electronic

humidistat and the humidifier electronic board at the three terminals marked “H-STAT”.

Please respect the sequence and connect

GND to GND

24V to 24V

ST1 to IN

1.3 The outdoor sensor (please see Fig.1c) is supplied with the humidistat (wall or duct mount). It ideally should be installed on an outside wall facing North. This outdoor sensor automatically reduces the setting
of the humidistat according to the outdoor temperature in order to avoid condensation on windows during extremely cold days. It does the opposite during the mild days without your having to manually adjust the humidistat. The outdoor sensor is a 10 kilo-ohms NTC thermistor (negative temperature coefficient).

COMFORTSTEAM TM
HUMIDIFICATION SYSTEM
Fig. 1c

1.4 A two wire control cable is required to connect the outdoor sensor to the terminals marked COM & ODR on the electronic humidistat. Please see Fig. 1d. The outdoor sensor is not polarized so there is no wiring
polarity to follow.

To Humidifier
GND 24V IN

From Outdoor Sensor

Red LED – Warning light, flashes when abnormal conditions occur Green LED – Lit when humidistat is calling for humidity

GGNNDD 24V ST1 COM ODR

Jumper – MUST be removed when outdoor sensor is connected – remains in place if the outdoor sensor is not used

GND 24V ST1 COM ODR

Red LED
Green LED

COMFORTSTEAM
HUMIDIFICATION SYSTEM

35

30

40

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Red LED
Green LED

20

50

Baseplate

Fig. 1d

Frontplate

IMPORTANT : Whenever an outdoor sensor is connected to the electronic humidistat, the jumper located at the top of the electronic board must be removed so that the outdoor sensor becomes operational (i.e. the jumper short circuits the terminals dedicated to the outdoor sensor). If the outdoor sensor is not installed, keep the jumper in place.

1.5 If you decide to use a duct mount humidistat, it has to be installed on the return duct. Please use
the drilling template printed at the end of these instructions. This duct mounting method allows a better
“average sensing” of all the air returned to the furnace, thus offering superior humidity control. However, since the humidistat has pilot lights giving information about the humidifier status, they may not be visible if the humidistat is installed in the basement.
Three holes have to be drilled in the duct, two for screws (approx. 1/8″ dia.) and one for sensing (approx. 5/8″ dia.). The humidity sensor is located in the rectangular opening visible at the back of the humidistat baseplate. This location will prevent potential dust accumulation on the sensor. Please see Fig. 1b.
Warning : Before installing anything on a duct, always check that you are not about to cut or drill into an air conditioning coil or electrical accessories.

Drilling Template for Duct Mount Humidistat
5/8″ dia.