DriSteem DS 301 Setup guide

1
Safety, Installation, and Operation Manual
DRISTEEM Duct Mounted On-Off Humidistat (DS 301)
and Duct Mounted Modulating Humidistat (DS 401)
READ COMPLETE INSTALLATION INSTRUCTIONS BEFORE STARTING.
WARNING
1. Contact with energized electrical circuits may cause serious injury
from electrical shock. Disconnect electrical power to the Humidifier
before starting installation.
2. Sharp edges may cause serious injury from cuts. Use care when
cutting plenum openings and handling ductwork.
WARNING This product must be installed by a qualified heating and air conditioning contractor. Failure to do so
could result in serious injury from electrical shock or damage to product and voids product warranty due
to possible product misapplication.
CAUTION
1. Do not set humidity higher than recommended or moisture can
accumulate, which may cause bacteria and mold growth or dripping
water into building spaces. Dripping water may cause property
damage; bacteria and mold growth may cause illness.
2. Do not set humidity up to recommended levels if there is
condensation on the inside of windows. Condensation damage
may result.
3. Do not mount Humidistat on supply plenum or duct. High supply
temperatures will cause the control to malfunction.
4. When installing Humidistat on downflow furnaces, ensure that
blower continues to run as programmed after a heat call is satisfied
to eliminate high temperatures from damaging the Humidistat.
THESE INSTALLATION INSTRUCTIONS ARE FOR THE HUMIDISTAT ONLY!
For DRISTEEM®Humidifier installation, follow DRISTEEM Humidifier Installation Instructions.
PRINCIPLES OF OPERATION
The DRISTEEM Duct Mounted On-Off Humidistat (DS 301) and Duct
Mounted Modulating Humidistat (DS 401) are designed to be installed in
the return duct or return plenum only of the HVAC system. The Control
supplies a modulating signal to the humidifier. In terms of outdoor
temperature compensation, the Control can be set up in automatic or
manual mode, regardless of the humidifier model being controlled. The
automatic mode incorporates the supplied Outdoor Temperature Sensor to
automatically adjust the control set-point based on the outdoor
temperature. The manual mode does not require an outdoor temperature
measurement and is used for specific set-point control with the control set-
point manually adjusted by the user. The DRISTEEM Duct Mounted On-Off
Humidistat (DS 301) and Duct Mounted Modulating Humidistat (DS 401) will
accurately control the humidity in the conditioned space within the range of
15% – 55% RH.
CONTROL TYPE
ON-OFF CONTROL
The DRISTEEM Duct Mounted On-Off Humidistat (DS 301) sends a 10 VDC
signal to the humidifier when the measured return air relative humidity is
3% or more below the set-point. This energizes the humidifier at 100%
output. The Humidifier is either on at 100% capacity or it is off.
MODULATING CONTROL
The DRISTEEM Duct Mounted Modulating Humidistat (DS 401) sends a
signal to the humidifier between 0 and 10 VDC based on: a) the difference
between measured relative humidity and set-point relative humidity, and b)
where this difference or ‘error’ falls within an adjustable proportional
control band. The output of the Control, and therefore the Humidifier, is a
‘proportion’ of maximum output based on ‘a’ and ‘b’ above. See Figure 1
for graphical representation of the output.

2
MEASURED %RH - SETPOINT %RH
OUTPUT
Note:
The Proportional
Control Band
can be adjusted
to 6%, 9%, 12%,
or 15% RH. The
factory setting
of 12% is
depicted at left.
PROPORTIONAL
CONTROL BAND
0 +6-6
10 VDC
5 VDC
0 VDC
FIGURE 1 –Modulating Control Output
90-890
FIGURE 3 –Split System Installation
OM-4016
Outside
Air
Filters
Heating Coil
Cooling Coil
Air Flow
Proving Switch
Duct High Limit
Humidity Control
from Dispersion
Point “A”
Motorized
Air Dampers
Dispersion Tube A
Dispersion Tube B
Roof
Economizer
control device
HUMIDISTAT
Supply DuctReturn Duct
FIGURE 2 –Rooftop Unit Installation
90-894
AUTOMATIC MODE
The automatic mode is the preferred method when the application
requires that the Control automatically adjust the RH set-point based on
the outdoor temperature. This is recommended for all comfort-based
applications such as office buildings, schools, day cares, etc. It is also
recommended for any application where the primary concern is to avoid
the potential for condensation that can form on areas within the building
such as windows and within walls. When installed in this mode, the
Control utilizes an Outdoor Temperature Sensor that will track the actual
outdoor temperature. The Control then automatically adjusts the desired
indoor RH.
MANUAL MODE (SPECIFIC SET-POINT CONTROL)
The manual mode is the preferred method when the application requires
that a specific set-point be maintained regardless of the outdoor
temperature. This is recommended for all process-based applications
such as print shops, book stores, test facilities, etc.
When installed in this mode, the Outdoor Temperature Sensor is replaced
with a “manual”resistor case that prevents the Control from adjusting
the space RH set-point based on the outdoor temperature, and controls
to the specific set-point selected on the Control.
Note: If the building is not designed to handle the amount of RH the
humidifier is supplying, the building occupants may need to adjust the RH
setting on the Control to a lower value during extreme days to prevent
condensation on interior surfaces. The RH setting should be adjusted
upward when the outdoor temperature goes up.
As an example, using the 12% proportional band (factory-setting), when the
measured RH is 6% above the set-point the output will be 0 VDC; when the
measured RH is 6% below set-point the output will be 10 VDC; when the
measured RH is 3% below set-point the output will be approximately 7.5
VDC. The humidifier uses this varying signal to time-proportion the
operation of the heating elements in the tank. 10 VDC output corresponds
with 100% humidifier capacity, 5 VDC with 50% capacity, etc. Modulating
control will result in a more precise control of relative humidity.
OUTDOOR TEMPERATURE COMPENSATION
STEP 1: DETERMINE LOCATION FOR CONTROL
AND MOUNT ON DUCT
INSTALLATION
The Control must be mounted in the return duct of the HVAC system.
See Figure 2 for a rooftop unit installation and Figure 3 for a split-system
installation. The Control must be at least 1 foot upstream of the steam
dispersion tube and any fresh air intake ductwork. Use the template in the
back of this manual to mark the duct opening. After cutting the hole in the
duct, mount the Control tightly to the duct using 4 sheet metal screws
(not provided).

3
Above expected
snow line
Outdoor
Temperature
Sensor leads
North, East
or West side
of building
Outdoor
Temperature
Sensor
Sensor
Sensor
Bracket
FIGURE 4 –Outdoor Temperature Sensor Location
STEP 2: DETERMINE LOCATION FOR OUTDOOR
TEMPERATURE SENSOR
The location of the Outdoor Temperature Sensor must meet these three
requirements:
1. Must be mounted on North, East or West side of building out of
direct sunlight
2. Must be at least 3 feet from all exhaust vents
3. Must be above expected snow line (See Figure 4)
Incorrect humidity levels will result if these requirements are not met.
Attach the sensor bracket to the building with a #8 galvanized screw.
STEP 3: LOCATE ACCESS HOLE FOR WIRING TO
OUTSIDE SENSOR
Look for or provide an opening in the building envelope for running wire to
the Sensor. A convenient way to get wire to the Sensor is to make use of
unused wires running to the A/C condensing unit (if applicable). Other ways
are to use existing holes for telephone lines, A/C lines, water meter, etc.
Read all equipment instructions beforehand for possible conflicts and
warnings. Do not run outdoor temperature sensor wiring alongside
wires carrying high voltage (120VAC or higher).
STEP 4: ALTERNATE LOCATION FOR OUTDOOR
TEMPERATURE SENSOR
The Sensor can also be mounted in the center of either:
•PVC fresh air intake pipe for the split system furnace
OR
•Fresh air intake duct. Mount the sensor with a #8 galvanized screw.
In both cases, the Sensor must be no more than 3 feet from the
outside wall. See Figure 5.
If it is not feasible to use the Outdoor Temperature Sensor in any of the
ways described, the Humidistat can be set for Manual Operation. See
Figure 6 for details.
90-895
STEP 5: ROUTE THE WIRE TO CHOSEN
SENSOR LOCATION
Run wire to the outdoor temperature sensor. Sensor is not affected by lead
length up to 300 feet. Use standard thermostat wire. Do not run outdoor
temperature sensor alongside wires carrying high voltage (120 VAC
or higher).
36" MAX.
CENTER
LINE
OUTSIDE WALL
FRESH AIR INTAKE
FIGURE 5 –Alternate Location for Outdoor
Temperature Sensor
90-896
STEP 6: ATTACH SENSOR WIRE TO HUMIDISTAT
Strip wires 1/4 inch, and insert the wires from the Sensor into the terminals
labeled “ODT”on the Humidistat.
INSTALLING THE HUMIDISTAT FOR
MANUAL OPERATION
1. Insert the Manual Mode Resistor Case into the terminals
labeled “ODT” on the Humidistat.
2. Snap the Manual Mode Resistor Case into the slot
provided so that Resistor Case sticks out from the bottom
edge of the base.
3. Remove the control knob and apply the Manual Mode
label to the cover, aligning the sticker and knob holes.
Re-install the knob.
6
912
15
H- ODTI+ I- C24V H+
R17
FIGURE 6 –Manual Mode
90-899

4
STEP 7: WIRE THE CONTROL TO THE HUMIDIFIER
Wire the Control to the field wiring terminal block of the Humidifier
according to Figure 9. Use 3-wire shielded cable with ground for the wiring
from the Control to the Humidifier. Note the terminal designations below.
HUMIDISTAT:
24V +24 VDC input power
CCommon
H+ Command Signal to Humidifier
ODT Outdoor Temperature Sensor
HUMIDIFIER:
30 +24 VDC output power
CHumidifier Common
1Command Signal from Control
2Enable/Safety Circuit
I+ I- H-
30 C1
24V C H+ ODT
3-WIRE SHIELDED
CABLE W/GROUND
HUMIDIFIER PANEL
C TERMINAL*
COMMAND
SIGNAL
+24VDC COMMON
TO OUTDOOR
TEMPERATURE
SENSOR
SERIAL COMMUNICATION
TO THERMOSTAT (OPTIONAL)
HUMIDISTAT
HUMIDIFIER
FIELD WIRING
TERMINAL
BLOCK
FIGURE 7 –Wiring Diagram
90-900
SYSTEM CHECKOUT
OPERATION
1. For system test, be sure that all Humidifier plumbing, distribution, and
electrical connections are set-up in accordance with the instructions in
the Humidifier Installation, Operation, and Maintenance Manual and all
precautions therein are followed.
2. Turn on the water supply to the humidifier. Make sure the drain valve
is closed.
3. Turn on power to the humidifier.
4. Allow humidifier to fill with water.
5. Set up a fan call at the thermostat. If the humidifier is configured to
bring on the equipment fan when a demand for humidity is recognized,
skip to the next step.
6. Initiate a humidity demand from the Control by rotating the control knob
of the Humidistat clockwise to the ‘Test’position.
7. If all is set up properly, the ‘Steam’indicator light on the humidifier will
illuminate and the heaters will be energized. In the ‘Test’position, the
humidity demand will last for one minute.
8. If the ‘Steam’indicator light does not illuminate when the Control is
turned to the ‘Test’position, refer to the troubleshooting section of
this manual.
9. Setting the Control:
•If using Automatic Mode and the conditioned space is occupied,
set the Control to knob-setting 4.
•For Manual Mode and the conditioned space is occupied, set to 35%
or to a level that matches the application’s needs.
•If the conditioned space is unoccupied, set the Control to ‘Off’
For information on the initial adjustment period, refer to the operation
notes in the next section.
10.Make sure the Red Diagnostic Light on the Control (see Figure 8) is not
lit. If the Red Diagnostic Light is lit, re-check the wiring. If the Red
Diagnostic Light does not go off, refer to the troubleshooting section of
this manual. Note that the Red Diagnostic Light will turn on momentarily
when first powered up.
CAUTION
A high relative humidity setting on the Control may cause
excessive condensation on windows and within walls. Set the
relative humidity in accordance with the instructions in this manual.
Do not set the relative humidity higher than recommended or
moisture can accumulate, which may cause bacteria and mold growth
or dripping water into building spaces. Dripping water may cause
property damage; bacteria and mold growth may cause illness.
R17
H+24V CI-I+ ODTH-
15
129
6JP2
123
FIGURE 8
Red Diagnostic
Light
90-891
*C Terminal –for location drawing please reference Figure 9-1 in the VT
Series Electric Humidifier Installation, Operation and Maintenance Manual.

5
OPERATION NOTES FOR MODULATING CONTROL
As explained in the ‘Principles of Operation’section of this manual, when
configured for modulating control, the Humidistat sends a 0-10V signal to
the humidifier to vary the capacity of the Humidifier depending on where
the measured return air relative humidity falls relative to the set-point as
well as the proportional control band. This will result in a more precise
control of relative humidity.
The proportional control band can be set to
6%, 9%, 12%, or 15% RH. The factory-
setting is 12%. Note that the proportional
control band is centered on the RH set-point.
Refer back to Figure 1. If the humidifier is
cycling on and off too frequently, the
proportional control band setting may need to
be widened. To change, use a small flat-head
screwdriver to rotate the potentiometer in the
Humidistat board. See Figure 9.
6
912
15
FIGURE 9
90-901
AUTOMATIC MODE OPERATION NOTES
The Humidistat is installed in
the return duct. During the first
heating season, the
Humidistat needs to be
adjusted to match the
requirements and construction
of the conditioned space.
Please follow these steps
when adjusting the Control
(refer to Figure 10).
T
E
S
T
/
R
E
S
E
T
2
3
5
4
6
1
7
AUTOMATIC MODE
O
F
F
FIGURE 10
90-902
Turn the dial to a setting of “4”. At this setting, when the Outdoor Temperature
is 20°F, the indoor relative humidity set-point of the Humidistat will be 35% RH.
During the next 24-48 hours, it may be necessary to adjust the dial for more
or less humidity, depending on the occupants’comfort and the requirements
of the conditioned space. Refer to the ‘Operation Guide’(Table 1).
During the coldest portion of the first heating season, minor adjustments may
be necessary. This is dependent upon the unique features and construction of
the conditioned space. Refer to the ‘Operation Guide’(Table 1).
TABLE 1: Operation Guide
Condition Solution
Condensation on windows. Reduce the setting on the control
dial by 1 increment.
Lack of humidity. Increase the setting on the control
dial by 1 increment.
The relative humidity in the conditioned space will now be accurately
controlled and should need no further adjustment during future heating
seasons. Make note of the dial setting in the event the knob is temporarily
moved when performing annual maintenance of the Humidifier.
Table 2 shows the way the Humidistat automatically adjusts the relative
humidity based on the outdoor temperature. For example, when the knob is
set to “4”and the outdoor temperature is 20°F, the conditioned space will
be controlled to 35% RH.
TABLE 2: Relative Humidity Guide
Outdoor Temperature (°F)
-20 -10 0 10 20 30 40 50
1–––10 15 20 25 30
2––12 17 22 27 32 37
3–13 18 23 28 33 38 43
415 20 25 30 35 40 45 50
522 27 32 37 42 47 52 55
628 33 38 43 48 53 55 55
735 40 45 50 55 55 55 55
Dial Setting
MANUAL MODE OPERATION NOTES
The Humidistat is installed in the return duct. When installed in the Manual
Mode, the Control provides specific set-point control. If the building is not
designed to handle the amount of RH the humidifier is supplying, the RH
setting on the Control may need to be adjusted to a lower value during
extreme days to prevent
condensation on interior
surfaces. For example, with an
outdoor temperature of 20°F
the correct setting will be
35% relative humidity. If the
temperature is expected to fall
to 0°, then reduce the setting
to 25% several hours prior to
the temperature change. It is
important to adjust the RH
setting upward when the
outdoor temperature goes
back up again.
T
E
S
T
/
R
E
S
E
T
O
F
F
MANUAL MODE
%
H
U
M
I
D
I
T
Y
%
5
1
%
5
2
%
5
5
%
5
4
%
5
3
O
U
T
D
O
O
R
T
E
M
P
E
R
A
T
U
R
E
2
0
°
F
4
0
°
F
0
°
F
FIGURE 11
90-904
The recommended settings on the humidistat are based on years of research
for an average building. (See ASHRAE Handbook – HVAC Systems and
Equipment, Ch. 20 –Humidifiers.) Note: these settings may not be appropriate
for every application. These settings represent a compromise between RH levels
that would be most desirable for comfort reasons and humidity levels that are
suitable for protection of the conditioned space and to avoid condensation on
windows and within walls. For example, a wintertime indoor RH of 50% may
be considered ideal for comfort, but unfortunately, it probably would result in
damage to the conditioned space. Observance of the recommended RH levels
on the humidistat, therefore, is an important safeguard. Condensation of
water on inside windows in the form of fogging or frost is an indication of too
much relative humidity. This same condensation can occur in other areas of
the conditioned space with the possibility of damage resulting.
TABLE 3: Outdoor–Indoor Relative Humidity
Outside Temperature
+40˚F
+30˚F
+20˚F
+10˚F
0˚F
-10˚F
-20˚F
Recommended RH
45%
40%
35%
30%
25%
20%
15%

6
Applies to both Automatic and Manual Operation unless indicated otherwise.
Humidifier does not
operate in “Test”mode
•Make sure equipment blower is operating and thermostat is calling for heat.
•Make sure the Outdoor Temperature Sensor is connected to the “ODT”terminals of the control.
(For Manual Operation, make sure Manual Mode Resistor Case is in place of the Sensor).
•Check main wiring diagram for correct Humidistat installation.
•Check voltage at Humidistat “24V”and “C”terminals. Voltage should be 22 VDC minimum –26 VDC maximum.
•In “Test”mode, humidifier will operate for 1 minute only. DO NOT LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE.
•Make sure water supply valve is open.
•If humidifier still does not operate, refer to the Humidifier Installation, Operation, and Maintenance Manual.
SYMPTOM TROUBLESHOOTING PROCEDURE
Humidifier operates
constantly
•If the humidity level in the building is less than the knob setting or is within the proportional control band (DS 401 only), the
Humidistat will operate the humidifier until the humidity level is higher than the knob setting.
•In the “Test”mode, verify unit will operate for approximately one minute.
•Check the resistance of the sensor by removing the wires of the Outdoor Temperature Sensor and measuring the resistance
across the wires with an ohmmeter. Confirm reading to outdoor temperature in Table 4. (For Manual Operation, verify that
resistance across the leads of Resistor Case is between 44,000 and 48,000 ohms.)
•Make sure the Outdoor Temperature Sensor is mounted completely outside the building on the North, East, or West side of
the building and out of direct sunlight. (Automatic Mode Only).
•Rotate the Humidistat knob counterclockwise to the “Off”position, and observe whether the humidifier turns off (‘Steam’
indicator light on the humidifier should go off). If the humidifier still operates in the “Off”position, check summary wiring
diagram for correct Humidistat installation.
•If humidifier still does not shut off, refer to the troubleshooting section in the Humidifier Installation, Operation, and
Maintenance Manual.
Humidifier or Humidistat
“chatters”or clicks ON
and OFF rapidly
•Check voltage at Humidistat “24V”and “C”terminals.
Voltage should be 22 VDC minimum –26 VDC maximum.
•Make sure Outdoor Temperature Sensor wiring is not run alongside wires carrying high voltage (120 VAC or higher).
(Automatic Only)
Red Diagnostic Light is on •Check that the wiring is correct. See Figure 7.
•Measure the resistance of the Outdoor Temperature Sensor by removing the leads from the terminal and measuring
the resistance across the wires with an ohmmeter. Confirm the reading with the temperature in Table 4.
(For Manual Operation, verify that the resistance across the leads of the Manual Mode Resistor Case is between
44,000 and 48,000 ohms).
Humidifier operates only
in “Test”mode
•If outdoor temperature is greater than 60°F or less than -30°F, the Humidistat will only
operate in the “Test”mode. (Automatic Mode Only)
•If the humidity level in the building is higher than the knob setting or the proportional
control band (DS 401 only), the Humidistat will not operate the Humidifier.
•Check the resistance of the sensor by removing the leads of the Outdoor Temperature
Sensor from the terminals and measuring the resistance across the wires with an
ohmmeter. Confirm reading to outdoor temperature in Table 4. (For Manual Operation,
remove leads and verify that resistance across the leads of Manual Mode Resistor Case
is between 44,000 and 48,000 ohms).
•Make sure the Outdoor Temperature Sensor is mounted completely outside the building on the
North, East, or West side of the building and out of direct sunlight. (Automatic Mode Only)
•If Outdoor Temperature Sensor is mounted in fresh air intake duct, make sure the probe is
no more than 36 inches from the outside wall. (Automatic Mode Only)
•Make sure the Outdoor Temperature Sensor is located at least 3 feet away from all
exhaust vents. (Automatic Mode Only)
Outdoor
Temperature
-30˚F
-20˚F
-10˚F
0˚F
10˚F
20˚F
30˚F
40˚F
50˚F
60˚F
70˚F
80˚F
90˚F
100˚F
Resistance
kΩ
230.6
163.8
117.6
85.4
62.6
46.3
34.6
26.1
19.9
15.3
11.9
9.4
7.4
5.9
TROUBLESHOOTING GUIDE
TABLE 4

WARNING
Sharp edges on the opening may cause cuts. Use care when cutting the plenum opening
and installing the Humidistat.
CAUTION
•Do not mount Humidistat on supply plenum or duct. The unit will not withstand supply
temperatures and will malfunction!
•When installing Humidistat on counterflow furnaces, ensure blower continues to run after
a heat call is satisfied to eliminate high temperatures from damaging the Humidistat.
•Do not mount Humidistat downstream of the bypass outlet. False humidity conditions will
cause humidifier to operate incorrectly.
1. CUT TEMPLATE ALONG DASHED LINE.
2. PLACE THIS TEMPLATE ON THE RETURN PLENUM UPSTREAM OF (BEFORE) THE
DISPERSION TUBE.
3. TRACE THE OUTSIDE EDGES OF THIS TEMPLATE.
4. REMOVE TEMPLATE AND ACCURATELY CUT THE PLENUM OPENING.
5. USING 4 SHEET METAL SCREWS, INSTALL HUMIDISTAT IN PLENUM OPENING.
HUMIDISTAT
TEMPLATE
CUT ALONG DASHED LINE

For more information
www.dristeem.com
[email protected]
Technical support
800-328-4447
DRISTEEM Corporation
An ISO 9001: 2000 certified corporation
and a subsidiary of Research Products
Corporation
U.S. Headquarters:
14949 Technology Drive
Eden Prairie, MN 55344
800-328-4447
952-949-2415
952-229-3200 (fax)
European office:
Bell Place, Bell Lane
Syresham, Brackley
NN13 5HP, UK
[phone] (voice)
[phone] (fax)
E-mail: [email protected]
Continuous product improvement is a
policy of DRISTEEM Corporation;
therefore, product features and
specifications are subject to change
without notice.
DRISTEEM is a registered trademark of
DRISTEEM Corporation and is filed for
trademark registration in Canada and
the European community.
Form No. DSDH-IOM-1204
© 2004 DRISTEEM Corporation
CUT ALONG DASHED LINE