Honeywell H8908B Humidistat Thermostat User Manual

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H8908B Humidistat  
H8908C Dehumidistat  
INSTALLATION INSTRUCTIONS  
APPLICATION  
OUTDOOR  
HUMIDITY  
SE1T  
ING  
TEMPERATURE  
T
5
%
2
0
%
-
-1  
20 °F  
F
0
F
10 °F  
-30 °C  
The H8908B Humidistat and H8908C Dehumidistat  
Humidity Control  
Régulateur d'humidité  
0°  
°
--2  
2
0
5°  
°
C
C
2
5
%
+
-10 °C  
-5 °C  
°C  
30%  
35%  
40%  
Ov +20 °F  
er 20 °F  
Over  
0
(
humidity controllers) provide automatic low voltage  
control of humidifiers and dehumidifiers or ventilators,  
respectively, in central heating and air conditioning sys-  
tems. They have a spst, snap-acting, dust-proof switch  
and are designed for wall or surface duct mounting.  
INSTALLATION  
When Installing this Product...  
1
.
.
Read these instructions carefully. Failure to follow  
them could damage the product or cause a haz-  
ardous condition.  
Check the ratings given in the instructions and on  
the product to make sure the product is suitable  
for your application.  
Installer must be a trained, experienced service  
technician.  
After installation is complete, check out product  
operation as provided in these instructions.  
HOLE FOR WIRING  
THE DUCT MOUNTING  
INSTALLATIONS  
CASE REMOVAL  
SLOT  
2
M13371  
Fig. 1. H8908B Humidistat.  
3
.
.
4
Wall Mounting  
IMPORTANT  
Mount the control in an area with average  
CAUTION  
room temperature and average relative  
humidity.  
Personal Injury Hazard.  
Power supply can cause electrical shock.  
Disconnect power supply before beginning  
installation.  
The following mounting instructions are for mounting  
the H8908 on the wall next to the T8600. When install-  
ing the H8908 at another location, modify the procedure  
to fit the installation.  
Location and Mounting  
The styling of the H8908 is designed to blend with the  
latest T8600 family of Honeywell Chronotherm® IV  
Deluxe Programmable Thermostats. A mounting tem-  
plate is included for mounting the H8908 next to the  
T8600. The H8908 can also be mounted at any other  
convenient location in the living area or equipment  
room. See Fig 1.  
1. Hold the mounting template (included) next to the  
T8600. Select the mounting side for the H8908.  
The template is reversible for mounting on either  
the left or right side of the T8600. See Fig. 2.  
2. Mark the holes for the two mounting screws  
(included). Then mark the hole for the low voltage  
wiring on the template that corresponds with the  
side selected in step 1.  
NOTE: The H8908 electrical connections are not  
shared with the thermostat.  
3. Remove the template and drill the holes.  
4. Run low voltage wiring to the location and pull  
about 6 in. (152 mm) of wire through the hole.  
5.  
Plug the hole with nonflammable insulation to  
prevent drafts from affecting the control opera-  
tion.  
®
U.S. Registered Trademark  
Copyright © 1999 Honeywell Inc. •  
•All Rights Reserved  
69- 1341  
href="
H8908B HUMIDISTAT H8908C DEHUMIDISTAT  
6
.
Remove the H8908 case from the base. See  
Fig. 1.  
Position the base on the wall with the arrow up.  
Use the two 1 in. (25 mm) mounting screws to  
secure the base to the wall.  
ALTERNATE LOCATION  
7.  
.
8
RETURN  
AIR  
RETURN  
AIR  
MOUNTING  
THERMOSTAT  
TEMPLATE  
WALLPLATE  
6 in. (152 mm)  
MINIMUM  
BEST  
15 in. (381 mm)  
MINIMUM  
LOCATION  
RETURN AIR DUCT  
M13369  
MOUNTING  
HOLES (2)  
WIRING HOLES FOR MOUNTING ON RIGHT.  
USE LEFT HOLES FOR MOUNTING ON LEFT.  
M13370  
Fig. 3. Selecting duct location for control.  
1
.
Locate the control at least 8 in. (203 mm)  
upstream from the humidifier (or dehumidifier/  
ventilator supply) in the return air duct. See Fig. 3.  
Apply the duct template to the duct location.  
Use the duct template, Fig. 4, to make the open-  
ing and mounting holes for the H8908.  
Remove the H8908 case from the base. See  
Fig. 1.  
Fig. 2. Positioning mounting template.  
IMPORTANT  
Use 18- to 22-gauge wire for proper wiring.  
2
3
.
.
9
.
Connect the low voltage wires to the leads on the  
H8908.  
0. Replace the H8908 case.  
4.  
1
5
6
.
.
Position the foam gasket on the H8908 base.  
Position the base on the duct with the arrow up.  
Duct Mounting  
7. Use the four 1 in. (25 mm) mounting screws to  
secure the base to the duct.  
8
.
.
Connect the low voltage wires to the leads on the  
H8908.  
Replace the H8908 case.  
IMPORTANT  
When mounting near an elbow area, locate the  
9
control 6 in. (152 mm) upstream from the  
elbow so the element is exposed to the normal  
airflow (Fig. 3).  
IMPORTANT  
Use 18- to 22-gauge wire for proper wiring.  
4
X DRILL 7/64 IN. DIAMETER  
PERCER 4 X 7/64 PO.  
DUCT TEMPLATE  
GABARIT DE GAINE  
CAUTION  
Equipment Damage Hazard.  
Be careful when selecting control  
location and cutting hole in ductwork.  
Do not cut or drill into air conditioning  
or electrical accessories.  
Do not install control on supply (hot air) ductwork.  
To use template:  
1
.
.
Remove backing and apply template to duct.  
Cut along template dotted line and drill the  
mounting holes.  
2
MISE EN GARDE  
Risque d'endommager le matériel.  
Faire attention au moment de choisir  
l'emplacement du régulateur et de percer les  
trous dans la gaine.  
Ne pas couper ou percer les accessoires  
électriques ou de climatisation.  
Ne pas installer le régulateur sur la gaine  
d'alimentation (air chaud).  
Utilisation du gabarit:  
1
.
Retirer l'endos du gabarit et placer le gabarit  
sur la gaine.  
Couper le long de la ligne pointillée du gabarit  
et percer les trous de fixation.  
2.  
M13373  
Fig. 4. Positioning return air duct template.  
6
9-1341  
2
href="
H8908B HUMIDISTAT H8908C DEHUMIDISTAT  
WIRING  
H8908B  
WATER  
2
SOLENOID  
LEAD WIRE  
CAUTION  
TRANSFORMER  
Personal Injury Hazard.  
Power supply can cause electrical shock and  
injury.  
1
L2 L1  
(
HOT)  
Disconnect power supply before installation or  
servicing.  
CURRENT  
SENSING  
RELAY  
LO  
C
HI  
HUMIDIFIER  
All wiring must comply with applicable local codes, ordi-  
nances and regulations. Make wiring connections  
according to humidifier (or dehumidifier/ventilator)  
instructions, if available; otherwise, see typical wiring  
diagrams in Fig. 5 through 12.  
1
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
24V WIRING.  
M13386  
IMPORTANT  
Fig. 7. Typical wiring diagram of current  
sensing relay with humidifier.  
Select models of fan centers include humidifer  
taps so the current sensing relay or sail switch  
is not needed.  
SAIL  
SWITCH  
H8908B  
If not using a current sensing relay or sail  
switch, the humidifier must be energized dur-  
ing blower motor cycles for proper operation.  
2
TRANSFORMER  
On multispeed blower applications, do not wire  
the high voltage side of the transformer to the  
same power source that services the furnace  
blower. Premature transformer burnout can  
occur.  
1
L2 L1  
HOT)  
HUMIDIFIER  
(
1
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS  
AND OVERLOAD PROTECTION AS REQUIRED.  
24V WIRING.  
M13385  
On HE360 fan powered humidifier models,  
only the two yellow wires are connected to the  
control. The remaining two red wires are only  
used with electronic humidity controls.  
Fig. 8. Typical wiring diagram  
of sail switch with humidifier.  
FAN WIRING  
TERMINALS  
H8908B  
L1  
1
1
TO  
SYSTEM  
FAN  
(
HOT) POWER  
SUPPLY FAN CONTROL  
H8908B  
2
L2  
HUMIDISTAT  
TERMINALS  
1
TRANSFORMER  
HUMIDIFIER  
HUMIDIFIER  
FURNACE  
FAN  
MOTOR  
1
24V WIRING.  
NOTE: FOLLOW THE INSTALLATION INSTRUCTIONS  
INCLUDED WITH THE STEAM HUMIDIFIER  
TO WIRE THE SYSTEM FAN.  
1
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION  
AS REQUIRED.  
M13387  
2
24 VAC WIRING.  
M13368  
Fig. 9. Typical wiring diagram for steam humidifiers.  
Fig. 5. Typical wiring diagram for  
system with fan interlock.  
H8908C  
CHRONOTHERM  
® IV THERMOSTAT  
L1  
B
O
W
Y
G
R
(
HOT) POWER  
SUPPLY  
FAN CONTROL  
DPST  
2
H8908B  
L2  
1
TRANSFORMER  
SWITCHING  
RELAY  
HEATING  
RELAY OR  
VALVE COIL  
2
-SPEED  
H
L
FAN  
MOTOR  
COOLING  
CONTACTOR  
COIL  
FAN  
RELAY  
COIL  
HUMIDIFIER  
C
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD  
PROTECTION AS REQUIRED.  
1
PROVIDE OVERLOAD PROTECTION AND  
DISCONNECT MEANS AS REQUIRED.  
1
M13384  
M13366  
2
24 VAC WIRING.  
Fig. 10. Typical parallel wiring of humidity controller  
with Chronotherm® IV Thermostat for  
Fig. 6. Typical wiring diagram for system  
with 2-speed fan motor.  
dehumidification and mildew control.  
3
69-1341  
href="
H8908B HUMIDISTAT H8908C DEHUMIDISTAT  
ADJUSTMENTS  
CHRONOTHERM® IV THERMOSTAT  
Humidity Control Adjustment  
B
O
W
Y
G
R
To maintain optimum humidity control without causing  
condensation on cold surfaces such as windows, the  
homeowner must adjust the setpoint as the outdoor  
temperature changes.  
H8908C  
HEATING  
RELAY OR  
VALVE COIL  
To reduce the relative humidity, reduce the setpoint  
approximately three percent relative humidity every 24  
hours. To increase the relative humidity, increase the  
sepoint approximately three percent relative humidity  
every 24 hours.  
COOLING  
CONTACTOR  
COIL  
FAN  
RELAY  
COIL  
1
Setpoint Adjustment  
Set the humidity setpoint according to the prevailing  
outdoor temperature. See Table 1 for recommended  
settings.  
1
PROVIDE OVERLOAD PROTECTION  
AND DISCONNECT MEANS AS REQUIRED.  
M13367  
Fig. 11. Typical series wiring of humidity controller  
with Chronotherm® IV Thermostat for  
dehumidification and mildew control.  
Table 1. Recommended Humidity  
Controller Settings.  
Outdoor Temperature  
Recommended  
Humidity  
H8908C  
°
F
°C  
-29  
-23  
-18  
-12  
-7  
Controller Setting  
-
20  
10  
0
15  
20  
25  
30  
35  
40  
VENTILATOR/DEHUMIDIFIER  
-
DEHUMIDISTAT  
TERMINALS  
+
10  
20  
M13383  
+
>
+20  
>-7  
Fig. 12. Typical wiring diagram for HR150,  
HR200, ER150 and ER200 Ventilator  
or HD220 Dehumidifier applications.  
OPERATION AND CHECKOUT  
Place the system in operation and observe through at  
least one complete cycle to make certain that all com-  
ponents are functioning properly.  
Home and Building Control  
Honeywell Inc.  
Home and Building Control  
Honeywell Limited-Honeywell Limitée  
Honeywell Plaza  
P.O. Box 524  
Minneapolis, MN 55408-0524  
155 Gordon Baker Road  
North York, Ontario  
M2H 3N7  
69-1341 G.H. 10-99 Printed in Taiwan R.O.C.  
www.honeywell.com  

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