H8908B Humidistat H8908C Dehumidistat INSTALLATION INSTRUCTIONS OUTDOOR HUMIDITY TEMPERATURE SETTING -20 °F -30 °C 15% APPLICATION -10 °F -25 °C 20% 0 °F -20 °C 25% +10 °F -10 °C 30% Humidity Control +20 °F -5 °C 35% Régulateur d'humidité Over 20 °F Over 0 °C 40% The H8908B Humidistat and H8908C Dehumidistat (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 CASE REMOVAL them could damage the product or cause a haz- HOLE FOR WIRING SLOT THE DUCT MOUNTING M13371 ardous condition. INSTALLATIONS 2. Check the ratings given in the instructions and on the product to make sure the product is suitable Fig. 1. H8908B Humidistat. for your application. 3. Installer must be a trained, experienced service technician. Wall Mounting 4. After installation is complete, check out product operation as provided in these instructions. IMPORTANT Mount the control in an area with average room temperature and average relative CAUTION humidity. Personal Injury Hazard. Power supply can cause electrical shock. The following mounting instructions are for mounting Disconnect power supply before beginning the H8908 on the wall next to the T8600. When install- installation. ing the H8908 at another location, modify the procedure to fit the installation. Location and Mounting 1. Hold the mounting template (included) next to the T8600. Select the mounting side for the H8908. The styling of the H8908 is designed to blend with the The template is reversible for mounting on either latest T8600 family of Honeywell Chronotherm® IV the left or right side of the T8600. See Fig. 2. Deluxe Programmable Thermostats. A mounting tem- Mark the holes for the two mounting screws plate is included for mounting the H8908 next to the 2. (included). Then mark the hole for the low voltage T8600. The H8908 can also be mounted at any other wiring on the template that corresponds with the convenient location in the living area or equipment side selected in step 1. room. See Fig 1. 3. Remove the template and drill the holes. Run low voltage wiring to the location and pull NOTE: The H8908 electrical connections are not 4. shared with the thermostat. 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. 69- 1341 ® U.S. Registered Trademark Copyright © 1999 Honeywell Inc. • •All Rights Reserved H8908B HUMIDISTAT H8908C DEHUMIDISTAT 6. Remove the H8908 case from the base. See Fig. 1. ALTERNATE LOCATION 7. Position the base on the wall with the arrow up. 8. Use the two 1 in. (25 mm) mounting screws to RETURN RETURN secure the base to the wall. AIR AIR MOUNTING THERMOSTAT TEMPLATE WALLPLATE 6 in. (152 mm) MINIMUM 15 in. (381 mm) MINIMUM BEST 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. Fig. 2. Positioning mounting template. 1. Locate the control at least 8 in. (203 mm) upstream from the humidifier (or dehumidifier/ IMPORTANT ventilator supply) in the return air duct. See Fig. 3. Use 18- to 22-gauge wire for proper wiring. 2. Apply the duct template to the duct location. 3. Use the duct template, Fig. 4, to make the open- 9. Connect the low voltage wires to the leads on the ing and mounting holes for the H8908. H8908. 4. Remove the H8908 case from the base. See 10. Replace the H8908 case. Fig. 1. 5. Position the foam gasket on the H8908 base. 6. 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. IMPORTANT 8. Connect the low voltage wires to the leads on the When mounting near an elbow area, locate the H8908. control 6 in. (152 mm) upstream from the 9. Replace the H8908 case. elbow so the element is exposed to the normal airflow (Fig. 3). IMPORTANT Use 18- to 22-gauge wire for proper wiring. 4X 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. 2. Cut along template dotted line and drill the mounting holes. 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. 2. Couper le long de la ligne pointillée du gabarit et percer les trous de fixation. M13373 Fig. 4. Positioning return air duct template. 69-1341 2 H8908B HUMIDISTAT H8908C DEHUMIDISTAT WIRING H8908B WATER 2 SOLENOID LEAD WIRE CAUTION TRANSFORMER Personal Injury Hazard. Power supply can cause electrical shock and L2 L1 1 injury. (HOT) Disconnect power supply before installation or servicing. CURRENT SENSING LO All wiring must comply with applicable local codes, ordi- RELAY C HI HUMIDIFIER nances and regulations. Make wiring connections according to humidifier (or dehumidifier/ventilator) 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS instructions, if available; otherwise, see typical wiring AND OVERLOAD PROTECTION AS REQUIRED. diagrams in Fig. 5 through 12. 2 24V WIRING. M13386 IMPORTANT Fig. 7. Typical wiring diagram of current Select models of fan centers include humidifer sensing relay with humidifier. 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- 2 ing blower motor cycles for proper operation. TRANSFORMER On multispeed blower applications, do not wire the high voltage side of the transformer to the 1 L2 L1 HUMIDIFIER same power source that services the furnace (HOT) blower. Premature transformer burnout can 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS occur. AND OVERLOAD PROTECTION AS REQUIRED. On HE360 fan powered humidifier models, 2 24V WIRING. M13385 only the two yellow wires are connected to the Fig. 8. Typical wiring diagram control. The remaining two red wires are only of sail switch with humidifier. used with electronic humidity controls. FAN WIRING H8908B TERMINALS L1 1 1 TO (HOT) POWER H8908B 2 SYSTEM SUPPLY FAN CONTROL FAN L2 HUMIDISTAT TERMINALS 1 TRANSFORMER HUMIDIFIER FURNACE 1 24V WIRING. FAN HUMIDIFIER MOTOR NOTE: FOLLOW THE INSTALLATION INSTRUCTIONS INCLUDED WITH THE STEAM HUMIDIFIER 1 PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION TO WIRE THE SYSTEM FAN. 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 WY G R (HOT) POWER SUPPLY FAN CONTROL 2 H8908B L2 DPST 1 TRANSFORMER SWITCHING HEATING RELAY RELAY OR VALVE COIL 2-SPEED HL FAN COOLING FAN HUMIDIFIER C MOTOR CONTACTOR RELAY COIL COIL 1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED. 1 PROVIDE OVERLOAD PROTECTION AND 1 DISCONNECT MEANS AS REQUIRED. M13384 2 24 VAC WIRING. M13366 Fig. 6. Typical wiring diagram for system Fig. 10. Typical parallel wiring of humidity controller with 2-speed fan motor. with Chronotherm® IV Thermostat for dehumidification and mildew control. 3 69-1341 H8908B HUMIDISTAT H8908C DEHUMIDISTAT ADJUSTMENTS CHRONOTHERM® IV THERMOSTAT Humidity Control Adjustment BOW Y G R H8908C To maintain optimum humidity control without causing condensation on cold surfaces such as windows, the homeowner must adjust the setpoint as the outdoor HEATING RELAY OR temperature changes. VALVE COIL To reduce the relative humidity, reduce the setpoint approximately three percent relative humidity every 24 COOLING FAN hours. To increase the relative humidity, increase the CONTACTOR RELAY COIL COIL sepoint approximately three percent relative humidity every 24 hours. 1 PROVIDE OVERLOAD PROTECTION 1 Setpoint Adjustment AND DISCONNECT MEANS AS REQUIRED. M13367 Set the humidity setpoint according to the prevailing outdoor temperature. See Table 1 for recommended Fig. 11. Typical series wiring of humidity controller settings. with Chronotherm® IV Thermostat for dehumidification and mildew control. Table 1. Recommended Humidity Controller Settings. H8908C Outdoor Temperature Recommended Humidity °F °C Controller Setting VENTILATOR/DEHUMIDIFIER -20 -29 15 -10 -23 20 DEHUMIDISTAT TERMINALS 0-1825 +10 -12 30 M13383 +20 -7 35 Fig. 12. Typical wiring diagram for HR150, >+20 >-7 40 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 Home and Building Control Honeywell Inc. Honeywell Limited-Honeywell Limitée Honeywell Plaza 155 Gordon Baker Road P.O. Box 524 North York, Ontario Minneapolis, MN 55408-0524 M2H 3N7 69-1341 G.H. 10-99 Printed in Taiwan R.O.C. www.honeywell.com.