Installation, Operation and Maintenance Instructions ERV500e ERV000e ERV000e ERV000e ERV500e ERV000e
Table of Contents Safety Considerations.................................................................. General Information.................................................................... Installation Provide Support for Unit.................................................................. Field Fabricate Ductwork................................................................. Rigging and Placing the Unit.............................................................. Install Hoods........................................................................... Install Access Panel Handles.............................................................. Remove All Internal Packaging............................................................ Systems Integration..................................................................... Electrical Connections................................................................... 5 Start Up Controls.............................................................................. 5 Frost Control.......................................................................... 6 Sequence of Operation.................................................................. 6 Airflow Balancing....................................................................... 6 System Service Quarterly Maintenance................................................................... 7 Annual Maintenance.................................................................... 7 Testing and Replacement of the Damper Actuator............................................. 8 Motor and Blower Removal............................................................... 8 Motor and Blower Service................................................................ 8 Belt Tension Adjustment.................................................................. 8 Cassette Removal...................................................................... 8 Cassette Service....................................................................... 9 Appendix A: Roofcurb Detail............................................................... 0 Appendix B: Dimensional Drawing.......................................................... Appendix C: Rigging Drawing.............................................................. 6 Appendix D: Hood Installation And Typical Installation Layout..................................... 7 Appendix E: Components................................................................. 8 Appendix F: Terminal Control Diagrams...................................................... Appendix G: Airflow Performance Charts..................................................... 5 Appendix H: Trouble Shooting.............................................................. 9 Appendix I: Equipment Data............................................................... 0 Appendix J: Electrical Data................................................................ Manufacturer reserves the right to discontinue or change specifications or designs without notice or obligation. - -
Safety Considerations Hazards may exist within this equipment because it contains electrical and powerful moving components. Only qualified service personnel should install or service this equipment. Untrained personnel can perform basic maintenance such as maintaining filters. Observe precautions marked in literature and on labels attached to the unit. Follow all safety codes. WARNING Disconnect the main power switch to the unit before performing service or maintenance. Electric shock can cause personal injury. General Information Rooftop series, Energy Recovery Ventilators (ERVs): ERV500e, ERV000e and ERV000e The Rooftop series ventilators are intended for installation on a rooftop with a factory supplied or field supplied roofcurb. These ventilators provide 00% outdoor air ventilation and provide energy recovery between the exhaust and supply airstreams. The Energy Recovery Ventilators (ERVs) use an enthalpy wheel for total energy recovery which provides superior efficiency in hot and humid climates. These models are also effective in cold climates and use various types of frost control or frost prevention to ensure proper operation when the outside temperatures are extremely low. Installation Provide Support for Unit Roofcurb Care must be exercised in locating the roof opening. The HVAC system should cross enough roof supports to safely distribute the weight of the system over the roof. For hole sizes of the units see Appendix B. For more roofcurb information see Appendix A. Remove roofcurb from packaging. Assemble and install accessory roofcurb in accordance with instructions shipped with the curb. See Appendix A for curb dimensions and Appendix D for typical installation. Install cant strip, flashing and roof felt as per Appendix A. Ductwork must be attached to the roofcurb, not to the unit. IMPORTANT The gasketing of the unit to the roofcurb is critical for a watertight seal. Install gasket with the roofcurb as shown in Appendix A. Improperly applied gasket can result in water leaks and poor unit performance. Consult with local authorities or your building code for minimal intake hood height from the roof to determine the height of the roofcurb. See Appendix B for dimensions of the unit. Field Fabricate Ductwork On vertical discharge units, secure all ducts to the roofcurb and building structure. Do not secure ductwork to the unit. For duct size requirements, see Appendix B. Insulate and weatherproof all external ductwork, joints and roof openings with counter flashing and mastic in accordance with applicable codes. Ductwork running through roof decks must comply with local fire codes. Ducts passing through unconditioned spaces must be insulated and covered with a vapor barrier. Flexible connectors should be installed close to the unit in the duct leading to occupied spaces to minimize noise transmission. Rigging and Placing the Unit Inspect the equipment exterior and interior for damage. Ensure there is no damage to internal components such as fans, motors, dampers, enthalpy wheel, insulation and structures. File a claim with the shipping company if the unit is damaged. IMPORTANT The hoods for these units are not installed from the factory and must be installed on site. They can be installed prior to rigging the unit or after the unit is installed. Hoods are shipped on top of the unit. When rigging the unit, make sure that the hoods are secured and are not damaged by the spreader bars. See Appendix D for hood installation. Spreader bars are required to prevent damage to the roof flange. Rollers may be used to move the unit across the roof. Lifting holes are provided in the base rails as shown in Appendix C. For weights and overall dimensions see Appendix B. CAUTION All panels must be in place when rigging. Location Maintain clearance around and above the unit to provide proper airflow and service access. The fresh air intake hood must be positioned away from sources of contamination such as chimneys, exhaust vents, etc. Positioning the fresh air intake opposite to the prevailing winds will reduce entry of snow or moisture during periods of high winds. See Appendix B for service and maintenance clearances. Install Hoods Intake and exhaust hoods for these models are shipped separately from the unit. To install hoods see Appendix D. A quick connect for the damper motors is provided to connect to the main body of the unit. Make sure that all screws are secured to maintain proper support and keep seals watertight. - -
Install Access Panel Handles IMPORTANT Securing door fasteners too tightly has negative effects on the door gasket and should be avoided. Handles for access panels are provided but must be installed on site. Handles and fasteners are secured inside the unit. Remove from packaging and install according to the drawing below. Systems Integration Forced Air System When the ERV is installed in conjunction with a forcedair system, the air handler and the network of ducts associated with it are used to distribute fresh air inside the building. If this type of system is used, the main fan of the air handler must operate continuously when the unit is on. Fan Interlock can be connected in the unit control box to the integrated control board terminals J- and J- (for low voltage Class II circuit only). The controller makes relay contact between these terminals when the unit is operating, as shown below. Access Panel 86 POWER CONTROL BOARD #0 x / Screw Metal/or Polyamide Handle Remove All Internal Packaging Remove access panels and all packaging from the unit. Note that there is packaging for wheel support during shipping (ERV000e ONLY). Removal of all this packaging is critical. CAUTION Remove all ERV wheel packaging prior to start up. 6 9 J 7 FAN INTERLOCK CONTACTS COMM. N/C N/O J J Fresh air from the ERV should be introduced into the return duct of the air handler at a point no less than 6 feet [89mm] upstream of the air handler. The duct connection for return air to the ERV should be made on the return air duct at least feet [60mm] upstream of the fresh air duct connection. F F J I OC OL Y JU R G JUG-INTERMITTENT STANDBY (IS) JUF-EXTENDED DEFROST A B C D E F G B Separate Systems Select locations for exhaust grilles and supply diffusers to provide effective ventilation and avoid short circuiting airflows through the space. Adjustable dampers should be provided at every grille and diffuser to make balancing of the system possible. - -
Electrical Connections WARNING Unit cabinet must have an uninterrupted, unbroken electrical ground to minimize the possibility of personal injury if an electrical fault should occur. Failure to follow this warning could result in the installer being liable form personal injury of others. Power Supply Units are available in all voltages and phases. Please see Appendix J for Electrical Data. These units may, or may not, have a factory installed disconnect switch. If disconnect is field supplied, provide a disconnect as per NEC. Use copper conductors only. All field wiring must comply with NEC and local requirements. In Canada, electrical connections must be in accordance with CSA C. Canadian Electrical Code Part One. Field Connection A high voltage connection (shown below) is located on the outside of the unit with knockout. A field installed disconnect switch must use a liquid tight connector between the disconnect switch and the outside panel of the unit eliminating any water penetration into the control box. A wiring diagram is located on the control box lid inside the unit. Rooftop Unit (Cut-Away shown) /" LockNut Line Disconnect Switch (Cut-Away shown) /" LockNut (As seen from inside the unit) /" x -/8" Liquid Tight Connector The low voltage connection runs through the roofcurb and roof opening to the bottom panel. Low voltage remote wiring terminal is located inside the unit on the control box. Installer must provide wiring for the controls that may be supplied optionally. Start Up Controls A low voltage remote control wiring interface is provided on the unit. The installer must provide wiring for the controls that may be supplied optionally. The optional wall controls require a -wire LVT gauge (or equivalent). This control is VDC. Other terminals are VAC or dry contact control. Terminals are available for the following controls: LOW-COM-HIGH Makes dry contact for speed setting Wall Control -wire LVT gauge minimum ( VDC) Occupied (or Night Setback) Timer/Sensor Needs dry contact to operate. VAC required when timer is used. Do not use with Xtra wall control. Enthalpy Control VAC Remote Fan Control Requires single pole, double throw switch Dirty Filter Sensor Makes dry contact Low Temperature Control Makes dry contact Wheel Rotation Sensor Makes dry contact CO Ventilation Control Makes dry contact Unoccupied Recirc Contacts VAC Smoke Detector Makes dry contact For more information on the controls available for the outdoor energy recovery ventilators, see the following Appendix F references: F- Wall Control Connection F- Occupied Timer/Sensor Connection F- Enthalpy Control F- Remote Fan Control F-5 Dirty Filter Sensor F-6 Wheel Rotation Sensor used as Low Temperature Control (Wheel Failure) F-7 Wheel Rotation Sensor F-8 CO Ventilation Control F-9 Unoccupied Recirc Contacts F-0 Smoke Detector - 5-
Frost Control Recirculation Defrost Recirculation defrost is a temperature initiated timebased cycle which will de-energize the exhaust fan and the wheel drive motor, close the outdoor air damper and circulate return air through both sides of the wheel. If recirculation is in operation, it will run approximately 5% of the time, only when the outdoor air temperature falls below 5 F [-5 C]. Please note that if the indoor relative humidity is expected to be 0% or less, please contact a Venmar CES Representative or use the Venmar Select Software as frost control may not be required. Exhaust Only Defrost Exhaust only defrost is a temperature initiated timebased cycle which will de-energize the supply fan, close the outdoor air damper and exhaust return air through the exhaust side of the wheel as it continues to rotate. If exhaust only is in operation, it will run approximately 5% of the time, only when the outdoor air temperature falls below 5 F [-5 C]. Please note that if the indoor relative humidity is expected to be 0% or less, please contact a Venmar CES Representative or use the Venmar Select Software as frost control may not be required. Preheat Frost Prevention Preheat frost prevention is an outdoor air temperature controlled function that allows for continuous ventilation by monitoring the outdoor air temperature and ensuring a minimum entering air temperature (into the enthalpy wheel) of 5 F [-5 C]. There are fixed kw capacity options available based upon the unit model. For preheat capacity requirements, please use applicable ASHRAE formulas. Preheat frost prevention can have stage, stage or SCR control. VSD (Variable Speed Drive) Frost Prevention This variable speed frost prevention option is an exhaust air temperature controlled function that allows for continuous ventilation by reducing the enthalpy wheel rotational speed. The rotational speed and therefore effectiveness of the enthalpy wheel, is modulated to maintain an exhaust air temperature of F [ C]. This modulation maintains the wheel operating temperature at conditions that prevent frost formation. Special consideration must be given to applications where supply air is being heated, as the heating capacity maximum condition will be during the frost prevention cycle. Sequence of Operation IMPORTANT On initial power up, the unit will perform a system check and operate at high speed for 5 seconds. Before start-up, check the unit for obstructive packaging, objects near or in blowers, dampers, enthalpy wheel, etc. Once installation is complete, check all modes of operation to ensure that the unit is working properly. Close the doors and check for operation on LOW, COM and HIGH modes. Use a wall control or the dry contact switching to run fan speeds as shown in Appendix F- and F-. - 6- Unit check points: Power connected, no ventilation call - Both fans are off, supply damper (if equipped) closes off outdoor air. Power connected, low speed call (optional) - Both fans on low speed, supply damper (optional) opens outdoor air, recirculation defrost damper (optional) remains closed. Exhaust damper (optional) opens. If unit is single speed, it will come on that speed on a call for low or high. Power connected, high speed call. Both fans on high speed, supply damper (optional) opens outdoor air. Recirculation defrost damper (optional) remains closed. Exhaust damper (optional) opens. If unit is single speed, it will come on the speed on a call for low or high. Power connected, occupied timer/sensor connection open (factory installed jumper removed/ unoccupied mode) - Both fans are off, recirculation defrost damper (optional) remains closed. Supply and exhaust dampers (optional) are closed. Power connected, enthalpy control contacts closed, unit ventilating - wheel stops rotating, fans stay on set speed, recirculation defrost damper (optional) remains closed. Supply and exhaust dampers remain open. Power connected, enthalpy control contacts closed, unit not in ventilation mode - wheel does not rotate, fans come on low speed (optional), if unit is single speed, it will come on that speed on a call for low or high. Recirculation defrost damper (optional) remains closed, supply and exhaust dampers open. Power connected, recirculation defrost (optional) is factory installed. Recirc contacts are closed, exhaust fan is de-energized, supply fan runs and recirculation damper opens. Airflow Balancing For proper performance the unit must operate with equal supply and exhaust flow rates. Flow Measuring Stations (FMS) and magnehelic gauges can be used to measure and compare supply flow with exhaust flow. It is important to locate the FMS in the "warm side" ductwork to minimize the effect of differences in air density, especially when balancing during extremely cold outside conditions. Air density variations can effect the FMS by more that 5%. The FMS should be located downstream from straight sections of duct and not immediately after fans or obstructions that will cause turbulent flow. Flow control dampers should be installed downstream from the FMS so flow through the FMS is not disturbed. Dampers can then be adjusted to equalize flow rated in the ducts.
Another method for airflow balancing is to measure the pressure drop across the enthalpy wheel and correlate it to an airflow (see Appendix G). Setting Flow Rate Flow rates should be balanced with units operating on high speed. A damper must be used to establish the minimum duct pressure required so fans do not operate in overload regions. See Appendix G for Airflow Performance Charts. For belt drive units, adjust the motor sheave for the best fan speed. Set the dampers to establish the minimum duct pressure required. Further adjust the dampers to reduce flow to the desired, balanced rate. System Service Quarterly Maintenance WARNING Disconnect the main power switch to the unit before performing service and maintenance procedures. Quarterly maintenance (every three months) should include: Air Filters The standard medium efficiency filters and optional high efficiency filters (ERV000e ONLY) are disposable and should be replaced every three months. More frequent replacement may be required under extremely dirty operating conditions. Filter Service To replace the ERV500e and ERV000e filters, remove the enthalpy wheel access door. Grasp the filter frame at the left and right edges and pull straight out. The filter frame will slide completely out of the unit. Slide the filters up and out the top of the frame. Slide the new filters into the frame and slide the frame back into the unit. Replace the enthalpy wheel access door. For filter specifications, see Appendix I, Equipment Data. To remove the exhaust filters in the ERV000e, remove the screw holding the filter access door and slide the exhaust filter access door down to the bottom of the unit. The filters are set in frames and can be removed by pulling on the filter tabs and sliding them forward and out of the unit. First, the right filter must be removed, then the left filter must slide over to where the right filter was, then pull it forward and out of the unit (see Figure ). Cassette Panels and Interior of Unit Remove the filters from the unit. Wipe the foil-faced insulation surfaces and cassette panels with a soft cloth and mild cleaning solution. Annual Maintenance Annual maintenance should include: Air Filters Replace medium efficiency filters. Replace high efficiency filters in the ERV000e. For more detail on replacing filters, see the "Air Filters" section under "Quarterly Maintenance". Interior of Unit Wash the foil-faced insulation surfaces with a soft cloth and mild cleaning solution. Enthalpy Wheel No cleaning of the enthalpy wheel is required, it is selfcleaning due to the opposing airflows. If the enthalpy wheel needs to be cleaned, use low pressure air or vacuum. Wash the cassette panels with a soft cloth and mild cleaning solution. Visually inspect the cassette brush seals (shown below), perimeter seal and drive belt for proper operation. Rotor Figure WARNING Disconnect the main power switch to the unit before performing service and maintenance procedures. Brush Seal Fans Blower wheels and fan housing should be checked for dirt build-up. If they are dirty, it will be necessary to remove the blower assembly to clean the dust out through the fan mouth. System Operation Check Verification of all control modes should be checked to ensure proper operation. Refer to Start Up Section. - 7-
Testing and Replacement of the Damper Actuator After disconnecting the power from the unit, determine if the actuator is defective. Disconnect the v power source. Connect the actuator directly to a v power source with an appropriate cable. If the damper operates correctly, the problem is either in the wiring connections or main circuit board. If the actuator does not work, it must be replaced. Loosen the nuts on the jack shaft clamp, remove the actuator. Tighten the clamp on the damper jack shaft. Test for proper operation. Motor and Blower Removal WARNING Disconnect the main power switch to the unit before performing service and maintenance procedures. Disconnect the wire service connector between the motor and the control box (#, Figure ). Loosen the two front bolts (#, Figure ). Remove the two back bolts (#, Figure ). Slide the fan assembly away from the discharge opening and lift out of the unit. Belt Tension Adjustment Excessive belt tension is the number one cause of blower bearing failure. Proper belt tension and pulley alignment are essential for trouble free operation. A simple "Rule of Thumb" for checking belt tension is illustrated on the left. When the belt is grasped as shown, a total deflection of approximately " [5mm] should be attained. Insufficient deflection indicates that the belt is too tight, which may result in noise from excessive vibration, premature bearing failure and short belt life. Tight belts may overload a motor that would otherwise be adequate. Loosen the two pivot bolts (#, Figure ). Loosen the two adjustment bolts (#, Figure ). Rotate the motor and base plate to achieve the maximum belt deflection as described above. Tighten the drive belt side adjustment bolt. Adjust the motor plate so that the sheave and pulley faces are parallel and the belt is aligned. Tighten the remaining adjustment bolt and the two pivot bolts. # (x) Motor Base Plate # # (x) # (x) # (x) Figure : Supply Fan (ERV000 shown) Motor and Blower Service The belt tension is adjusted by positioning the rotating motor base plate (see Figure ). Set adjustment for proper belt tension. The fan RPM can be adjusted to achieve the design airflow by setting the adjustable sheave on the motor shaft. The pulley set screw torque setting is 0 in.lbs to 0 in.lbs. Figure : Motor (ERV000 shown) Cassette Removal After disconnecting the power from the unit, open the service door for the cassette access. Disconnect the service connector between the motor and the control box. Remove the exhaust filters and slide the cassette out of the unit. Take care not to damage the rotor face or any of the cassette seals. Proper support must be provided so the cassette is not dropped. - 8-
Cassette Service Perimeter Seal Replacement CAUTION When handling the enthalpy wheel, ensure not to damage the face of the wheel. To replace the perimeter seal, the enthalpy wheel must be removed from the frame. Disconnect the service connector to the drive motor of the enthalpy wheel cassette. Remove the cassette from the unit and stand the assembly on the floor or roof. Remove the dust cap (#, Figure ) from the bearing on the drive motor side of the cassette. Remove the bolt (#, Figure ) from the end of the wheel shaft with a socket or wrench on the drive motor side. Repeat this procedure for the other side of the cassette assembly. Remove the four bolts (#, Figure ) with a socket or wrench. Remove the beam and bearing assembly from the end of the wheel shaft. Loosen the four Nyloc nuts (#, Figure ) holding the drive motor using a socket or wrench. Rotate the drive motor in the slots to loosen the drive belt and remove the belt. Lift the enthalpy wheel out of the frame with assistance and set aside. Remove the perimeter seal halves (#, Figure ) from the cassette frame assembly. Install the two new perimeter seal halves by pressing them into place, cutting to the correct length as necessary. The perimeter seals are non-adjustable. Complete the installation by reversing the above procedure. # (x) Beam and Bearing Assembly Face Seal Replacement and Adjustment CAUTION When handling the enthalpy wheel, ensure not to damage the face of the wheel. To replace the face seals, the cassette assembly must be removed from the unit. Disconnect the service connector to the drive motor of the enthalpy wheel cassette. Remove the cassette from the unit and stand up on the floor or roof. Remove the screws holding the face seals (#5, Figure ). Replace the two seals (supply and exhaust sides), cutting to length as required. Adjust the seals in the slots so that the brush just touches the face of the wheel. Complete the installation by reversing the above procedure. Enthalpy Wheel Drive Belt Replacement and Tensioning Adjustment The enthalpy wheel drive belt can be tightened by only sliding the cassette assemble part way out of the unit. Disconnect the service connector to the drive motor of the enthalpy wheel cassette. Slide the cassette assembly out of the unit enough to access the drive motor. Loosen the four Nyloc nuts (#, Figure ) holding the drive motor using a socket or wrench. Rotate the drive motor to loosen the belt and replace the belt if necessary. Rotate the drive motor in the slots to tighten the drive belt. Secure the motor in it s new location by tightening the four Nyloc nuts. (#, Figure ). Complete the installation by reversing the above procedure. # Enthalpy Wheel # # # #5 Figure : Cassette and Drive Figure : Tension Adjustment - 9-
Appendix A Roofcurb Detail A-: ERV500e Roofcurb Detail End View Roofcurb Detail Front View SEE DETAIL "B" Supply Air Return Air Supply Air Return Air DETAIL "B" Unit /8" [0] Gasket (Supplied with Curb) Wood Nailer Overhang: 6.07" [5mm] Unit Baserail Counter Flashing (Field Supplied) NOTE: Dimensions in [ ] are millimeters Roofing Felt (Field Supplied) Cant Strip (Field Supplied) Rigid Insulation (Optional) Roofing Material (Field Supplied).000" [8] 9.000" [,5] 5.000" [,] 8.000" [57] Return Air Opening Supply Air Opening.000" TYP. [5] 6.000" [06] 8.5" [60] Wood Nailer " [76] Flange 9.5" [] 6.000" [9].750" [0] - 0 -
Appendix A Continued Roofcurb Detail A-: ERV000e Roofcurb Detail End View Roofcurb Detail Front View SEE DETAIL "B" Return Air Supply Air Supply Air Return Air DETAIL "B" Unit /8" [0] Gasket (Supplied with Curb) Overhang: 6.5" [56mm] Unit Baserail Wood Nailer Counter Flashing (Field Supplied) NOTE: Dimensions in [ ] are millimeters Roofing Felt (Field Supplied) Cant Strip (Field Supplied) Rigid Insulation (Optional) Roofing Material (Field Supplied) 8.000" [,057].55" [87] 77.000" [,956] Return Air Opening 5.6" [97].000" [,067] 7.875" [96].000" TYP. [5] 8.000" [57] Supply Air Opening " [76] Flange Wood Nailer.08" [05].57" [69] - -
Appendix A Continued Roofcurb Detail A-: ERV000e Roofcurb Detail End View Roofcurb Detail Front View SEE DETAIL "B" Supply Air Return Air Supply Air Return Air DETAIL "B" Unit /8" [0] Gasket (Supplied with Curb) Wood Nailer Overhang: 6.05" [5mm] Unit Baserail Counter Flashing (Field Supplied) NOTE: Dimensions in [ ] are millimeters Roofing Felt (Field Supplied) Cant Strip (Field Supplied) Rigid Insulation (Optional) Roofing Material (Field Supplied) 8.7" [,06] 77.7" [,959] 8.000" [7] 6.000" [06] 9.507" [95].70" [7].750" [98] 0.05" [].507" [,05] 7.507" [95].000" [56] - -
Appendix B Dimensional Drawing B-: ERV500e 6.090" [09]." [85] 0.575" [5].90" [,097] EXHAUST BLOWER ACCESS PANEL.90" [,5] LEFT VIEW 6." [].070" [5] 9.875" [,0] 7.59" [9].98" [76] SUPPLY AIR HOOD.68" [60] 7.57" [6] EXHAUST AIR HOOD A B CONTROL BOX.500" [56] C 6.000" [660] D TOP VIEW POWER LINE INPUT CASSETTE, FILTER, SUPPLY BLOWER ACCESS PANEL.556" [,06] 0.50" [60] A A 55.75" [,6].666" [7] FRONT VIEW 6.000" [06] 5.06" [5] 8.50" [6] RA-B.000" [05] SA-B 9.5" [5] 8.99" [88] 0.50" [60] 7.08" [79] SECTION VIEW AA 9.09" [9] ERV500e CORNER WEIGHTS PTS LBS KG A 5 68.5 B 60. C 55 70. D 6 6.7 Total 575 60.8 NOTES: Dimensions in [ ] are millimeters Center of gravity Optional NOTE: On vertical discharge units, ductwork is to be attached to accessory roofcurb only. On horizontal discharge units, field supplied flanges are to be attached to horizontal discharge openings and ductwork is to be attached to the flanges. NOTE: A minimum of.000" [,067] clearance from any obstruction is required for removal of energy recovery module, fans and filters. 6.797" [7] 5.5" [,58] 9.90" [] SA-E.000" [05] RA-E 8.000" [57] 50.09" [,7] EXHAUST FILTER AND CONTROL BOX ACCESS PANEL 0.76" [7] 8.0" [06] RIGHT VIEW BACK VIEW - -
Appendix B Continued Dimensional Drawing B-: ERV000e EXHAUST AIR OPTIONAL SUPPLY AIR 0.86" [75] 6.000" [9] OPTIONAL RETURN AIR OUTDOOR AIR PTS A B C D TOTAL LBS 8.89.80. 06.0 850.00 Kg 99.9 96.98 95.75 9.5 85.55 OUTDOOR AIR HOOD 6.000" [06] 6.80" [99] 8.98" [65].790" [96] 7.500" [5] 6.958" [685] EXHAUST AIR HOOD.6" [600] A B C D.55" [,05] TOP VIEW NOTES: Dimensions in [ ] are millimeters Center of gravity Direction of airflow Optional ERV000e NOTE: On vertical discharge units, ductwork is to be attached to accessory roofcurb only. On horizontal discharge units, field supplied flanges are to be attached to horizontal discharge openings and ductwork is to be attached to the flanges. 7.500" [] 8.79" [,9] 9.96" [5].500" [] FIELD POWER SUPPLY 6.000" [5] 0.657" [55] 85.05" [,6].5" [568] SUPPLY AIR OPENING HORIZONTAL 9.876" [,67] 9." [7] 7.598" [9].750" [9].79" [98] SUPPLY FAN CONTROL BOX ACCESS PANEL 89.00" [,6] CASSETTE, FILTER ACCESS PANEL A A 6.500" [9] 7.870" [5] 7.6" [8] SUPPLY AIR 9.500" [95] RETURN AIR EXHAUST AIR OPENING 8.087" [05] 5.09" [9] LEFT VIEW FRONT VIEW RIGHT VIEW TYPICAL.875" [7] BOTTOM FLANGE VERTICAL OPENING SUPPLY AIR.875" [7].50" [9] 9.000" [9].66" [67].000" [5] 7.7" [8] VERTICAL OPENING RETURN AIR NOTE: A minimum of 8.000" [,9] clearance from any obstruction is required for removal of energy recovery module, fans and filters. ENERGY RECOVERY MODULE 9.500" [] 5.7" [6].66" [9].000" [56] 0.66" [,08] SECTION VIEW AA 8.000" [,9] RIGHT VIEW - -
Appendix B Continued Dimensional Drawing B-: ERV000e - 5 -
Appendix C Rigging Drawing (ERV500e Shown) SPREADER BARS NOTE: Remove all packaging before beginning to rig the unit onto the installed roofcurb. - 6 -
Appendix D Hood Installation (ERV500e Shown) Detail "A" Male Detail "B" Female Black/Red Black Male Female Screw: #0 x / White White/Red Note: refer to unit wiring diagram for proper wiring. See Detail "B" See Detail "A" Typical Installation Layout (ERV500e Shown) EXHAUST AIR SUPPLY AIR Roofcurb SUPPLY AIR EXHAUST AIR - 7 -
Appendix E Components E-: ERV500e 5 6 6 6 7 0 7 5 9 8 5 6 6 5 0 7 9 8 Item Description. Housing. Fan. Fan pulley. Belt 5. Adjustable sheave 6. Fan motor 7. Enthalpy wheel 8. Wheel drive motor 9. Wheel drive pulley 0. Wheel drive belt. Wheel perimeter seal. Wheel wiper seal. Defrost damper actuator. Defrost damper 5. Exhaust damper actuator 6. Exhaust damper 7. Supply filter set - /set 8. Exhaust filter set - /set 9. Outdoor air intake hood 0. Exhaust air hood. Fan isolation. Purge section. Pressure differential switch (dirty filter). Aluminum mesh pre-filter 5. Control box 6. Preheater 7. Preheat outdoor air damper NOTE: Some unit components listed above are optional. Consult the unit nomenclature for standard and optional components. - 8 -
Appendix E Continued Components E-: ERV000e 7 5 6 5 9 0 7 9 5 6 8 8 0 Item Description. Housing. Fan. Fan pulley. Belt 5. Adjustable sheave 6. Fan motor 7. Enthalpy wheel 8. Wheel drive motor 9. Wheel drive pulley 0. Wheel drive belt. Wheel perimeter seal. Wheel wiper seal. Defrost damper actuator. Defrost damper 5. Outdoor air damper actuator 6. Outdoor air damper 7. Exhaust damper actuator 8. Exhaust damper 9. Supply filter set - /set 0. Exhaust filter set - /set. Pressure differential switch (dirty filter). Outdoor air intake hood. Exhaust air hood. Aluminum mesh pre-filter 5. Control box NOTE: Some unit components listed above are optional. Consult the unit nomenclature for standard and optional components. - 9 -
Appendix E Continued Components E-: ERV000e 8 7 6 5 9 9 0 7 6 0 6 5 8 EXHAUST FAN 5 6 7 SUPPLY FAN 5 5 0 9 8 Item Description. Housing. Fan. Fan pulley. Belt 5. Adjustable sheave 6. Fan motor 7. Enthalpy wheel 8. Wheel drive motor 9. Wheel drive pulley 0. Wheel drive belt. Wheel perimeter seal. Wheel wiper seal. Defrost damper actuator. Defrost damper 5. Outdoor air damper actuator 6. Outdoor air damper 7. Exhaust damper actuator 8. Exhaust damper 9. Primary supply filter set - /set 0. Exhaust filter set - /set. Pressure differential switch (dirty filter). Outdoor air intake hood. Exhaust air hood. Blower flex connector 5. Fan isolation 6. Purge section 7. Aluminum mesh pre-filter 8. Control box 9. Secondary supply filter set - /set 0. Preheater NOTE: Some unit components listed above are optional. Consult the unit nomenclature for standard and optional components. - 0 -
M Appendix F Terminal Control Diagrams F-: Wall Control Connection Two types of remote wall controls are available:. Standard Wall Control with fan switch and dehumidistat control.. Xtra Wall Control with fan mode selection, dehumidistat control and maintenance indicator. The remote wall controls work with the integrated electronic controls within the unit to control ventilation sequences. Each wall control above has different features and will require -wire connection to the unit as shown below. Without the wall control, fans can be operated with dry contacts or a switch as in control diagram F-. NOTE: All controls accessories (Ex. Night setback timer, CO controller, enthalpy controller, smoke detector or wheel rotation sensor) intended to provide a contact closure for occupancy control across terminals and cannot be used in conjunction with the Xtra wall control. If a wall control is required in addition to any of these options, only the Standard wall control may be used. Without these options, a factory installed jumper across terminals and must be installed. Occupancy control is achieved by connection to the terminal interface shown below. These terminals require a dry contact which could be provided by a number of types of controls such as a timer, light sensor, occupancy sensor, building management system or other. The unit will not operate unless these contacts are closed!! The drawing below shows a factory installed jumper and programmable timer option. NOTE: All controls accessories (Ex. Night setback timer, CO controller, enthalpy controller, smoke detector or wheel rotation sensor) intended to provide a contact closure for occupancy control across terminals and cannot be used in conjunction with the Xtra wall control. If a wall control is required in addition to any of these options, only the Standard wall control may be used. Without these options, a factory installed jumper across terminals and must be installed. F-: Occupied Timer/Sensor Connection JUMPER (factory installed) CONTROL CONTACTS BLACK GREEN NSB Timer OCCUPANCY CONTROL (field installed) CONTROL CONTACTS BLACK GREEN WALL CONTROL WALL CONTROL RED YELLOW RED YELLOW CONTROL CONTACTS BLACK GREEN WALL CONTROL Wall Control JUMPER OCCUPIED TIMER/ SENSOR LOW COMMON 5 OCCUPIED TIMER/ SENSOR LOW COMMON RED YELLOW 5 (-) VAC HIGH 5 5 (-) VAC HIGH 5 JUMPER OCCUPIED TIMER/ SENSOR LOW COMMON 6 7 (0 VA) (+) VAC ENTHALPY DIRTY FILTER INDICATOR (.5A- VAC) 6 7 6 7 (0 VA) (+) VAC ENTHALPY DIRTY FILTER INDICATOR (.5A- VAC) 6 7 5 6 7 (-) VAC (0 VA) (+) VAC ENTHALPY HIGH DIRTY FILTER INDICATOR (.5A- VAC) 5 6 7 8 9 0 (RECIRC UNITS) WHEEL UNOCC. ALARM RECIRC OPTION CONTACTS ( VAC) FIELD WIRED A B TERMINALS 8 9 0 8 9 0 (RECIRC UNITS) WHEEL UNOCC. ALARM RECIRC OPTION CONTACTS ( VAC) FIELD WIRED A B TERMINALS 8 9 0 8 9 WHEEL ALARM OPTION ( VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS 8 9 CLASS VOLTAGE NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. CLASS VOLTAGE NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. 0 A FIELD WIRED TERMINALS B 0 Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. CLASS VOLTAGE NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. - -
Appendix F Continued Terminal Control Diagrams Energy Recovery Ventilators (ERVs) can be controlled by an enthalpy controller that switches between free cooling and A/C unit cooling. When free cooling is possible, the ERV will ventilate without energy recovery (the enthalpy wheel stops) on a call for cooling. The ventilation rate is not affected. If the unit is not operating, enthalpy control contact will initiate low speed ventilation. The enthalpy control must be connected in conjunction with a cooling thermostat control to prevent free cooling from initiating in heating seasons as shown below. + TR TR S F-: Enthalpy Control THERMOSTAT (Field Supplied) Y R C C700A SENSOR added for differential H705A SETPOINT enthalpy control option. ENTHALPY CONTROL Mounted in return airstream. (Mounted in outdoor airstream) Setpoint PN 60 (H705A) Differential PN 60 (H705A and C700A) FIELD INSTALLED FREE COOLING CONTROL WITH SINGLE STAGE COOLING SR + To A/C Unit JUMPER 5 6 7 8 9 0 CONTROL CONTACTS BLACK RED WALL CONTROL OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) (+) VAC ENTHALPY WHEEL ALARM OPTION ( VAC) A FIELD WIRED TERMINALS LOW COMMON HIGH DIRTY FILTER INDICATOR (.5A- VAC) UNOCC. RECIRC CONTACTS CLASS VOLTAGE GREEN YELLOW (RECIRC UNITS) NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. B 5 6 7 8 9 0 JUMPER 5 6 7 8 9 0 CONTROL CONTACTS BLACK RED WALL CONTROL OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) (+) VAC ENTHALPY WHEEL ALARM OPTION ( VAC) A F-: Remote Fan Control Remote fan control can be achieved by connecting dry contact controls to the terminal interface at terminals labeled: LOW - COM - HIGH (Not all units have two speeds). Placing a jumper across the 'LOW' and 'COM' terminals will put the unit in low speed ventilation or placing a jumper across the 'HIGH' and 'COM' terminals will put the unit into high speed. DO NOT jumper all three terminals together. These controls could also be the following: SPDT switch, dehumidistat, CO sensor, light sensor, heat sensor, timer, building management system, etc. The drawing below represents a switch connected to the unit. CAUTION: Do not use a wall control and remote fan switch at the same time. Damage to the unit may occur. FIELD WIRED TERMINALS GREEN YELLOW LOW COMMON HIGH DIRTY FILTER INDICATOR (.5A- VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS B 5 6 7 8 9 0 LOW REMOTE FAN SWITCH HIGH NOTE: Not all units have two speeds. Single speed units will be activated with either LOW-COM or HIGH-COM connection. CLASS VOLTAGE Setpoint/Differential Enthalpy Control NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. B THERMOSTAT (Field Supplied) Y R C JUMPER 5 6 7 CONTROL CONTACTS BLACK GREEN WALL CONTROL RED YELLOW LOW OCCUPIED TIMER/ SENSOR COMMON (-) VAC HIGH (0 VA) (+) VAC DIRTY FILTER INDICATOR (.5A- VAC) ENTHALPY 5 6 7 F-5: Dirty Filter Sensor The ERVs can be equipped with dirty filter sensors which monitor the pressure across the filters and close the contacts when the filters become restricted with dirt. Connections on the terminal interface labeled "Dirty Filter Indicator" provide the dry contact and may be connected as shown below. R W To A/C Unit 8 9 WHEEL ALARM OPTION ( VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS 8 9 CONTROL CONTACTS BLACK RED WALL CONTROL GREEN YELLOW T675A SETPOINT CONTROL (Mounted in outdoor airstream) Setpoint PN 600 (T675A) 0 FIELD WIRED A B TERMINALS CLASS VOLTAGE 0 JUMPER OCCUPIED TIMER/ SENSOR LOW COMMON FIELD INSTALLED FREE COOLING CONTROL WITH SINGLE STAGE COOLING NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. 5 6 7 (-) VAC (0 VA) (+) VAC ENTHALPY HIGH DIRTY FILTER INDICATOR (.5A- VAC) 5 6 7 Thermostat (Drybulb) Control 8 9 0 (RECIRC UNITS) WHEEL UNOCC. ALARM RECIRC OPTION CONTACTS ( VAC) FIELD WIRED A B TERMINALS CLASS VOLTAGE 8 9 0 VAC LIGHT or INDICATOR (Supplied by others) NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. - -
Appendix F Continued Terminal Control Diagrams F-6: Wheel Rotation Sensor used as Low Temperature Control (Wheel Failure) ERVs can be equipped with a wheel rotation sensor board but must be ordered with a control board. On power up of the unit, the wheel rotation sensor board's relay coil is activated and closes the 'NO' set of contacts that are wired to the 'Occ/Unocc' control terminals on the unit. In this condition, the unit is allowed to operate in a normal occupied state. When a wheel rotation failure occurs, the relay coil is de-activated and opens the contacts that are wired to the 'Occ/Unocc' control terminals. In this condition, the unit is in an unoccupied state. The fans are de-energized and the outdoor air dampers will close. The wheel rotation sensor board has jumpers that can be used to set the time duration (,, or 8 minutes) for the alarm to be activated after the wheel failure. This alarm can be used to turn on an alarm light (see "Wheel Rotation Alarm" drawing below) or to protect downstream coils from freezing in below zero conditions. NOTE: The wheel rotation sensor option must be ordered with a unit control board for wall control compatibility. The wheel rotation sensor option cannot be ordered with a non-defrost unit. WRS BOARD RELAY 'N/C' CONTACTS (Normally closed - opens on wheel failure) VAC LIGHT or INDICATOR (Supplied by others) 5 6 7 8 9 0 CONTROL CONTACTS BLACK RED WALL CONTROL OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) (+) VAC ENTHALPY WHEEL ALARM OPTION ( VAC) A FIELD WIRED TERMINALS CLASS VOLTAGE GREEN YELLOW LOW COMMON HIGH DIRTY FILTER INDICATOR (.5A- VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. B 5 6 7 8 9 0 F-7: Wheel Rotation Sensor ERVs can be equipped with a wheel rotation sensor option. This option cannot be ordered for a non-defrost unit. This option cannot be used in conjunction with a digital wall control and must be ordered with a control board. With the wheel rotating, the wheel rotation sensor board activates the relay coil and closes the 'NO' (normally open) set of contacts across the occupied/timer sensor contacts (pin and ), allowing the unit to operate. If the wheel rotation stops (unless in an enthalpy state, defrost mode or unoccupied condition), the contacts will be open and cause the motors to shut down and the dampers (optional) to close. NOTE: If the wheel rotation sensor board shuts the unit down, the only procedure to re-start the unit is to turn the power off and then back on again. A set of VAC wheel alarm contacts are available on the terminals to power a light or indicator. The drawing below shows the wiring necessary to power the VAC light or indicator. CAUTION: The wheel rotation sensor printed circuit board has 0 VAC wired to two terminals. Improper wiring or handling of the circuit board could damage the board, the unit or cause personal injury. CONTROL CONTACTS LED J J DELAY BLACK GREEN WALL CONTROL CAUTION 0 VAC RED YELLOW NO COM NC V COM SEN VEN NO COM NC ALA DIS NO = NORMALLY OPEN NC = NORMALLY CLOSED COM = COMMON DEF+ DEF- RELAY COM NO NC WRS BOARD RELAY 'N/C' CONTACTS (Normally closed - opens on wheel failure) 5 OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) LOW COMMON HIGH 5 COM SEN V = VAC COM = COMMON SEN = SENSOR COM SEN 6 7 (+) VAC ENTHALPY DIRTY FILTER INDICATOR (.5A- VAC) 6 7 VEN ALA DIS CAUTION 0 VAC DEF+ DEF- ALA = RELAY ON ( VAC LIGHT, MAX. AMP) DIS = ROTATION DETECTOR DISABLE ( VAC) VEN = VENTILATION MODE (DISABLE WRS) ( VAC) DEF+ = DEFROST MODE (DISABLE WRS) (0 VAC) DEF- = DEFROST MODE (DISABLE WRS) (0 VAC) VAC LIGHT or INDICATOR (Supplied by others) 8 9 0 (RECIRC UNITS) WHEEL UNOCC. ALARM RECIRC OPTION CONTACTS ( VAC) FIELD WIRED A B TERMINALS 8 9 0 DELAY J & J = DETECTION DELAY CLASS VOLTAGE J J LED J J DELAY min. * X min. X min. X X 8 min. *default = RELAY ON (RED) = POWER ON (GREEN) = SENSOR DETECTION INDICATOR (YELLOW) SENSOR MAGNET NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. Wheel Rotation Sensor Board Wheel Rotation Alarm - -
Appendix F Continued Terminal Control Diagrams F-8: CO Ventilation Control ERVs can be controlled by a CO controller that can be connected to fan control LOW-COM-HIGH (Not all units have two speeds). As the CO levels exceed acceptable limits, the dry contact across HIGH-COM is closed, raising high speed fan ventilation. FACTORY MOUNTED JUMPER 5 6 7 8 9 0 CONTROL CONTACTS BLACK RED WALL CONTROL OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) (+) VAC ENTHALPY WHEEL ALARM OPTION ( VAC) A FIELD WIRED TERMINALS CLASS VOLTAGE GREEN YELLOW LOW COMMON HIGH DIRTY FILTER INDICATOR (.5A- VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. B 8 5 6 7 8 9 0 CO SENSOR NC AC GROUND AC INPUT NO NOTE : Terminal 5 on CO Sensor used only with speed units. NOTE : Terminal 7 and 8 on CO Sensor used only with blower VFDs. NORMAL OPERATION - LOW SPEED CO LEVELS EXCEED SETPOINT - HIGH SPEED F-9: Unoccupied Recirc Contacts On recirc defrost units, an unoccupied recirc control can be achieved by connection to the terminal interface shown below. These terminals require a VAC signal which could be provided by a timer, thermostat or other. Closure of these terminals will cause the unit to go into a 'recirc mode' where the supply fan runs on high speed and the exhaust fan stops. NOTE: Although these contacts are intended for use during unoccupied periods, they are still active during an occupied condition. Therefore, the VAC signal should be applied such that it is disabled during occupied periods, preventing the unit from going into a recirc condition unnecessarily. CONTROL CONTACTS BLACK RED WALL CONTROL GREEN YELLOW 7 6 5 Locate in a normally occupied area of premises. Recommended for compliance to NFPA-90A and IMC code 606. ERVs can be equipped with a duct mount smoke detector which will monitor the air when passing through the duct system into the ERV. When sufficient smoke is detected, an alarm condition is activated. By connecting the occupied timer/sensor contacts to the N/C alarm auxiliary contacts on the duct sensor, an alarm condition will open the auxiliary contact and stop operation of the ERV. RED GRN. F-0: Smoke Detector ALARM 5 COMMON 6 FIELD 7 INSTALLED JUMPER 0 POWER AVAILABLE POWER INPUTS V 0 VAC 0/0 VAC ALARM AUXILIARY CONTACTS FOR FAN SHUTDOWN, ETC. 5 6 7 8 9 0 N.C. C. N.O. N.O. C. N.C. ALARM AUXILIARY CONTACTS SHOWN IN STANDBY. CONTACTS TRANSFER DURING ALARM AS INDICATED BY THE ARROWS. ALARM INITIATION CONTACTS 8 9 N.O. TROUBLE CONTACTS CLOSED IN ALARM AND STANDBY. CONTACTS OPEN WHILE DETECTOR HEAD OR POWER IS REMOVED, AND DURING RESET. OPEN CONTACTS SIGNAL TROUBLE CONDITION TO PANEL. 5 6 7 (+) ALARM SIGNAL (D) AUX POWER (+) AUX POWER TROUBLE CONTACTS POWER INPUTS ACCEPT VDC, VAC 50-60 HZ, 0 VAC 50-60 HZ, OR 0/0 VAC 50-60 HZ. CONNECT POWER SOURCE TO APPROPRIATE TERMINALS OF EACH DETECTOR. ALARM AUXILIARY CONTACT RATINGS 0A @ 0 VDC 0A @ 50 VAC (0.75 POWER FACTOR) 0VA @ 0 VAC (0. POWER FACTOR) /8 HP @ 0 VAC / HP @ 0 VAC 500mA MINIMUM @ VDC NOT INTENDED FOR CONNECTION TO CONTROL PANELS. ALARM INITIATION CONTACT RATING.0A @ 0 VAC/DC (0.6 POWER FACTOR) TROUBLE CONTACT RATING 0.A @ VAC/DC TROUBLE CONTACTS CLOSED IN STANDBY AND ALARM. CONTACTS OPEN WHILE DETECTOR HEAD OR POWER IS REMOVED AND DURING RESET. OPEN CONTACTS EXTINGUISH OPTIONAL APA5 GREEN POWER LED TO INDICATE TROUBLE CONDITION. CONTROL CONTACTS BLACK RED OCCUPIED TIMER/ SENSOR (-) VAC (0 VA) (+) VAC WALL CONTROL ENTHALPY GREEN YELLOW LOW COMMON HIGH DIRTY FILTER INDICATOR (.5A- VAC) 5 6 7 5 OCCUPIED TIMER/ SENSOR (-) VAC LOW COMMON HIGH 5 8 9 WHEEL ALARM OPTION ( VAC) (RECIRC UNITS) UNOCC. RECIRC CONTACTS 8 9 6 7 (0 VA) (+) VAC ENTHALPY DIRTY FILTER INDICATOR (.5A- VAC) 6 7 0 A FIELD WIRED TERMINALS B 0 8 9 0 (RECIRC UNITS) WHEEL UNOCC. ALARM RECIRC OPTION CONTACTS ( VAC) FIELD WIRED A B TERMINALS 8 9 0 VAC Required CLASS VOLTAGE NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. CLASS VOLTAGE NOTE: Connections are all dry contacts except wall control, wheel alarm contacts and VAC power contacts. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. NOTE: Unoccupied Recirculation is available on units with Recirculation Defrost Option only. Use of VAC circuit requires isolating contacts (ex. thermostat) to prevent interconnection of Class outputs. - -