king MAU Series Make Up Air Unit Installation Guide

Where should the outside air inlet be
located?
Avoid locating it near hazardous materials or explosives.
Can the MAU be operated without filters?
No, filters must be installed before operating the unit.

What should be considered by the HVAC designer
regarding outdoor air supply?
The designer must consider the impact on building comfort and
mechanical systems, including airflow frequency and volume.

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104471 Rev. 3-10-25

The King make up air unit (MAU) is a packaged unit comprised of a fan driven fully modulating electric heating unit with a fresh air relay logic control circuit providing an extremely versatile all-in-one packaged unit. It is designed to supplement other HVAC equipment by providing quality indoor air into the return side or supply side of the ductwork system or alternatively directly into the building space.
This equipment is warranted to be free from defects in materials and workmanship, under normal use and service, for a period of 24 months from date of shipment. This warranty shall not apply if: 1. The equipment is not installed by a qualified installer per the installation instructions shipped with the product. 2. The equipment is not installed in accordance with federal, state, and local codes and regulations. 3. The equipment is used in the manner not intended by the manufacturer. Any internal wiring changes, modifications or
bypass of any controls, or installation practices not according to the details of the instruction manual will void the product warranty. 4. The equipment is misused or neglected, or not maintained per industry standards. 5. The equipment is not operated within its published requirements and standards. 6. The installer is not authorized to make any modifications to the MAU the unit without factory consent. The installer will be held responsible for any damage resulting from this modification, and the UL certification could be void.
King shall not be liable for incidental and consequential losses and damages potentially attributable to malfunctioning equipment. Should any part of the equipment prove to be defective in materials or workmanship within the 24-month warranty period, upon examination by King, such part will be repaired or replaced at no charge. The customer shall pay all labor costs incurred in connection with such repair or replacement. Equipment shall not be returned without prior written authorization and all returned equipment shall be shipped freight prepaid to King.
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Before installing and operating this product, the user and/or installer must read, understand, and follow these instructions. This product must be installed by a qualified HVAC technician and the power connection by a certified electrician, in accordance with the NEC and local building codes. The following instructions must be followed to avoid personal injury, death, or property damage: 1. When performing installation, servicing, or cleaning of the system, it is recommended to wear safety glasses and
gloves. 2. Make sure that all screws and electrical terminal connections are tightly secured before operating the unit in case they
may have loosened during transportation. 3. Protect the equipment with the appropriately sized circuit breaker or fuse. 4. Make sure the line voltage matches with that indicated on the unit’s nameplate. 5. The MAU must be grounded. 6. Switch off the power at the circuit breaker/fuse before installing, repairing, or cleaning the unit. 7. Make sure the unit is sized appropriately for the intended use. If the unit’s capacity is undersized for the application, it
could prematurely fail. 8. When notching or drilling into framing, rim joists, and wall studs, comply with code and manufacturer limitations on
allowable modifications to these structural members. 9. Maintain the minimum clearance distances indicated on Page 7 of this manual. 10. When cutting or drilling into wall or ceiling, do not damage electrical wiring or other hidden utilities. 11. This unit must not come in contact with water and must be protected from splashes. Do not use if any part of the unit
has been immersed. Moreover, do not turn it on or off when standing in water or if your hands are wet. 12. The unit can be hot when in use, it may pose a burn risk even under normal operation. To avoid burns, do not let bare
skin touch any hot surfaces. Let the unit cool down before handling or servicing it. 13. Do not block the intake air or discharge air ducts. This obstruction could lead to overheating, which could result in a
fire. Do not insert or allow foreign objects to enter any air duct as this may cause electric shocks, fires, or damage to the unit. 14. It is not designed to be used or stored in wet areas or areas containing flammable liquids, combustible materials, or corrosive chemicals. 15. It is the user’s responsibility to evaluate the frequency that the filter must be changed based on the cleanliness of the environment it is operating in. An excessively dirty filter may lead to the MAU malfunctioning which could cause a fire hazard. 16. A tripped high temperature limit control indicates that the unit has been subjected to abnormal operating conditions. If the limit control continues to cycle on and off, then a qualified contractor must examine the MAU to find out the source of the problem and repair it. If the unit is damaged or defective, cut off power supply at the circuit breaker/fuse immediately and do not use the unit until it is repaired.
1. This system is not designed to provide combustion air for fuel-burning appliances. 2. Do not connect the system directly to a combustion appliance of any type. 3. Do not locate outside air inlet near hazardous materials or explosives.
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4. System shall not be installed to introduce air from crawl spaces, garages, attics, adjacent dwelling units, or other locations within the building shell. System shall be installed to bring in fresh air directly from outdoors.

5. Do not install the MAU and supply ductwork directly above or closer than 36 inches to any furnace or its supply plenum, boiler, or other heat producing appliance.

6. Any ductwork used in conjunction with the system must be installed in compliance with applicable local/national codes.

7. Do not operate the MAU until the filters have been installed.

8. The MAU must be installed in an accessible location which allows for regular inspection and maintenance.

9. The HVAC designer/contractor must take into consideration the effects that the supply of outdoor air by the MAU will have on the building’s comfort and mechanical systems. The HVAC designer should know the makeup air system’s frequency and duration of use as well as the cfm of outdoor air coming into the building.

10. Do not supply outdoor air to a space or duct where water pipes or water coils could possibly freeze.

11. Locate the outside air inlet hood above any anticipated snow drift level and away from any architectural and landscape features to ensure that the intake area for the outside air duct is never blocked and provides a clear pathway for the incoming air.

12. When federal, or state legislation comprises more restrictive installation and/or certification requirements, these requirements prevail over those in this document and the installer must conform to these at his own expense.

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Mounting Hardware Not Included
Mounting Hardware Not Included
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1. Select a location that will minimize the noise from vibration and blower air noise to the building occupants. Ideally in a service room intended for this purpose, where the temperature is maintained between 40°F and 100°F and preferably, close to an exterior wall, to limit the length of the insulated inlet air ducts.
2. Unit can be installed vertically or horizontally. When vertical, inlet must face down. 3. Make sure you can easily access the MAU to perform maintenance (24″ minimum clearance required from the
electrical entrance cover). 4. The unit can be mounted within the ceiling (between joists if it will fit) or ceiling hung, at any convenient location
between the outside inlet hood and the fresh air discharge connection. 5. The discharge connection is where the conditioned fresh air is to be distributed within the building, such as a HVAC
return air duct or directly into a room or hallway register. 6. Leave a minimum space of 2″ above the MAU.
1. The outside hood, damper and ducting material are not included with this unit. It is the installer’s responsibility to provide these materials and the necessary weather protection for the inlet.
2. Select the inlet and outlet ducting size in accordance to the system design requirements. 3. Plan the simplest system, using the least number of elbows and joints. Keep the length of insulated ducts to a mini-
mum to prevent a choke point and improve ventilation. 4. Use only rigid metal ducts. 5. Do not install elbows less than twice the diameter of the MAU duct. 6. In cold climates, frost and or condensation may collect on metal parts of this product. Insulated ducting must be
used between the outside inlet air hood and the inlet of this unit. Insulate the inlet ducts only, it is not necessary to insulate the outlet ducts as they are heated by the MAU. The inlet damper and insulated inlet piping will prevent cold air migration and a slight incline will keep moisture collection at the inlet end.
1. The fresh air intake hood must be installed at least 18 in. above the ground. 2. Make sure the fresh air intake hood is at least 6 ft. away from the following elements: garbage can or any other con-
taminating source, gas meter outlet, dryer outlet, any other combustion source outlet. 3. Install the fresh air intake hood at least 3 in. from the edge of the building to avoid turbulence, which could cause
dust to enter the hood. 4. See the illustration below on how to connect the fresh air intake hood to the exterior hood.
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(Included)
The two most frequently used installation methods are independent installation and installation connected to a forced air system. The MAU can be installed to have its own dedicated outdoor fresh air duct system that is filtered, pre-heated and then is distributed DIRECTLY to each room and hallway through register grills. In this way, it acts independently to the primary heating system that could be hydronic, electric zonal heat or a centralized HAVC system. When installed as a direct system, make sure the Temperature rise is sufficient to bring adequate warm tempered air into the building. For example, in a cold climate when the outside air is at 0°F the Temperature rise would need to be at least 70°F to warm the air adequately before delivering it directly to the occupied space.
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MAU-ECM
MAU-ECM
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The King MAU has a wide range of airflow options that can be field adjusted to match the needs of a specific installation. Providing fresh air into a building has several design parameters that must be taken into consideration: 1. The amount of fresh air required is normally calculated as Cubic Feet per Minute (CFM) per person or CFM per square feet of
the building or a room. The required CFM can also be designed to meet a specific exhaust air condition such as in a commercial kitchen where the MAU is set to match the exhaust air of the cooking hoods. 2. Static pressure is one of the most important factors in HVAC design. Simply put, static pressure refers to the resistance to airflow in a heating and cooling system’s components and duct work. To determine operating total external static pressure, measure pressures where air enters and leaves the MAU equipment. Add the two readings together to find total external static pressure. Make sure not to exceed the external static pressures listed in the design tables, doing so will cause harm the equipment. 3. Temperature rise or Delta T is the difference between the incoming air temperature and the discharge temperature of the MAU. In make-up air applications the required temperature rise is influenced by the geographic territory where colder climates require much more heat capacity to temper cold incoming air into the building. Another factor to consider is whether the fresh air is delivered directly such as to a room, hallway or delivered to the supply side of an HAVC system where the conditioned air might need to be 70°F versus the fresh air being delivered to the return air intake where the design temperature could be 55°F. Under sizing the MAU could lead to insufficient delivery temperatures causing colder than desired air to enter the building.

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The versatility of the King MAU allows for the ECM motor torque to be adjusted in the field. Pressure test the system to find the actual external static pressure, then fine tune the system by adjusting the motor torque. The goal is to meet the CFM/Temperature rise combination for the intended design criteria. Refer to the diagram below showing the terminal strip. The ECM motor is pre-programmed with 5 torque values and terminated at the 5-point terminal strip. Only one speed can be selected for the modulating heat mode and one speed for fan only mode. Note: the heat mode and fan mode cannot be wired to the same speed, otherwise a back feed will energize the heat circuit in fan mode.

Motor Tap# 1 2 3 4 5

1/3 HP Torque 6.8 in-lb. 9.4 in-lb. 12.0 in-lb. 17.0 in-lb. 20.0 in-lb.

1/2 HP Torque 15.5 in-lb. 19.0 in-lb. 22.5 in-lb. 26.0 in-lb. 30.0 in-lb.

3/4 HP Torque 26.0 in-lb 30.0 in-lb 35.0 in-lb 40.5 in-lb 45.0 in-lb

Wire Color RED ORANGE BLACK ORANGE/BLACK BROWN/BLACK

Refer to the wiring diagram provided with the MAU for the supply line connection points, typically a two or three pole contactor marked L1, L2, L3 and Ground. Size the wire gage supplying the unit per the NEC building wire ampacity standards and protect the supply circuit with the appropriately sized circuit breaker or fuse. Install a disconnect switch when called for, an optional field installed disconnect is available,
refer to the data table to select the correct model number.

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(Lock-Out)
The VT7225 series controllers are microcomputer-based, proportional and integral (PI) devices with one analog 0 to 10 Vdc output, one 8 Vdc and one 24 Vac proportioning pulsed output. The King MAU uses the analog 0 to 10 Vdc modulating output to control the room or supply air temperature by modulating directly a 0 to 10 Vdc SCR power controller.
Adjust the temperature set point by pushing the up and down arrows. An Override can be made during an unoccupied period. If the Override option is enabled in the lockout configuration pressing the override key will resume occupied setpoints for a time specified by parameter ToccTime. Refer to the Viconics VT7225 Series User Guide for additional information.
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The filter housing is shipped separately to be field installed. The filter housing is mounted to the intake side the MAU, which is the same side as where the blower is mounted. The filter can accept a 1″ or 2″ thick 16″ by 20″ filter. Install the 1″ filter brackets when using a 1″ thick filter. Please refer to the assembly drawings below.
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1. Apply power to the MAU.
a. Verify with a voltmeter on the line side of the contactor lugs that the proper voltage is present and phases correctly.
2. If the lockout circuit is being used close the auxiliary devices or jumper across L-L to test the unit.
3. Close R1 and R2 with the activation switch being used or jumper across R1 & R2 to test the unit.
4. Increase the thermostat set point above the ambient air temperature and make sure the duct sensor is connected, otherwise no heat will be produced.
5. The Fan and heating circuit should engage.
6. Check that the Fan is operating, and the green LED lights are blinking on the SSR controller, this will indicate the SSR relays are modulating the heating elements. Tempered air should be discharging out of the MAU.
a. If not check the load side of the contactor to verify voltage is present.
b. Check the terminal strip points marked 24V HOT/24V COM for 24VAC, this is the control power for the internal control circuit, the contactor coil, the relay coil, and the ECM motor. They require 24VAC coming from CPT-1 and will not operate if no voltage is present.
c. If 24VAC is not present in the control circuit, check to see if the high temp limit is tripped. It is an electrically held limit and is reset by opening the R1-R2 switch or turning off power to unit for a few minutes and then turning the power back on. The limit can also be tested by jumping around the switch to see if it is defective. Do not operate unit without a working limit switch, it can create a dangerous overheating situation.
d. If the High limit is working, check the element high temperature limits that are wired in series, one per element, check for continuity across the string and then individually, these are normally closed devices, if an open limit is found, replace it.
7. Check that the 24VAC power is present across D 24V – D com, this is the damper circuit. The control relay energizes a separate control power transformer to run the damper motor. It requires a spring return damper. This circuit is activated in both the modulating heating mode (R1-R2) and the Fan only mode (G-R1)
8. Check that the 24VAC power is present across EF 24V – EF com, this is the exhaust fan circuit. The control relay energizes a separate control power transformer (CPT-2) to close an exhaust fan relay or other auxiliary 24VAC devices.
9. Note: Maximum limit of 40VA for the sum of these two circuits, D-D and EF-EF.
10. Remove the R1-R2 switch or jumper to test the Fan only circuit by closing G-R1. The fan should operate without the heating circuit activated. The power contactor will not close, only the control relay will close to supply 24VAC to the damper and exhaust fan circuit.
a. If the fan does not operate check L1, L2 and L3 to verify line voltage is present. The motor takes the operating power from the line side of the contactor. The motor is switched on and off using the 24VAC control power from CPT-1.
b. Make sure the brown fan only wire is connected from the motor terminal block (1-5) to the G terminal as noted in the wiring schematic.
c. Check that there is 24VAC at the motor terminal block.
11. In fan only mode, check that there is 24VAC at the damper (D-D) terminals and 24VAC at the exhaust fan (EF-EF) terminals.
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We’re Here to Help!
For any difficules installing or operang this product
Call Us at:
1-800-603-5464 OPT: 2
7:00 am -3:30 pm PST Mon-Fri Visit king-electric.com or email us at tech@king-electric.com
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Documents / Resources

king MAU Series Make Up Air Unit [pdf] Installation Guide
MAU Series, MAU Series Make Up Air Unit, Make Up Air Unit, Air Unit

References

User Manual

king MAU Series Make Up Air Unit Installation Guide

MAU Series Make Up Air Unit

Specifications

Product Usage Instructions

Frequently Asked Questions (FAQ)

Documents / Resources

References

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