Magic Aire

All Magic Aire unit ventilators with Hydronic Coils include an automatic reset,  single-pole, double-throw low limit switch that changes state at 38°F and 42°F.  This is mounted on the leaving side of the coil (heating coil for 4-pipe).  The hydronic low limit is marked as LLT on the unit’s wiring diagram.

All Magic Aire unit ventilators with DX coils include an automatic reset,  single-pole, double-throw low limit switch that changes state at 28°F and 35°F.  This is mounted on the leaving side of the coil.  The DX low limit is marked as LLR on the unit’s wiring diagram.

Both low limits are snap-acting SPDT devices, with terminal 2 as the common.  Terminal 3 closes on temperature rise and Terminal 1 closes on temperature fall.

No, Magic Aire utilizes ASHRAE cycle II which requires modulating the unit ventilator’s outside air/ return air damper.   While some thermostats allow you to program the unit ventilator’s damper control  through the economizer feature, they do not allow modulation but control damper to maximum open or closed position.

The changeover (aquastat) switch is factory wired to the DDC controller as shown on the unit wiring diagram.  During installation in the field, this switch must be clamped onto the pipe supplying water to the unit upstream of the valve.  See the unit ventilator IOM for more details.

Electric Heat stages are assigned according to the number of elements of electric heat.  1 Element = 1 Stage; 2 Elements = 2 Stage; 3 or more Elements = 3 stage.

A low limit thermostat (freeze stat) is factory installed on all Magic Aire Unit Ventilators with Hydronic and DX coils.  For extra freeze protection, a face and bypass damper is recommended to protect from coil freeze-up. With a face and bypass damper there is a constant flow of hot water through the coil unlike a valve system.  The units feature a one piece Outside Air / Return Air damper that is made of heavy gauge extruded aluminum material with airtight seals to prevent unwanted air from entering the unit. The damper is insulated with closed cell foam insulation.  An optional cold weather damper section is also an option that has thicker insulation for maximum cold weather protection.  With field provided DDC Controls, if the low limit thermostat trips, there should be a sequence of operation to drive the outdoor air damper closed.

PD = ((Q*√G)/Cv)²

Where
PD = water pressure drop across control valve, psig
Q = water flow rate in gallons per minute
Cv = flow coefficient
G = specific gravity of fluid(1.0 for water)

Magic Aire’s team has vast experience working together with Sales Offices and Control Contractors to customize a Control Package that will fit Customer’s specifications. Our team of Design Engineers and Product Managers will work directly with your team to ensure we are designing to your Customer’s expectations.  During the recent peak seasons, our team has coordinated and shipped dozens of custom jobs.  We have mounted and wired field supplied DDC Controllers, actuators, sensors, and thermostats plus the parts necessary to support the required control scheme , such at resistors, jumper combs, and relays.
This is almost “anything goes” option within the confines of available physical space and safety codes.

The DDC Ready Package consist of terminal blocks mounted on a hinged panel (shown below), a wiring harness (shown below),a 75VA control transformer, and a fan start/stop relay with a 3 speed fan switch (not included with variable speed motor option).  The following are provided when applicable: a DX Relay and low limit; and/or a water low limit; and/or an outside air damper actuator (shown below); and/or a face and bypass damper actuator.