Call us


We're Available

Mon - Fri: 8:30 - 5:00 CST

DX Cooling Make-Up Air Unit

DX cooling makeup air uses 100% outdoor air. It has no return air. 100% outside air air comes through in the hood and through a filter gets cooled and dehumidified. There are models that are able to incorporate heating options.

In this article DX (direct expansion) cooling Make up air system are also be referred to as:

  • Make up air unit
  • MAU
  • 100% OA Unit
  • Dedicated OA Unit
  • Dedicated MAU

They are essentially the same thing.

MAU are typically constructed of galvanized steel. However, there are a complete line of DX Cooling units for industrial applications that are constructed of other materials due to the insulation requirements with respect to the environment.

direct gas fired make up air with dx cooling

Table of Contents

DX Cooling Diagram

dx cooling diagram make-up air unit

Tempered Make-Up Air Using DX Cooling Coils

Tempered make-up air units featuring DX cooling are offered with the latest technology. The system has reliability and energy efficiency as well as low installation costs.

Patented technology in the many DX cooling make-up air units are specifically designed to provide airflow throughout the year to accommodate a broad variety of demanding commercial and industrial equipment. The quality for the cost of 100% fresh outside air system is unmatched with a DX cooling module.

The byproducts of combustion, while safe, remain in the heated air. This is why these types of units are ideal for industrial and commercial applications.

Authorized MUA Dealers

We are the authorized distributors for the leading American manufacturers of makeup air units. We’ll be pleased to provide the ideal make up air unit for your application as authorized representatives.

For a fast quote or if you have inquiries about commercial or industrial MUA, get in touch with us.

Does a make-up air system have cooling?

Standard make-up air systems can provide buildings with cooled fresh air.

There are several models of make up air systems that provide cooled air; the most popular being the DX cooling module in a make up air unit.

Types of DX Cooling Equipment

Field-Assembled DX System

DX systems that are not manufactured (and rated) as a single package, but are instead assembled on-site from individually manufactured components. A refrigerant coil is inserted directly in the supply air stream in DX cooling equipment. As the refrigerant evaporates and expands, it removes energy and lowers the supplied air’s temperature.

Hydronic Coil

A hydronic coil is a collection of tubing placed in a supply airflow through which hot or cold water flows to heat or cool the supply air stream, thereby providing heating or cooling to a space.

In various heating and air-conditioning system configurations, hydronic coils, central furnaces, and DX coils are utilized.

Packaged Terminal DX Unit

Packaged Terminal DX Unit – A packaged terminal DX air conditioner (PTAC) is a wall-mounted, self-contained air conditioning unit.

It delivers cool air straight into the area, bypassing the need for ducts.

PTACs are often fitted with electric resistance heating components and occasionally with hydronic coils or steam coils.

Single Package Vertical Unit

The unit is designed for exterior installation on, adjacent to, or through an exterior wall. A factory-assembled single package that provides temperature control and dehumidification in addition to cooling.

The unit’s primary components are vertically organized and may feature multiple ventilation methods, including ducting.

Split DX System

Commonly referred to as a unitary split system air conditioner or a split system.

It is comprised of two factory-made assemblies: a condensing unit that uses outside air as a heat sink, and an inside DX coil with inbuilt supply fan.

Inside the same assembly, the indoor unit is frequently paired with a central furnace, hydronic coils, or steam coils.

It is difficult to equip a split system with an air economizer due to the interior unit typically being situated far from exterior walls.

Rooftop Packaged DX Unit

A unitary single-packaged air conditioner is another name for a rooftop DX unit. This device is a self-contained DX air conditioner, which is normally positioned on the roof of a building and uses ducts to deliver cool air throughout the conditioned room.


DX Cooling Modules for Restaurant Applications

High-performing make-up air units provide an option for an inbuilt air-cooled packaged DX cooling system designed exclusively for restaurant applications.

The system, which is available in configurations with 100% outside air and variable volume airflow, is made to chill makeup air to a supply air temperature of 70 to 75 °F to increase comfort for the kitchen workers.

Multiple tempered makeup air units can be configured using the packed DX configuration, which offers single-source accountability and lowers installation and control installation fees. Air flow ranges from 1,000 to 7,500 cfm, and cooling capacities range from 3 to 16 nominal tons.

DX Cooling Components

A DX cooling coil with copper tubes, aluminum fins, a galvanized steel frame, and brazed type connectors is required as part of the DX Cooling Module. Coils with numerous distributors and headers must also have interlaced circuiting, and the DX cooling coil must have counter flow circuiting.

The DX cooling coil for units designated as remote split systems must be provided with dry nitrogen charged into it. Sight aids, filter-dryers, and expansion valves must all be factory-installed.

To avoid condensate carry-over past the drain pan, a moisture eliminator shall be installed where necessary on the DX cooling coil face. All factory installed refrigerant pipe for packaged units must be physically supported, and all suction lines must be insulated.

Should Make up air units Be Modulated?

A method to modulate cooling should be considered in order to be prepared for a state of climate that doesn’t occur often.

For example, during off peak days of the summer, the cooling coil that is set to 55 degrees may make people in the building uncomfortable.

1 option would be to turn the tempered air off. However, if you turn the compressor off then it doesn’t dehumidify. That is why the cooling module is kept separate to meet the lower load.

This can be accomplished with a variable capacity compressor or a VFD compressor. They both essentially do the same thing.

Having modulated hot gas reheat is imperative in order to control the tempered air especially on days when environmental conditions warrant it.

Modulating Condenser Fans

There are several benefits when the condenser fans are modulated; the unit is more efficient. The lifespan of the unit will be extended and lower maintenance requirements due to the improved acoustics. They prevent the exhaust fan from jump starting to 100%. This saves the belt drive motors and operating costs of the exhaust fans which is separate from the dx cooling module.

Benefits of DX Cooling MUA

DX cooling mua provides precision cooling under various load circumstances with a great degree of flexibility. The system can be placed outside or inside of the space. Furthermore, and it can be enlarged to accommodate changing building needs or sizes.

It is possible to operate specific areas without using the entire building’s HVAC system. DX Cooling modulated units are available with a valve system which has the ability to slow or halt the flow of refrigerant to each interior unit. As a result, each room can be controlled separately.

As is the case with DX Cooling make up air units they typically take up less room than other cooling systems. There is the option of installing numerous units if there are heavy air conditioning loads.

To suit fluctuating load situations, one of the units can be shut off and the other can run at full capacity when there is less heat load. A system with variable speed technology that offers better capacity modulation is available for commercial applications. It gives consumers the option to exactly match a facility’s load demand at any given time by reducing the unit’s energy usage.

DX cooled make up air unit mounting options

Horizontal or Vertical with down discharge

Is a DX system or chiller better?

The question shouldn’t be which is better, DX or Chiller; but which cooling make-up air system is better for the application.

Both provide unique benefits and drawbacks.

That being said, a combination of systems is common.


Steam Heated Make-Up Air Unit Proper header assembly design ensures uniform steam distribution to each of the coil core tubes. A perforated plate type baffle

Read More »

We Sell Make-Up Air Units Official representative of industry leading make-up air units backed by industry leading warranties. From commercial to industrial applications, we know

Read More »