United CoolAir

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Choosing a Dedicated Outdoor Air System to fill fresh air needs

In order to comply with current strict ventilation standards in the HVAC industry, manufacturers’ are introducing innovative new equipment to improve indoor air quality. Dedicated outdoor air systems (DOAS) are one such method used to regulate temperature and humidity in schools, hospitals, offices, and other commercial spaces. As these systems become more popular throughout the USA and Canada, technicians and end users need to understand the operation and importance of these units.

DOAS units are not the primary source of cooling but are often used in conjunction with other HVAC equipment. These units function by bringing in fresh air independently of other cooling and heating equipment. This pretreated air will ultimately save fan energy on the main HVAC unit and improve the overall indoor air quality. These units can be air-cooled, water-cooled and chilled water and may include variable capacity compressors.

Specifying a DOAS unit usually begins with selection software, which takes the basic parameters of the installation and then focuses on the specific needs and requirements for fresh air to be introduced. The software will calculate the performance expectations and recommend additional modifications to the basic package. A variety of fresh air units handle a range of CFM and tonnage and include options such as water-source heat pumps and modulating hot gas reheat. Other fresh air units could include direct expansion with an energy recovery enthalpy wheel. The unit should be able to handle the large latent ventilation load and deliver “neutral” air of 72°F to 75°F @ 50% RH. By separating the sensible load from the latent load, the unit will remove moisture from the primary source of fresh outside air. This, in turn, reduces the load on the primary AC unit that will be used in cooling the space and leads to greater efficiency and better indoor air quality with a lower overall cost.

Many HVAC manufacturers provide outdoor rooftop equipment as DOAS units, but occasionally a customer might require an all indoor packaged unit when the building topography does not allow for outside mounting. Additionally, codes affecting historic buildings may not allow for unappealing HVAC equipment to be installed even if there were ample room on the roof or outside. This indoor packaged solution typically realizes a smaller footprint and can be used for new installations as well as retrofitting as part of a VRF or conventional DX air conditioning project.

Ideally, the performance of your DOAS unit should meet or surpass the ASHRAE 90.1 standards of ISMRE 11.1 and ISCOP 8.0 and adhere to a sound rating of less than NC-40. Dedicated Outdoor Units also include options such as the installation of MERV 8 or 13 filters. Units can also include special coil coatings to prevent rust and corrosion when installed in harsh conditions such as marine or paper mill applications. Lastly, units may also include a manual on/off override switch and meet the power requirements of 208/230 single or three phase or 460/3 phase power.

When calculating the need for a DOAS unit it is important to understand all the benefits that can be realized with this type of installation.

  • By removing outdoor contaminants before they enter the building the indoor air quality will be greatly improved and will allow the main cooling unit to run more efficiently.
  • Much like the operation of a dehumidifier, moisture is removed from the entering air, which can prevent the formation of mold growth that affects the health of the building occupants.
  • Energy savings can be achieved by separating the ventilation requirement from the main cooling or heating unit.

Dedicated Outdoor Air Systems have become an integral component to an overall approach to HVAC installation. As concerns about climate change drive governments to enact more stringent energy requirements in the manufacturing process, DOAS units will continue to grow in importance. Ongoing developments will ensure that these types of units will become even more efficient and used well into the future.

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HVAC Replacement Made Better

What if there was a way to replace existing indoor HVAC equipment that has reached its lifespan without expensive demolition and alterations to the building structure?
Many contractors, engineers and property managers are challenged with this question every day. It would seem to be a question that is easily answered. Outdated equipment could simply be chopped up and the debris hauled away to make way for a replacement unit. The problem is most replacement units are not small enough to be brought into the space without major disruption and structure modifications. Countless numbers of HVAC units were installed while the building was under construction thus confining the unit in its chosen location. The current protocol is to chop up a brand new unit and bring it into the space and then reassemble the equipment, or the alternative of knocking down a wall or removing part of the roof in order to accomplish the replacement task. The problem with both of these solutions is the damage that can result in new equipment and the expense of building demolition and reconstruction. These building alterations can add tens of thousands of dollars to the total replacement cost.

There is a better way

United CoolAir equipment is a better solution for replacement HVAC units. Our units are modular in construction with quick connects and re-sealable fittings that allow replacing equipment without demolition. Most of our units can fit through a standard doorway or elevator, around tight corners of hallways and into the space. The process of installing United CoolAir units can save time and money leading to greater satisfaction in the retrofit process.

What if there was a way to replace existing indoor HVAC equipment that has reached its lifespan without expensive demolition and alterations to the building structure? Many contractors, engineers and property managers are challenged with this question every day. It would seem to be a question that is easily answered. Outdated equipment could simply be chopped up and the debris hauled away to make way for a replacement unit. The problem is most replacement units are not small enough to be brought into the space without major disruption and structure modifications. Countless numbers of HVAC units were installed while the building was under construction thus confining the unit in its chosen location. The current protocol is to chop up a brand new unit and bring it into the space and then reassemble the equipment, or the alternative of knocking down a wall or removing part of the roof in order to accomplish the replacement task. The problem with both of these solutions is the damage that can result in new equipment and the expense of building demolition and reconstruction. These building alterations can add tens of thousands of dollars to the total replacement cost. There is a better way United CoolAir equipment is a better solution for replacement HVAC units. Our units are modular in construction with quick connects and re-sealable fittings that allow replacing equipment without demolition. Most of our units can fit through a standard doorway or elevator, around tight corners of hallways and into the space. The process of installing United CoolAir units can save time and money leading to greater satisfaction in the retrofit process.

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VariCool Renovator

Developed as a Direct Replacement
for Trane SWUD Units

VariCool Renovator Picture
Exploded View

During the 1980s the Trane SWUD was installed in thousands of buildings throughout the USA. In most cases these Variable Air Volume and Constant Volume Systems units were installed while the building was being erected and the walls were built around the units enclosing them inside mechanical rooms or other hard to access spaces. Now years have gone by and the Trane SWUD units that are reaching the end of their lifespan. This presents a problem as well as an opportunity. While the old AC units can be torn down and hauled away, it is quite another thing to bring in a suitable replacement unit. Building managers are routinely told they need to knock down walls or remove part of a rooftop and hire a crane to accomplish the replacement task. The expense and logistics to replace the Trane SWUD units can be enormous, leading to much frustration to the end user.

The United CoolAir Renovator was born out of the need to change-out the numerous Trane SWUD units that are in need of replacement. The Renovator is designed to be a direct replacement for Trane SWUD units 42 through 80 tons. These self-contained water-cooled units are shipped in 10 sections and fit through a standard 3.0 door or smaller, all while maintaining their original factory charge. The Renovator maintains the original Trane SWUD footprint while simultaneously eliminating the cost of rigging, permits and tenant disruptions, resulting in cost savings and time for clients.

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Grow Room Units

As cannabis growth facilities begin to expand in popularity, they present a challenge for HVAC units and how best to control the environment in temperature and humidity. Unlike most crops that are grown outdoors, cannabis is grown indoors and therefore needs an environment that can be controlled with the utmost precision. The indoor conditions to promote plant growth must be well ventilated with some way of circulating the indoor air. To begin with, grow lights are used in these types of facilities in the daytime to simulate sunlight and these lights produce a great amount of heat. Cannabis grows best in a moderate temperature that does not fall below 60°(F), or rise above 80°(F), with a humidity level that needs to remain around 50 to 60 percent. If these conditions are not maintained at a consistent level it can lead to mold growth that can damage the crop leading to thousands of dollars in crop damage. United CoolAir has developed special grow room units that solve the problem of how to maintain the best environment for plant growth. The grow units are built with special controls that allow for the AC unit to perform differently during the day and night. These special units are built to mimic the natural flow of cooling during the day and reduce cooling at night all while keeping humidity at optimum levels for healthy plants. United CoolAir all indoor units continue to provide cooling and heating needs for many unique applications.

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Emergency Temporary Portable Cooling and Heating

When tragedy strikes in the form of natural disasters such as hurricanes, tornadoes and other extreme weather events, time and resources are of the essence. Without reliable temporary cooling and heating systems, critical infrastructure can fail, resulting in important social services such as hospitals and other institutions unable to function as well as data loss. Moreover, evacuations require large populations to be housed in large tents or makeshift shelters and having appropriate systems can save lives. Furthermore, AC units that are sold on the retail market are simply not powerful enough to provide adequate relief to a large space or populace as retail units only go up to 14,000 BTUs. Therefore, it is imperative to have mobile, rugged and powerful systems that can reach up to 360,000 BTUs, such as Untitled Cool Air’s units. In addition, larger units are in development.

Built to last

An emergency unit must be built tough enough to hold up under harsh conditions and transport. Instead of cabinets built out of flimsy plastic, you will need a unit constructed from thick metal and quality parts. United CoolAir portable units are built in such a way, with each one tested before leaving the factory. This line of portable units under the name Therm~Air, are self-contained and built with various capacities and sizes such as air-cooled, water-cooled and heat pumps. For over 30 years these well constructed reliable units have been built in the USA.

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Dedicated Outside Air Systems (DOAS) part 3

DOAS and VRF

The choice of installing a DOAS, especially if the existing HVAC system already includes provisions for OA, is for operating efficiencies and the need to meet ventilation code requirements or occupant comfort. But we are now seeing new cooling technology being specified that has no provisions for OA and requires a dedicated outside air system for this purpose. One of these systems is the variable refrigerant flow (VRF) system.

Japan introduced the variable refrigerant flow technology in the 1980s as a flexible way to condition spaces without the complexity of large HVAC systems that require bulky mechanical rooms and expensive ducting. As technology improved, the American market embraced VFR systems but to a lesser degree.

Today’s VRF units offer the building owner/manager many benefits including low first cost, simple installation, minimal maintenance and the ability to run multiple evaporator units from a single condensing unit. But with all its benefits, VRF systems have limited to no ability to satisfy ASHRAE ventilation requirements or remove excess latent loads typical of certain geographical regions.

With rising energy costs and expanding energy consumption awareness, its no wonder variable refrigerant flow technology continues to gain ground in the U.S. marketplace. VRF has the potential to achieve significant energy savings compared to older HVAC systems, according to a study by the U.S. General Services Administration.

Reports going as far back as 2012 indicated the U.S. market was estimated to be worth over $7 billion for VRF systems. More recent estimates of the U.S market indicate a compound annual growth rate of 5.2 percent is expected through 2019. You can expect the sales of DOAS systems will grow as much if not better to match the upcoming surge in OA units.

Not All DOAS Systems Are Built Alike

DOAS systems are an ideal choice for new construction

Retrofit installations add to your existing HVAC system to improve performance. Traditional HVAC roof-top systems require adequate space for the air handler location and ducting large enough to handle both the ventilation/supply and return air. A DOAS is an ideal unit to handle the latent load requirements for OA requirements and dehumidification while the existing HVAC system manages the sensible load.

A DOAS system is ideally suited for retrofit applications where the new HVAC system (air handler and DOAS) must work within the confines of the existing space. The original HVAC system could have been installed in one of many configurations, requiring the design engineer and contractor to manage challenges as needed. Some manufacturers of DOAS units like United CoolAir Corporation have taken this serious problem into account and designed their units with special features to overcome even the most perplexing installation challenges.

United CoolAir’s DOAS, like their entire line of air conditioning equipment, is designed specifically for indoor installation. This feature is extremely important for multi-story buildings that have limited or no access to the roof or ground pad. Units are sized to accommodate floor-by-floor installations, and multiple units are easily installed if more cooling capacity is needed. Air-cooled condensers are easily mounted indoors near an outside wall for waste heat removal, or a water-cooled condenser option is offered if tower water is available.

Unlike the “one size fits all” approach by some manufacturers, the United CoolAir outside air system is made specifically for each project. Vertical configurations are ideal for small mechanical rooms, including closets while horizontal styles offer in-ceiling mounting, saving valuable floor space.

Having the ability to customize your DOAS unit to fit your installation requirements can save thousands of dollars in contractor charges and shorten installation time. United CoolAir’s OmegaAir II allows modification in air paths, component configuration, and utility placement before leaving the factory. They also offer a comprehensive list of factory-installed options to meet even the most complex cooling requirements.

Retrofit applications generally have limited access to the job site. United CoolAir’s indoor, customizable DOAS units can be broken down into sections that fit through standard doorways, halls and into elevators. Lifting units by crane and modifying the building structure to accommodate equipment becomes a thing of the past, saving time and thousands of dollars in building modifications.

United CoolAir charges and tests each of their units before leaving the factory. DOAS units include resealable refrigerant couplings between separable sections to preserve the factory refrigerant charge. Refrigerant couplings are reattached during job site assembly, and ready for immediate operation. Brazing, recharging, and testing is eliminated by saving additional time and money.

Dedicated outside air systems are as necessary to the safe and efficient cooling and dehumidification operation in commercial buildings as their HVAC cooling counterparts. It is important to investigate the many systems available to find a DOAS that best fits your unique retrofit installation requirements.

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