Fresh air Archives | United CoolAir

January 22, 2021 by Kevin Stepp

What ERVs Can’t Do

Background

Energy recovery ventilators (ERVs) have flooded the HVAC market. Building owners want more fresh air in their buildings, but don’t want to pay the costs associated with conditioning it. They know it is far more costly to remove heat and humidity from 95° air than it is to do the same with return air. So, the industry has turned to the energy recovery ventilator as a means of efficiently reducing ventilation costs.

ERVs use a device (typically a wheel or a fixed plate) with heat transfer media to exchange heat from a building’s exhaust air to its fresh air source. In the summer, this means pre-cooling the outside air before it reaches a cooling coil, and in the winter it means the opposite; pre-heating the air before it reaches a heating coil. Pre-treating the air reduces the amount of energy required to heat or cool it. ERVs accomplish this with little power consumption, making them a desirable means of adding fresh air to a building.

The ERV Problem

Standard energy recovery ventilators, though, are a half-measure. While ERVs provide energy savings, they stop short of fully conditioning the air they are responsible for bringing into a building. Most ventilators discharge air off of the media at around 80° db and 67° wb in the summer. These are the classic full load design conditions for commercial comfort cooling applications. So, while an ERV reduces the outside air load, it adds more CFM of relatively warm, wet air that must be conditioned by the building’s other equipment.

A Better ERV

What if, instead of adding load, an ERV delivered fully conditioned air? The size of the comfort cooling equipment could be reduced and energy dollars would be saved. United CoolAir’s Alpha Aire does just that. By using two energy recovery devices, a small compressor, and a hot gas reheat coil, the Alpha Aire delivers room neutral air to a space. It does so without increasing load on the existing equipment. Plus, the unit is so efficient that it operates at near identical FLAs to the top ERVs on the market. Click this link for more details on the Alpha Aire, and join our mission to provide healthier, more efficient buildings.

February 27, 2019 by Matt Hanson

Choosing a Dedicated Outdoor Air System (DOAS)

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 methods used to help regulate temperature and humidity. Schools, hospitals, offices, and other commercial spaces can all benefit from a DOAS unit. 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.

Although DOAS units are not the primary source of cooling, they help the main HVAC unit work more efficiently. 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.

How to Get Started

Specifying a DOAS unit usually begins with selection software. This takes the basic parameters of the installation and focuses on the specific needs and requirements for fresh air. 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. What this does is reduce the load on the primary AC unit that will be used in cooling the space. Ultimately, this leads to greater efficiency and better indoor air quality with a lower overall cost.

Why Install Equipment Indoor?

Many HVAC manufacturers provide outdoor rooftop equipment as DOAS units, but occasionally a customer might require an all indoor packaged unit. This is the case when the building topography does not allow for outside mounting. Furthermore, codes that affect historic buildings often don’t allow for HVAC equipment to be installed outdoors. This is the case even if there were ample room on the roof or outside. The indoor packaged solution typically realizes a smaller footprint. This aides in new installations as well as for 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. Some examples would include 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.

By removing outdoor contaminants before they enter the building the indoor air quality will be greatly improved. Additionally, this will allow the main cooling unit to run more efficiently.
The dehumidification process removes moisture from the entering air which helps prevent the formation of mold. These elements can negatively affect the health of the building occupants.
Energy savings are also 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.

August 2, 2018 by Matt Hanson

Mold Prevention and IAQ Improvement

IAQ is a major concern and can have a devastating impact on your life. However, not providing the proper ventilation and fresh air in an occupied space can make people sick. Additionally, this can also have a major financial impact. Hundreds of schools annually are experiencing mold in their classrooms as you can see in the article below (Mold Case Study). A state office building in Texas experienced just this situation. As a result, the cost to the state of Texas was over $15,000 dollars. This incident also sent staff home which has an impact on productivity as well as financial cost. Mold prevention has become a vital element in keeping buildings safe for occupants.

Mold Case Study

United CoolAir has an IAQ Product designed to provide fresh air to avoid mold growth. In fact, Alpha Aire is a packaged Dedicated Outside Air System, Air Source Heat Pump with both an Energy Recovery Wheel and Plate Heat Exchanger. Having two devices in one unit brings in the fresh air at very low dew points while exhausting the interior space air to the outside. Follow the link below for more information on mold prevention with this revolutionary product.

Alpha Aire Overview

Please feel free to contact United CoolAir at (717) 843-4311 if you have any questions.