For Helping Meet ASHRAE Standard 241 – or to Replace ANY other IFB Coil – the Marlo Stratomizer is For You!

December 1, 2023

The Marlo Stratomizer Integral Face and Bypass Coil (IFB), also known as a Dampered Face and Bypass Coil, offers a reliable and efficient way to bring fresh outside air into a building, without the risk of coil freezing – even in very cold temperatures. It preheats outside air and maintains full steam pressure to steam coils, or constant hot water flow in water coils, at all times.

Originally designed to prevent freezing, while delivering more consistent air volume and more accurate temperature control, the Stratomizer now has a new and important role to play in a post-pandemic world. Covid-19 dramatically increased the awareness of, and importance placed on, indoor air quality – including the valuable health benefits of bringing more fresh outside air into a building, rather than simply recirculating indoor air.

As a result, in July of this year, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), published a new code-enforceable standard, called Standard 241, Control of Infectious Aerosols. Developed to reduce the risk of infectious aerosol transmission in buildings, Standard 241 establishes minimum requirements to reduce transmission risk of airborne viruses such as SARS-COV-2, the flu virus and other pathogens.

Helping meet the new ASHRAE Standard 241 for control of infectious diseases.

The single most important aspect of Standard 241 is the concept of “equivalent clean airflow” requirements. According to the standard, equivalent clean airflow is the “flow rate of pathogen-free air that, if distributed uniformly within the breathing zone, would have the same effect on infectious aerosol concentration as the sum of actual outdoor airflow, filtered airflow and inactivation of infectious aerosols.”

This language gives the user of the standard the flexibility to determine how to achieve compliance. In many cases, increased outdoor ventilation will be a more preferred and cost-effective method compared to increased air filtration or the addition of air purification devices designed to inactivate airborne viruses and other pathogens.

However, in colder climates, bringing in more fresh outside air in fall and winter can present significant challenges. The more cold outside air that needs to be heated, the harder a traditional HVAC system will have to work to keep up. Plus, the extra load will result in additional energy usage and associated costs.

But a Marlo Stratomizer dampered face and bypass coil can solve these problems. It is specifically designed to preheat cold incoming air, and to do so much more efficiently than other options, such as the addition of a separate heating coil. It can allow more outside air to flow into a building, while minimizing energy costs – and at the same time, providing coil freeze protection.

How a Stratomizer gets the job done

We’ve written an entire blog post you can read on How a Marlo Stratomizer Works, so we won’t go into great detail here. But, for a quick description, the Stratomizer consists of multiple heating coils, each with damper blades which open and close to allow some air to be directed through the heating surface and some air to bypass the heating surface.

The cold bypass air is then precisely mixed with the heated air to achieve the desired exit air temperature. Temperature sensors in the downstream air automatically control the positioning of the damper blades as outside air temperatures change, maintaining a very consistent and accurate downstream air temperature.

The hot water flow (in water coils) or steam pressure (in steam coils) is never modulated. Rather, the coils operate with maximum water flow or full stream pressure at all times, generating constant heat – which eliminates the possibility of the coils freezing.

Stratomizers can replace IFB coils from any manufacturer.

Because every Stratomizer is custom built – just like all Marlo coils – to meet the individual needs of its application, we can design and build a replacement for any IFB coil, whether it was made by us or by any other coil manufacturer. As with our other coils, you can also choose from a wide range of materials, depending on your needs, including copper, aluminum, stainless steel, and many others.

With cooler temperatures on the way, now is an ideal time to determine how a Marlo Stratomizer can help you meet your heating needs in the coming winter months. Your local Marlo representative can use our MarloMetrics® selection software to design and quote a unit that’s perfect for your application. Search your zip code to find your rep.

Email Registration

Please complete the form below to sign up for our news alerts and other email communications.

"*" indicates required fields