Best practices for HVAC efficiency

As the calendar turns to the hottest time of the year for most locations, it is imperative that hotel HVACs are working optimally. If a room isn’t being properly air conditioned, guests will complain and that could lead to bad reviews. A broken unit will cause a room to be closed to guests, losing valuable revenue-generating space.

Modine, headquartered in Racine, WI, has been around for more than 100 years since its founder began manufacturing thermal solutions for the automotive industry. The firm has supplied dedicated outdoor air system units that have been installed in many hotels, including Hilton, Marriott and IHG properties.

The company has offered up a number of best practices to make sure an HVAC is running properly.

Indoor air quality has become a hot topic during the COVID-19 pandemic, as hoteliers and guests have worried about virus transmission inside guestrooms and other areas of a hotel.

In order to maintain good indoor air quality, the first thing is to ensure you get the proper amount of ventilation into the building, noted Joe Ellison, sales manager, Modine.

“ASHAE 62.1 provides guidance on how much ventilation air is required depending on the type of space you are conditioning,” he said. “As part of good indoor air quality, humidity levels within a building are often overlooked. It’s important to properly dehumidify the outside air that is being introduced as ventilation to prevent odors and mold/mildew growth.”

Proper filtration is also key. “Many organizations are recommending that buildings upgrade their filtration to a minimum MERV 13 as a result of the pandemic,” said Ellison. “This efficiency level is higher than was often used in the past, and therefore will capture more particulates in the air. The hotel operations must, however, change their filters more regularly.”

Outdoor air, and how it’s being incorporated, is a key factor. Ellison said dedicated outdoor air system (DOAS) units are growing in popularity.

“In this type of system, there are rooftop units that heat, cool and dehumidify 100% outside and deliver this air to various zones within the building at load-neutral conditions (70 deg F, 50% rH),” he noted. “This helps to ensure the proper amount of ventilation air is being introduced into each zone within the building. Additionally, DOAS units incorporate important features like hot gas reheat that help make sure the outside air being introduced to the building has been properly dehumidified without overcooling the space. Terminal equipment in each zone (i.e. each hotel room) handles the sensible heating and cooling load, still allowing for individual occupant comfort and control by zone.”

Modine manufactures the Atherion DOAS unit, which has been incorporated into many hotel HVAC systems to help ensure superior indoor air quality, according to the company.“Innovative features, such as its condensing efficiency gas furnace, can reduce heating bills, potentially qualify for utility rebates and cut down on CO2 emissions,” he said. “Unique control strategies, such as Modine’s patented hot gas reheat circuit for dedicated outdoor air equipment, can help to reduce temperature variations within a building while maintaining ventilation rates and dehumidification control in high occupancy spaces.”

Ellison pointed out that the company recently supplied the Atherion DOS unit to a Tru by Hilton property in New Hampshire.
“The hotel is required to meet demanding ventilation standards to maintain healthy indoor air quality for guests,” he said. “To meet these standards, the developers wanted to use a high-efficiency ventilation solution that would qualify for rebates from National Grid, an electric and gas company serving the citizens of New Hampshire. CDB Mechanical LLC, the commercial HVAC contractor for the project, worked with Emerson Swan and Resilient Buildings Group to source and install a Modine Atherion unit on the roof of the building. The system offers indirect-fired, condensing efficiency gas furnace heating using our Conservicore technology. The Atherion is consistently meeting all ventilation standards for the hotel. Its indirect-fired, condensing efficiency gas furnace technology provides up to 94% thermal efficiency.”

Ellison also offered some maintenance tips. “Regularly change your filters to ensure they don’t plug up with debris,” he said. “A blocked filter could lead to improper airflow over the coils within an HVAC unit, thus creating a larger maintenance issue. Utilize a proper start-up when equipment is first installed.”

Every hotelier wants to save money and keep HVAC units as energy efficient as possible. Ellison suggested that energy recovery devices should be used to pretreat the ventilation air “These include devices such as heat pipes, fixed plate heat exchanger and, most commonly, energy recovery wheels,” he said. “Energy recovery wheels use the energy in the relief air (air being expelled from the building) to pretreat the ventilation air being introduced. They can be incorporated into dedicated outside air systems and reduce both the size and capacity of the HVAC equipment needed to serve the space, as well as the operational costs to run that equipment. Although this may increase the first cost of the HVAC equipment, the hotel owner sees operational savings in running the HVAC systems.”

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