LONG-STANDING TRADITION

The oldest heating technology is the boiler, having been installed for residential and commercial space heating purposes for over 200 years. As Syed Shahzer, commercial trainer for Bosch Thermotechnology explained, buildings were initially heated via steam boilers, using coal as the primary fuel. Since then, the technology has evolved drastically, and for the last 15 years, the industry has been utilizing energy-efficient condensing boilers to heat buildings.

Compared to other heating technologies, boilers are more technically advanced in terms of efficiency and controls, said Shahzer.

“Updated controls technology allows the condensing boiler to adjust to the needs of its respective users and heat the building per their comfort requirements,” he said. “Boilers can also adapt to outdoor weather and have the ability to heat different heating segments/elements per their requirements.”

Boilers can cost more initially than other technologies, which is why it is important that contractors help their customers understand the total cost of ownership and not just first cost.

“Making low-cost investment decisions can cause higher costs of ownership to customers in the long run,” said Shahzer. “Although the initial investment cost might be higher than other options, generally, boilers will have a quicker payback and can help to save money in terms of utilities.”

In addition, equipment designs are changing, with manufacturers placing more emphasis on boilers that have a smaller footprint, minimal piping, and are easier to install and service. Bosch, for example, has designed its boilers so that all of the components are easily accessible and do not require frequent maintenance, according to Shahzer.

WIDELY USED

The rooftop unit (RTU) is another technology that can be used to effectively heat (and cool) commercial buildings. While they may not have the long history of boilers, RTUs have been available for decades, and it is estimated that they are used in approximately 40 percent of all commercial buildings.

The greatest advantage of RTUs is the simplicity of implementing them, said Chris Stocker, product manager of commercial rooftops, Daikin Applied Americas, as a rooftop unit is ready to operate as soon as it is connected to the power and ductwork.

“What sets today’s rooftop technology apart from other HVAC equipment is the ability to modulate and tightly maintain indoor air quality and occupant comfort to levels previously only available in more applied systems,” Stocker said.

This ability to incrementally control the airflow, heater, and refrigerant volume allows the minimum amount of airflow tempering to prevent the overshooting and undershooting of space requirements experienced with staged equipment, he added. The direct-drive fans of Daikin Applied’s Rebel®, for example, can moderate wheel speed to provide the precise airflow required in a space, whether it is a single-zone variable air volume (VAV), multi-zone VAV, or even a dedicated outdoor air system (DOAS) unit with demand control ventilation modulation.

The greater level of comfort control offered by VAV systems is one of the reasons why Steve Stachorek, president, Atomatic Mechanical Services Inc., Arlington Heights, Illinois, believes that RTUs are a great choice for many commercial customers.

“They are also easy to install, they’re reliable, and they typically have a lower first cost compared to other types of HVAC equipment,” he said. “For a single-story building, installation is extremely simple. And because the controls are typically packaged, the system usually works out of the box without much troubleshooting.”

Rooftop technology, in general, provides simpler installation, service, and maintenance compared to other HVAC solutions, said Stocker. The smart and connected controls offered on many rooftop units, such as Daikin’s Intelligent Equipment, allow contractors to remotely log into the equipment and have complete operational control.

While initial cost may vary depending on the application, rooftop solutions implemented with technologies such as electronically commutated motor (ECM) direct-drive fans, modulating gas burners, and inverter compressors offer building owners a system that is both budget-friendly and easy to install, said Stocker. And they are flexible.

“No two buildings, wings, or individually occupied spaces are exactly alike,” he said. “So why should buildings be conditioned with devices that can’t treat them as unique facilities? Rooftops have the ability to optimally modulate the heating, cooling, ventilation, and overall airflow for the specifications of each space. Beyond the comfort and conditioning of the space, modulation creates the additional benefits of energy conservation and minimized maintenance.”

THE NEWCOMER

The relative newcomer to the commercial heating market is the VRF system, which exploded onto the U.S. scene less than 10 years ago. VRF technology is a great option for building owners who are looking to minimize operational costs while simultaneously increasing occupant comfort, said Chuck Hughes, director of applied products sales, LG Air Conditioning Technologies.

“With the ability to do simultaneous heating and cooling through heat recovery, not only do occupants get to personalize their comfort, but they do so within a single system, eliminating the need for a separate heat source, reducing the impact to the outdoor environment, and contributing to lower operational costs,” he said.

In addition to being energy efficient, VRF technology is flexible, as systems can be configured to be ducted, duct-free, or a hybrid of the two, allowing building owners to choose the system that best fits their needs. This flexibility allows VRF to be installed in almost any comfort heating/cooling application, including projects where traditional systems are not feasible.

Flexibility is just one of the many reasons why VRF systems can be a good choice for commercial customers, said Ike Beyer, president, Integrated HVAC Systems & Services Inc., Islip, New York. He also likes that they offer high energy efficiencies, precise temperature control, and heat recovery, and they have the ability to simultaneously heat and cool a building.

Beyer noted that VRF systems are easy to sell, as far as air conditioning is concerned, and when it comes to heating, his company tries to incorporate a hybrid philosophy.

“If gas is available and already being used, we like to combine hot water baseboard, for example, to wash the building perimeter with heat, while utilizing the VRF as second-stage or auxiliary heat,” Beyer said. “In buildings where VRF is the only source of heat, once we explain to the owners the dependability of the systems at very low outdoor temperatures, they are generally fine with the offering.”

Hughes added that in the vast majority of cases, VRF can handle 100 percent of a building’s space heating needs. LG’s Multi V 5, for example, provides an all-weather solution, offering an expansive operating range that allows it to properly heat and cool a space all year long.

VRF systems are also cost effective, explained Hughes, citing an independent survey conducted in 2016 that compared the all-in first costs of HVAC systems. The report concluded that the reductions in the structural, mechanical, and electrical costs of installing a VRF system offset the higher cost of the mechanical system itself, making the all-in first cost of VRF comparable to other HVAC solutions.

In terms of life cycle cost, VRF is often the most economical solution available, said Hughes. “Typically, VRF has the lowest electrical consumption of any comparable system,” he said. “Combine this with the comparable first cost and low maintenance cost of operating VRF, and you have very low overall life cycle cost.”

When it comes to selecting a space heating solution, building owners and managers have plenty of options from which to choose. Depending on their particular needs, a boiler, rooftop, or VRF system may be the right choice, and provided that it is designed and installed properly, whatever system they choose will likely offer many years of comfortable, cost-effective, and reliable heating.

Publication date: 10/1/2018

Want more HVAC industry news and information? Join The NEWS on Facebook, Twitter, and LinkedIn today!