Compact Energy Recovery Ventilator Complements Variable Refrigerant System

A real-world lesson in advanced technology can be found above the ceiling in a newly renovated wing of the Finger Lakes Technical & Career Center (FLTCC). The wing includes offices and conference rooms, which are now being conditioned using variable refrigerant (VRF) technology and ventilation air supplied by three Systemair Topvex energy recovery ventilators (ERVs).

Finger Lakes Technical & Career Center

A Place for Learning

The Finger Lakes Technical and Career Center offers unique opportunities for High School Juniors and Seniors. Students that attend FLTCC develop important skills as they engage in diverse experiences and prepare for the future.

Easy as 1-2-3

The set-up and installation of the ERVs, including the connections to the indoor split units, were extremely straightforward since all Topvex units arrive at the jobsite preprogrammed for the specific project. Operating parameters including CFM, temperature set points, etc. are already programmed into the controller.

EC Equipped

Electronically commutated motors are the key to the Topvex part-load efficiency, as well as the overall longevity of the unit. EC motors are designed to operate at high efficiency even during low RPM periods and consume an average of 30% less energy than AC motors. The motors are standard on all Topvex units so no separate variable frequency drives (VFDs) are required, which reduces wiring at the jobsite.

Americas
2014
Education
Systemair supplied

Topvex FR

Finger Lakes Technical & Career Center

Americas
1–100

How it began  

The Center, one of numerous Boards of Cooperative Educational Services (BOCES) in New York State, offers state-of-the-art technical programs such as Metal Trades, Carpentry and Electrical Trades to hundreds of high school students in Ontario, Seneca, and Yates Counties of New York. Thanks to the recent renovation, it’s now a working example of cutting edge heating and cooling technology.

The mechanical design chosen for the school is representative of a growing trend in multi-zone applications – one that varies and distributes refrigerant rather than water or steam to multiple zones. VRF systems are extraordinarily efficient and flexible, and the fact that they are almost entirely ductless makes them easy to install, particularly in existing structures where space may be lacking. But they do not incorporate a means for fresh air supply. That’s where a decentralized fresh air solution like the Topvex FR ERV comes in. And, as design engineer Al Cook of Beardsley Design Associates says, it was the perfect complement the VRF system chosen for this project.

The Right Fit and CFM

Beardsley Design Associates, a firm specializing in sustainable architectural and mechanical design for a variety of commercial and institutional markets, was selected to design the mechanical renovation at the Stanley campus, but there were challenges. The “D” wing of the Stanley facility included some conference rooms and other spaces with outdated baseboard heating, but no cooling or means for fresh air. Built nearly a half century ago, the building had rooftop load restrictions that eliminated the option of installing conventional air handlers on the roof to supply fresh air. Furthermore, a traditional ducted system would have been difficult if not impossible to discreetly install given the existing walls and layout.

Given these circumstances, Beardsley chose a zoned VRF heat pump system for heating and cooling, and Topvex ERVs for fresh air supply. The latter was small enough to install above the ceiling where it is ducted directly to the VRF indoor split (terminal) units that were also installed above the ceiling.

An outdoor VRF heat pump is piped to the indoor split units, supplying refrigerant as need to the individual zones. This combination of space and energy efficient equipment not only brought the spaces up to code, but introduced a whole new level comfort and control to the building spaces.

As a firm, we are very efficiency conscious and we always use energy recovery ventilation on our projects, but It’s hard to find any ERV that delivers CFM in the 750 to 1000 range. These units can do that.

Al Cook
P.Eng., project engineer for Beardsley Design Associates.
Topvex FR

Standard Features Enhance Longevity, Efficiency

The fresh air challenges at the Stanley campus are common to many K-12 renovations. Space limitations and rooftop load restrictions often rule out more conventional, centralized HVAC solutions. These are the primary reasons a school might typically opt for a solution like the Topvex that actually fits within the building envelope. But many other benefits apply such as longer equipment life, part-load efficiency, and serviceability.

Electronically commutated motors, or EC-motors as they are commonly called, are the key to the Topvex part-load efficiency, as well as the overall longevity of the unit. EC motors are designed to operate at high efficiency even during low RPM periods and consume an average of 30% less energy than AC motors. The motors are standard on all Topvex units so no separate variable frequency drives (VFDs) are required, which reduces wiring at the jobsite. The motors do not require any greasing and are virtually maintenance-free. They are also quiet, which makes them particularly appealing for above ceiling installations in classrooms and conference rooms.

Bag filters are another unique standard feature of the Topvex unit. The filters are designed with greater surface area so they last longer. When replacement is required a built in pressure transmitter that measures the filter pressure drop alerts personnel via the control panel or Building Management System (BMS). The filters are mounted on guiderails for easy removal and replacement. This is the only maintenance procedure required for the Topvex ERVs, which is a big plus for K-12 campuses where maintenance staff is often limited.

Design and Control

The set-up and installation of the ERVs, including the connections to the indoor split units, were extremely straightforward since all Topvex units arrive at the jobsite preprogrammed for the specific project. Operating parameters including CFM, temperature set points, etc. are already programmed into the controller.

Topvex installations can be designed to work in concert with a VRF system, or operate independently. At the Stanley campus, each of the three Topvex units are ducted to individual indoor split units serving the various zones. Fresh outdoor air passes through the ERV where it is pre-conditioned with return air, and then enters the indoor split units where it may be heated or cooled depending on whether the space temperature is satisfactory. During shoulder seasons, the VRF system operates very little, with the ERV providing ample fresh air and temperature maintenance. During cold weather operation the ERV has an exterior mounted, electric pre-heater which heats outdoor air as needed to keep the internal heat wheel from freezing. On the supply side of the ERV (but still internal to the unit) there is a hydronic reheat coil and modulating valve that modulates flow as needed to heat the supply air if the heat wheel cannot recover enough energy from the exhaust air.

Both ERV and the VRF systems have user interface and remote controllers, which are connected to the campus’ BMS.

“I think the greatest advantage to this ERV is the slim design. Other ERVs tend to be much taller and wider because of how their heat wheels are designed. But the Topvex FR can fit above a drop ceiling, so you can install them in close proximity to the indoor split units. And there’s very little ductwork to be installed.

Benjamin Hardy
Service technician for Modular Mechanical Service

Size. Quality. Capacity.

The Stanley campus renovation illustrates the problem-solving potential of the Topvex ERV, particularly with VRF applications.

Schools are expected to provide many decades of service, so investing in high efficiency equipment that also meets stringent indoor air quality standards makes sense. Topvex ERVs are the perfect complement to VRF systems as they provide the necessary ventilation in an energy efficient package that can be located in spaces where most ERVs cannot.

Benjamin Hardy, service technician for Modular Mechanical Service, oversaw the HVAC start-ups at the Stanley campus, and agrees that the combined systems provide an excellent solution for schools and other light commercial projects.

Want to know more?

If you would like to know more about this project or would like to speak to one of our IAQ experts, please reach out to our sales team, at sales@systemair.net 

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