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The 15 Mitsubishi R2 Series units on the roof of Towson City Center have freed up the 13th floor

mechanical room, which is now used as the building’s data center. Photo courtesy Mitsubishi.

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Field Notes on Commercial VRFcompiled by Terry McIver | Contracting Business

Variable refrigerant flow heating and air conditioning technology has found a secure footing as a

comfort option for a variety of commercial HVAC applications.

Here are two case studies of successful VRF installations, and comments from contractors posting

to HVAC-Talk.com.

Variable refrigerant flow (VRF) heating and air

conditioning technology has found a secure footing as a

comfort option for a variety of commercial HVAC

applications. Here are two case studies of successful VRF

installations. Comments are also included from contractors

posting opinions on HVAC-Talk.com.

VRF Replaces School Boiler

Sycamore Elementary School, Dorr, MI, is just one example of a school where

administrators are starting to pay attention to energy efficiency.

Sycamore Elementary School asked Vytau Virskus, with Millennium Energy, to help

them replace their previously outdated boiler system with more effective and energy

efficient HVAC system. The project

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Building size made rooftop installation impractical,

so the LG Multi V IV units were staged on Sycamore

school grounds. Photo courtesy LG.

needed a solution that not only had low

energy consumption, but would also keep

the children warm during the chilly

Michigan winters and cool during the hot

summers.

“We were looking for a system that

would not only cut costs, but also provide

a quiet and functional classroom

environment for the students,” said

Virskus, “We were also able to connect

the unit to a dashboard that will measure

the energy efficiency over time.”

After evaluating a variety of different

options, Millennium Energy chose LG

Electronics’ Multi V IV Air Cooled

VRF Heat Pump system because of the

quality and benefits it provided.

The Multi V IV is designed to meet the

needs of a varying Michigan climate

such as Michigan — which can have very cold winters and very hot spring/summer

temperatures. The Multi V IV system allows teachers to heat or cool specific areas of the

building simultaneously in an energy-efficient manner, which is a significant benefit over

ducted systems. Rooms in direct sunlight can be kept cool, while rooms that receive no

sun can be warmer. The LG Multi V IV also offers users a more compact product that is

lighter in weight than any other model currently on the market, according to the

company.

The flexible design enables the VRF system to adapt to any current setup a building can

offer and requires fewer materials than other systems. For Sycamore Elementary, Virskus

was able to integrate the HVAC system into the existing environment using the AC Smart

Premium control system provided with the LG package.

‘Sick’ Building Cured with VRF Makeover

In 2002, a 15-story office tower in Towson, MD was diagnosed as a “sick” building, and

closed due to major ventilation issues. Today, the Towson City Center is certified as a

LEED Silver building, thanks in part to a VRF system from Mitsubishi.

Caves Valley Partners, a

Towson-based real estate

development firm, acquired the

building in 2012, and was intent

on reviving it through a state-of-

the-art modernization program.

The renovation included a new

glass curtain wall façade and full-

scale replacement of the 170,000

sq.ft. building’s electrical and

mechanical systems.

The massive amount of work was

completed by Mechanical

Engineering & Construction

Corp. (MEC2) of Baltimore.

Steve Wagner, director of

engineering for MEC2, and

company principal Rich Beattie,

said the challenging work ahead

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Taking the Current Out of Current Switches

New technology allow s a current sw itch to be configured

outside of an electrical enclosure and installed on a cold

w ire, thereby eliminating the need for a PPE suite and

preventing arc f lash hazard. PPE suits, w orn by

technicians w orking in a live enclosure, are often More

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Towson City Center

of them include gutting the entire

tower, with only structural steel,

slabs, and elevator core left

standing. Another challenge was

working with the low deck height

of the building’s original design.

The space between floors

measured only 10 ft., 6-in., not

the usual 14-ft. found in most

buildings. Therefore, a ducted

HVAC solution was unworkable.

Only a non-ducted solution

would do, and keep the project a

condender for LEED status.

The team selected a Mitsubishi

VRF R2 Series zoning system,

which helped the design team

meet the challenges before them.

They installed 15 rooftop units.

“It was combined with a

dedicated outdoor air system

(DOAS) providing all the

ventilation to the building, which

left the Mitsubishi system to be

the heating and cooling

component of the system. The system trades heat between the interior and exterior. So in

the shoulder months you’re getting heating and cooling for free,” Wagner explained.

“Because the Mitsubishi multi-port controller makes the system so flexible, we were able

to easily orchestrate the piping and wiring for each floor,” he continued. “It’s so much

easier and less costly to install, that individual zoning becomes immediately available.

When a building isn’t leased, and there’s no interor tenant improvement plan, this system

allows you to install indoor fan coils when space becomes rented and rooms identified.

"We needed to integrate the system into a building management system. We had a

separate BMS which controls many of the functions of the building. The Mitsubishi

Electric system integrated seamlessly into that BMS, where we can access the data locally

or remotely through any computer. It's all web-based.

According to Wagner, one of the main benefits of the Mitsubishi installation is that it’s a

two-pipe system rather than a three-pipe system. This results in a reduced number of

fittings.

“What we’ve found in the past and we’ve installed plenty of different systems, is that the

labor it takes to complete the pipefitting is reduced with the Mitsubishi system, thus

saving money,” he said.

Mitsubishi Electric’s low-profile (9 7/8-in.) indoor unit fan coils helped the design team

overcome the ducting heigh limitations posed by the low decks. The Mitsubishi zoning

technology earned the project 11 LEED energy points.

Commercial VRF Discussion Forum

On the Contracting Business HVAC-Talk.com discussion forum, contractors share their

experiences with HVAC technology. Here's something of what these contractors had to

say about their experiences with various commercial VRF systems. These comments are

edited. You can visit these links for more of their comments: bit.ly/VFRchat1 and

bit.ly/VRFchat2.

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What Do You Say are Commercial VRF's Advantages?

A1: ”I’ve installed and serviced VRF systems from the ‘big three’ — Mitsubishi, Daikin,

and LG. It’s nice to be running piping next to ancient hot and chilled water pipes,

knowing that you don’t have to mess with those. Performance is almost never a question

with equipment selection. The system modulates to load, so an indoor unit that’s slightly

over-sized isn’t an issue.” — tech45

A2: ”The LG Multi V IV is a very good retrofit application, in areas where space is

limited.” — controlsinmt

A3: ”In the very cold climate of Maine, VRF systems can’t really stand alone without

making some considerations in heating mode. We did a 42-ton unit in a two-story bank

office building. We had six condensers. That system works phenomenally well. We made

provisions to use hydronic coils as the backup, to operate in extremely cold weather. My

biggest complaint is that the building design engineers don’t understand them VRF

products they design them in, so we wind up making modifications to the design from a

technical perspective. They tend to draw piping layouts that don’t meet the

manufacturer’s requirements, such as the distance from the BC (branch control) boxes —

where the 3-pipe system splits — and the units.” — meplumber

A4: ”The drawback is the integration into a Tridium AX front-end. We’re using a BACnet

interface, and it doesn’t seem to communicate as well as we were promised. The dead

band from heating to cooling is also frustrating from an energy conservation standpoint.

I believe the default is two degrees. We have it set at six degrees. So at a 72F set point, it

should go to cooling at 75F and call for heat at 69F. That works, but it will stay in cooling

until the area drops below 69F. The main occupant complaint we have been getting is the

default “fan on” during cooling mode. This complaint is basically from the cassette style

units in individual offices. The only way to have the fan off is to command it off or turn

the unit to heating mode. Occupants do seem to get confused with the room controllers.

They’re not the easiest things to set up.“ — controlsinmt

A5: “You can put three outdoor units together and serve 38 tons. They also seem to have

less piping and refrigerant. Three-pipe systems are very nice. They essentially transfer

heat from one room to another, as opposed to sending it out through the condenser if you

have varying loads. as an example, you can remove BTUs from a server room all winter,

and send them to the occupied space, instead of out through the roof. really makes a

system efficient.” —flange

A6: ”VRF seems to perform well, in the end. Like any system, each job requires tweaking

and time to sort out issues. The good: variable capacity throughout each zone by default;

centralized control by default; definite rules of installation and practices; reliability due to

constant monitoring from the system controls. The not so good: labor expectations

(longer than some are promised); service clearances in occupied ceilings for BC

controllers and branch selectors; wall hung units and condensate.” — tech 45

A7: ”Installers need to be a bit particular during the install, about keeping it clean and

doing it right. For companies starting out, it can be hard to ‘get it together’ when starting

out in the VRF world. You should anticipate some issues with installation when you start

to offer VRF. Heating/cooling costs are typically quite a bit less after putting one of these

in, aside from the ability to dehumidify, heat, and cool all at once.” — numbawunfela

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