What do Ducted Mini-Splits Look Like?

• Posted by Chris Laumer-Giddens on July 31, 2013 at 5:18am
• View Blog

The most recognizable and commonly used mini-split system is the wall-mounted ductless system. They’re seen all over the world and are starting to become noticed and used here in North America, particularly in homes with small heating and cooling loads. Typically, they are thought to serve only small spaces like bonus rooms, garage apartments, etc. They can actually serve a whole house, and even a whole commercial building. One of the things keeping these systems, with inverter compressor technology, from exploding as whole-house heating and cooling systems is their appearance. Not many homeowners are keen on having these systems “exposed”. That’s what an HVAC closet is for, right?

Here is a picture of me installing one of the two ductless fan coils in our Atlanta Condo. This was a “dry-run”, since we painted the walls prior to final installation.

In response to the demand to “conceal” these “mini” air handlers, or make them disappear, manufacturers started making ducted mini-split systems, where the indoor fan coil is concealed in a dropped-ceiling, attic, or crawlspace, and uses ductwork to distribute the air throughout the zone that it serves. Each zone has multiple rooms, all served by a single fan coil.

The unit shown below is a concealed ducted unit by Mitsubishi Electric as it was being prepared to be installed in the encapsulated attic of a home in Grant Park, Atlanta, GA. As you can see by the person’s foot and leg next to it, it’s not very big. The dimensions for this 15,000 btu/h fan coil is 39″ wide x 28″ deep x 8″ tall.

One of the many questions I get about the ducted mini-splits systems I design for single- and multi-family homes is, “what do the air handlers look like during the construction phase when they’re installed?“, and, “can you have long duct runs with their low static pressures?” (this question comes from the construction industry, mostly HVAC contractors, other home energy raters and builders).

In response to the first question, I’ve included a sampling below of a few local projects we’ve designed to show how and where they can be installed. Every home is different, so the size, location and configuration should be determined individually through a design process.

In response to the second question, definitely! While many of the ducted fan coils come with very low available static (e.g. 0.14 – 0.30 iwc), there are several that are available with 0.60 iwc (inches of water column) and slightly higher. For the systems with low-static fan coils, the Duct Designs (Manual D) we do calculate and verify that duct runs can perform well at as long as 30 feet or more. We will also test these systems (air flow, balance, static pressure, etc.) after they have been installed to confirm that they perform as designed and as expected. The few times we discovered poor performance, we found the installation did not follow the design or manufacturers recommendations.

Project 1 (Grant Park Residence, Atlanta, GA): Mitsubishi MR SLIM – Outdoor Unit: MXZ-4B36NA – Indoor Units: (2) SEZ-KD15NA4

Indoor Unit 1 in Encapsulated Attic

Indoor Unit 2 in Encapsulated Crawlspace

Outdoor Unit (a.k.a. the Heat Pump) in a security cage on the South side of the home

Project 2: Mitsubishi MR SLIM – Outdoor Units (2): MXZ-8B48NA – Indoor Units: SEZ-KD12NA4 (1), SEZ-KD15NA4 (1), SEZ-KD18NA4 (1), PEAD-A24AA (1)

This is one of three fan coils installed in the encapsulated attic to serve the East wing of the home.

Here is the Optional Filter Box (FBM and FBL series) on all Fan Coils in the Accessible Encapsulated Attic Areas

Here is the largest of the fan coils. It serves the entire second floor of the home, and is installed in the encapsulated attic above. This is one of the high-static units that has a range of available static pressure between 0.14 – 0.60 iwc, and can be easily adjusted at the controller. The duct design determines the appropriate static pressure.

This is the fan coils serving the basement. It was suspended from the HVAC Closet ceiling, leaving the floor area available for storage and other equipment.

The basement unit was installed so that it return side of it backed up directly in to an opening the same size as the opening in the fan coil. This eliminated all return plenum ductwork, and transfer grilles (Return Air Pathways, Tamarack) were installed to provide a return pathway from all rooms in the basement.

Project 3 (Proud Green Home at Serenbe): LG Electronics HVAC Division – Outdoor Unit: ARUN036GS2 (1) - Indoor Units: ARNU093BHA2 (2), ARNU123BHA2 (1)

Here are a few shots of this system at the Proud Green Home. We have a more extensive post on the entire mechanical system at this home, including the Zehnder ERV.

Here I am having a little fun. I’m “bangin’ metal” at the Proud Green Home at Serenbe, helping make one of the return plenums

Hope you enjoyed today’s post!

Ductless Market Will Continue to Grow

Manufacturers Weigh In on Future of Ductless

By Angela D. Harris

April 29, 2013


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Contractors, manufacturers, and distributors acknowledge that the ductless market is growing immensely. As more and more consumers opt for ductless solutions, contractors are encouraged to take hold of this trend by acquiring the proper training.


Once considered an overseas staple and domestic add-on, ductless HVAC equipment is now pushing the limits of the add-on market and spilling into contractors’ businesses as a primary system option.

Spanning across residential and commercial applications, HVACR contractors and end users are learning more about ductless equipment and its capabilities, due in part to numerous ad campaigns and word-of-mouth advertising touting its simplicity and benefits. This growing awareness is edging demand upward.

The key to taking advantage of this emerging market, according to some, is preparing HVACR contractors. “Contractors need to understand spot cooling and heating opportunities for mini-splits and how they’ll solve comfort problems without requiring the replacement of a customer’s current system,” said Roy Kuczera, senior vice president, Fujitsu General America Inc., Fairfield, N.J. “More money can be made by installing whole-home or whole-business solutions created by current flexibility and system design.”
Changing the Field

Along with growth and expanded demand, new players in the ductless arena are popping up in the U.S. market.

“The market continues to be very robust and it is expected to once again experience double-digit growth,” said Lee Smith, assistant vice president of product marketing for Daikin AC (Americas) Inc., Carrollton, Texas. “Many traditional manufacturers, some of whom resisted ductless technology as more of a fad, now offer ductless solutions of their own. This heightened awareness is helping to fuel the rapid growth of ductless products.”

A few of the latest manufacturer additions to the ductless product category are Johnson Controls, Unitary Products Group; and Trane, a business of Ingersoll Rand.

Johnson Controls has been in the ductless market outside of North America for some time. In November 2012 the company officially introduced the products in America. “We recently started bringing this equipment to the North American market at the end of last year,” said Mimoun Abaraw, senior product manager, Johnson Controls, Unitary Product Group. “Even so, our customers, including our own branches, have been selling ductless products for 15 plus years.”

As for Trane, the company has had ductless products in its portfolio for more than 20 years. It rolled out its new ductless line in 2012, covering both mini- and multi-split applications for the commercial and residential markets.

“Ductless represents a small but rapidly growing part of the Trane product portfolio in North America,” said Dave Patlovich, product manager, ductless systems, Trane. “Ductless is also an important component of the global Trane portfolio.”

Patlovich mentions that, according to the U.K.-based Building Services Research and Information Association (BSRIA), the North American VRF [variable-refrigerant flow] market is projected to reach $505 million in 2013.

“Trane has always offered a comprehensive HVAC solution,” he said. “With our new VRF line, we now offer an HVAC solution to meet any need.”
The Future Is Now

The word that manufacturers are primarily using in terms of the ductless market in 2013: growth. Some are even predicting significant growth. Increased consumer and contractor awareness is leading to the recognition of the technology’s benefits, which, ultimately is contributing to this growth pattern. Another factor is the continued slow-recovering residential market.

“Housing indicators point to a slow-recovering residential market,” pointed out Kuczera. “Until new construction is back into full swing, the retrofit market will continue to improve.”

Looking toward the possible future of ductless equipment, manufacturers speculate as to what may be for ductless equipment two to five years down the road.

A rising trend in home automation equipment is pushing ductless manufacturers to engage this sector of comfort management, and Fujitsu representatives explained they are expecting to see improvements in ductless equipment regarding the integration of such equipment. The company is also expecting to see increased product breadth, flexibilities, and efficiencies.

Daikin AC is not only seeing the rise in home automation, but it is also proclaiming an advance in ductless features that help expand the units’ applications.

“Manufacturers have taken steps to enhance ambient operation ranges to cover more and more application needs and climatic zones,” explained Smith. “Higher technologies, lower sound levels, smaller footprints, and other features inherent to ductless products are contributing to the success of contractors who want to set themselves apart from their competition.”

LG Electronics USA Commercial Air Conditioning agrees that new products are on the horizon.

“As the market for duct-free solutions matures, we should expect to see greater diversity in system capacities, zoning capabilities, design options, and price points,” said Lorie Quillin-Bell, director, go-to-market, LG Electronics. “Based on customer satisfaction, word-of-mouth, and new applications, we are already seeing a tremendous shift in both the variety of products coming to market, as well as contractors and customers embracing these new solutions.”

With an influx of new manufacturers to the ductless market, some are concerned this will lead to increased competition.

John Clements, senior marketing manager, residential products, Mitsubishi Electric US Cooling and Heating Division, sees this growth as a positive but warns that, “because of the growth potential of the ductless market in the U.S., we foresee increased competition from new manufacturers, some of which will be providing low-cost solutions. The concern is that these low-cost solutions will be lacking in quality and customer support.”

Clements added, “Ductless HVAC is growing exponentially and will continue to grow and thrive as more people become familiar with the technology. Ductless products will continue to adapt to the North American market with improved appearance, flexibility, and controls capabilities.”

Abaraw predicts the market will be introduced to a ductless unit that can be installed in a ducted application in the next two to five years. “In a retrofit application today, an old ducted unit can only be replaced with another ducted unit,” he explained.
Advising Contractors

Just as growth is an overwhelming theme when looking at current ductless predictions, so is involvement when considering manufacturers’ advice to contractors. Most manufacturers are encouraging HVACR contractors to seek adequate training.

“Now more than ever, contractors need to remain current on training and product education, ensuring that all sales staff and technicians are knowledgeable about the technology, duct-free options, and proper installation,” advised Quillin-Bell. “Contractors should work with their manufacturer partners to keep current on trends, applications, and new products available, and to troubleshoot or share best practices.”

In addition to training and education, Clements advised contractors to also take advantage of the marketing tools supplied by many manufacturers. He also stressed having a solid understanding of ductless benefits so when customers have questions, they can be answered with authority.

“Take the time to learn about the many benefits of these systems so you can convey them to potential customers,” he said. “Look for opportunities in every home to provide ductless solutions from hot and cold spots and individual spaces to combination systems and whole-floor multi-zone ductless systems.”

A final piece of advice for contractors who are involved or looking to be involved with ductless equipment comes from Ethan Hoberman, director of sales at Pridiom Group LLC.

“Know what kind of support your ductless brand provides. Ask for it and expect it,” he said. “If your manufacturer can’t provide technical support, warranty supports, and sales support, look for someone else.”

Smith echoed this advice when he said, “Whatever happens, you want to be comfortable in your selection and know that the manufacturer is fully standing behind their products and your reputation in the marketplace by being on hand to support you via
its partners.”

Publication date: 4/29/2013

Carbon Monoxide Alarms Required, Default Leakage Rate Removed In New ASHRAE Residential IAQ Standard

Apr 29, 2013


Contact: Jodi Scott
Public Relations
678-539-1216
jscott@ashrae.org

ATLANTA – The newly published 2013 version of ASHRAE’s residential indoor air quality standard removes the default leakage rate assumption and also requires carbon monoxide alarms.

ANSI/ASHRAE Standard 62.2-2013, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, is the only nationally recognized indoor air quality standard developed solely for residences. It defines the roles of and minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in low-rise residential buildings.

One of the biggest changes in the standard over the 2010 version was an increase in mechanical ventilation rates to 7.5 cfm per person plus 3 cfm per 100 square feet. This is due to the earlier removal of the earlier default assumption regarding natural infiltration.

The Standard 62.2 Committee had previously assumed homes got a minimum of 2 cfm, per 100 square feet, according to Don Stevens, committee chair.

“Because research shows houses have gotten tighter and apartments have always been tight, the 2013 edition drops this default assumption and calls for the entire amount to be provided mechanically,” he said. “The only exception is when single family homes have a blower door test – then the predicted average annual leakage rate can be deducted.”

Another major change is a requirement for carbon monoxide (CO) alarms in all dwelling units. CO poisoning leads to hundreds of deaths and thousands of injuries each year in homes, resulting from automobiles left running in attached garages as well as from portable generators, power tools and heaters, according to Paul Francisco, committee vice chair. A small fraction of poisonings also result from failed central heating combustion appliances.

“Residents have very little ability to sense the presence of CO without detectors, unlike many other indoor polluting events,” he said.

Whether to include CO alarms as a requirement in the standard had been discussed since the standard was first proposed with debate focused on the unreliability and cost of alarms.

Francisco said the committee believes the time has come to make this change, noting that it brings the standard into closer alignment with the International Residential Code, which requires alarms if the house has combustion appliances or attached garages, and with many states that have passed laws requiring CO alarms.

The requirement goes a step further, expanding the protection to all homes, regardless of fuel type or garage configuration, reflecting the fact that many CO exposures occur due to causes completely independent of these factors, he said. It also requires that alarms be hard-wired with battery backup to address an increased likelihood of high CO exposure events during power outages.

Other significant new changes include the removal of the climate limitations on pressurization and depressurization; specifications related specifically to multifamily buildings; and new calculations and weather data for estimating annual leakage based on a blower door test.

The cost of Standard 62.2-2013, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, is $58 ($48, ASHRAE members).

To order, contact ASHRAE Customer Contact Center at 1-800-527-4723 (United States and Canada) or 404-636-8400 (worldwide), fax 678-539-2129, or visit www.ashrae.org/bookstore.

ASHRAE, founded in 1894, is a building technology society with more than 50,000 members worldwide. The Society and its members focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability within the industry. Through research, standards writing, publishing and continuing education, ASHRAE shapes tomorrow’s built environment today.

North America Will Lead the World in Building Commissioning Services Revenue Through 2020

March 22, 2013

Unlike automobiles, which are tested and tuned up on a nearly annual basis, buildings – which consume far more energy – often go through their entire lifecycles without ever being tuned, let alone re-tuned.  According to a new report from Navigant Research, the demand for building commissioning services, which ensure that a commercial building’s equipment and control systems are performing as designed, is accelerating worldwide.  North America will lead the world in this expanding market, accounting for $13.8 billion, or nearly half, of the $28.8 billion in total worldwide revenue for building commissioning services during the period from 2012 to 2020, the study concludes.

“Concerns about the initial costs of commissioning, as well as a lack of understanding and awareness of its benefits, have kept the practice of commissioning relatively rare in the construction industry worldwide,” says senior research analyst Eric Bloom.  “In the long term, however, these barriers will start to fall as the concept is further proven and as green building certification and other high-performance building standards become more commonplace and desirable.”

Over time, the delivery of commissioning services will be transformed through the advent of building energy management systems with continuous commissioning capabilities, according to the report.  These systems, which tie into a building’s existing building management system or building automation system , can continuously monitor and provide fault detection and diagnosis within a portfolio of buildings, enabling a level of continuous improvement that today’s commissioning services and solutions cannot.

The report, “Building Optimization and Commissioning Services”, examines the worldwide market for building commission services, including initial commissioning, recommissioning, retrocommissioning, and continuous commissioning.  Market drivers and barriers are explored in detail, along with global demand-side dynamics. The report analyzes future technology trends in continuous commissioning and profiles 22 key industry players. Market forecasts, segmented by region and by type of commissioning, are provided through 2020.  An Executive Summary of the report is available for free download on the Navigant Research website.

Contact: Richard Martin

+1.303.493.5483

richard.martin@navigant.com

* The information contained in this press release concerning the report, “Building Optimization and Commissioning Services,” is a summary and reflects Navigant Research’s current expectations based on market data and trend analysis. Market predictions and expectations are inherently uncertain and actual results may differ materially from those contained in this press release or the report. Please refer to the full report for a complete understanding of the assumptions underlying the report’s conclusions and the methodologies used to create the report. Neither Navigant Research nor Navigant undertakes any obligation to update any of the information contained in this press release or the report.

4th Generation of VRV - setting the standards

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Available in the UK from January 2013

The new VRV IV heat pump units will be available from January 2013. Daikin products are distributed in the UK by Daikin Airconditioning UK Ltd, a wholly owned subsidiary of Daikin Europe NV, and Space Air Conditioning Plc, the largest independent Daikin distributor.

VRV IV heat pump achieves a new benchmark for efficiency, as it features major enhancements to the already industry-leading VRV solution. VRV IV heat pump offers three revolutionary innovations: variable refrigerant temperature, continuous heating during defrost and the VRV configurator for simplified commissioning and servicing.

Variable refrigerant temperature technology allows installers to customise the system using a choice of presets.

In automatic mode, the system is configured for high efficiency levels throughout the year, while allowing rapid response on the hottest days, thereby ensuring comfort at all times. This technology is capable of delivering a 28% increase in seasonal efficiency, because the system continually adjusts the refrigerant temperature according to the total required capacity and weather conditions.

For example, in mid-season when little cooling is needed, the room temperature will already be close to the setpoint, so a small difference between room and refrigerant temperature is sufficient for the system to operate effectively. In automatic mode, the system will change the refrigerant temperature from 6°C (the current operating standard) to a higher temperature, resulting in reduced energy consumption and significantly improving the seasonal efficiency.

The other available mode is the “high sensible” mode, where energy efficiency is maximised with guaranteed high outblow temperatures and no cold drafts, but the set point may not be maintained so accurately.

Continuous heatingduring defrost is another revolutionary innovation that sets a new standard in comfort, making VRV IV the best heat pump alternative to traditional heating and cooling systems.

Continuous heating finally overcomes any perceived disadvantages of specifying a heat pump because the heat pump continues to provide continuous comfort, even when in defrost mode.

This is important because all heat pumps accumulate ice during heating operation, which must be melted periodically. This defrost operation reverses the refrigeration cycle, causing a temporary temperature drop within the room. VRV IV features a unique heat-accumulating element which provides dedicated energy for the defrost function, while indoor units continue to provide heating and maintain a comfortable indoor climate.

The new VRV configuratorcompletes the trio of innovations, offering an advanced software solution which simplifies commissioning and servicing. The software allows the remote configuration of settings that can be used at multiple sites, so less time is required on the roof, configuring the outdoor unit. Ongoing maintenance is easier too, thanks to a graphical interface that allows engineers to evaluate operational data and errors.

VRV IV integrates with intelligent solutions

To complement the VRV IV heat pump system, Daikin’s new intelligent Touch Manager (iTM) offers an intuitive user interface with a visible floorplan, which can manage up to 2,560 indoor units and provides energy management tools to maximize efficiency.

The VRV IV heat pump can be used together with a wide range of ventilation units, hot water hydroboxes, Biddle air curtains and Daikin’s wide range of fan coil units, including the latest round flow cassettes, which feature a daily auto cleaning filter option that could reduce energy consumption over the year by up to 50%. The Roundflow cassette is also available with a presence sensor that adjusts the set point or switches off the unit when nobody is in the room. This produces potential further savings in energy consumption of up 27% over a typical three hour working period.

Daikin Invests In R&D Jobs

HVAC equipment company to invest $9.2M in Va expansion, creating 50 jobs in Augusta County


By Associated Press, Published: February 13


RICHMOND, Va. — Daikin McQuay plans to invest $9.2 million to expand its manufacturing and research and development operation in Augusta County, creating 50 jobs.

Gov. Bob McDonnell says the subsidiary of Japan-based Daikin Industries plans to upgrade its facility to increase its ability to generate energy-saving global chiller products.

The company is a global manufacturer of commercial heating, ventilating, air conditioning, refrigeration and building management equipment and systems.

McDonnell met with Daikin Industries officials in Japan during his Asia marketing mission in 2011. He also met with the company in New York City on marketing trips in 2011 and 2012.

McDonnell approved a $250,000 grant from the Governor’s Opportunity Fund for the project.

Ontario sets drilling rules to prevent disaster

Ontario is strengthening drilling regulations for geothermal energy systems after averting a potential disaster in Oakville recently.

By: Tony Van Alphen Staff Reporter, Published on Fri May 18 2012


Ontario is strengthening drilling regulations for geothermal energy systems after averting a potential disaster in Oakville recently, but a business leader says the extra costs will put the industry at risk.

The rules will add “significant costs” to vertical geothermal heat pump systems and make them less attractive to consumers, says Denis Tanguay, president of the Canadian GeoExchange Coalition.

“It is very likely that these additional costs will put the industry at risk to a point where the customer return on investment will be delayed by many years,” he said Friday. “The geothermal industry in Ontario is already challenged by high electricity rates. Any additional cost will have a negative impact.”

The Ontario government announced earlier in the day that it will require geothermal installers to obtain provincial approval for vertical closed loop systems. They must also consult with a certified geoscientist or engineer and develop an emergency plan before drilling. The rules are effective immediately.

Furthermore, the Environment Ministry said it will consult industry stakeholders in the next few months about the regulations and conduct inspections to ensure installers are meeting safety standards.

Geothermal energy is a form of renewable energy that leverages underground temperatures to heat and cool buildings. Systems to tap that energy provide an excellent source of green heating and cooling.

They support the government’s long-term plan to use more renewable energy and eventually close dirty coal plants.

“The actions we are taking today and in the coming months will ensure geothermal drilling takes place safely,” said Environment Minister Jim Bradley.

The government moved quickly after urgent calls last week by Oakville Mayor Rob Burton, his town council and the provincial association of fire chiefs for an immediate moratorium on unregulated drilling for geothermal energy installations until it implemented rules for public safety.

Last month, a contractor drilled a borehole for a heating system and struck significant volumes of pressurized natural gas hundreds of metres deep, which could have sparked major explosions, property damage and loss of lives in Oakville.

The local gas utility and town fire department received an emergency call from the owner of a home about 100 metres from the drilling site a few days later.

High levels of natural gas (which is odourless in its naturally occurring state) were found inside and outside the home. Officials took steps to ensure proper ventilation and monitoring.

Tanguay acknowledged the new rules may help avoid a similar incident. But he noted that in the Oakville case, an engineer or a geoscientist could not have guessed installers would hit natural gas at 120 metres since underground mapping of the area showed its presence at about 380 metres.

“Disaster could be averted with multiple gas detectors on the drilling rig so that the operator knows precisely what is happening when it is happening,” he added, offering an alternative.

“In short, drilling activity comes with a risk. Anything that can be done to reduce those risks is good. But the current regulation may not be the answer.”

Since 2008, companies have installed more than 8,800 geothermal systems in Ontario. About 15 per cent involve closed loop vertical systems.

The average price for a four ton vertical geothermal heat pump system in Ontario is about $32,000. A similar system with a horizontal loop has a price tag of about $28,000.

Tanguay said it would be difficult to estimate how much more the systems would cost with the new rules.

ACCA Names Magic Touch Mechanical 2013 Residential Contractor of the Year

For Immediate Release:
January 30, 2013

Contact: Melissa.Broadus@acca.org
703-824-8842


ACCA, the nation’s largest association of indoor environmental systems professionals, has named Magic Touch Mechanical in Mesa, Arizona, its 2013 Residential Contractor of the Year.

“Each year many of the best residential contractors in the industry apply for this award, and share the unique business practices that make them so successful,” said Paul T. Stalknecht, ACCA president and CEO. “It is always a difficult decision for our panel of judges to choose who they consider the ‘best of the best’ from the group. This year’s winner, Magic Touch Mechanical, is an extremely deserving company that truly exemplifies the qualities that all of the best companies in the industry share.”

Magic Touch Mechanical will be presented the Residential Contractor of the Year award on February 27 at the opening general session of ACCA 2013 in Orlando, Florida.

Magic Touch Mechanical’s customer-centric business model is bolstered by the use of social media and review sites to enhance their customers’ overall experience.

Over the past 15 years, Magic Touch Mechanical has grown to be a leader in their market by focusing on “doing the right thing” by their customers. The company puts a focus on educating their customers and providing a full range of options that allows the customer to make a decision about what work needs to be done now, what needs to be done later, and what they feel doesn’t need to be done. The company is a firm believer that the “whole home approach” is the best way to provide their customers with the best comfort possible.

Magic Touch Mechanical has connected with customers through its investment in social media and review sites. The company is active on both Twitter and Facebook, sharing company information, updates, and tips with their service area. They also encourage all of their customers to post reviews on sites such as Angie’s List and Kudzu, and they consistently follow up with those customers who do so.

“To be named Residential Contractor of the Year out of all of the best contractors in the nation is the equivalent of being a Gold Medalist at the Olympics,” said Rich Morgan, president of Magic Touch Mechanical. “It’s probably pretty easy for an Olympic athlete to win an award in his or her event when up against a lesser athlete; it’s a whole other achievement when pitted against the finest athletes in the world. For that reason, winning this award is Magic Touch’s Gold Medal!”

Magic Touch Mechanical is only one of the thousands of top contractors who will be attending ACCA 2013, February 26 – March 2 in Orlando. Learn more and register online at www.accaconference.com or call 703-824-8856.


The Air Conditioning Contractors of America (ACCA) is a non-profit association serving more than 60,000 professionals and 4,000 businesses in the indoor environmental and energy services community. Founded more than 40 years ago, today ACCA sets the standards for quality comfort systems, provides leading-edge education for contractors and their employees, and fights for the interests of professional contractors in every state in the country. Learn more at www.acca.org.

Variable Refrigerant Flow: An Emerging Air Conditioner and Heat Pump Technology

 


Ammi Amarnath, Electric Power Research Institute
Morton Blatt, Energy Utilization Consultant


ABSTRACT
This paper reviews the attributes of  an emerging space conditioning technology;
variable refrigerant flow (VRF) systems. Material presented in this paper was synthesized from
the open literature, private interviews with industry experts and data (sometimes proprietary
data) obtained from manufacturers. VRF systems are enhanced versions of ductless multi-split
systems, permitting more indoor  units to be connected to each outdoor unit and providing
additional features such as simultaneous heating and cooling and heat  recovery. VRF
technology uses smart integrated controls, variable speed drives, refrigerant piping, and heat
recovery to provide products with attributes that include high energy efficiency, flexible
operation, ease of installation, low noise, zone control, and comfort using all-electric
technology. VRF systems are very popular in Asia and Europe and, with an increasing support
available from major U.S. and Asian manufacturers are worth considering for multi-zone
commercial building applications in the U.S.

 This paper provides an overview of variable refrigerant flow system technology,
including the market situation, advantages and disadvantages for the customer, possible impact
on the electric utility, applications recommendations, and technology attributes. Also addressed
are what is holding back the technology, including lack of verified third party field data; codes
and standards issues; technology improvements needed; and market actions needed to increase
penetration of these systems.


Evolution of the Technology

Ductless space conditioning products, the forerunner of multi-split and VRF systems,
were first introduced in Japan and elsewhere in the 1950s as split systems with single indoor
units and outdoor units. These ductless products  were designed as quieter, more efficient
alternatives to window units (Smith, 2007).

Products have evolved from a few indoor units operating off each outdoor unit, to multisplit products with 4 units to 8 units in the late 1980s, to 16 units in the early 1990s, to 32 units
by 1999. Today’s advanced systems permit as many as 60 or more indoor units to operate off one
outdoor unit, enabling application in large commercial buildings. Electronically commutated
motors, inverter-driven/capacity modulated scroll compressors, multiple compressors, versatile
configurations and complex refrigerant and oil circuitry, returns, and controls have enabled this
addition of up to 60 indoor units. Refrigerants have also changed. The early “mini-split” systems
used R-22 refrigerant, then R-407C, and today’s systems rely on R-410A. Figure 1 shows the
piping and refrigerant flow for conventional split systems (one indoor and one outdoor unit)
multi-split systems, and variable refrigerant flow systems (Dyer, 2006).

Multi-splits offer some of the major advantages of VRF systems, such as zoning, capacity
control, ease of retrofit, low installation costs, and minimizing ducting and use of secondary
2008 ACEEE Summer Study on Energy Efficiency in Buildings 3-1fluids and associated costs and losses. On the other hand, their simpler piping results in longer total length of piping compared to VRF systems. Similarly, multi-split heat pumps do not have the opportunity for heat recovery between units that are cooling and units that are heating. As such, multi-split systems should be considered  for smaller, simpler buildings where heat recovery is not a possibility and fewer numbers of zones need to be conditioned.


How Does VRF Work?
 
Multi-splits include multiple indoor units connected to a single outdoor unit. Ductless
products are fundamentally different from ducted systems in that heat is transferred to or from
the space directly by circulating refrigerant to indoor units (evaporators or condensers) located
near or within the conditioned space. (When the indoor units are in the cooling mode they act as
evaporators and when they are in the heating  mode they act as condensers.) In contrast,
conventional ducted systems transfer heat from the space to the refrigerant by circulating air (in
ducted systems) or water (in chillers) throughout the building.

VRF systems are enhanced versions of ductless multi-split systems, permitting more indoor
units to be connected to each outdoor unit and providing additional features such as simultaneous
heating and cooling and heat recovery. VRF heat pump systems permit heating in all of the indoor
units, or cooling of the all the units, not simultaneous heating and cooling. Heat recovery systems
provide simultaneous heating and cooling as well as heat recovery to reduce energy use during the
heating season.

Over the past 15 years the technology has advanced in a number of areas:
• Standard compressors to variable speed and capacity modulated scroll compressors
• Direct driven outdoor fans to variable frequency drive, inverter-driven fans
• Direct driven indoor coil motors to direct current or ECM-type motors
• Variable capacity indoor units
• Better heat exchanger surfaces with multi-segmented coils
• Improved controls and diagnostics
• R-22 to R-410A
• Better refrigerant charge and oil management
 
 Other features include the addition of  concealed ducted units and ceiling cassette
configurations to the traditional wall-mounted units. Refrigerant piping runs of more than 200
feet are possible and outdoor units are available in sizes up to 240,000 Btu/ hr.

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