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issue: December 2009 APPLIANCE Magazine

Cover Story: 46th Annual Report on HVAC
Putting On the Heat


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Lisa Bonnema, contributing editor

New standards and growth of alternative HVAC technologies are challenging engineers to balance efficiency, cost, and quality.

European HVAC OEM Vaillant Group began producing solar heat collectors, initially for sale in residential heating applications in France and Southern Europe. The company estimates homeowners can use the solar thermal systems to supply an annual average of 20% of their heating energy and 70% of the energy needed for hot water.

HVAC has seen its share of changes in the last five years, but the work has only just begun. With some strong nudges from the Obama Administration, the stakes in the already-competitive race toward efficiency are being raised. And fast. “High efficiency” is shifting from a premium feature to a benchmark you’d better be ready to meet at any price point.

Take U.S. furnace standards as an example. In April, the DOE decided to reconsider the 80% efficiency furnace standard put in place by the Bush administration. The agency is now looking at a 90% standard. The good news is that many furnaces are already operating at this level. However, that does not mean the industry’s work is done.

“As with any new efficiency standard, the change to a 90% standard will bring more pricing pressure to the new ‘entry-level’ products,” notes Andy Armstrong, director of marketing, Unitary Products, Johnson Controls Inc. (Glendale, WI, U.S. www.johnsoncontrols.com). “The designs of today’s furnaces will, of course, continue to improve, but the temptation will be to value-engineer current products to meet what will be an increasing price competition. The greatest engineering challenge for the industry will be to continue to design quality in products, without significantly impacting price.”

As was the case with the 13 SEER air-conditioning standard, Armstrong says the new furnace standard will require strong engineering discipline and testing. “The industry’s engineering community worked hard to come up with easier ways to meet the 13 SEER requirement, including redesigned compressors, condenser coils, and evaporator coils,” he says. “Some of these changes are working better than others. The same forces that challenged manufacturers to create a more-cost-competitive air-conditioner and heat pump will influence the process of 90%+ [efficiency standard].”

Armstrong expects more stringent standards to affect the value-added aspect of furnace design. “Expect to see a proliferation of features within the narrow range of 90%+ efficiency furnaces,” he tells APPLIANCE. ”The industry is already seeing some of these features, including two-stage, three-stage, 10-stage, and 100-stage modulation; fully modulating units; variable-speed blowers; and X13 circulating fans.”

In an effort to offer the consumer more than just high efficiency, Haier recently launched the iFP series intelligent air-conditioners in the China market. The units can sense how many people are in a room and their location within the room. The air-conditioner automatically adjusts the temperature setting and directs the airflow to optimize the comfort level in the room. It saves energy by not running the system unnecessarily.

 New Comfort Zones
A new U.S. federal furnace standard may reduce fossil fuel consumption and may be arguably manageable for the industry, but Matt McBurney, director of the Commercial Products Group at Modine Manufacturing (Racine, WI, U.S., www.modine.com), believes that nationwide standards no longer make sense. “The cost of higher efficiency equipment needs to be equitable in proportion to the benefit received by the consumer,” he says. “A flat, nationwide energy standard may impose unreasonable costs on consumers in areas where lower heating loads are experienced.”

For example, McBurney points out that in southern states higher energy standards would mean high first-cost investments with long payback periods for both the consumer and the environment. Cold climate regions, on the other hand, would benefit largely from moving to a 90% minimum efficiency standard. “The challenge is to come up with meaningful minimum efficiencies standards for different areas of the country,” McBurney says.

Ten years ago, the U.S. industry would have chastised McBurney for those words. But the tide is turning. In October, several residential central air-conditioner, furnace, and heat pump OEMs signed a voluntary agreement with several U.S. energy-efficiency advocacy groups in support of regional efficiency standards that will replace a quarter-century of national standards.

The agreement divides the U.S. into three climate regions—North, South, and Southwest. The proposed standards include three regional standards for split central air-conditioners, two regional standards for package air-conditioners, a single federal standard for split heat pumps, a single federal standard for package heat pumps, a single federal standard for gas-pack systems, two regional standards for gas furnaces, and a single federal standard for oil furnaces.

It’s a lot to keep straight, but most producers seem pleased with the outcome. And they should be. They helped create it. Months of negotiations eliminated more complicated scenarios, including the DOE’s original plan for five different regions that would have split up cooling and heating. At one point, California argued for 16 different climate regions.

According to Dave Calabrese, vice president of Public Policy at the Air-Conditioning, Heating and Refrigeration Institute (AHRI), that is exactly why the industry decided to cooperate with the advocacy groups they fought for so many years. Once the Energy Independence Act of 2007 was signed, HVAC producers knew it was only a matter of time before regional standards took over. “I think our members realized that there are some things you can fight and win, and there are some things you can fight and lose. And this was one we were probably going to lose,” Calabrese says.

And with the memories of 13 SEER fresh in everyone’s minds, Calabrese believes it was a better business strategy to be a part of the process. “It’s better to have a seat at the table and negotiate…than it is to sit back, oppose, and have other people come up with something you are going have to live with,” he tells APPLIANCE. Now, manufacturers know exactly what to expect, and they have three years to prepare.
“It was a long journey, but we ended up in the right place,” says Ken Parks, vice president, Commercial System Unitary Engineering at Trane (www.trane.com). “This gives us certainty on standards and adequate lead time, which will allow us to design and build products to meet the next phase of energy-efficiency standards.”

Thanks to tax incentives and strong support from the U.S. Environmental Protection Agency (EPA), geothermal heat pumps like this Rheem unit are starting to gain acceptance among environment-conscious consumers. In 2007–2008, shipments of both commercial and residential units increased 40%, although the industry expects a 5–10% decline in 2009 due to economic conditions.

Details, Details
Most manufacturers agree that achieving these new efficiencies will mean higher-efficiency compressors, the use of more permanent-magnet motor technologies, and variable-speed technologies. Mogens Rasmussen, marketing manager at compressor supplier Danfoss (Baltimore, MD, U.S., www.danfoss.us) notes that simply investing in variable-speed technology does not guarantee optimal system efficiencies. “To get the full advantage from variable-speed technology equipment, manufacturers must look at the complete system with optimal control of evaporators and condenser fans aligned with the variable compressor operation,” he explains. This means engineers need to consider everything from controllers and piping designs to the selection of heat exchangers and/or reduction of circuits. “It’s a complex and timely process,” Rasmussen says.

The HVAC producers taking this design approach are seeing the results. Lintao Lu, director of Home Comfort at Haier America (New York City, www.haieramerica.com), says that careful application of high-efficiency compressors has been the key to reaching the right system performance, particularly for Energy Star models. “We have partnered closely with leading compressor OEMs such as Hitachi and Toshiba in joint development projects to make sure that both systems and components are optimized for their best performance,” Lu tells APPLIANCE.

Lu says air-moving devices and airflow optimization have also been key to increased efficiency. “We have done countless computer simulations and experimental tests to make sure that each component does perform its intended function and contributes to the optimal system performance,” he says.

Fully modulating equipment is another way manufacturers are improving efficiency. Trane’s residential business recently introduced the XC95m furnace, combining full modulation and Trane’s own communication technology to achieve 95% annual fuel utilization efficiency (AFUE). The modulating communicating technology is designed to prevent the system from overshooting the set temperature and almost eliminates temperature swings. Called ComfortLink II, it connects the system’s key components to automatically configure and calibrate for optimal performance.

The new furnace modulates from 40% to 100% of capacity, in less than 1% increments, based on indoor conditions. “You could compare it to a dimmer switch for your lights,” says Dale Green, vice president and general manager, dealer and distributor channel for Trane, Residential Solutions. “Whereas a single-stage is like an on-and-off switch. It’s either full capacity or nothing.”

Modine has put a lot of engineering focus on improving heat exchanger design. The company’s Effinity93 gas-fired unit heater is based on a high-grade stainless-steel secondary heat exchanger. Unlike traditional aluminum secondary heat exchangers, Modine says its exchanger was designed to withstand the acidic condensate that is a byproduct of combustion. “The selection of appropriate materials for the Conservicore secondary heat exchanger is a key component to its longevity,” McBurney tells APPLIANCE. “The design of the heat exchanger, including the materials selected, has enabled Modine to increase the efficiency of the furnace without increasing the needed footprint of the appliance.”

McBurney says engineers also worked hard to assure proper flow and removal of condensate during the heating and off-cycles of the product. “Proper inlet and outlet heat exchanger header design and configuration assure that condensate does not collect and remain in critical areas of the heat exchanger where it could pose corrosion issues over time,” he explains.

Modine Manufacturing says the design of the secondary heat exchanger, including the materials selected, helped increase the efficiency of its Effinity93 furnace line without increasing its footprint. The condensing unit heater utilizes a bent-tube secondary heat exchanger constructed from high-grade stainless steel.

Innovation Incentives
Of course, the expense of these advancements is a real issue for manufacturers. Playing around with efficiency gains means nothing if it passes on costs to the consumer. Consumer incentives like the American Recovery and Reinvestment Act (ARRA) of 2009 are helping to ease the pressure on manufacturers—or so it would seem. The stimulus package gives homeowners a tax credit of 30% of the installed cost, up to $1500, for qualified equipment. However, as Adam Schuster, manager of product marketing and development at Rheem Manufacturing, notes, this may only add to the pressure. “Manufacturers across the industry are introducing new models that meet the ARRA requirements in a shorter time period and are looking for more cost-effective methods to design products that can achieve the requirements,” he says.

Rheem (Atlanta, GA, U.S., www.rheem.com) expects the ARRA tax credits to continue to drive demand for its HP-50 heat-pump water heater. With a 2.0 Energy Factor, the company is touting the new unit as the most advanced, energy-efficient water heater on the market. Like most air-source heat-pump water heaters, the unit extracts the heat from warm air, intensifies the heat with a compressor, delivers the heat to the water, and exhausts the cooler air.

According to Tommy Olsen, product manager, Rheem Water Heating, it is the unit’s integrated design that sets it apart from other heat-pump water heaters. “Advanced computer and software controlled circuitry is able to efficiently manage both the heat pump operation and water heater operation,” he explains. “This control system allows for the brains of the system to determine just how the water is being used (quick on/off or full draw on the tank). In addition to the water usage, thermistors throughout the system monitor room temperature, refrigerant-to-water heat transfer, and tank temperature.”

Another key feature is that the unit will protect itself from extreme temperature conditions, which Olsen says has been a downfall of previous heat-pump water heaters. The unit reverts to “electric only” operation if conditions exceed its capabilities for heat-pump operation. Rheem also utilized a direct refrigerant-to-water, double-walled heat exchange coil to quickly and efficiently transfer heat to the water.

Ground-loop and geothermal heat pumps may also see a boost in sales thanks to ARRA, which removed the $2000 cap listed in previous legislation and allows consumers to get the full 30% tax credit. It might also help that the U.S. Environmental Protection Agency (EPA) has referred to geothermal as “the most energy-efficient, environmentally clean, and cost-effective space conditioning systems available today.”

Robert Brown, vice president of engineering at WaterFurnace International (Fort Wayne, IN, U.S., www.waterfurnace.com), feels the tax incentive “will be huge” for geothermal. The firm’s residential Envision line of geothermal heat pumps, introduced last year, has a 30 EER and 5 COP. Brown says that while current compressor technology limits manufacturers to around 25 EER, further optimization of heat exchangers and other system components allowed engineers to reach the 30 EER level. “The Copeland UltraTech dual-stage scroll compressor by Emerson was a vital component in our development,” Brown says, explaining that, while most capacity modulation techniques require complicated start components or compressor motor windings, the UltraTech needs only the activation of a simple refrigerant solenoid valve to switch between part load and full load capacity.”

WaterFurnace engineers also worked closely with suppliers to develop the water-to-refrigerant heat exchangers, air-to-refrigerant heat exchangers, and the charge balance and internal air pressure drop requirements for the variable-speed ECM fan motor. “These are all areas where excess energy is lost unnecessarily,” Brown says.

What’s next for this up-and-coming technology, now that all the “low-hanging fruit” has been picked? “We are all awaiting the next generation of technologies, which would include variable-speed compressors, compressor refrigerant management methods to improve capacity and efficiency, and compressor optimization at geothermal conditions as opposed to traditional air-conditioning operating points,” he says.
“Most air-conditioning compressors are optimized for 130ºF (54ºC) condensing temperature and 45ºF (7ºC) evaporating temperature,” Brown says. “More recently compressor manufacturers have recognized that optimization at other conditions can be beneficial for air-source heat pumps and even geothermal heat pumps to better match the compressor optimization with the heat-pump ARI performance points.”

Geothermal has another challenge looming. The U.S. Energy Star minimum performance requirement for closed-loop water-to-air heat pumps will increase from 14.1 to 16.1 EER and 3.3 to 3.5 COP (ARI 13256-1 GLHP) next August, with a second increase scheduled to take effect in 2012.

Ahead of the Game
Yes, there is a lot of work to do, and manufacturers don’t expect it to let up any time soon. “Higher energy efficiency and sustainability are the current trends, and it will stay that way going forward,” Lu of Haier says. “We have applied our resources constantly in those important areas to make our products more energy-efficient, greener, and more sustainable. That’s the proactive way to stay ahead of the curve—anticipate and prepare for the changes, instead of just reacting to the changes.”
Are you prepared?

More of our 46th Annual Report on HVAC:

Engineering Efficient Heat Exchangers

 

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