Ductless systems have been popular in Europe and much of Asia for many years, and they’re gaining popularity in the U.S. market. However, there are still some out there who believe ductless systems can be used for cooling-only applications. Or, they should only be used in retrofit situations where it’s not possible to install ductwork.

But the world of ductless is being shaken up. Sanyo’s recently introduced “Eco Multi” ductless heat pump system makes it possible to connect a series of multiple indoor evaporator units to one outdoor condensing unit. It is possible to install up to eight 12,000-Btu indoor units to each 72,000-Btu condensing unit. This is possible because the system is rated for up to 135% of the outdoor condensing unit’s maximum capacity.

The system provides true zoning capability because it offers the ability to run the indoor units at part-load conditions. Theoretically, that means less energy will be wasted; each of the indoor units will run only long enough to satisfy the demand.


Commercial customers have long been asking for a ductless system just like the Eco Multi, says Tom Crock, national sales manager, Sanyo Air Conditioning Division, Chatsworth, CA.

“Customers were saying they liked the ductless products, but they had no place to put multiple condensing units,” he says. “They were asking for multiple indoor units but only one condensing unit that they could stick up on the roof or some other obscure location. We provide that capability with the Eco Multi.”

For now, the system is limited to commercial applications because of its 208/230-V, three-phase condensing unit. The indoor units themselves are single-phase units, just like the other ductless heat pump products Sanyo manufactures. The company says it did that in order to ease the inventory burden on the distributors, who now only have to stock one line of indoor heat pump units to satisfy multi- and single-zone applications.

What’s really interesting about this system is that it can keep growing. If an application needs more capacity, all that’s necessary is to put in more condensing units. It’s possible to install multiple condensing units with an eye toward future expansion requirements, and the units can be wired together in order to operate as a seamless system. One system controller can handle up to 64 indoor units and multiple outdoor condensing units.

“You could effectively separate the system into four different zones if you wanted,” notes Crock. “It can all be controlled individually, or up to 16 groups can be registered to each zone. There’s so much flexibility in the controls. And each unit has its own separate remote controller with self-diagnostic capability.” Even a timer can be integrated into the system.


The system can run all the time, some of the time, or not at all, depending on the load. That is unlike some other “zoned” systems, which run at full capacity in order to satisfy the thermostat, then turn off again.

As an example of how the Eco Multi system works, if an indoor unit can produce 96,000 Btu but the current load only requires 24,000 Btu, that’s all the unit will produce. It produces enough to satisfy the circumstances, so it’s not necessary to run the system at full bore in order to get the room heated or cooled. Sanyo says this capability allows the system to consume less wattage while still doing the job.

“The Eco Multi gives you the capability of truly zoning a system,” says Crock. “Consider an application with eight indoor units: Two of the rooms are conference rooms, so you may want to run those two units at full capacity. Two others may run at three-quarters capacity, and the other four may run at one-quarter capacity. That provides no particular problem for the condensing unit, as it’s quite capable of handling that load. In a true sense, you have the ability to use the system in a part-load condition.”

While the condensing coil is a standard coil, where Sanyo achieves its “magic” is in the Eco Multi’s two dual-rotor compressors. Each compressor has a two-rotor system in it, so theoretically there are two compressors in one.

One is called the power control compressor. Its principle of operation is that one compressor will pretty much run all the time. It has the capability of turning one compressor on or off depending on the mode in which it’s running. The compressors have the capability of running at 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5%, or 100% capacity, in any combination.

“As that sequence takes place and the demand goes up or down, one or more or both compressors will come on. If you think about four separate rotary chambers in two separate compressor bodies, you’re dealing with a rather simple process here. You’re not dealing with a lot of solenoid valves, etc. You only have one power control valve in each compressor and one external bypass valve between the compressors,” says Crock.

Another benefit, says Sanyo, is that the Eco Multi does not use inverter technology. Its “Power Control” compressor technology can operate without creating harmonic current emissions (hmc’s). Hmc’s distort the electric sine wave and emit electronic noise into the electric system, which can damage electronic equipment in high doses.


In a multi-zone ductless application, the compressor will theoretically not consume as much wattage in a part-load condition, which should lead to a higher efficiency rating.

“We’d like to see ARI recognize the uniqueness of our product and test this product under different criteria,” says Crock. “ARI only allows for multiple-zone systems to be rated at full capacity. Our argument at the moment is that our unit has the capability of running in a partial-load condition, and we need credit for that.”

Another point contractors often bring up when discussing ductless systems is the higher first costs involved with these types of systems. In a retrofit situation, it’s quite possible that the first cost of a ductless system will be comparable to a traditional ducted hvac system. That’s especially true if you’re talking about an existing building that doesn’t have a lot of space for new ductwork or other equipment that won’t physically fit in the space.

With new construction, chances are that the Eco Multi may be more expensive than a traditional system. “Then again, when you do that, you’re losing the true zoning capability. Even though there are zone dampers out there, it’s not as efficient as having a truly zoned system,” notes Crock. This system is truly zoned, he concludes.

Sidebar: Energy Star Adds Labels

Energy Star, the government-backed symbol for energy efficiency, has launched a label for commercial solid door refrigerators and freezers.

According to Energy Star, the label indicates that such designated units are more energy efficient because they are designed with components such as ECM evaporator and condenser fan motors, hot gas anti-sweat heaters, or high-efficiency compressors. All are designed to reduce energy consumption and utility bills as much as 46%, compared to standard models.

Advocates said replacing all existing commercial solid door refrigerators and freezers with Energy Star labeled models would result in savings of almost $250 million per year, or roughly 25% of the energy consumed by models currently on the market.

For more information, visit yosemite1.epa.gov/estar/consumers.nsf/content/refrigerator.htm (website).

Publication date: 02/18/2002