High Efficiency A/C

The Thomas residence in rural Lancaster County, Pa. sits within a large, nicely landscaped lot near Amish fields and horse meadows. But recently, inside, the family had a comfort conundrum.

The two-story, 3,000 square foot home has two central HVAC systems; one for the first floor and a separate one for the upper floor. But to put the above-garage ‘bonus room” to use, they needed to heat and cool the space. They contacted Dave Yates, president of nearby F.W. Behler, Inc., to help them out.

Yates determined that the new media room ‘ because of its size, the challenge of heating and cooling the space above a non-conditioned garage and with so much exposure to western wind and sun ‘ was a larger load than the existing equipment could handle without major changes.

‘We compared the cost of a separate ductless mini-split heat pump system with changes that could be made to the home’s existing comfort systems,” said Yates. ‘Working with the equipment already in place, we found that we’d need to install a zoned damper system, new ductwork to be routed through restrictive attic spaces, wiring and an extra thermostat.”

Financially, they were almost a coin-toss apart, but there were many unique advantages to the use of a new mini-split.

A ductless system would avoid ceiling registers and the energy losses that come with holes through the home’s R-45 attic insulation (attic ductwork insulation values are typically R-8). Ceiling registers hold the potential for cold drafts in winter and also the likelihood in summer of ducted hot air blasts following an off cycle. Any alteration of the ducts serving the sleeping quarters would affect air-flow with the possibility of throwing the system out of balance. For more about insulation, visit FirstDefenseInsulation info.

Spot cooling and heating

In the parlance of pros in the HVAC industry, ductless technology is often applied for ‘spot” cooling and heating, conditioning interior spaces right where you want it and just where you want it. This technique saves energy by containing the heat or air conditioning. Other, lesser-used areas of the home aren’t overcooled or heated unnecessarily ‘ common with central systems. At night, energy dollars are saved by conditioning only the rooms that are used at night and allowing the temperature to rise (or fall) in the rest of the home.

Mini-splits are ideally suited for home improvement, whether an existing central air system is installed or not. This approach can be less expensive and less disruptive than retrofitting an existing HVAC system.

Professional hvac services calculated that the Thomas’ second floor central HVAC system could handle the added heat loss and gain for the media room. But to get the job done, a zone damper system would be needed to deliver the A/C or heat. Yet that couldn’t change the fact that their seven-year-old central air conditioning equipment runs at one speed only, full tilt. Micro-loading zone damper systems require that a by-pass relief damper be added so that enough air can move around to the return side for proper air flow through the air conditioning coil. The result would be wasted energy as the HVAC system short-cycles, greatly reducing the system’s efficiency.

Frequent on-off sequences or ‘short-cycling” of the equipment also increases wear and tear, reducing lifespan. And then there’s the question: Why turn on and run a large central heating air conditioning unit when it’s really just one room where new comfort conditioning is needed?

Sleek, new mini-splits with variable speed ‘inverter” technology have been in use for several decades in Eastern and European countries, and now they’re catching on in the U.S. as energy costs continue their upward spiral. The notion that every room in a home must be conditioned to the same temperature all the time is losing its appeal among Americans.

Punch the gas? Or feather it?

Old school, on-off technology for any type of HVAC equipment is rapidly losing its appeal here in the land of plenty.

‘With this old-style technology, it’s like driving your car with the gas pedal glued to the floor and controlling it purely by turning the ignition key on or off,” said Yates.

The new approach ‘ and one that made sense to the Thomas family ‘ is the use of equipment that continuously modulates its energy production to match heat loss and gain. That’s like feathering the gas pedal in your automobile to meet the speed you need. Toss in new ‘automatic modulation,” and you get ultra-high efficiency operation, complete with the chauffer to drive the car.

Before the Thomas’ agreed to have the system installed, Yates offered some details about the advantages of these highly efficient inverter mini-splits, including the one ton (12,000 BTU) Fujitsu split system he proposed for the Thomas home.

There is no need for electricity-guzzling, back-up heating elements. The systems offer superb air filtration, and because they are ductless, there is no downstream concern about contaminated ducts.

They are great at removing airborne humidity. The Thomas’ new unit would offer a dry mode setting for dehumidification without altering room temperatures by more than one degree and operation with low ambient (outdoor temperatures) as low as zero degrees Fahrenheit. And it would provide precise programmable comfort control using a wireless remote controller. Ductless installation is simple and affordable.

Use of electricity is highly efficient

‘The Thomas’ were satisfied with our explanation and agreed to us installing the system,” said Yates. ‘On a muggy summer day in June, my son Mike, ace technician Bob Sieger and I went to work on the install. Three hours later, the job was done and operational.”

Stealth conditioning

‘The room was noticeably cooler within minutes, and water was streaming steadily through the outside condensate line,” said Yates. ‘But when the homeowners checked on us toward the end of the job, they couldn’t believe the system was running ‘ both the indoor fan coil and outside condensing unit operate so quietly that you have to strain to hear them.”

Mr. Thomas was skeptical. ‘I don’t hear it. How could it be working?” he asked.

To verify that the outdoor unit was running, Mr. Thomas had to get on his hands and knees to see the fan blade turning and feel the gentle movement of hot air from the condenser’s coil as heat was transferred from the indoor air handler. He was amazed at the unit’s stealthy operation. Upstairs, Mr. Thomas had the same experience. He could feel the comfort; he just couldn’t hear it operating at less than a few feet. ‘No noise to interfere with the new surround-sound system,” he said.

‘Fujitsu smartly went with significantly more efficient 410a refrigerant and automatic inverter technology,” said Yates. ‘Other suppliers stuck with R22 refrigerant, which will be phased out in just two years. And now those firms with the more advanced technology are eating their lunch.

‘With energy rates the way they are today, it’s not uncommon to see an ROI of 15 to 25 percent, which is a whole lot better than the stock market’s been doing lately,” added Yates. ‘As an added bonus, the ROI is tax-free.

‘We explained that 410a systems run at higher pressure, so line sets can be smaller,” said Yates. ‘And that’s no small savings with current copper prices. The new refrigerant compound also permits higher operational efficiency, and the compressor can be ramped up to 130 percent for short periods, transferring a lot more heat into or out of the interior living space.”

The one-ton (12,000 BTU) Fujitsu heat pump has an HSPF (heating seasonal performance factor) of 10.55 in the heating mode, and a 21 SEER (seasonal energy efficiency rating) rating for cooling. Those ratings are almost off the charts for air-sourced heating and cooling equipment.

While the newly established U.S. standard dictates a minimum of 13-SEER, those manufacturers that chose to develop inverter technology managed to leave that efficiency rating in the dust.

‘The unit we installed for the Thomas’ offers energy efficiency that’s equal to or higher than many, substantially more expensive and site-disruptive geothermal systems,” said Yates.

Typically today, central heat pump systems have HSPFs of 5 or 6, and SEER ratings of 13 to 18, and many remain mired in the inefficient, on-off realm with no clue about the actual load required to meet comfort levels. Each rise of 1-SEER represents roughly a 10 percent improvement in energy consumption.

Another facet of this advanced equipment is that inverter technology runs all key components at variable speeds, enhancing efficiency and extending the life of the unit ‘ all at a reasonable cost.

Ultimately, the homeowner is rewarded with a whisper-quiet comfort system that gingerly sips electrical current, is better for the environment and goes in fast. Professionals like it for the same reason.

John Vastyan is a journalist whose work for 20 years has focused on plumbing and mechanical technology. He can be reached at 717/664-0535, or cground@ptd.net.

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