Inverters Invade the U.S.

I first saw an inverter heat pump about eight years ago. I felt as if I'd been standing in a dark room and someone had flipped on a 1,000W bulb (a CFL bulb, to be politically correct)! It was, as I recall, not long after I had embraced the concept of mod-con boiler technology.

Every now and then, I get pretty riled up over an issue that gets under my skin. According to my bride, that occurs just about every third second! Well, given the so-called bail-out crafted by pork-barrel spenders in our nation's capitol, who have long ignored the need to establish better energy-usage standards (challenges) for fuel utilization appliance efficiency, can you really blame me?

The new efficiency-challenge laid down for furnaces in 2010 is 80%, and the challenge for boilers is 82%? Wow! All the way up from 78% too. I'm in awe.

Let's see, York has their new Affinity furnace that modulates its output in 1% increments based upon outdoor reset - not two-stage - it's a mod-con furnace with an ECM blower motor that can achieve a 98% operating efficiency. There's a shot that should be heard around the furnace world.

And Nortek, with its 23-SEER inverter A/C unit, has quietly captured consumer sales. Toss in mini-split inverter heat pumps offering 21-SEER and 11-HSPF that are selling like hot cakes and add in 27-SEER 14-HSPF ground source heat pumps that are suddenly a hot commodity.

What, you might ask, is going on? With 78% for furnaces/boilers, 13-SEER for A/C and 6.8-HSPF serving as our existing challenge from the Feds, why are these folks so far ahead of the curve?

Well, while our fearless leaders in D.C. banter about the economy, bluster about alternative energy systems (while largely ignoring solar and wind) and fail to adequately challenge their constituents on appliance efficiencies, we're left to guide consumers to make informed and intelligent decisions that often require them to seriously consider a heavier upfront investment in equipment that offers a much better ROI than anything available in stocks, bonds or real estate!

We've been wallowing at the hog trough of cheap energy and lax regulations for so long, we feel entitled to keeping 100-year-old heating systems and 4-SEER A/C units alive! As technicians, we take pride in our deft skills by resurrecting the damned beasts to serve for decades to come.

I first saw an inverter heat pump about eight years ago. I felt as if I'd been standing in a dark room and someone had flipped on a 1,000W bulb (a CFL bulb, to be politically correct)! It was, as I recall, not long after I had embraced the concept of mod-con boiler technology.

In a nutshell, inverter units work as follows: the incoming 220V single-phase current is converted to 370V D.C. current and then inverted to 200V simulated three-phase current. If you've worked around three-phase motors, you know they can be infinitely varied in speed. (If you've worked with mod-con boilers, then you know they also operate as variable-speed units.)

So, all of the motors (including the compressor) can now be operated in sync with each other as variable-speed to alter the amount of air and refrigerant they move. Move more or less of them both and you not only move more or less Btus, you use more or less energy in the process - a mod-con heat pump!

The rub was in modulating the refrigerant flow to match the other motors and that's no longer an issue. Inverter units throttle the refrigerant flow, just as you'd feather a gas pedal in your vehicle. Combined with the fan and compressor motors, they work in perfect harmony.

Naturally, they are more sophisticated when it comes to the control side, but they incorporate robust on-board diagnostics to aid technicians in diagnosing any problems that will ultimately arise.

Inverter heat pumps are currently available as small mini-split units that operate as single indoor to single outdoor units or as multiple indoor units connected to a single outdoor unit. The units communicate with each other by monitoring outdoor air temperature, indoor humidity and temperature in order to determine how hard and fast they need to run to quickly, efficiently and quietly meet demands at that moment in time.

So, you may ask, what the heck does this have to do with me? We are in the business of providing comfort, economy and sage advice to our customers. Everyone is affected by the current cost for heating and cooling his or her home. But not everyone is in a position to pony up $29,000 for a ground-source heat pump or $15,000 for a retro-fit mod-con boiler. In addition, lots of folks have window-shakers for their summer cooling needs - a potentially huge waste of energy for older equipment.

Installing an inverter mini-split heat pump in one or more areas can be the perfect solution. With efficiencies of up to 21-SEER and 3.22-COP (11-HSPF), the inverter mini-splits will heat (today's electric rates vs. fossil fuel costs) for less money than a 95%-efficiency fossil-fuel appliance! The 21-SEER A/C comes along for the ride and costs far less than the current government's minimum 13-SEER “standard” rating. Spot conditioning essential areas within a home allows the main whole-house central-system to idle at set-back temperature while the homeowner can maintain selected areas at optimum comfort conditions, all the while reducing their carbon footprint and saving money.

Dave Yates owns F.W. Behler, a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at [email protected].

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