The Benefits of Combining VRF and Geothermal Technologies

Two of my favorite (and most efficient) technologies can actually be combined to form an uber-efficient HVAC system. Both Mitsubishi and Daikin have provided water-cooled condensing units as part of their US line-up for several years. However, only recently has this technology been refined through plate and frame heat exchangers and control logic to perform optimally with geothermal ground loop heat exchangers. Mitubishi’s WR2 series (heat recovery) and WY series (heat pump) along with Daikin’s VRV-WIII series can combine the benefits of variable speed inverter compressor technology and geothermal heat pump efficiency. Add to this the additional benefit of being able to install multiple types of ductless, ducted and concealed indoor evaporators and you have one of the most flexible and highly efficient solutions for a green building project. Because of the system’s flexibility, it can be designed into new building and retrofit mechanical schemes (see Mitsubishi schematic).

Unfortunately, as these systems are only available in larger sizes of 6 tons and up and only available in 3 phase, they are not yet a viable option for single family homes. However, we are seeing these systems specified on multiple dwelling residential projects like apartment buildings and condominiums. For the most part, this is really primarily a commercial option that can deliver added points for LEED buildings and deliver the ultimate in sustainable design. Existing ground source heat pumps on the market provide dual speed for their premium models (like the WaterFurnace Envision line), but there has not been a variable speed inverter compressor option available to the market. In redeveloping their water-cooled condensing unit lines to accommodate the geothermal market, these VRF/VRV manufacturer’s have provided a significant boost in efficiency. Based upon an energy modeling study for assisted living facilities in various cities across the country, it was proven that this type of hybrid VRF-Geothermal installation provides on average a 37% efficiency increase over VRF air-cooled heat pumps. Although VRF/Geothermal is still a costly initial installation versus established fossil fuel and air-cooled systems, emerging energy efficiency technology experts are now touting ground-source variable refrigerant flow heat pumps as an affordable energy option.

As always, to keep up to date with what’s new in HVAC technology, visit our website at and follow us on Twitter @airideal and at our Facebook page!


Thermostat Replacement and Environmental Impact

Beware the mercury bulb thermostat

With the advent of all of the buzz circulating around the new Nest and internet enabled thermostats, there is one big question that goes unanswered. What happens to all of the cast-offs? When a homeowner or contractor replaces a thermostat, the vast majority become land-fill or end up burned in incinerators. Considering the fact that many older mechanical thermostats contain mercury, this creates quite a significant environmental impact. A spokesperson for the New York Public Interest Research Group points out that “an estimated 310,000 mercury thermostats are disposed of every year in New York, but only slightly more than 1 percent of those are recycled.” If this is just the number of mercury laden thermostats introduced to the waste stream annually in New York State alone, consider the implications nationally and internationally. For years, Honeywell and other control manufacturer’s have lobbied against legislation that would require manufacturers alone to recycle thermostats and reclaim mercury. Today, Honeywell responded to allegations that it has prevented such environmental legislation by stating “Honeywell strongly supports legislation that bans the sale of mercury-containing thermostats and mandates mercury thermostat recycling, with responsibilities shared among thermostat manufacturers, wholesalers and contractors.”

New York State Assemblyman Robert Sweeney (D-Lindenhurst) is sponsoring a bill that would require manufacturers to meet targets for safe disposal of mercury thermostats.”There is no reasonable way for the average person to legally dispose of mercury containing thermostats,” Sweeney has stated. There is currently a voluntary program in place through an industry funded non-profit called the Thermostat Recycling Corporation ( TRC looks for contractor, distributor and manufacturer volunteers to act as collection sites with a free thermostat recycling program. Members are shipped recycling bins to be returned at no charge to the TRC once they are filled. Environmentally minded industry advocates are urged to join the program.

As always, to keep up to date with what’s new in HVAC technology, visit our website at and follow us on Twitter @airideal and at our Facebook page!

Nest Undressed

The folks at SparkFun did a teardown of what makes the Nest learning thermostat tick. As the author says, “It’s always fun to see the wizard behind the curtain”.
Link here to the SparkFun article.

Add to this the NY Times Tech Guru David Pogue is enamored with his new Nest and it looks like Tony Fadell has really hit a nerve. It looks like techies may be falling over themselves to spend $250 on their new “iStat”.
Link to David Pogue’s article here.

The Wall Street Journal’s “All Things D” interviews Tony Fadell, who discusses the design concept, selling out the first production lot and funding: Link Here

Yes, if you haven’t noticed, we drank the Nestade. That is our new Nest pictured below…

As always, to keep up to date with what’s new in HVAC technology, visit our website at and follow us on Twitter @airideal and at our Facebook page!