Prepare to Mobilize: 10 Steps to Prepare Your Business to Go Mobile
Oct. 28, 12 p.m. EDT – Learn how to get the most out of your mobile investment - Click here for details

HVAC Residential Market / Geothermal Heat Pumps

Homeowners Cut Costs With Hybrid Geothermal System

August 1, 2011
KEYWORDS energy / geothermal
/ Print / Reprints /
/ Text Size+
Dave Kyle installed four split system geothermal heat pumps, two of which have desuperheaters to provide domestic hot water for the home.

MASON NECK, Va. - Perched on the banks of the Occoquan River is a unique house that was just retrofitted with a remarkable HVAC system. The approximately 7,500-square-foot house, with its wall of windows overlooking the scenic river, started out as a small cottage in the 1970s and was then supersized in the early 1990s. As part of this expansion, four high-efficiency propane furnaces and four air conditioning units were installed to heat and cool the newly enlarged space, but after 19 years, it was time to replace the systems with new equipment.

Dave Kyle, general manager, Trademasters Service Corp., Newington, Va., installed those original systems and maintained them over the years, and he relished the opportunity to suggest something different for the homeowners. “The equipment was at the end of its life cycle, and I told the homeowners they should consider a geothermal system, which is what I have in my house. I told them about the generous tax credits available for geothermal, and they did the research and said they absolutely wanted to go that route.”


Geothermal wasn’t always on the homeowners’ radar, as they briefly considered replacing their existing high-efficiency propane furnaces and air conditioners with similar equipment. However, the rising cost of propane - combined with the federal tax credits - prompted their interest in higher efficiency systems.

“Saving energy was the homeowners’ first concern, because their propane bills were running about $1,300/month,” said Kyle. “With the lower energy costs and tax credits for geothermal systems, we figured out that they would recover all their costs in seven or eight years. If we replaced the system with conventional equipment, the return on investment would be much longer, because the original equipment was already high efficiency, so we wouldn’t gain much in terms of energy savings.”

Propane furnaces act as a back-up in case there is extremely cold weather or the electricity goes out.

The homeowners also liked the idea that since there is no outdoor equipment, the geothermal systems would be much quieter than conventional air conditioners. In addition, they wanted a “greener” system, and they wanted to stay somewhat independent if the power went out during extreme weather. For that reason, Kyle proposed installing a hybrid system that would pair high-efficiency propane furnaces with geothermal systems.

“I argued for the propane furnaces, because the infrastructure for this equipment was already in place, and they can act as a back-up in case there is extremely cold weather or the electricity goes out,” said Kyle. “If there is a loss of power, the propane will run the generator (which is not powerful enough to run the geothermal systems) and the furnaces; otherwise, the homeowners will rarely have to use them.”

It was a challenge to design a heating and cooling system for this home, which featured very high ceilings, an open floor plan, and a wall of windows facing the river.

Kyle ended up installing four split system geothermal heat pumps from Carrier - three 3-ton units and one 4-ton unit - as well as four Carrier high-efficiency propane furnaces - three 60,000 Btu units and one 80,000 Btu unit. Desuperheaters were added to several of the geothermal heat pumps in order to provide domestic hot water for two of the home’s three hot water tanks. The kitchen, bedrooms, and laundry all receive hot water from the geothermal systems, while the master bathroom has its own high recovery propane water heater.

For IAQ needs, the homeowners chose to have Kyle install steam humidifiers from Aprilaire, air purification units from AtmosAir, and pleated filters. The web-based Schlage LiNK system operates the home’s 10 zones and also automates the door locks, lighting, and security.

“The homeowners were tired of running around, trying to program all the thermostats in the house,” said Kyle. “With the LiNK system, they can just use their smartphone, laptop, or iPad and go to the website and adjust their lighting, temperature control, and door locks. They can also see what’s going on inside their house through the use of web-enabled cameras.”

This 7,500-square-foot house was recently retrofitted with a hybrid geothermal system in order to cut down on the increasing cost of propane.


While the homeowners were interested in geothermal technology, they did not want their yard torn up in the process of installing the loop fields. To overcome those concerns, a horizontal directional drill was used to install the piping over the expansive lot, which resulted in minimal disruption to the existing landscape.

“Directional drills are just amazing,” said Kyle. “In this case, we had to run a large portion of the geothermal piping into a forest full of 100-year-old trees. We didn’t want to cut the roots or hurt the trees, and we didn’t have to worry about it with the directional drill.”

Geothermal piping was laid behind the helicopter pad (to the left of the house) and extended under the hill and into the mature woods.

To that end, the operator used the horizontal directional drill to make a 3-inch hole in the ground that went down about 15 feet into the ground, thus missing most tree roots. If he encountered an obstruction, such as a boulder, he could maneuver the drill up, down, left or right in order to work around the obstacle.

“The drill rig operator basically shot the drill under the yard, the tennis courts, and the driveway, and out into the woods. The drill bit popped up out of the ground, we tied our piping onto it, pulled it back, stepped on the dirt to cover the hole, and we were done,” explained Kyle. “From the point where the directional drill rig was located, the operator would just move the drill 2 to 3 degrees at a time, so the loop piping ended up looking like spokes going out into the forest.”

The kitchen, bedrooms, and laundry all receive hot water from the geothermal systems, while the master bathroom, shown here, has its own high recovery propane water heater.

There was almost no destruction, except for a small trench that had to be dug in order pull the pipe to the house, and the homeowners were very happy that their landscaping remained virtually unscathed. They are also happy with their propane bills, which have almost disappeared since the new systems were installed.

“A month after the system was up and running, the propane company didn’t even bother to fill the tanks, because so little had been used,” said Kyle. “At the end of the second month, only 85 gallons of propane were needed, which is a significant decrease. With our new systems, we basically murdered their propane bill.”

And the homeowners are perfectly comfortable being accomplices to this “crime.”

Publication date: 08/01/2011

Did you enjoy this article? Click here to subscribe to The NEWS Magazine

Recent Articles by Joanna Turpin

You must login or register in order to post a comment.



Image Galleries

2014 SMACNA Annual Convention

Views from the 2014 SMACNA Annual Convention in San Antonio.


NEWSMakers: Chris Mathis

Chris Mathis, president of Mathis Consulting Co. and vice chair of ASHRAE’s residential ad hoc committee, talks about ASHRAE’s exploration into the residential market. Posted on Oct. 17.

More Podcasts


NEWS 10-20-14 cover

2014 October 20

Check out the weekly edition of The NEWS today!

Table Of Contents Subscribe


DOE has denied AHRI’s petition for reconsideration of walk-in standards. Is it getting harder to reach consensus on efficiency standards?
View Results Poll Archive


2015 National Plumbing & HVAC Estimator

Every plumbing and HVAC estimator can use the cost estimates in this practical manual!

More Products

Clear Seas Research


Clear Seas ResearchWith access to over one million professionals and more than 60 industry-specific publications, Clear Seas Research offers relevant insights from those who know your industry best. Let us customize a market research solution that exceeds your marketing goals.


Magazine image
Register today for complete access to Get full access to the latest features, Extra Edition, and more.


facebook icontwitter iconyoutube iconLinkedIn i con