Thinking Outside the Box

Thinking Outside the Box

Winner: New Construction less than $1 million

Jenniges Plumbing & Heating, Inc.
Redwood Falls, MN

By Terry McIver, senior editor

Winner at a Glance:

    Jenniges Plumbing & Heating, Inc.
    J & D Construction, Inc., Montevideo, MN
    John Jenniges, president, designer & implementer
    John Jenniges
    Kenneth Jenniges, project foreman & installer; Duane Jenniges, HVAC installer & producer; Dale Halgren, sales & load calculation designer; Doug Nelson, CEO, and Jerry Pauling, president, J & D Construction, and team.
    • Terra-Therm: air handlers; fan coils; pressure gauges; 5-gallon bladder tanks;52-gal. buffer/storage tank; 120-gal. storage tank; 1- and 2-pump foam packs; CI pumps
    • Grundfos: CI pumps; 1-pump foam packs; 3/4 hp pump; 1/2 hp pump; single-phase pump
    • Spirotherm: Spirovents; microbubble separators
    • Honeywell zoning systems; Honeywell Space Control thermostats
    • tekmar Control Systems
    • Zurn PEX radiant tubing
    • Embassy radiant floor heating system

The office section of the new J&D Construction headquarters reflects J&D's specialty of building grain bins.

The circular office design was a duct fabrication challenge.

Terra-Therm stainless steel foam packs move the water from the ground coil to the heat pump unit.

Detail of main line runs

To conserve space, GeoSource heat pump units were stacked high against the wall, on platforms built by J&D Construction.


The best HVAC Design/Build contractors live for the special projects that offer opportunities in which they can really flex their D/B muscles.

In the case of John Jenniges, it was a project that required some out-of-the-box thinking, uniquely shaped ductwork, geothermal technology, and a responsive, "design as you go approach," all the while adhering to industry standards of excellence.

Jenniges — owner of Jenniges Plumbing & Heating, Redwood Falls, MN — combined the latest heating technology and 34 years of experience to design a geothermal system for the new offices of J&D Construction, Montevideo, MN, a portion of which is a two-story, circular office space built to resemble a grain silo.

J&D wanted a cost-efficient, spacesaving, non-fossil fuel-based heating and cooling system for its 39,450 sq. ft. office and warehouse. The answer-was found in a geothermal system with a new plumbing design to properly control and maintain the temperatures with complete efficiency. The total cost of the installation was $281,000, and it will provide an annual, estimated energy savings of more than $35,000.

"The geothermal system saves on energy costs, and simplifies the controls," says Jenniges, a master plumber.

"This system utilizes a one-pipe loop system in lieu of four, 120-gallon buffer tanks. As a result, less space is being used for buffer tanks and piping, and more area is available for warehousing and manufacturing."

"We found the capital costs a lot higher than conventional heating and cooling, but beyond that, decided ground source was right for us," says Doug Nelson, J&D's chief executive officer.

"Considerations that persuaded J&D to use ground source were our belief that using a renewable energy source in lieu of fossil fuels is vital to the next generation; reducing dependence on foreign oil, which is a must for our nation's security; and a low operating cost," Nelson says.

"Although there were significant savings on projected operating costs and some tax incentives, these things alone did not provide an attractive return on investment," explains Nelson.

"As many of the challenges were overcome, and we started looking more at the HVAC needs, we chose to think outside the box. Ground source heating and cooling has been becoming more popular in residential and small commercial applications, so we decided to pursue it on a larger scale," Nelson says.

Teamwork from the Very Start
John Jenniges first learned of this unique project from Dale Halgren of Terra-Therm, a specialty distributor with more than 20 years of experience in geothermal and radiant floor systems. Halgren had contacted the local power company that also sells geothermal systems, and asked if they wanted to submit a bid. As it turned out, the power company turned the project down due to its size; it was too big for them to handle.

After hearing some of the details from Halgren, Jenniges met with Jerry Pauling, a co-owner of J&D Construction, in August of 2005, and the two reviewed some rough plans for the project.

"At this time, there were no mechanical or electrical specs; only the building pad was built," recalls Jenniges.

After preparing a quote for the project, Jenniges met with Halgren again, to discuss the plans he had come up with to complete the project.

"One of the obstacles we encountered was the cost of materials," says Jenniges.

"While Terra-Therm would guarantee their prices, I couldn't be sure the copper supplier and the duct work suppliers would guarantee theirs.

"When we won the project, I received a hard quote on the materials, which the suppliers honored nine months later."

The system as proposed would have complete, in-floor PEX tubing to heat three areas: the warehouse, a connecting building, and the main office area.

Jenniges quoted Jerry Pauling a total cost for the project, with 73 geothermal wells and the in-floor PEX installed. And then, he waited.

"Jerry is a thinker, and I knew it would take him time to make a decision," says Jenniges.

"I provided information on how much it would help him save in energy costs, and this left a favorable impression on him. Jerry called several times to ask questions, but there was no definite answer as to whether or not Jenniges Plumbing & Heating would be awarded the project."

Patience Pays Off
Jenniges remained patient, being confident that he had provided the most efficient heating and cooling system solution possible in this situation.

"I could see that this project was unique, and would fall into a category we could handle," he says.

Jenniges' willingness to offer advice without having a commitment from J&D paid off. On December 15, J&D awarded him the project.

"I assured Jerry and Doug that they would not be disappointed, and that I'd guarantee it in writing," says Jenniges.

"And they're not disappointed. It's working out unbelievably well."

Jenniges met once more with Dale Halgren from Terra-Therm in early January, and finalized pipe and pump sizes.

"With the way clear as to what size piping and how many heat pumps we would need, I ordered out copper materials and other items, which arrived on February 8," says Jenniges.

"We opted to use copper as the conduit for moving treated water to and from the heat pumps, rather than CPVC or polyethylene piping, due to the fact that the CPVC and polyethylene expands and contracts, which would not be good for the project."

Sheet Metal 'In the Round'
The 90-ft x 50-ft. grain bin design for the two-story office space reflects J&D Construction's specialty, which is building and repairing grain elevators.

Jenniges says the circular design of the office posed a big challenge in terms of sheet metal fabrication and installation.

"We installed 10-ft. at a time, and attached various size fittings. It was trial and error," says Jenniges, whose cousin, Duane — a 25-year employee — had attempted to fit some sections together by using conventional methods, but found that the sheet metal wouldn't fit without special fittings to match the graduated curves around the space. Later, the duct work was sealed with a high density foam.

Knowing that comfort is an essential part of any work area, Jenniges next installed a duct system to cool and circulate fresh air in the center of the office area. The main source of heating is the in-floor hot water radiant heat, with multiple zones, each controlled by its own thermostat.

To make the best use of the space, Jenniges stacked the Econar GeoSource heat pump units high on the wall, on platforms built by J&D. The main runs were suspended from the ceiling, so as not to interfere with traffic in the warehouse/ manufacturing area.

"All of the equipment is installed with ease of maintenance and repair in mind," says Jenniges.

The in-floor heating system was installed on both floors of the main office and the connecting building.

Controls from tekmar Control Systems are used to operate the heat pumps. The controls stage the units to operate as needed, so the heat pumps are used just enough to maintain the temperature of the treated water.

Jenniges Plumbing and Heating used Honeywell thermostats, and incorporated Honeywell zoning on the duct system for the main office, to balance airflow between the main offices and reception area.

"As of today, the ground source heating and cooling equipment is the most energy efficient source available," says Jenniges.

"And, as an added benefit, the electric supplier is giving J&D Construction a discount on their energy costs."

Terra-Therm stainless steel foam packs move the water from the ground coil to the heat pump unit. Another foam pack moves the hot or cool treated water. It's a foam-insulated pump that doesn't collect condensation when running in cooling mode.

Spirovent microbubble separators were installed to remove entrained air and bubbles from the water. The Spirovent, in conjunction with the heat source, removes what were dissolved gases from the water, which conditions it to a highly absorptive state. This reduces corrosion, improves efficiency, and eliminates poorly heated or inadequately cooled rooms, and reduces component wear.

Great IAQ, Too
Indoor air quality (IAQ) was not necessarily a key factor in the selection of the ground source heating and cooling, however, cleaner air has certainly been an added benefit. The amount of dust moved around the building is minimal, therefore, fewer allergens are circulated.

As with any warehouse and manufacturing facility, J&D has many overhead doors used to move materials in and out.

"Those doors are often opened during the hot summers, but with this system, we can control the temperature fairly well, even with doors being opened and closed frequently," says Jenniges.

"We also bring in outside air for the office and the connecting building, circulated by the cooling fan coil units, and we're pressurizing the office and connecting area (5,000 sq. ft.) to keep welding and manufacturing dust out of that area."

Jenniges says communication between himself and J&D Construction was a key to the success of this project, which was completed in May 2006.

"When we started this job, there was nothing written in stone; all we knew was that we'd have 76 tons of ground source equipment, all this pipe buried in the floor, and 73 geothermal wells. But as far as the ductwork and zoning, that was designed and completed as we went along," he says.

"We feel ground source HVAC will be huge going forward, and are proud to be part of the team — Jenniges Plumbing and Heating, Terra-Therm, and Econ Air — that helped make our project a reality," says Doug Nelson.

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