For the Media: CASE STUDY – CCAT
Sustainable Building Authority Walks the Walk When Promoting Energy-Saving Green Products
New, 97%-efficient Phoenix Solar water heater provides storage and boiler backup for solar-driven radiant and DHW systems.
ARCATA, CALIFORNIA — “Do what we say and what we do!” might well be the mantra for the Campus Center for Appropriate Technology (CCAT) at Humboldt State University in Arcata, California. When CCAT decided to remodel its live-in demonstration home and educational center for technology and resource conservation, the change was drastic, cutting-edge and yes, green, too. Read more...
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The front exterior of the newly renovated Buck House, home of the Campus Center for Appropriate Technology (CCAT) at its new location in Arcata, California.
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Stephen Bohner of Alchemy Construction Inc., with the newly installed Phoenix Solar water heater, which provides hot water storage and boiler backup to the CCAT’s solar thermal space heating and domestic hot water systems.
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Stephen Bohner of Alchemy Construction Inc., with the newly installed Phoenix Solar water heater, which provides hot water storage and boiler backup to the CCAT’s solar thermal space heating and domestic hot water systems.
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Stephen Bohner of Alchemy Construction Inc., with the newly installed Phoenix Solar water heater, which provides hot water storage and boiler backup to the CCAT’s solar thermal space heating and domestic hot water systems.
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Phoenix Solar water heater (left) with system controls and components board (right).
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Stephen Bohner inspects X-Pump Block pumping station, which uses an outdoor reset to control the amount of hot water sent from the Phoenix Solar water heater to the radiant tubing loops at CCAT.
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Controls and components board for the solar thermal system at CCAT, including the X-Pump Block (upper left), the Oventrop Regusol EL-130 pumping station (middle), and the thermal actuators (lower left).
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The one-story home, called the Buck House, was likely built in the 1920s and in recent years displaced by the HSU Behavioral and Social Sciences Building. In the spirit of sustainability, the house was lifted from its site and “recycled” by moving it down the road to a new foundation that will also be used as a room for lectures and training.
CCAT, an authority on sustainable building for more than 30 years, knew that the move provided the perfect opportunity to add new, green amenities to the home. Early on, the CCAT committee decided to use radiant in-floor heating and took the essential first step of having PEX (crosslinked polyethylene) tubing installed in the newly poured basement slab. This tubing, manufactured by Uponor Inc., would eventually carry warm water from a yet-to-be-determined heating source to warm the slab and the people and environs above.
Once the tubing was in place, CCAT decided to call in a local expert to help decide how to heat not only the lecture-library room in the basement, but also the upper level, which would provide living quarters for the director of CCAT and the HSU students who live and work there. The expert they ultimately contacted to assist with system design and heat-source selection was contractor Stephen Bohner and his wife Amy, who co-own Alchemy Construction Incorporated, also of Arcata. Bohner (pronounced BAW-ner) is a Certified Green Building Professional, a member of the Radiant Panel Association (RPA), and a recently nominated RPA All-Star. Committed to green building practices, Alchemy Construction received Humboldt County’s Waste Reduction Award for 2007.
First Choice – Phoenix Solar: Shortly after his initial meeting with CCAT, Bohner visited the manufacturing operations of Heat Transfer Products (HTP) in East Freetown, Massachusetts. There he learned about the company’s new Phoenix Solar water heater, which combines domestic hot-water storage (from a solar collector panel) with a 97%-efficient, gas-fired backup – all in one unit. The sealed-combustion, direct-vent Phoenix Solar delivers both high-efficiency space heating and domestic hot water, using state-of-the-art condensing boiler technology and a modulating, load-matching gas burner.
“I was pretty excited about it,” recalls Bohner, who urged approval of the Phoenix 119-gallon, 130,000 BTU unit as a perfect fit with the CCAT mission of promoting sustainable, high-efficiency products. Working with CCAT co-directors Zachary Mermel and Beckie Menten, Bohner finalized a design for the new heating system, built around the Phoenix Solar, which would feed both the 1,550-square foot basement with its radiant floor heating, as well as the radiators that would heat another 1,550 square feet upstairs. In addition, the unit provides domestic hot water for the entire house.
The Phoenix Solar incorporates a dedicated, high-output solar heat exchanger at the base of the unit. Made of finned cupronickel, this exchanger can transfer up to 175,000 BTU per hour of heat energy from the solar panels to the water in its storage tank. The solar heat exchanger and the secondary, gas-backup heat exchanger are encased in a corrosion-resistant tank made of 316L stainless steel, so no sacrificial anode rod is required.
During periods when solar power cannot meet demand, the Phoenix Solar uses the latest in modulating and condensing (Mod-Con) technology to pick up the slack. Two components are key to this secondary heat source:
- Load-matching burner: This gas-fired, modulating burner assembly features a high-grade Inconnel “NIT” burner with a reliable spark ignition system, so there is no standing pilot to waste energy. The burner assembly, located at the front-middle exterior of the unit, is a streamlined version of the one used on Heat Transfer’s popular Munchkin condensing boilers. This fully modulating, ultra-low-NOx burner is load-matching, limiting its firing to current demand and saving substantial amounts of energy in the process. This is in sharp contrast to a conventional burner system, which fires to the maximum – regardless of demand – thereby wasting energy.
- Corrosion-resistant, combustion heat exchanger: Made of cupronickel and stainless steel, a second heat exchanger at the top of the Phoenix Solar unit extracts all the latent energy from the backup combustion process, as well as from the by-products of that process. This, in turn, is what drives the unit’s ultra-high thermal efficiency rating. In fact, so much latent heat is extracted, the resulting low exhaust temperatures permit venting with plastic – rather than metal – pipe.
A number of important factors drove CCAT’s decision to install the next Phoenix Solar unit, according to Bohner:
- All-in-one package, solar capability, tank size: The Phoenix Solar has “a small footprint, offers solar thermal capabilities and combines domestic hot water and space heating in one package,” says Bohner, who liked the idea of having both applications in a single unit, rather than two standalone pieces of equipment: “It makes for an easier installation,” he says.
The old Buck House used a solar system to provide domestic hot water, so it was paramount that the new system also incorporate solar. “If a manufacturer could not offer both solar thermal harvesting and a boiler backup in the same system, they were out of the race,” says Bohner. “As we evaluated different systems, the ‘all-in-one’ approach of the Phoenix Solar – as well as its 119-gallon tank capacity – really shined for us.”
- Positive track record with Heat Transfer: Another point in favor of the Phoenix Solar was the “great success” Bohner has enjoyed with HTP’s Munchkin offering. “I understand them very well,” he remarks, “so I wasn’t nervous about the Phoenix Solar being a new product. I was comfortable with the Munchkin line and I knew Heat Transfer Products’ reputation with indirect tanks. You’re not just buying a boiler; you’re buying the people and parts that fix the boiler if something should go wrong.”
Installation Relatively Easy: With the committee sold on the Phoenix Solar, Heat Transfer sales representative Morgan Muir of Hydronic Specialties Company in Oakland, Calif., arranged for one of the first units produced to be shipped to CCAT. Installation proceeded with relative ease: When Bohner first filled the new Phoenix Solar with cold water, the tank temperature read 64°F. Within only eight minutes, he says, “the Phoenix stopped humming and the tank temperature read 119°F. It’s kind of an amazing product – even simpler than a Munchkin to install. You plug it into the wall and off it goes.”
Bohner’s crew did encounter one minor glitch when the original rough-in work pitted them against a poly-steel wall. “The framing crew had built a hollow concrete wall over the poly-steel wall to use as a chase for utilities,” Bohner says. “As a result, we were unable to fasten our controls and piping directly to the concrete wall with concrete screws. So we hung a sheet of formaldehyde-free plywood and mounted our controls to that.”
Measuring only 27 inches in diameter, the one-piece Phoenix Solar commands a relatively small footprint, as compared with a conventional sectional boiler, and its height of 74 inches should fit through most doorways without a hitch. Bohner also notes that, like the Munchkin, the Phoenix Solar must be piped with a minimum ¾-inch supply gas line. “If you’re looking to retrofit this appliance into an existing home, make sure there is a ¾-inch gas line entering the mechanical room.”
How the System Works: A firm believer in closed-loop systems, Bohner separated the Phoenix Solar’s auxiliary heating port for the domestic hot water from the space heating system via a Taco X-Pump Block, a heat exchanger that is also an all-in-one unit.
The auxiliary ports of the Phoenix Solar feed domestic hot water to the X-Pump Block. Using its internal heat exchanger, two pumps and control logic, the X-Pump Block relies on an outdoor reset to control the amount of hot water sent to the radiant tubing loops. Bohner explains how the system works:
“We monitor indoor temperatures by running thermostat wire to each room in the Buck House. We monitor outdoor temperatures with an outdoor sensor on the north side of its exterior. When there is a call for heat, the X-Pump Block mixes and delivers the correct water temperature – based on the outside temperature – to the radiant manifold.”
Individual room zoning is accomplished at the radiant manifold via thermal actuators, also made by Uponor. “When a zone calls for heat,” Bohner explains, “those actuators pop their heads and warm water flows through the corresponding PEX loops attached to them. Again, the colder it is outside, the warmer the water delivered to the room needing heat.”
Finally, Bohner chose another all-in-one unit, the Oventrop Regusol EL -130 solar pumping station, to move water from the solar collectors to the radiant loops whenever that water is hotter than the water inside the Phoenix Solar. “Pairing the Taco X-Pump Block and Oventrop EL-130 with the new Phoenix Solar was a great way for us to easily integrate a solar thermal system into the newly remodeled CCAT.”
No Cold Showers: To date, the three student-residents, having never run out of hot water, are very happy with the new system. “Although I told the committee that they could expect to see a savings in their energy costs, I didn’t claim they’d never run out of hot water. But I knew they wouldn’t – especially with a 119-gallon tank. There have been no complaints.”
CCAT offers university students and the general public tours, workshops and opportunities for hands-on involvement. They don’t just preach sustainable products; they actually live with them to discover whether or not they like them. “CCAT provides classes on solar thermal, solar electric and now – with the move and the renovation – radiant floor heating. “It is like a live-in classroom for sustainability,” says Bohner.
Installing the Phoenix Solar water heater was a big step-up for CCAT. “We may not live in New England, but the temperature dropped to 34 degrees just a few days ago,” says Bohner. “CCAT is preaching sustainability, so they liked the idea of the Phoenix Solar because it would allow them to actually ‘walk the walk, as well as talk the talk.’ That’s what interested us, too. CCAT is a very influential body here – a pillar in the community for green building, and they have quite a history, which excited us.”
Bohner believes that Phoenix Solar installations will grow in number as installers discover its benefits. “If you have either an existing radiant system, are building new, or swapping out that old furnace for a new fan coil, the Phoenix Solar would be a good choice with its small footprint, single-storage tank, solar thermal-readiness and high efficiency,” says Bohner. “With Heat Transfer’s experience in not only stainless tank manufacturing, but also Mod/Con heating appliances, we should see the Phoenix popping up in all kinds of places.”
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HEAT TRANSFER: Founded in 1974, Heat Transfer is a designer and manufacturer of advanced heating and hot water systems. Product categories include high efficiency boilers and advanced boiler control systems, high efficiency gas-fired water heaters, oil-fired and electric water heaters, indirect water heaters, and marine and pool heaters.
For more information about these products, visit Heat Transfer at www.htproducts.com. Or call toll-free: 800-323-9651 (508-763-8071 if calling from Massachusetts).
For editorial assistance, contact John O’Reilly c/o LNC Communications:
815-469-9100 or John@LNCmail.com.
[CONTRIBUTOR]
Stephen Bohner
Alchemy Construction Incorporated
P. O. Box 4154
Arcata, CA 95518
707-822-8013
info@alchemyinc.com
www.alchemyinc.com
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