Radiant For The Common Man
At last year's Radiant Panel Association conference in Rhode Island, contractor Dave Yates met a man who'd traveled to the show from Pennsylvania in search of a professional to design and install the hydronic system for his family's new home.
The man explained that he and his family were planning to construct a new, 3,000 sq.-ft. home in Lancaster County, only 20 miles from Yates' home base of York, Pa.
The man was no tire-kicker. He added that his wife was a native German, and he'd come to appreciate the value of European hydronics.
Well before the convention, they had both decided on Runtal panels and an extensive list of Wirsbo radiant heat and plumbing products. Not only did they know name brands, but they also knew where some of the products should be placed.
The homeowners, for example, knew they wanted a 10-ft. vertical wall panel installed in the entry area. "I was more than surprised," adds Yates, president of F. W. Behler Plumbing, Heating & Air Conditioning. "That's exactly the spot I would have chosen. This guy had done a lot of research. He knew what he wanted."
He also knew what he didn't want. A heat pump was absolutely out of the question. And so was a furnace, despite their need for central air.
"A furnace would have been the easiest alternative to a heat pump," Yates says. But the homeowners didn't want to put up with the discomfort of forced air. "While hot water heat would be more expensive on the front end, the homeowners knew they'd be much more comfortable for the many years they expected to spend at their new home."
Still, money was an object. The customer wanted quality craftsmanship from Yates and superior comfort from hot water heat, yet all at a realistic cost. In the customer's own words: "Radiant for the common man."
According to Yates, a home's heating and cooling system, particularly when it involves extensive use of radiant heat, snowmelt and air conditioning, can be expected to cost between 20 percent and 30 percent or more of the home's total building cost.
For this project, Yates brought the work in at the low end of that scale because of various cost-saving measures both contractor and homeowner identified early on. At the end of this project, Yates says the homeowners trimmed more than $14,000 from the final price tag. Let's take a look at how Yates did it:
Intelligence GatheringWhile the homeowners had done a lot of research beforehand, Yates still needed to pull it all together. Luckily, the enthusiastic homeowners were very willing participants in the discussion.
Soon after the show, for example, the homeowners e-mailed Yates with a few questions. "That began the most extensive online dialog weOd experienced with one customer," Yates says. "They often asked several questions each evening. I responded, and theyOd asked more questions."
With each volley of questions, or drawings and diagrams sent via e-mail, and comments about products found on the Internet, Yates and the homeowners drew closer to the job.
As a matter of course, Yates asks "a thousand questions" to determine a familyOs habits. For example, what areas of the home need to be warmer or cooler? Would some areas of the house be more frequently used? What about floor covering? Where would there be carpet, hardwood, tile or bare concrete? Had they determined where theyOd want radiant? Then, of course, came the considerations for the homeOs architectural style, building materials, the sunOs influence, amount and type of insulation, etc.
"Hydronics is a passion for us," Yates says. "These folks were talking my language. They even referred to Ôbuilding the house around the mechanical system.O "
Yates was soon invited to a meeting with the homeowner and projectOs general contractor. During the meeting, Yates explored the house plans and offered some recommendations.
Shortly after submitting his quote, Yates learned that he was to do the job, even though his quoted price was substantially higher than the competing firm.
"There really was no comparison in the level of detail, or insight, and the way Dave probed for answers based on our needs and habits," the homeowner told us. "Another contractor asked for the number of square feet, and gave me a quote over the phone! We were willing to make some sacrifices elsewhere in the house in order to get Dave to do the work."
This fact gathering immediately led to one cost-saving measure. Yates learned that they wanted to have baseboard heat for not only the home office, but the master bedroom, both located on the otherwise radiantly heated first level. It was an odd request to Yates, at first. As it turned out, both the homeowners liked to sleep in a very cool bedroom under a down comforter. That made sense considering the wifeOs European heritage.
"Many Europeans will even sleep with windows cracked all winter long," the husband says.
This also presented a slight design challenge because of the heating curve for baseboard heat, and the typical desire to reset system temperatures based on outdoor ambient temperatures.
"With baseboardOs inability to provide adequate convective heat with water at less than 130 degrees," Yates adds, "I knew these areas would need to be zoned individually." More on this later.
Cost savings for using baseboard in these rooms vs. a full radiant system: $2,000.
Not much, but itOs a start. A bigger chunk of change came from deliberating on the snowmelt system.
The homeowners definitely wanted radiant heat to provide warmth at just over freezing temperatures to keep the automobiles and garage floor free of ice and snow. They also wanted 800 sq. ft. of snowmelt for the upper driveway and entry areas. While 800 sq. ft. isnOt the largest of spaces, the costs were huge considering the tubing, labor and extra equipment, such as heat exchanger and controls, required just for the snowmelt system. The final tally for this job made the homeowners reconsider.
Cost savings for not installing the snowmelt system: $5,000.
To conserve costs further, the homeOs upper floor = with two bedrooms, hallway, a game room and balcony overlooking the living room = would be heated with a hydro-air system. And since the attic was the only space large enough to house this equipment without interfering with closets, Yates decided to isolate the loop with a Wirsbo flat-plate heat exchanger and glycol for added protection. This would also provide ductwork for the air conditioningOs second zone and, unlike other levels, was the only combined source of heating and cooling.
Cost savings of going with hydro-air system vs. full radiant on the second floor: $4,000.
Finally, one last question-and-answer session provided additional cost savings. The homeowners planned on radiant heat for the entire basement slab. ItOs hard to beat that sort of basic radiant comfort. Then again, the family wouldnOt regularly use all the space. As the result, the homeowners decided to install radiant in about half of the space.
Cost savings of installing radiant in only half of the basement: $3,000.
Now to tie it all together. WeOve already mentioned how baseboard in the first-floor master bedroom, as well as the office, presented Yates with his first test.
Other rooms presented other challenges for Yates and two of his techs, Scott Barnett and Bob Seiger. For one, a large, timber-framed great room would have a 25-ft. ceiling, lots of glass and a wood floor. The heat loss exceeded safe floor temperatures for standard staple-up radiant, even with the aluminum plates and foil-faced insulation used in many other areas of the house. As a result, Yates opted for WirsboOs Quik Trak, which is mounted on top of the subfloor. That option allowed for much lower water temperatures, and wouldnOt harm the roomOs hardwood floor.
The master bathroom also came up short on a staple-up application, despite the use of ceramic tile. Again, the aluminum plate-backed, grooved sections with small-diameter pipes solved the problem.
All of the homeOs remaining radiantly heated areas were done with staple-up, using double-track aluminum plates that reduced the water temperature needed on a design day from 160 degrees F to just over 130 degrees F.
According to Barnett, the daylight basement recreation, bath and bedroom areas were a no-brainer. Mostly below grade with concrete floors and in-slab tubing with an insulation barrier, this was quickly pegged as a low temperature zone.
Based on previous research, the homeowners had selected a Peerless boiler and 60-gallon indirect-fired hot water heater, particularly well suited not only for domestic water, but also to fill a large, whirlpool tub. The cast-iron boilerOs high mass heat retention and electronic controls would also meet the demand of the homeOs hybrid heating/cooling design, and often could replenish the indirect unit without firing.
"With multiple zones, the indirectOs load was not factored into the total load for sizing the boiler," Yates explains. "Setting up an indirect on a priority zone in a radiantly heated home works perfectly because of the very slow loss of heat while the system idles. That allows the full power of the boiler to quickly regenerate the domestic tank."
Controlling OperationsWith all of these things to consider, it wasn't until the design of the main panel that Yates and Barnett felt the weight of the challenge.
"This is the heart of any radiant system," Barnett says, "and it sets the tone for how all parts of it will operate. We needed to provide a multiple-temperature system from a single temperature source. Plus, we had two high temperature zones, the indirect hot water tank and the hydro-air system on the second floor, and a very low temperature zone in the garage."
In addition, Yates' team also had to factor in the varying temperatures needed for staple-up, hardwood flooring, in-slab below grade, and baseboard.
"Plus, everything needed to be as quiet as a church mouse," Yates says.
Yates and Barnett admit a particular fondness for injection piping and zone pumping. With seven different temperatures required, the job became a control strategy game.
"As with any system we install," Yates says, "we try to keep it simple and cost-effective. The fewer bells and whistles, the fewer long-term maintenance issues. I like my sleep to be uninterrupted, so designing things right at this stage is a critical issue!"
The first step was to consider individual zone temperature needs and then judge their operation when in use. Two of the zones - the water heater and hydro-air system - received water directly from the boiler. Yates and his crew also considered whether to isolate the garage and hydro-air zones with a glycol solution and flat-panel heat exchangers, or to simply install glycol in the entire system. In the end, they chose to isolate two glycol loops.
Beyond that, they still had five zones with varying temperature needs. Since the Wirsbo Duo-Mix controls Yates typically uses each manage two separate injection panels, he opted to use two on the control board.
That left one remaining zone for a four-way valve or even a twinned three-way valve set-up. Instead, it was a slight-of-hand move that solved the challenge by taking the last Quik Trak hardwood floor zone off the injected staple-up return loop, allowing a stepped-down injection induced temperature to be circulated under the hardwood.
Yates' crew then wrapped the main hydronic panel with a 1 1/4-inch copper primary loop and piped each of the various zones with tees placed closely together. This acted to hydraulically uncouple them so that, along with the thermal traps, ghost flow is prevented. These were piped according to their temperature needs from hottest to coolest as the primary loop makes its way to the boiler's return.
"Running the primary loop at ceiling height also set up the thermal traps needed as we dropped down to serve each of the injection or secondary loops," Seiger explains. "And, wrapping the entire hydronic panel with the 1 1/4-inch copper makes the frame picture perfect."
Control of each zone was accomplished either with the Wirsbo Duo-Mix microprocessor controls for injection panels, or with relays that energize the high temperature zones. In all cases, a boiler-enable signal energizes the boiler. Flue gas condensation is prevented through a return water sensor. Because they had several high temperature zones and were using injection piping with outdoor reset, Yates decided not to add reset control of the boiler's water temperature to minimize short cycling.
Flipping through a tablet with notes about the job, Yates rattled-off a few remaining notes about the mechanical system:
- The indirect hot water storage tank is first with an Aquastat governing the relay.
- The hydro-air system has direct injection to a Wirsbo flat-plate heat exchanger on the main panel and then a pumped glycol loop to the coil located in the attic air handler. That loop is served with a separate thermal expansion tank and air eliminator; of course, no fresh water make-up. That side of the system also includes an altitude gauge as quick reference for recharging the glycol/water mix.
- The Runtal wall panel radiator was included in the staple-up system injection loop. A separate manifold served the Quik Trak; its source is the secondary injection panel, set up for full outdoor reset from 70 to 131 degrees.
- The baseboard injection panel is set for partial outdoor reset and will operate between 130 F and 180 degrees F.
- The basement injection panel has full outdoor reset, operating with water temperatures between 70 degrees F and 110 degrees F.
- The garage injection panel passes through another flat-plate heat exchanger and then is pumped to a remote panel where it's split into four manifold loops. A sensor located on this remote panel informs the Duo-Mix of changes in water temperature. This injection panel resets from 40 to 70 degrees. A separate thermal expansion tank and air eliminator serve the isolated loop. This side of the system also includes an altitude gauge for quick reference and recharging the glycol/water mix.
- All components received isolation valves. A bit more costly up-front, but greatly valuable in years to come as the mechanical components require service.
Yates and his men also can take credit for one more cost-saving measure - reduced energy costs. A 1,000-gallon, underground LP tank was initially filled with less than 600 gallons. "But that still provided heat for the entire house during a severe winter, all of our hot water for showers, baths and laundry, plus the gas for a fireplace, stove and clothes dryer."