Radiant Heating System Soothes the Chicago Bears

But after being banged up throughout most of a dismal 1997 season, the "Monsters of the Midway" emerged looking more like baby cubs than bullies. The Bears haven't been sifting around licking their wounds, though. They've been working harder than ever to claw their way back to the top.

And the 1998 Bears team already has one less thorn in its paws. Thanks to a new radiant heating system at the team's state-of-the-art, $20-million training facility in Lake Forest, Ill., the Bears will never have to practice on a frozen field again.

The system is built around a concept known as "field heating," a concept that is becoming more popular throughout the National Football League as a way to prevent the freezing of playing surfaces. The Green Bay Packers use a similar system to heat the frozen tundra of Lambeau Field.

The field heating process begins in the facility's mechanical room. There, enormous amounts of water are heated to a temperature of 140° F. The heated water is treated with antifreeze, and a series of pumps distributes the water through 16 miles of specially designed plastic tubing. The water passes through the tubing, which lies just 6 inches below the turf and heats the playing surface.

Along the plastic tubing, electric sensors are placed throughout the field to monitor the temperature of the ground. The sensors are connected to a master controller that tells the boilers and pumps to turn on and off, thus maintaining a proper temperature in the tubing and on the playing surface.

This radiant field heating system is crucial to the maintenance of the practice field. It doesn't just keep the players toes toasty. It helps the growth of the turf's root system and prevents cold, brittle turf from being torn up by the players' spiked shoes. That means less injuries because of cold and brittle turf and no more having to replace torn-up chunks of turf weekly. Because torn turf often leads to severe injuries and replacing turf weekly can be very costly, the field heating system is a huge asset to the Bears' facility.

One of the finest aspects of the operation of the system is its efficiency. And with 6 million BTUs necessary to heat the vast amount of water in circulation, efficiency was certainly a key factor in choosing the right boilers to fit with this system.

The system utilizes three 2,000,000-BTU Lochinvar Copper-Fin boilers, each with two firing stages. With multiple firing stages, the boilers are able to match the BTU demand of the system without having to always run at "full fire," thus lowering operating costs and maximizing efficiency. Using Lochinvar's multiple-staged boilers, the Bears are saving more than 7 percent in efficiency compared to a standard on/off boiler. And when you consider the system utilizes 6,000,000 BTUs, that increased efficiency is saving the team lots of money.

Another factor that made Lochinvar the right fit for the Bears' field heating system was the boilers' footprints. Many high-output boilers are large and bulky and will barely squeeze into mechanical rooms. But the Lochinvar boilers' exceptionally small footprints and lower weight made installation quick and easy, with the boiler's taking up very little space in the Bears' mechanical room.

"With the facility already utilizing Lochinvar water heaters for its domestic water system, the boilers were the logical choice for the Bears' field heating system," says Rick Butler, Lochinvar district sales manager. "Being similar in parts, maintenance and service, the Lochinvar products can save the Bears a lot of time and money down the road."

Lochinvar can be contacted at 205 Elm Hill Pike, Nashville, TN 37210, phone: 615-889-8900, fax: 615-885-4403.

Church Heats Floor to Raise Spirits

The church's heating contractor, Vigilante Plumbing & Heating, turned to Rathe Associates, a New York-area manufacturer's representative, for heating equipment suggestions that would dovetail with the renovation plans.

The first step, they decided jointly, was to replace the old steam boiler with a two-boiler Slant/Fin hot water modular boiler system. The new boiler system would provide improved efficiency and reliability, as well as the design flexibility to set up a multizone, hot-water injection system to meet the diverse demands of the church's new radiation system.

Because renovation plans called for new tile floors in much of the church, radiant heating was specified for those areas. The pews and the floor beneath them, however, were not scheduled to be renovated. In this area, Slant/Fin free-standing fin-tube radiation would provide ample heat without disturbing the decor of the walls. Eventually, the floor would be replaced, and radiant heating would be installed there as well. The free standing fin-tube could be removed at that time without disturbing the walls.

Half-inch Slant/Fin Terra Therma radiant tubing was installed before pouring a 1-1/2-inch lightweight concrete slab. The finished tile floor installed on the concrete slab is ideal for delivering the comforts of radiant heat. It is highly effective at providing heating comfort to people at floor level without wastefully heating the air that rises to the high ceiling.

Modular Terra Therma supply and return manifolds simplified installation of the radiant tubing. Individual supply or return manifold modules snap together on-site to build a manifold with the right number of loops for the area being served. A built-in balancing valve for each loop makes it easy to fine-tune the system. Moreover, Slant/Fin system design software calculates the tubing lengths per zone and determines the specific zone setting for each loop.

A hot-water injection system was designed to supply the radiant tubing at a modulating water temperature between 90° F and 130° F while allowing the fin-tube radiation to be supplied at a much higher water temperature at the same time. The system is controlled with a tekmar 252 two-stage indoor/outdoor reset control. If demand is not satisfied by the first boiler, the second boiler kicks in. An important aspect of the control strategy is to provide a variable start-up time based on indoor and outdoor temperatures, so that the church would be comfortable prior to the first morning service.

The addition of radiant heating has helped make things more as they should be at St. Boniface: floors warm and spirits high.

Research Your Toilet Technology Options

There are two basic choices of tank-type toilet operating systems: gravity-fed and pressure-assist. Gravity toilets rely on generating a siphoning action to draw out bowl contents, while pressure-assist units are hydraulically designed to "push" the contents out of the bowl. Both are considered low-consumption toilets and are designed to conserve water. However, pressure-assist consistently out-performs gravity in one-flush operation. This increases water savings and reduces ongoing maintenance problems, as one professional engineer discovered while working on several hotel projects on the East Coast.

Shortly after completing work on a 600-room hotel, Joe Smaul, P.E., received a suggestion from the fixture manufacturer for his next hotel project. "The manufacturer wanted me to consider using pressure-assist toilets for a variety of reasons," says Smaul, who currently does engineering work for Marvin Waxman Consulting Engineers, in Glenside, Pa. "I immediately questioned why the manufacturer for the previous 600-room project had recommended gravity toilets," Smaul recalls. He decided to contact the head of maintenance engineering at the hotel to discuss the matter. What he found out re-affirmed that pressure-assist was the only way to go.

After further research, Smaul discovered that other hotels in Las Vegas were either installing pressure-assist on new construction or replacing gravity units with pressure-assist on existing installations. One of the casinos had even replaced all of their new gravity toilets with pressure-assist units and had since reduced their service factor on toilets to zero. In addition, Smaul received feedback from people who had bought new homes, and he is convinced that in some instances pressure-assist is better suited for residential installations as well.

"All of this information made the decision easy-we recommended pressure-assist toilets," Smaul says. One type of pressure-assist toilet, from Sloan FLUSHMATER, is available through leading fixture manufacturers including American Standard, Crane, Gerber, Kohler, Mansfield and Universal Rundle.

Performance should be a top concern in any project. Fixtures that incorporate pressure-assist technology provide the best performance in terms of the water conservation that people expect.

The Case of the Over-Performing Pump

The pumps were installed, and the system was put into operation. Bill Gilmore of the energy department of the physical plant called to report that the 30-HP motors were overloading and the variable speed drives had to reduce the frequency being applied to the motors from 60 to 54 cycles per second. This changed the rpm of the motors to 1600 rpm. The standard question-"What's wrong with your pumps? I want to operate them at full speed for peak requirements and reduced speed at lower loads."

The calculations were made to determine the effect of a 30-percent ethylene glycol solution at 45° F on the pump horsepower. At the design point, the pumps should only require 28 HP, yet at full speed the motors were overloading.

Pressure readings were taken at the pump suction and discharge flanges. The readings indicated a higher flow than design point, which agreed with the increased horsepower requirements. A flow meter had been installed in a line, but Taco felt the meter did not indicate the total flow from the pumps.

A Taco Sentinel 12-inch Wet Tap Metering Station was installed in a straight run of line, which would monitor the total flow of any of the pumps operating. One of the physical plant workers welded the Wet Tap Station to the wall of the charged 12-inch line. The Wet Tap Drill was used to drill a hole in the wall of the pipe. The Wet Tap Station ball valve was closed, and the Drill was then removed.

The Wet Tap chamber was reinstalled in the ball valve, and the Wet Tap Metering Probe was inserted into the pipe. The differential pressure gauge was connected to the probe, and the flow readings were taken.

With two pumps running at 54hz, which equaled about 1600 rpm, the flow meter indicated a flow of 1,913 gpm. Corrections to the readings had to be made for the effect of the 1.05 specific gravity on the flow and the pressure-gauge readings. Each pump was pumping 956.5 gpm. The pressure gauges indicated 85 feet of head, however, this reading had to be divided by 1.05, which equaled 80.9 feet. Another correction had to be made for velocity head because the FM5010 had a 5-inch discharge and a 6-inch suction. With the flow known, a resultant velocity head of 1.9 feet would be added to the 80.9 feet to equal 82.8 feet.

The actual system design resistance was now calculated, based on the pump performance data gathered for the design point of 800 gpm. The resistance at this point was found to be 57.9 feet. This was calculated by (800/956.5)2 x 82.8 feet. The calculation of the true system resistance solved the mystery why the pumps were operating further out on their performance curve and overloaded the motors. The pumps had been sized for 106 feet of head but only needed 57.9 feet. The flow and head readings had determined the system conditions, but did the pump agree with published performance curve?

The pump laws were now applied to the head and flow readings to bring them from 1600 rpm to full operating speed of 1760 rpm. (1760/1600) x 956.5 = 1052 gpm. (1760/1600)2 x 82.8 feet = 100 feet. Applying the new calculated flow and head to the 10.2-inch catalog curve showed that the pump did agree with the published curve.

The impellers were removed and reduced in diameter so the pump performance would match the true system requirements. The pumps could now be operated at 1760 rpm, achieve the design point and not overload the motors.

This case was a good example why a pump is not a good flow meter. The many factors such as velocity head, specific gravity of the fluid, viscosity of the fluid and rpm complicate checking performance of a pump.

The installation of the averaging pilot tube flow meter gives an inexpensive, accurate flow reading and only adds 1 to 2 inches of pressure drop to the system. This flow meter could be connected to the system computer for more detailed energy analysis and system control. It should be noted that with most flow meters there should be 10 pipe diameters of straight pipe before and five pipe diameters after a flow meter to achieve an accurate flow reading.

For more information, contact George Taber, senior applications/field manager for Taco at 401-942-8000.

Piping Made Easy With Wirsbo

The Cox home is a showcase of modern heating technology. The system consists of three boilers supporting 12,779 square feet of radiant floor heating and 5,000 square feet of snow and ice melting. Two 198,000 BTU/h cast iron boilers, piped in parallel reverse return, supply heat to the majority of the radiant panel through a modulating four-way mixing valve. The domestic hot water is supported from secondary piping off the primary loop to two 80-gallon tanks piped in parallel reverse return counter flow. Three makeup air fan coils and one large air-to-air heat exchanger are supplied from a secondary loop being controlled by a variable speed drive. Flow to the fan coils is performed through tertiary loop piping. The fan coils have individual modulating three-way valves utilizing P&I logic 4-20 ma controls. Accuracy is +/- 1° F.

A third 1,200,000 BTU/h low mass boiler supports a snow and ice melting area of 5,000 square feet and another 1,500 square feet in the garage. The snow and ice melting area, made up of three separate zones and controlled with automatic and manual controls, is done with primary/secondary piping with thermosiphon traps on each branch.

"Just imagine the piping that goes in on some of these large installations," says Mark Eatherton, of Radiant Floors, Inc. Eatherton is a hydronics and energy management expert with 23 years of field experience. "On this particular job, we've utilized every hydronic configuration known to man, and a few that aren't."

In an effort to keep the piping simple and efficient, Eatherton finds that the use of large diameter Wirsbo hePEX tubing has proven to be reliable, dependable and offers substantial savings in labor. Wirsbo hePEX tubing was used for the supply and return lines from the boiler rooms in sizes up to 1-1/2-inch diameter. "The plumbers and contractors are amazed at how quickly we can turn these jobs," Eatherton says. "We installed most of the mains in about one-third the time it would have taken to install it with regular copper tubing. It results in tremendous labor savings, and you know, time is money."

The Cox project won the Best of Show Award during the recent Radiant Panel Association Annual Meeting in Bellevue, Wash. "This home has over 23,000 feet of Wirsbo tubing installed," Eatherton says. "Wirsbo makes designing and installing these jobs much more fun because the products can be installed as a system instead of a bunch of parts thrown at a job.

"With Wirsbo hydronics, the only thing we can't do is air conditioning," smiles Eatherton.

Snow Melting a Mall

When the city was returning a downtown pedestrian mall, which had been closed to traffic since 1970, back to a street again, the project called for snow melting storefront to storefront, including the street. There are many benefits to snow melting: no more snow plowing and no need to use salt (both of which damage the decorative brick pavers used in the street and sidewalk areas), plus significant maintenance labor savings. Cleaner, dryer streets and walks benefit store owners by having safe, clean access to their businesses.

Steam from the county's trash incinerator was delivered to a unique heat transfer system that provides the energy required. Part of the uniqueness of the system is that it utilized two heat exchangers. The first converted energy from incoming steam to the water/glycol fluid circulating through the system. The second heat exchanger utilized the condensate from the first heat exchanger, extracting additional energy that was normally wasted to preheat the system return fluid before it reached the first heat exchanger.

The project design criteria was based on a 0T F outside temperature with 10 mph winds and must melt snow at the rate of two inches per hour. The system is totally automated and designed to maintain a standby (idle) surface temperature of 39T F. The surface temperature is automatically increased to a maximum of 45T F when moisture is detected by the sensors. When moisture is no longer detected by the sensors, the system returns to the idle mode. The total project encompassed 66,000 square feet and 124,000 feet of 5/8-inch Pex-C UV-resistant tubing set six inches on center. This required 400 loops of pipe at 310 feet each, using 70 manifolds.

Selection of materials for this project posed additional challenges for the contractor, Andy J. Egan Company. The project was to be completed in stages: first the sidewalks, then the streets. Decorative brick pavers were used in both areas over a concrete slab.

Heatlink USA was chosen to be the supplier for three vital reasons. First, Heatlink makes the only Pex-C black UV-protected pipe that was specifically designed for this type of application. Ultraviolet protection was critical on this project because pipe would be exposed to direct sunlight and standing water for long periods of time. Second, with Heatlink's Twistseal manifold with 1-1/2-inch inlet and outlet, up to 3.2 gallons per minute could be sent through each loop and a maximum of 24 gpm per manifold. Third, the Twistseal manifold provides the ability to individually balance each loop within the system. Manifolds were installed in planter boxes every 40 feet on both sides of the street: one manifold to control the sidewalk portion of the 40-foot section, and a second manifold to control the street.

The project was designed by Barry Vezino and Bill Bartlette, Heatlink system engineers, Bob Fisk of Andy J. Egan Company, and Raley Brothers, Heatlink's manufacturer's agent for Michigan.