Traverse City, Mich.-based consulting firm Apollo Engineering; Oak Park, Mich.-based manufacturers rep Dale Prentice Co. and boiler manufacturerViessmann have the same energy-efficiency philosophies.
When like minds get together, good things tend to happen as was the case when the three entities teamed up on boiler-replacement projects at the Alpena County Annex Building in Alpena, Mich., and a new indoor athletic facility at Northwood University in Midland, Mich.
“You don’t go out and replace just a boiler,” Apollo Engineering Chief Engineer John Richards, P.E., says. “The entire system has to agree with the boiler being installed. When I look at a new or retrofit system, I focus my design on making the entire system the most efficient it can be.”
Prentice Co.’s Charlie Dashner, P.E., part of a firm providing application engineering services since 1926, has seen the opposite occur. “Replacing an old 50- or 60-year-old atmospheric boiler with any condensing boiler will deliver savings and you may look good doing that, but there is so much more that must be considered,” he says.
“Engineering the entire system in and around the boiler is how you maximize its true efficiency and deliver on energy savings. We work in cooperation with Viessmann specialists and the designing engineer whenever we lay out a project to maximize energy savings and provide our customers with the best solution.”
TWO-FOR-ONE
Richards encountered an out-of-date boiler system at the county annex building. “We took out a steam boiler that was basically being converted to hot water to do its work,” he says. “It was three or four times oversized and from the early 1960s or 1950s. The efficiency was poor.”
According to a local newspaper story, the county used a portion of a federal grant to install the building’s new $70,000 boiler system. The grant comes from the Northeast Michigan Council of Governments. Presque Isle County in Michigan was selected as the fiduciary. Alpena County had to pay the cost of the project up front, but quickly was reimbursed.
Richards specified three rack-mounted Viessmann Vitodens condensing boilers and modified existing air handlers with larger hot-water coils. A key in the system retrofit was lowering the incoming water supply temperature.
“We designed it for 140° F water and lowered it 30° or 40° F,” Richards says. “Once the system was installed, the boiler was condensing at 90-plus percent. Part of the focus was maintaining the condensing aspect in the boiler installation. With the annex building we managed the heat source. We didn’t do any extra stuff. It was purely boiler and managing the water temperature.”
Steam coils in the system were replaced by Trane hot-water coils. “The boilers and air handlers were in the same room so we didn’t have to run new pipe in the building,” Richards says. “That made it easy to remove the steam coils and install new ones. “
An existing WaterFurnace closed-loop heat pump was modified to accommodate the new condensing boilers, which presented one particular challenge during the retrofit process.
“We had to get those boilers through a small 3-ft. door,” Richards says, speaking of the limited space in the basement-level mechanical room. “We could have done a cast-iron sectional and brought it in pieces, but the decision was made to go with the Viessmann boilers and they turned out perfectly for the application.”
Dashner adds the use of a Viessmann boiler rack greatly aided the installation process. “Sometimes a boiler room will present some obstacles. In this case we did not have available wall space to hang the boilers,” he says. “The solution was a rack with a prefabricated distribution manifold, which is easy to assemble in the field. There are no installation errors and the rack easily accommodates the boilers.”
The new boilers provide acoustic benefits as well. “After connecting the external piping and startup, they run so quietly,” Dashner says. “I had to walk directly up to them to hear them.”
The savings generated by the system retrofit have been significant. Dashner references the same newspaper article where County Commissioner Cam Habermehl stated one gas bill for a particular month prior to the upgrades was $3,004. In the same month a year later it dropped to $959. Richards says he was told the county was spending $16,000 during pre-upgrade heating seasons, but that number has dropped to about $6,000.
“Making modifications to the entire system will maximize overall output,” he says. “If you didn’t do that, it would be like putting a Ferrari engine in a Vega. You can’t have true energy savings without looking at the entire system.”
THE TURF IS GREENER
Northwood University added a 60,000-sq.-ft. indoor athletic training facility that includes a turf training surface and a 1/8-mile running track to its existing sports complex. The older 55,000-sq.-ft. building, constructed in the 1960s-1970s era, includes a gymnasium and swimming pool.
An atmospheric copper-tube boiler was sized to satisfy the heating needs of the original building and pool. At some point, the pool was disconnected from the boiler.
“The boiler was double the size it needed to be, had a draft inducer on the vent, was piped direct return (meaning water ran through it continuously) and the draft inducer ran all the time,” Richards says. “It was as bad as you could have for any installation for any boiler working at any capacity. I couldn’t have made it less efficient if I tried.”
The school, which doubled the size of its indoor athletic footprint with the addition of the new building, contemplated adding a second boiler room during the construction to accommodate the added space. Richards had a better idea. “Why not combine them?” he asks.
Richards suggested replacing the old boiler and connecting the new building into the existing one. However, that solution bid out slightly over budget.
Enter Prentice Co. Applications Specialist Melissa Melton. She evaluated how installation costs could be reduced by designing a hybrid system that would specify one Viessmann Vitocrossal condensing boiler and one Vitorond non-condensing unit. Melton suggested a design where the Vitocrossal boiler would be able to condense when lower temperatures are needed (early and late heating seasons), and then use an 85% non-condensing boiler to help out in the season where higher water temperatures are required.
“We reduced upfront cost, but had minimal effect on overall system efficiency,” she says.
Melton notes the system’s Viessmann Vitocontrol S boiler controller has the built-in capability to do the particular kind of boiler functioning needed with only startup programming changes required instead of field modifications. The controller also operates two combustion air fans and system pumps. A Viessmann gateway simplifies communication to the building management system.
The hybrid system was designed using 160° F water instead of 180° F water. A ∆T of 30 brings the water down to 130° F. “That’s to maintain some chance you could condense with the boiler,” Richards says.
The new Viessmann boilers replaced the older 4 million Btu model. Richards did an extensive load count modeling of the facility and came up with some impressive results.
“It was about 4 million Btu to condition the new building and the existing building together,” he says. “The size of the facility doubled. We just took out 4 million Btu and put 4 million back in.”
In the new building, Richards specified Carrier air handlers for ventilation and conditioning. Yaskawa frequency drives on the air handlers allow for the tempering of air control as needed. The building’s ventilation is monitored and maintained by a Honeywell direct digital control system with Tridium controls.
“We can do more demand control with the building so we’re not always ventilating for 500 people,” he says. “It’s the old adage if you flow 50% of the design air flow, you can reduce energy usage 90%.”
Richards asked the facilities manager how energy and gas usage was shaping up after the addition of the new facility and got an answer he had hoped to hear.
“He said the gas bill has not gone up,” Richards says. “The energy usage is the same. It’s like we didn’t have the 60,000 extra sq. ft. with an added boiler.”
Dashner further demonstrated the drastic shift in energy usage when he conducted training for building management at the facility.
“The university was used to running 190° F water all year,” he says. “I made the guys a graph from 70° to -10° outdoor air temperature, drew a horizontal straight line representing continual usage of 190° water from 70° down to -10° and then plotted on the same graph the curve for the water reset ratio we put into the system.”
“The temperature difference between the 190° line and the temperature on the curve was all wasted energy they had been spending by using the constant 190° water all heating season. It was an eye-opener for them.”
Both Apollo and Dale Prentice are major advocates of educating their clients on the products and systems they install. Dale Prentice’s Michael Cullen notes for years Prentice has conducted educational seminars throughout Michigan.
“We work with engineers to help them quantify the anticipated savings through the use of Viessmann’s Commercial Project Evaluation Program,” Dashner says. “John forecast a $50,000-per-year savings for the university. When purchasing high-quality equipment and paying an engineer to do an energy-efficient design, it is important to demonstrate to the customer the overall value of the engineered solution.”
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Source: pme
