High & Dry- Low Humidity DryAir System Used To Heat 16-Story Condominium
Besides the spectacular view of Downtown Madison and Lake Monona, one of the selling points of Metropolitan Place is the extensive woodwork in the condominiums.
“There´s a lot of wood. I´d say 80 to 90 percent of the units have wood flooring. The only places in the units that generally don´t have wood, would be the bathrooms,” said Don Jochem, project superintendent with KBS Construction, Inc.
Metropolitan Place is a 16-story condominium building with a fourstory parking ramp topped by a landscaped plaza in Madison, Wis., being constructed by KBS Construction, Inc., which has offices in Milwaukee and Madison.
Construction started in November of 2001, and is expected to be complete in June of 2003.
With all the woodwork in the condominiums, Jochem was concerned about humidity from open flame heaters commonly used on construction sites in winter.
As a result, Metropolitan Place is being heated this winter by a DryAir system rented from Lincoln Contractors Supply, Inc., the certified DryAir distributor in Wisconsin.
With the DryAir system, contractors can heat their project with no open flame inside the building. The water heater, the only fuel-burning component of the system, is located away from the project structure in its own enclosure.
The water heater warms the heat transfer fluid, which is pumped through a heat distribution system loop to portable heat exchangers.
Portable heat exchangers include a heat transfer coil, fan, and thermostatic temperature control. The heat transfer fluid flows through the transfer coil, where heat is transferred to the air being drawn through the coil by the fan.
The coil is designed for optimum heat transfer, without adding any moisture or combustion byproducts to the air. The exchangers recirculate and reheat internal air. “It´s a very dry heat, unlike what we´ve seen in heaters in the past, which have been open flame throwers whether they use natural gas or propane. Those put out a lot of moisture.
“I can remember one of the first jobs I was on as an apprentice, there´d be a half inch of ice on the windows from the condensation from moisture put into the building from the heating system. This heating system, we see none of that,” Jochem said.
Low humidity with the DryAir system minimizes expansion and contraction of wallboard, and reduces the chance of shrinkage at mitered joints in finish trim materials.
The Great Outdoors
Metropolitan Place is being heated by a pair of 1.2 million BTU burners that have been placed on the top level of the parking structure.
“They´re open to the atmosphere, so the open flame and gas is outside the building,” said Tim Lickel, climate control specialist with Lincoln Contractors Supply, Inc.
A pair of 2-inch lines run from the burners to manifolds, and then on to portable heat exchangers.
Three different sizes of heat exchangers can be used with the system: 600,000 BTU, 200,000 BTU, or 80,000 BTU.
KBS Construction is using several 200,000 BTU exchangers and approximately 20 of the 80,000 BTU exchangers at Metropolitan Place.
“As we turn on the permanent heat on the lower floors, we keep one heater on the floor to keep the hallway warm. We get a lot of cold air infiltration with the skip hoists and the upper floors aren´t heated, so we need the portable heaters to keep the sprinkler pipes and plumbing pipes from freezing,” Jochem said.
There are no heat exchangers on the top three floors of the building.
“The top three floors heat themselves; it´s just rising hot air going up there. The top three floors, which aren´t even insulated on the outside, are anywhere from 50 to 60 degrees, depending on how much cold air is coming in through the skip hoists and how often the doors are opened,” said Jochem. Fewer BTU´s are needed to heat a multi-story building than a single-story building because, of course, heat rises.
“The heat you´re losing out a ceiling on a sub floor is going to the floor above. You can skip floors in multi-story buildings,” Lickel said.
The lines that extend from the burners to the heat exchangers run up stairwells at Metropolitan Place.
A DryAir heat transfer plate system, which is being used at Metropolitan Place, allows heat exchangers to be placed at a greater distance from the burners.
“We can run 200 feet straight up with the heat transfer plate. Typically, we could only go 30 feet up because you can only pump so high in the air with a 2 HP pump,” said Lickel.
Two-inch lines can be extended as far as 300 to 400 feet from the burner, while a 1-inch line can typically reach 100 to 150 feet.
The use of the DryAir system helps with dry wall work.
“You don´t see the problems with shrinkage with the screw holes,” said Jochem.
Low humidity allows for daily application of joint compound or finish texture for drywall, and reduces the amount of downtime between finished drywall and paint application.
“With an open flame, you´re going to run into 60 to 70 percent relative humidity. That´s not real conducive to a dry job site.
When you build with DryAir, you´re getting a low relative humidity to begin with. It´s a clean, dry heat,” Lickel said.
No Worries
Because there is no open flame inside the building, there are no worries about carbon monoxide and carbon dioxide.
The heating fluid used with the system is also non-toxic.
“It´s a food grade preservative that is clear like water. There´s no consequence if it spills on the job site,” said Lickel.
“It´s a lot safer than having gas lines strung out throughout the job.”
A computer program is used to do calculations based on the cubic feet of the building, the number of floors, the R-value in ceiling and walls, and the desired temperature, to let customers know how many BTU´s of DryAir are need to heat the site.
“There´s no guess work,” Lickel said.
For smaller construction projects, Lincoln Contractors Supply offers DryAir portable heating systems in 900,000 BTU, 400,000 BTU oil fired, and 200,000 LP/NG models.
Besides heating a building in cold weather, the system can also be used to thaw frozen ground.
By placing 3/4-inch hoses 18 inches apart, covering the hoses with plastic and two layers of blankets, the DryAir system can be used to thaw up to 24,000 square feet of frozen ground.
Another application is curing concrete in low temperatures.
“If you´re pouring concrete and worried about the slab freezing, you just coil the hoses on top of the concrete and put blankets on it and let it cure that way,” Lickel said.
The system can also be used to dry out a building to prevent mold from forming. To dry out a building, air is added to the building and expelled through a roof vent before insulation is placed.
“We´re picking the moisture up and out of the building. We´re not adding any moisture with our equipment,” said Lickel
Reprinted from the February 6, 2003 issue of WESTERN BUILDER
By Barry Gantenbein, editor, Western Builder