Page 651 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 523

Air movers remove water from wet materials through evaporation. Air moving across the wet surface
collects available moisture in the form of vapor. Dehumidifiers wring water out of the vapor by passing
moist air over cooling coils or desiccant. Refrigerant coils in a dehumidifier collect moisture like a cold
glass collects water droplets on a humid day. Desiccant dehumidifiers cost more but are more effective
in cold temperatures. The portable dehumidifier in Figure 19-10 weighs about 125 pounds and will
extract about 100 pints a day when the air temperature is 80 degrees and relative humidity is 60
percent.

A negative air scrubber will be needed when working with toxics in a containment structure. (See Figure
19-11) The scrubber draws air out of a room or containment structure so air flows continually from
outside the room or structure to the interior. That prevents escape of airborne toxics from the area where
work is being done. The scrubber has to be placed inside the containment area. A HEPA filter in the
scrubber traps nearly all airborne particles before exhausting air through 12" or 14" flex duct, either to
the exterior or outside the containment structure. Some negative air scrubbers also include an odor
absorption filter. Other units can be reversed to provide clean positive air to a room that has to be kept
free of airborne particles. A single 1,400-CFM scrubber will provide one clean air change a minute in a
12- x 14-foot room.

Scrubbers usually have two or three filters. The primary filter should be replaced daily. The secondary
filter, if there is one, should be replaced every three to five days. The HEPA filter will require replacement
after 500 to 1,000 hours, depending on conditions.

Hardwood flooring presents a special problem. Hardwood swells and cups at the edges when wet for
more than a few hours. Drying the floor promptly will prevent most damage. It's easy to remove water
standing on a hardwood floor. Any wet-vac or sponge mop will work fine. But it's harder to remove water
that's soaked through wood seams into the subfloor. Mat drying, as in Figure 19-12, is one good
solution. A vacuum extracts moist air from under mats laid over wet portions of the floor. A hardwood
floor with 30 percent moisture should dry to a normal moisture level (under 10 percent) in four or five
days. Cupping and swelling will disappear as the floor dries, leaving a floor that may need refinishing but
won't have to be torn out.