COPYRIGHT
TENNANT COMPANY 1999
4
Humidity Control
Using Dryers to speed the rate of evaporation in an en-
closed area can cause humidity to escalate. As humidity
elevates, airmovers become less effective and the rate of
drying slows. It is vital that Dryers be used with adequate
dehumidification. For safety, indoor humidity should not
exceed 60% Rh. For maximum drying of porous materials,
indoor humidity should be maintained below 45% Rh.
Even lower humidity between 25-40% Rh is helpful for
drying saturated, dense materials such as walls and floors.
To assist in the drying process, close off the building area
being dried from the rest of structure. Regulate the heating
or air conditioning system of the structure. When dehu-
midifiers are not available, turn on exhaust fans in the at-
tic, kitchen and bathroom to remove some humidity. Use a
thermo-hygrometer such as the DHT200 or DHT600 to
determine the indoor relative humidity.
DRYING PROCEDURES
It is possible to dry both the stretched in carpet and syn-
thetic cushion at the same time on many flood jobs. Dryers
are used to force air under the carpet so that a cushion of
air floats the carpet off the floor. Along with humidity
control, the high volume airflow will usually dry most car-
pet, cushion, and flooring.
When hardwood flooring is present under wet carpet,
strong consideration should be given to removing carpet
for drying. Consideration should also be given to removing
water damaged carpet cushion when it has a non-porous
plastic "skin", when it shows signs of severe wear or in
contaminated situations.
Sub-surface Carpet Drying
Dryer with Carpet Clamp.
For most subsurface drying, place Dryers in a corner or
door opening. Place the snout of the Dryer between the
carpet and cushion. For subsurface carpet drying, the car-
pet must be disengaged and folded back several feet. Place
the airmover snout below the carpet edge and staple
through the tackless on both sides of the Dryer. Note the
condition of the tackless strip, cushion and floor. They
may require additional procedures.
Stapling Down
After placing the dryer, staple through the tack strip on
both sides of the dryer. This is done to keep the carpet
from floating off the tackless and losing float. To relieve
excess pressure, open an opposite corner and staple as if
placing a dryer.
Adjusting Airflow
When adjusting the volume of air under the carpet, care
should be exercised to not force too much air into the
space. Too much air volume may disengage the carpet
from the tackless strip and tear it as it comes off the strip.
If the carpet is a tightly stretched installation, the carpet
may stretch if too much air is forced under it, and the
stretching may cause difficulty in the final steps of rein-
stallation. Air pressure can be relieved by releasing the
carpet from the tackless strip at the opposite side from the
Dryer until the proper lift has been attained.
CAUTION
Increased air movement and evaporation without proper
dehumidification may result in extremely saturated air.
Drywall and other hygroscopic materials may absorb the
excess moisture in the air. This can result in "secondary
damage" to materials. When using Dryers, monitor hu-
midity levels and use dehumidifiers as required. Maintain
the humidity below 60% Rh at all times.
Surface Drying of Carpet and Walls
In some cases, stretched-in carpet, pad and subfloor can be
dried from the surface, without disturbing the installation
in any way except lifting corners of carpet to inspect.
Factors for success in surface drying include: exceptionally
complete extraction, use of enough Dryers strategically
placed to create constant airflow across all affected areas,
use of enough dehumidifiers to quickly and constantly
maintain a lowering of humidity in the drying area, and
careful monitoring with adequate moisture and humidity
meters.
The advantages of surface drying include less restretching,
repair and replacement of materials, fewer problems with
difficult types of carpet, less disturbance of furniture and
contents, greater reliance on equipment rather than labor
(except that extraction may take more time to guarantee
