Nortec MH Series - Manual (Page 52)

49 | Operation
Selecting an RH Setpoint
The optimum humidity setpoint depends on the reasons that a space is being humidified. The
“ASHRAE Handbook – HVAC Applications” recommends specific design relative humidities for
specific applications. See also Nortec publication “When You Need Humidity” (Form 124A) for
more information on humidity settings.
Health and Comfort - The benefit of humidity is most pronounced for health and comfort in the
40-60% range. A humidity setting of 40-50 % is recommended for this purpose to prevent over
humidifying.
Temperature Setback - In cold climates it is often necessary to reduce the humidity level in a
space to prevent build up of condensation on the inside of exterior walls, windows, and trim. It
is highly recommended that the temperature setback function of the Nortec digital controls be
used under these conditions to prevent damage from condensation. The digital control with an
outdoor temperature sensor installed will automatically setback the humidity setpoint to
correspond with outdoor temperature.
Duct High Limit – The duct high limit is intended to prevent saturation and wetting in duct work
at high load conditions. The evaporative principle of operation of the MH prevents the air from
being overhumidified. As a result a duct high limit is generally not required for an MH unit.
However if the duct work is very cold or in contact with exterior cold surfaces it may be
necessary to install a high limit to prevent humidity levels from becoming too high.
Note:
The job site design may have specified a setpoint chosen specifically for the site.
Refer to site documentation and where possible use setpoints specifically determined
for the site.