Nortec MH Series - Manual (Page 51)

Operation | 48
air passing through the media. As a result of the evaporation the humidity of the air is
increased and the temperature of the air is decreased.
 Any water that is not evaporated collects in the drain pan and;
MHTC Reflow - flows back to the hydraulic unit reservoir to be recirculated. As water is
evaporated the water level in the reservoir decreases and the float opens. The MH then
refills until the float is closed.
MHTC Flow / MHB – flows down to drain. The MHTC Flow / MHB does not have a reservoir
or pump and water simply flows through the staging valves when they are open using supply
water pressure to generate flow.
 During operation the controller responds to changes in demand by opening and closing
staging valves. This allows the MH to match its output to demand.
 When demand is satisfied the MH will;
MHTC Reflow – turn off all staging valves and after a delay turn off the UV light and pump.
MHTC Flow / MHB – turn off all staging valves.
Water Management (MHTC Reflow only)
 During the evaporation process minerals are left behind by the evaporated water resulting in
an increase in concentration in the remaining water. To prevent minerals from collecting in
and fouling the evaporative media the MH always supplies more water than can be
evaporated to the media. The unevaporated water carries the minerals left by evaporated
water to the reservoir.
 To prevent the mineral concentration from increasing to the point where excess water can
no longer dissolve minerals left in the media by evaporated water, the MH will periodically
flush the tank. The method used to determine when to flush the tank is configured using
display and keypad. Two triggers can be set.
Trigger 1
Time – The MHTC flushes the tank at a specific time every day.
Periodic – The MHTC flushes the tank after a fixed number of operating hours.
Demand - The MHTC flush the tank after a fixed number of weighted hours ( weighted hours
= hours of operation x demand% )
Trigger 2
Cycle – The MHTC flushes the tank after a fixed number of fill cycles.
μSSensor (requires optional conductivity sensor)– Flushes the tank when the conductivity
sensor indicates the concentration of minerals exceeds a configured maximum value.
 In general more frequent drains result in less maintenance and longer media life. The
amount of water drained to control mineral concentration in the recirculating water can be
configured in the MHTC’s software.
Pressure Equalization Line (MHTC Reflow only)
 In order to ensure that water flows properly from the duct unit’s drain pan to the MHTC
Reflow’s reservoir a pressure equalization line must be installed between the reservoir and
the duct downstream of the duct unit. The line ensures pressure in the reservoir and duct
are equal and water flows properly from the drain pan to the reservoir.