M52 Microprocessor User's Guide
M52UMCT Oct-03 9
(Temp 1) and the glycol loop temperature (temp 2) is greater than 5°C, (9°F). When the glycol
temperature drops below 7.2°C (45°F) the compressors will stop automatically. The glycol
temperature is monitored by the unit using Temp 2 input. Temp 1 and Temp 2 can be viewed in the
Test Mode section on page three.
Note: The Status screen on the controller indicates free cooling is on when it displays 2/2 and off
when it displays 0/2 under the percentage demand next to the Free Cooling icon.
Reheat:
On demand for heat the demand signal ramps up and heater contactor closes at 100% demand, for
one stage or at 20% with SCR. SCR modulates from 20 to 100% output to match the demand
signal. On multi-stage heaters each stage will be energized at equal intervals as the demand
increases from 0 to 100%.
Heater stops when:
Loss of demand
Loss of air flow
Heater high temp cut out
Humidifier:
When the “On/Off/Drain “ switch is in the “On” position, a demand for humidification causes the
humidifier contactor(s) to close in stages 1 to 4 or 8, (depending on Series and number of units
connected together with Co-Work), as demand for humidification increases from 0 to 100%.
After a short time delay, approximately 1 to 3 minutes, the fill valve will energize allowing water to
fill the boiler bottle. The fill valve closes when the humidifier reaches its FLA current or when the
water level reaches the high water level sensor. Water begins to boil after a few minutes. The
humidifier will continue to boil and fill to maintain the humidity setpoint. Periodically the
humidifier will initiate a flush cycle to maintain constant steam output and to flush some of the
mineral content from the boiler bottle.
When the boiler bottle reaches the end of its useful life it will activate a Boiler Dirty Alarm and will
shut off the humidifier. It is common for the Boiler Dirty Alarm to sound on an initial start-up as the
humidifier begins the process of concentrating the mineral content of the contained water.
To drain the humidifier you must cause a humidification demand and then switch the “On/Off/
Drain” switch to Drain. You must set the switch back to “Off “when the bottle has completely
drained.
Humidifier stops when:
“On/Off/Drain” switch is switched "Off"
Loss of demand
Loss of air flow
Boiler Dirty Alarm intervention.
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