high water sensor board has a primary voltage side. One leg connects to the primary leg; one leg connects to the short sensor pin in the top of the cylinder. A potential, somewhat less than primary, is picked up by the sensor at high water level, which “makes” the red/black circuit on the low voltage side. This creates a resistive loop across terminals
Back at the electronics, the contactor receives its “hot leg” from terminal 12. The fill receives its “hot leg” from terminal 14. The drain receives its “hot leg” from terminal 16. Unlike the contactor and fill, the drain gets its “ground leg” directly from the transformer. It does not depend on the air proving switch to activate.
The yellow and green status lamps are LED’s. Polarity is important. Terminal 26 is positive dc supply. Terminal 22 and 24 are switched dc grounds for yellow and green respectively.
BLOWER PACKS
An optional blower pack (BP), if present, gets its primary voltage from inside the humidifier. This way, only one external power source has to be connected to the equipment.
TERMS USED
RATED AMPS: Refers to amps listed on the humidifier specification label.
SHORT CYCLING: When the ‘on time’ of the humidifier is less than ten minutes upon a call for humidity. To correct short cycling, all humidifiers have a capacity adjustment which allows the output of the humidifier to be reduced as low as 20% of rated output, thus extending the ‘on time’ required to maintain output.
FOAMING: The phenomenon which can occur in water when the impurities, already in the water, reach an excess concentration as result of boiling away pure water and the continued boiling action agitating the contained water. The humidifier electronics are designed to prevent this occurrence although in extreme cases water will foam with little concentration, making it necessary to have the drain time of the water, contained in the cylinder, increased. Foaming is normally caused by short cycling, a restricted drain, or back pressure. The foam, generated in these instances, is conductive and may lead to a false full cylinder indication if the level of the foam approaches the top of the cylinder.
BACK PRESSURE: Restriction of steam flow caused by long steam runs, improperly sloped steam lines, elbows changing the direction of the steam flow from horizontal to vertical without a drain leg, any plumbing detail allowing the accumulation of condensate, undersized steam line, improper steam distributor, downward air flow onto the distributor creating excess static pressure at the steam outlets or high static pressure ducts (not probable). To overcome excess static pressure in the duct, a fill cup extension kit should be used. In downflow applications, a downflow distributor should be used but in some cases the fill cup extension will also be required.
RESET UNIT (HUMIDIFIER): To reset the
humidifier, the on/off/drain switch at the front of the humidifier should be switched to the off position for a minimum of five seconds and then switched back to the on position.
MONITORED LEG: Refers to the primary wire, to the cylinder, which loops through the current sensing device on the main pcb. This wire is terminated at the red cylinder plug at the cylinder. Units with six primary wires to the cylinder will monitor only one of the two wires, terminating with red plugs.
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