Excess Humidity; Leaking Water; Noise; General Maintenance - Aprilaire 220 Service Manual

II. EXCESS HUMIDITY
Humidity Control Check —
Check Wiring — A closed short in the low voltage control circuit leading to the humidistat may
cause the unit to run continually.
Check Relay/120 Volt Humidifier Control — A defective or sticking contact on the relay or a
defective 120 Volt humidifier control (Models 110, 112, 330, 350, 360, 445, 448, 760, 768 or 700)
may cause the unit to run continually.
Electrical Components — Failure of any electrical component in the humidifier may cause the
humidifier to run continually, if stuck in the operating position. Examination with a neon light tester
or an appropriate testing instrument will help locate which electrical component is malfunctioning.
III. LEAKING WATER (All Units Except Models 400, 445, 445A & 448)
Water Backing Up Drain Line — If the drain line does not have a continuous slope to the drain, it
is possible for it to air lock and for water to back up in the drain line. A drain safety overflow has
been molded into the lower housing of all the black plastic Aprilaire units. This safety overflow is
designed to eliminate water inside of the furnace plenum if there is a malfunction. Removing dips
and hills from the drain line and flushing it with water under pressure will eliminate the problem.
Replace drain line every year or as necessary.
Water Panel Evaporator & Scale Control Insert — A clogged Water Panel evaporator could
cause the scale control insert to fill with residue and block the drain opening, causing leaking.
Clean scale control insert and install a new Water Panel ® evaporator.
Solenoid Valve — Be sure that the water flow through the valve is in the correct direction. Note an
arrow designating water flow direction on the valve bodies. Should a piece of dirt lodge between
the valve plunger and seat on the solenoid and prevent it from fully closing, the solenoid will leak.
After shutting off the water at the saddle valve, disconnect electrical power, remove the solenoid
and backwash with water under light pressure or blow out. This is quite effective unless the valve
seat has been permanently damaged, in which case, it will be necessary to replace the entire sole-
noid valve.
Water Pressure — Water pressure above 125 psi can cause leakage. Check pressure and use a
pressure reducer if necessary.
IV. NOISE
Solenoid Valve — There will be a "click" each time the valve opens and closes. A light gauge
plenum will amplify this noise. If the unit is not snug against the plenum, the noise is increased. If
water hammer is a problem, a length of high pressure hose installed before the valve, acts as a
cushion to reduce the noise. Check local codes before using plastic hose.

GENERAL MAINTENANCE

V.
Water Panel ® Evaporation Check — When the openings become clogged and restrict the air-
flow through the panel, it should be replaced. The life of the Water Panel evaporator will vary with
the hardness of the water, the amount of use, and the application. It is recommended that the
Water Panel be changed at least once every year (twice a year for Model 400). Replace with only
genuine RP Water Panels for continued peak efficiency and overall performance. The Water Panel
evaporator will be most efficient when installed with the colored spot at the top. Make sure the
entire Water Panel is enclosed in the scale control insert.
Evaporation Check — The evaporative capacity of the Aprilaire humidifiers (excluding the models
400, 445 & 448) can be checked by determining the time it takes to fill a quart jar from the water
supply and the drain. The following formula can be used to determine the evaporation of the unit
on an hourly basis.
lb 7509
hr seconds to
fill quart jar
The constant 7509 is obtained by multiplying the seconds per hour
(3600) times the weight of one quart of water (2.086 lbs.) Subtract the
result of the supply water check from the result of the drain water
check. The answer is the pounds of water evaporated per hour. To
convert pounds of water to gallons of water, divide by 8.343.
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