Apriaire 800 Installation and operating instructions

Model 800 Steam Humidifier
TABLE OF CONTENTS
Safety Cautions..........................................2
Materials List ...........................................2
Principles of Operation...................................3
Sequence of Operation...................................4
Specifications & Dimensions .............................4
Installation Instructions ..................................6
Choosing a Location .....................................6
- Dispersion Tube......................................6
- Humidifier ..........................................9
Prepare Humidifier for Mounting ..........................10
Install Steam Dispersion Tube ............................10
Mount Humidifier ......................................10
Install Steam Hose .....................................10
Supply Water..........................................10
Drain Line.............................................11
Automatic Digital Control and Control Wiring................11
Electrical Power Wiring & Shut-off Switch ..................12
Start-up Procedure .....................................17
Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Shut Down Procedure...................................18
Display Panel ..........................................18
Maintenance...........................................19
Checking System Operation & Troubleshooting ............20
Replacement Parts......................................23
READ AND SAVE THESE INSTRUCTIONS
Model 800 Steam Humidifier
Installation & Maintenance Instructions

CAUTION
ATTENTION INSTALLER
Read this manual before installing. This product must be installed by qualified HVAC and electrical contractors and in
compliance with local, state, federal, and governing codes. Improper installation can cause property damage, severe personal
injury, or death as a result of electric shock, burns, or fire.
Read all cautions and instructions.
Read this manual before performing service or maintenance procedures on any part of the system. Failure to follow all cautions
and instructions could produce the hazardous situations described, resulting in property damage, personal injury, or death.
Failure to follow the instructions in this manual can cause moisture to accumulate, which can cause damage to structure and
furnishings.
HOT SURFACES AND HOT WATER
This steam humidification system has extremely hot surfaces. Water in steam canister, steam pipes, and dispersion tube can
be as hot as 212°F (100°C). Discharged steam is not visible. Contact with hot surfaces, discharged hot water, or air into which
steam has been discharged can cause severe personal injury. To avoid severe burns, follow procedures in this manual when
performing service or maintenance procedures on any part of the system.
DISCONNECT ELECTRICAL POWER
Disconnect electrical power before installing supply wiring or performing service or maintenance procedures on any part of
the humidification system. Failure to disconnect electrical power could result in fire, electrical shock, and other hazardous
conditions. These hazardous conditions could cause property damage, personal injury, or death.
Contact with energized circuits can cause property damage, severe personal injury, or death as a result of electrical shock or
fire. Do not remove access panels until electrical power is disconnected.
Follow the shutdown procedure in this manual before performing service or maintenance procedures on any part of the system.
ELECTRICAL SHOCK HAZARD
If the humidifier starts up responding to a call for humidity during maintenance, severe bodily injury or death from electrical shock
could occur. Follow the procedures in this manual before performing service or maintenance procedures on this humidifier.
EXCESSIVE SUPPLY WATER PRESSURE
Supply water pressure greater than 120 psi may cause the humidifier to overflow.
SHARP EDGES
Sharp edges may cause serious injury from cuts. Use care when cutting plenum openings and handling ductwork.
EXCESS HUMIDITY
Do not set humidity higher than recommended. Condensation may cause damage.
SAFETY CAUTIONS
MATERIALS LIST
MATERIALS FURNISHED NOT FURNISHED
Humidifier
Automatic Digital Humidifier Control
Dispersion tube
Steam hose (6 feet)
Main power disconnect switch
Wiring
1/4” O.D. supply water tubing
Boards for mounting (if required)
7/8” I.D. drain tubing (10 feet)
Hose clamps
Saddle valve
Mounting screws
2

Minerals that are naturally found in water cause the water to be electrically conductive. Water conductivity is measured in micro Siemens per
centimeter (uS/cm). Mineral content, also described as “water hardness” is usually measured in grains per gallon. Because of the variety of
minerals that are found in water, there is no direct correlation between water hardness and conductivity, but generally the higher the mineral
content, the higher the conductivity.
The Model 800 Canister Steam Humidifier is designed to operate on water with conductivity between 125 and 1,250 uS/cm. This correlates
loosely with water with hardness between 3 and 36 grains/gallon. Water that is considered “hard” and also softened water work well in the
Model 800. The humidifier will make steam when plumbed to low-conductivity water but it takes longer to reach nominal capacity.
With low conductivity water, it may take the Model 800 humidifier one week or more of operation to reach rated capacity,
especially if it is wired to operate on 120 volts. When operating on 240 volts, the Model 800 usually will reach nominal capacity
within a few hours, even with lower conductivity water.
As water in the canister boils and turns into steam, minerals are left behind. Minerals remaining in solution increase the conductivity of the
water. Minerals also deposit onto the submerged portions of the electrodes rendering those areas ineffective. As this occurs, the level of water
in the canister rises to expose uncoated electrode surface.
There are benefits and trade-offs to consider when the application allows a choice between hard and softened water:
Hard water: The benefit of hard water is less frequent draining and filling than with soft water, which results in better energy and water
efficiency and more consistent steam output. However, canister replacement could be more frequent with hard water, because hard water scale
coats the electrodes. The harder the water, the more frequent the need for a new canister.
Softened water: The benefit of softened water is longer canister life (depending on water chemistry) than with hard water, because softened
water does not coat the electrodes nearly as much as hard water. However, softened water ions stay in solution to much higher concentrations
than hard water ions. This requires more frequent draining and filling, which results in less energy and water efficiency and less consistent
steam output.
The Aprilaire®Model 800 Canister Steam Humidifier delivers
humidity in the form of steam to the conditioned space via the
HVAC system duct or optional Aprilaire Model 850 Fan Pack.
The humidifier generates steam by energizing two electrodes
that extend into a canister of water. Current flowing between
the electrodes causes the water to boil, creating steam. Water
is introduced to the humidifier through a fill valve to a fill cup
located in the top of the cabinet. The fill cup serves as an overflow
reservoir and provides an air gap between the humidifier and water
source. The steam canister is filled from the bottom. The canister
is seated in a drain cup assembly which includes a drain valve. The
drain and fill valves work together to maintain water level in the
canister to deliver the rated steam capacity based on the electrical
conductivity of the water and to temper drain water. See Figure 1
for representation of fill and drain system and canister.
Steam is delivered into the airstream through a dispersion tube
mounted in the HVAC system ductwork. Openings in the dispersion
tube are fitted with “Tubelets™” which extend into the center of
the tube. The design of the dispersion tube and tubelets distribute
steam over a wide area in the duct and direct any condensed
moisture back into the steam hose.
This humidifier is able to produce steam at various capacities
depending on the voltage and current applied. The unit can be
wired to use an input voltage of 120, 208 or 240 Volts and input
amperage can be set to 11.5 or 16.0 amps by changing a dip switch
on the control circuit board (see the Electrical Power Wiring &
Shut Off Switch section). Configure the unit appropriately for the
application (see Table 2 for capacity specifications).
PRINCIPLES OF OPERATION
FIGURE 1 – Fill and Drain System and Canister
90-1522
Steam
Outlet
Drain
Supply
Water
Drain Cup
Drain Valve
Canister
Electrodes
High Water
Level Sensor
Flow Control
Orifice
Inlet
Fill Valve
Overflow
Fill
Fill Cup
WATER QUALITY
3

SPECIFICATIONS & DIMENSIONS
TABLE 2 – Humidifier Capacities
Amperage Voltage Maximum steam capacity (gal/day)
11.5
120V 11.5
208V 20.5
240V 23.3
16.0
120V 16.0
208V 30.0
240V 34.6
Humidifier Shipping Weight: 28 lbs
Humidifier Operating Weight: 23 lbs*
*As minerals precipitate unit weight can increase to approximately 30 lb.
When the Automatic Digital Humidifier Control (ADHC) detects RH below the set point, and provided the humidifier is turned on and the HVAC
system blower is operating, the internal controller in the humidifier energizes the electrodes and measures the current flowing through the water
between them. The controller adjusts water level in the canister via a fill valve and a drain valve to maintain current at either 11.5 or 16.0 amps.
The operating water level in the canister depends on the mineral content of the water which determines conductivity.
The ADHC has the ability to turn on the HVAC system blower if the homeowner or installer chooses to utilize that feature. See ADHC installation
manual.
SEQUENCE OF OPERATION
TABLE 1 – Water Quality Guidelines
Conductivity (uS/cm)
of water connected to
humidifier
Estimated grains/gallon
(prior to any water
softening)
Hardness (prior to any
water softening) Canister behavior Solution
0-125 0-3 Naturally Soft Humidifier does not
function. Installation not recommended.
125-300 3-9 Naturally Soft Long start up time. Power with 240VAC, use constant fan to decrease
time to reach full capacity.
300-500 9-15 Slightly Hard
Optimal performance
range. Use hard or softened water.
500-640 15-20 Moderately Hard
640-840 20-25 Hard
840-1250 25-36 Very Hard Shortened canister life
due to scale build up. Use softened water.
above 1250 36 Extremely Hard Canister performance
degrades quickly. Installation not recommended.
4

FIGURE 2 – Humidifier & Dispersion Tube Dimensions
10 1/8"
20 7/8"
FRONT VIEW
3 3/8"
7 7/8"
8 7/8"
3 3/8" 1 5/8"
4 1/4" 5 3/4"
Dispersion Outlet
Electrical Knockouts
Fill Cup
TOP VIEW
7 1/8"
SIDE VIEW
1"
4"
4"
12"
BACK VIEW
Mounting
Holes
3 3/8"
7 7/8"
2"
3 3/8"
Water Fill Line Connection
Drain
BOTTOM VIEW
3" sq
2" sq
8 1/4"
1" dia
STEAM DISPERSION TUBE
3" Mounting Plate
to first opening
1 3/4"
UP
90-1518
SPECIFICATIONS & DIMENSIONS (CONTINUED)
5

CHOOSING A LOCATION
DISPERSION TUBE
When choosing a location for the dispersion tube three things must be considered: Location in duct, elevation with respect to the humidifier, and
distance from humidifier to dispersion tube.
Duct Location and Absorption Distance
The preferred location for the dispersion tube is in a supply duct because higher temperature air will absorb moisture more readily. The
dispersion tube must be in a straight section of duct far enough upstream of any obstruction or bends in the duct to allow the steam to be fully
absorbed, preventing condensation in the duct. The exact distance from obstructions in the duct depends on air temperature, RH set point, and
airflow velocity in the duct. Most installations can use an absorption distance between 24 and 36 inches, however if there are obstructions in
the ductwork use Table 3 to determine the appropriate absorption distance. Size absorption distance based on the lowest temperature,
lowest air velocity and highest humidity that the system will see. When installing the humidifier in a system with variable speed blower,
determine absorption distance based on airflow at the lowest speed. Operation during AC calls is not recommended because of the potential for
condensation in the ductwork. If humidifier operation is needed during AC operation, make sure absorption distance is adequate. If absorption
distance is insufficient, configure controls to lock out humidifier during the AC calls and use the blower activation feature to allow the humidifier
to run with the blower only. Call Aprilaire Tech Support at 1-800-334-6011 for additional information on absorption.
The dispersion tube must be mounted with the plate on a vertical surface with the tube angled up as shown in Figure 3. The steam outlets must
face up regardless of the airflow direction in the duct. The plate is labeled “UP”to indicate proper orientation. On horizontal duct runs install the
dispersion tube low in the duct, on vertical runs center the tube on the duct.
If the dispersion tube is mounted on insulated ductwork, make sure insulation is not more than 2” thick at tube location to prevent insulation
from blocking first steam outlet.
Note: If two dispersion tubes are installed in one duct, double the dispersion distances. If three dispersion tubes are installed, triple the
dispersion distance. Position dispersion tubes so one does not discharge directly onto another.
INSTALLATION INSTRUCTIONS
CAUTION
Each humidifier requires its own steam hose and dispersion tube. Do not connect steam hoses from more than one humidifier
together. Back-pressure from one humidifier can lower the water level in the canister in the other humidifier and cause
operational problems.
Do not install the dispersion tube in a duct with greater than 2 in. wg static pressure. High duct pressure can cause back-
pressure in the canister which can result in unstable unit operation.
6

*Velocity in feet per minute = Duct airflow volume in cubic feet per minute / duct area in square feet.
Example: 1,200 cfm through 16” x 12” duct = 1,200/(12 x 16/144 sq. in./sq ft.) = 1,200/1.333 = 900 fpm
TABLE 3 – Absorption Distance (Minimum distance from dispersion tube downstream to any obstruction or bend in duct)
Humidifier
Output (gal/day) Airflow Velocity* 70°F & 30% RH
Setpoint 70°F & 45% RH
Setpoint 65°F & 45% RH Setpoint 45°F & 45% RH Setpoint
Up to 16.0
300 fpm 13” 19” 23” 30”
600 fpm 6” 10” 12” 18”
1200 fpm 3” 5” 6” 13”
1800 fpm 2” 3” 4” 10”
20.5 – 25.0
300 fpm 15” 23” 28” 45”
600 fpm 6” 12” 13” 26”
1200 fpm 5” 6” 7” 19”
1800 fpm 3” 4” 5” 16”
25.0 – 35.0
300 fpm 24” 31” 36” 60”
600 fpm 17” 22” 26” 48”
1200 fpm 12” 15” 18” 25”
1800 fpm 10” 13” 15” 20”
INSTALLATION INSTRUCTIONS (CONTINUED)
Elevation
The preferred location for the dispersion tube is higher than the
humidifier so that the steam hose has a constant downward
slope of at least 2” per foot from the dispersion tube to the
humidifier. If hard pipe is used, the slope can be 1/4” per foot.
With the constant downward slope, any condensation that forms
in the steam hose will drain back into the steam canister. See
Figure 3.
FIGURE 3 – Dispersion Tube Mounted Above Humidifier
90-1521
90° long sweep
or two 45° elbows
Pitch*
Duct
Dispersion tube
Steam hose or pipe.
Insulate pipe with 1” fiberglass
to reduce steam loss.
*Pitch steam hose down from
dispersion tube to humidifier:
2"/ft (15%) minimum when
using steam hose.
1/4"/ft when using hard pipe.
7

FIGURE 4A
Elevation (continued)
If the dispersion tube must be mounted below the humidifier or
if the steam hose needs to run up and over an obstruction, a drip
tee with drain trap, Part #4028, must be installed as shown in
Figure 4. When using a fan pack, adding Part #4028 close to the
humidifier outlet can help prevent noise from gurgling as shown
in Figure 4A.
CAUTION
Controlling condensate flow and collection in an
electrode steam humidifier system is critical to
maximum performance. Failure to follow the steam
piping recommendations in this manual can cause
system pressure fluctuations and increase cylinder
pressure, and condensate noise.
Distance from Humidifier to Dispersion Tube
The capacity of the humidifier is reduced by the length of
the steam hose or pipe due to condensation. The maximum
recommended length of steam hose is 6 feet. Use hard pipe
insulated with 1” fiberglass for lengths greater than 6 feet.
Table 4 provides humidifier capacity with various lengths of
steam hose and pipe. If 6-foot steam hose does not reach from
humidifier to dispersion tube, splice in 1” copper pipe using
3/4” x 1” reducing couplings as shown in Figure 5.
INSTALLATION INSTRUCTIONS (CONTINUED)
Pitch
Obstruction
90° long
sweep or two
45° elbows
6" min
8" min
Insulate hard pipe to
reduce steam loss
To
Dispersion
Tube
1" air gap
Open drain required,
see note 1.
Drip tee installation for
piping over obstruction,
or if dispersion tube is
lower than humidifier.
NOTES:
1. Refer to governing codes for
drain pipe size and materials.
2. Support steam hose so there
are no sags or low spots.
Drip tee
Drain trap
Part #4028
FIGURE 4 – Dispersion Tube Mounted Below Humidifier
90-1520
90-1527 90-1844
Steam Hose
Dispersion
Tube
Steam Hose
1-1/2" Hose Clamp
1-1/2" Hose Clamp
1" Copper Pipe
3/4" x 1"
Reducing Coupling
Humidifier
#4028 KIT
CONTENTS:
Hose Clamps (5)
Trap (1)
Tee Assembly (1)
Tee
Assembly
Flared
End
Trap
Note: Prime with water
before using humidifier
Hose Clamp
Hose
Clamp
Hose Clamp
To Steam
Dispersion Tube
or Model 850
Fan Pack
Steam
Hose
1" I.D.
Steam Hose, 1" I.D.
(Downward Slope to Tee)
Drain Hose
7/8" I.D.
Steam Hose
1" I.D.
(Downward
Slope from
Humidifier
to Tee)
Hose Clamp
Steam
Humidifier
FIGURE 5
8

TABLE 4 – Steam Humidifier Capacity in Gallons/Day
Steam
Hose or
Insulated
Pipe
Length
120 Volts 208 Volts 240 Volts
11.5 Amps 16.0 Amps 11.5 Amps 16.0 Amps 11.5 Amps 16.0 Amps
Steam
Hose Insulated Pipe Steam Hose Insulated Pipe Steam Hose Insulated Pipe Steam Hose Insulated Pipe Steam Hose Insulated Pipe Steam Hose Insulated Pipe
< 2 ft. 11.5 11.5 16.0 16.0 20.5 20.5 30.0 30.0 23.3 23.3 34.6 34.6
2 ft. 11 11 15.5 15.5 20 20 29 29.5 23 23 34 34
4 ft. 10 11 14.5 15.5 19 20 28 29.5 22 23 33 34
6 ft. 911 13.5 15 18 20 27 29 21 22 32 33
8 ft. 10 14 19 28 22 33
10 ft. 10 14 19 28 22 33
12 ft. 10 14 19 28 22 33
14 ft. 913 18 27 21 32
16 ft. 913 18 27 21 32
18 ft. 913 18 27 21 32
20 ft. 913 18 27 20 31
HUMIDIFIER
Do not mount humidifier in a location where ambient
temperature exceeds 104°F or where freezing temperatures
may occur. Extreme temperatures may cause the humidifier to leak
which can damage furnishings or structure.
Mount humidifier in a location that allows access for servicing, and
clearance to remove front panel for replacing the canister and side
panel for access to the electrical components during installation.
See Figure 6 for minimum clearances around humidifier.
The humidifier should be mounted as close to the dispersion
tube as possible. Table 4 shows how capacity is reduced as the
distance between the humidifier and dispersion tube increases. If
the humidifier is mounted on the duct directly below the dispersion
tube, allow space for a bend in the steam hose. Allow a minimum
of 2” of steam hose to extend straight out of the humidifier before
beginning any bends; this will help ensure a tight connection with
the top of the canister.
The humidifier can be mounted to a wood surface, or to sheet metal
ductwork if it is structurally stable. Do not mount humidifier to fiber
duct board.
The humidifier must be mounted to a vertical surface and must be
mounted level in the upright position.
16" for
Steam
Hose
30" for
Service
Access
16" for
Electrical
Access
4"
16"
for Drain
FRONT VIEW
SIDE VIEW
FIGURE 6 – Clearances
90-1519
INSTALLATION INSTRUCTIONS (CONTINUED)
9

SUPPLY WATER
Plumb the humidifier to cold, hard or softened water. Do not use hot water because unheated supply water is used to cool water
draining from the humidifier. Do not use demineralized or reverse osmosis water. For proper operation, supply water pressure must be
between 25 psi and 120 psi. Hard or softened water may be used provided it has conductivity between 125 microS/cm and 1250 microS/cm.
Supply water piping must be free of oils, lubricants, solder flux and other contaminants, which can cause foaming in the canister that can lead to
water sputtering from the dispersion tube into the duct.
Install the saddle valve according to the instructions printed on the bag. Run 1/4” copper tubing from the saddle valve to the humidifier. Connect
it to the fill valve. Double wrench to prevent leaking and damage to valve. Addition of a stainless steel braided water line can help reduce valve
noise.
Note: Adding an inline particulate filter can increase canister life in areas with high levels of suspended solids. DO NOT use filters that time
release scale inhibitors, filters of this type can significantly decrease canister life.
PREPARE HUMIDIFIER FOR MOUNTING
Unpack carton. Open front panel by removing screw and lifting panel up and away from humidifier. Disconnect three wires from top of canister
by pulling straight up. The two large wires are the electrode conductors. The smaller wire is connected to the high water level sensor. Remove
canister by pulling it up and out of drain assembly. Remove two screws on right side of humidifier and lift side panel off housing to expose
electrical compartment.
MOUNT HUMIDIFIER
Secure humidifier to sturdy wall using screws provided, or to sheet metal duct. Humidifier initially weighs 23 lbs with a full canister, but will
increase in weight over time due to the precipitation of minerals inside the canister. Make sure mounting system will support weight. If mounting
to stud frame wall, install two spanner boards to studs and fasten humidifier to spanner boards. Make sure humidifier is mounted plumb.
INSTALL STEAM DISPERSION TUBE
Note: If humidifier will deliver steam via the Model 850 Fan Pack instead of the dispersion tube, follow instructions included with Fan Pack.
Make sure steam dispersion tube is mounted higher than the humidifier so that condensation that forms in the tube runs back into the canister.
If the dispersion tube cannot be mounted higher than the humidifier or if the steam hose must extend up from the humidifier then down to the
dispersion tube due to an obstruction, a drip tee and drain trap system (Part #4028) must be installed as shown in Figure 4.
Drill a 1-1/4” diameter hole in a vertical surface of the duct at the location chosen for the dispersion tube. Position the tube so it is angled up,
regardless of airflow direction. Secure with four sheet metal screws provided.
INSTALLATION INSTRUCTIONS (CONTINUED)
Six feet of steam hose is provided with the humidifier. If the steam hose must be cut, use a hacksaw. If additional length is required, use
1” O.D. metal or copper pipe. Do not use PVC pipe for steam line. Insulate pipe with 1” thick fiberglass to reduce steam loss. See Table 4 for
humidifier capacity at various lengths of steam hose and pipe.
Use the steam hose provided. Other hoses may have impurities which can cause foaming in the canister. Foaming can cause water level
inaccuracies and reduced steam production. When using pipe, remove all traces of residual materials used to connect the pipe to prevent foaming.
Verify that the O-ring is in place in the groove in the drain assembly. Dampen the O-ring with water (DO NOT use oil, grease,or any lubricant
besides water), then reinsert the canister with the caution label positioned toward the front of the unit.
Attach steam hose to dispersion tube and then to top of canister using hose clamps provided. Use heavy wire clamp to secure hose to canister.
Make sure steam hose has a constant slope of at least 2” per foot between the dispersion tube and the humidifier. Any and every low spot in the
steam hose or pipe must have a drip tee and drain trap. Fill drain trap with water before making final connections.
Attach and fully seat the electrode conductors (interchangeable) and the high water level sensor wire.
INSTALL STEAM HOSE
10

DRAIN LINE
Attach the 7/8” I.D. drain tubing provided to the drain assembly at the bottom of the humidifier. Secure with the hose clamp provided. Do not
over tighten.
Make sure the drain line has a constant downward slope from the humidifier to the drain and is not kinked or blocked.
If floor drain is not available, use condensate pump (Part #4856) to route water to a suitable drain.
Note: The humidifier uses cold water to temper drain water to less than 140°F.
AUTOMATIC DIGITAL CONTROL AND CONTROL WIRING
The control circuit operates on 24VAC.
The ADHC (Automatic Digital Humidifier Control) Model 62 must be mounted in the return air duct at least 6” upstream of any fresh air intake
ducts or sources of moisture and at least 12” from the steam dispersion tube if it is mounted in the return. Follow instructions provided with the
control. Connect “H” terminals on ADHC to “HUMIDISTAT” terminals on humidifier circuit board. The “H” terminals on the Model 62 provide a
dry contact switch to energize the humidifier, if 24V is applied to the Humidistat terminals on the Model 800, the control board will be damaged.
If the application requires a wall-mounted humidistat in the conditioned space, use Manual Humidistat Part #4655 or Digital Manual Humidistat
Part #65. In order to allow the humidifier to turn on the HVAC system blower when humidity is required with either of these humidistats, use
Blower Activation Relay Part #4851.
If protection from over-humidification is desired, install optional high humidity limit switch Part #4594 at least 4 feet downstream of the
dispersion tube. If airflow verification is desired, install optional airflow proving switch Part #4592 in duct. The high humidity limit switch and the
airflow proving switch are wired in series with the ADHC (humidistat) circuit. See Figure 7.
INSTALLATION INSTRUCTIONS (CONTINUED)
24 VAC from HVAC
Equipment “R” & “C”
Communication with
Aprilaire 8570 Thermostat
Outdoor Temperature Sensor
Heat Signal from HVAC Equipment
Fan Signal from Thermostat
Fan Signal to HVAC Equipment
MODEL 62 DIGITAL HUMIDIFIER CONTROL
24V TERMINALS
OPTIONAL:
AIR FLOW PROVING SWITCH #4592
Connect 1/4" plastic tubing from H (High) side
of proving switch to the airflow sensing probe
located 1.5 duct diameters downstream of
blower. Leave L (Low) side open to amosphere.
OPTIONAL:
HIGH HUMIDITY LIMIT SWITCH #4594
Switch breaks C to NC connection when
measured RH is above setpoint RH.
HGfRCAB ODT GWH
FAN PACK HUMIDISTAT
CNO NC
C
NO
NC
FIGURE 7 – Model 800 Accessory Wiring
90-1544
11

ELECTRICAL POWER WIRING & SHUT-OFF SWITCH
All wiring must be installed in accordance with all governing electrical codes and with the wiring diagram provided inside the front panel.
Do not loop power wiring.
Do not use aluminum wire.
A safety grounding system that meets all governing electrical codes is required. The ground connection must be made with solid metal to metal
connections. Ground wire must be the same size as the power wiring.
With factory settings, the Model 800 draws 11.5 amps +/- 10%. Use a minimum 20 amp dedicated circuit when installing to operate at 11.5
amps. The model 800 can be set to draw 16.0 amps +/- 10% by repositioning dip switch #1 on the control circuit board (see Figure 8). When set
to 16 amps, use a minimum 25 amp dedicated circuit. For both applications, size wire according to local codes.
The Model 800 Steam Humidifier is shipped from the factory wired for 240 VAC operation, but it can operate on 120, 208 or 240 VAC.
If using 120V or 208V, move the black/white jumper wire attached to L1 tab on the power terminal block to the proper tab on the
transformer terminal block. See Figure 9.
CAUTION
Only qualified electrical personnel should perform field wiring procedures. Improper wiring or contact with energized circuits
can cause property damage or severe personal injury.
INSTALLATION INSTRUCTIONS (CONTINUED)
12

WIRING INSTRUCTIONS
Install disconnect switch (not provided) between line power source and humidifier.
Knock-outs for power wiring and low voltage control circuit wiring are located on the top of the humidifier.
Connect power and ground wiring as shown in appropriate wiring diagram.
 •240VAC–Figure 10
 •208VAC–Figure 11
 •120VAC–Figure 12
Do not run high voltage power lines over internal circuit boards.
INSTALLATION INSTRUCTIONS (CONTINUED)
SLIDE DIP SWITCH #1 TO “ON” POSITION
FOR 16.0 AMP NOMINAL OPERATION
FACTORY SETTING FOR 11.5 AMP
NOMINAL OPERATION
BLACK/WHITE JUMPER WIRE
IN FACTORY WIRED POSITION.
MOVE TO APPROPRIATE TERMINAL
IF NOT INSTALLING ON 240 VAC.
90-1778 90-1777
FIGURE 8 – Control Circuit Board with Dip Switches FIGURE 9 – Transformer Terminal Block Jumper
13

NOTE: MODEL 800 IS SHIPPED
FROM THE FACTORY WIRED IN
THE 240 VOLT CONFIGURATION.
(PROVIDED)
(NOT PROVIDED)
MAIN POWER SWITCH
J10-1
AUTOMATIC DIGITAL
J1-1
J1-2
ELECTRODE
WATER LEVEL
ELECTRODE
24V AC
COM
ORG
BLU
J5
J2
RED
RED
BLK
BLK
YEL
YEL
BRN
BRN
BLU
WHT
WHT
COM
24V AC
COM
24V AC
COM
24V AC
DRAIN VALVE
FILL VALVE
POWER RELAY COIL
J3
J4
J6-2
J6-1
J8
J7
120/208/240 VAC
SAFETY SWITCH
BLU
+24V DC
+24V DC
J11-2
J11-1
J13-2
J13-1
J12-2
J12-1
STEAM CYLINDER
J3-2
J3-1
J1-2
10
L1 N, L2
BLK
BLK
42
68
24V AC
YELBLU
CONTROL PCB CURRENT SENSING PCB
J1-1
HUMIDITY CONTROL HIGH LEVEL PROBE
(OPTIONAL)
FAN PACK
+24V AC
COM
HUMIDISTATFAN
BLK
YEL
YEL
POWER RELAY CONTACTS
PROBE
J4
J2
J10-2
DISPLAY PANEL
RIBBON CABLE
GROUND
TRANSFORMER
208 240
120
WHT
BLK / WHT
RED ORG
BLK
JUMPER WIRE
CONTROL CIRCUIT WIRING
HIGH VOLTAGE WIRING
FIELD WIRING
STATIC
DISCHARGE
GROUND
L1 L2
POWER
TERMINAL
BLOCK
TRANSFORMER
TERMINAL
BLOCK
FIGURE 10 – 240 VAC Wiring Diagram
90-1660
INSTALLATION INSTRUCTIONS (CONTINUED)
14

NOTE: MODEL 800 IS SHIPPED FROM
THE FACTORY WIRED FOR 240 VOLTS.
THE BLACK / WHITE WIRE FROM L1
MUST BE MOVED TO THE 208 VOLT
TERMINAL FOR 208 VOLT OPERATION.
(PROVIDED)
(NOT PROVIDED)
MAIN POWER SWITCH
J10-1
AUTOMATIC DIGITAL
J1-1
J1-2
ELECTRODE
WATER LEVEL
ELECTRODE
24V AC
COM
ORG
BLU
J5
J2
RED
RED
BLK
BLK
YEL
YEL
BRN
BRN
BLU
WHT
WHT
COM
24V AC
COM
24V AC
COM
24V AC
DRAIN VALVE
FILL VALVE
POWER RELAY COIL
J3
J4
J6-2
J6-1
J8
J7
120/208/240 VAC
SAFETY SWITCH
BLU
+24V DC
+24V DC
J11-2
J11-1
J13-2
J13-1
J12-2
J12-1
STEAM CYLINDER
J3-2
J3-1
J1-2
10
L1 N, L2
BLK
BLK
42
68
24V AC
YELBLU
CONTROL PCB CURRENT SENSING PCB
J1-1
HUMIDITY CONTROL HIGH LEVEL PROBE
(OPTIONAL)
FAN PACK
+24V AC
COM
HUMIDISTATFAN
BLK
YEL
YEL
POWER RELAY CONTACTS
PROBE
J4
J2
J10-2
DISPLAY PANEL
RIBBON CABLE
GROUND
TRANSFORMER
208 240
120
WHT
BLK / WHT
RED ORG
BLK
JUMPER WIRE
CONTROL CIRCUIT WIRING
HIGH VOLTAGE WIRING
FIELD WIRING
STATIC
DISCHARGE
GROUND
L1 L2
POWER
TERMINAL
BLOCK
TRANSFORMER
TERMINAL
BLOCK
FIGURE 11 – 208 VAC Wiring Diagram
90-1659
INSTALLATION INSTRUCTIONS (CONTINUED)
15

NOTE: MODEL 800 IS SHIPPED FROM
THE FACTORY WIRED FOR 240 VOLTS.
THE BLACK / WHITE WIRE FROM L1
MUST BE MOVED TO THE 120 VOLT
TERMINAL FOR 120 VOLT OPERATION.
(PROVIDED)
(NOT PROVIDED)
MAIN POWER SWITCH
J10-1
AUTOMATIC DIGITAL
J1-1
J1-2
ELECTRODE
WATER LEVEL
ELECTRODE
24V AC
COM
ORG
BLU
J5
J2
RED
RED
BLK
BLK
YEL
YEL
BRN
BRN
BLU
WHT
WHT
COM
24V AC
COM
24V AC
COM
24V AC
DRAIN VALVE
FILL VALVE
POWER RELAY COIL
J3
J4
J6-2
J6-1
J8
J7
120/208/240 VAC
SAFETY SWITCH
BLU
+24V DC
+24V DC
J11-2
J11-1
J13-2
J13-1
J12-2
J12-1
STEAM CYLINDER
J3-2
J3-1
J1-2
10
L1 N, L2
BLK
BLK
42
68
24V AC
YELBLU
CONTROL PCB CURRENT SENSING PCB
J1-1
HUMIDITY CONTROL HIGH LEVEL PROBE
(OPTIONAL)
FAN PACK
+24V AC
COM
HUMIDISTATFAN
BLK
YEL
YEL
POWER RELAY CONTACTS
PROBE
J4
J2
J10-2
DISPLAY PANEL
RIBBON CABLE
GROUND
TRANSFORMER
208 240
120
WHT
BLK / WHT
RED ORG
BLK
JUMPER WIRE
CONTROL CIRCUIT WIRING
HIGH VOLTAGE WIRING
FIELD WIRING
STATIC
DISCHARGE
GROUND
L1 N
POWER
TERMINAL
BLOCK
TRANSFORMER
TERMINAL
BLOCK
FIGURE 12 – 120 VAC Wiring Diagram
90-1658
INSTALLATION INSTRUCTIONS (CONTINUED)
16

START-UP PROCEDURE
1. Once the supply water, drain, steam hose, electrical power and control wiring connections are complete, make sure canister is fully seated
into drain valve and three wire connectors on top of canister are secure. (High water probe wire and two interchangeable electrode wires.)
2. Attach side panel and front door.
3. Open saddle valve allowing water to flow to humidifier. Check for leaks.
4. Turn Automatic Digital Control knob to OFF.
5. Close main power switch energizing humidifier.
6. Press On/Off button on humidifier. The On/Off light will illuminate green.
7. Make sure the HVAC blower is operating and adjust the ADHC dial up to initiate a call for humidity.
Note: The ADHC can be placed into TEST mode to force a call for humidity but this only lasts for one minute.
The Steam light will illuminate green indicating a call for humidity and the Fill light will illuminate green indicating the fill valve is open
allowing the canister to fill. You should also hear the water flowing. If water flows down drain while humidifier is filling, check for
kinks or obstructions in the fill hose or fill cup and make sure the O-ring in the drain valve is properly seated in the groove and
not damaged or deformed.
8. Once the Fill light turns off, to verify that the humidifier will drain properly, press the On/Off button to turn humidifier off. You may hear the
fill valve open allowing cold water to flow into the canister to cool the water in the canister. The Drain light will flash green for 15 seconds
then turn green for four minutes while the canister drains. Once the Drain light turns off, the drain cycle is complete.
9. Set ADHC to proper level.
10.Press On/Off button to turn humidifier on.
When the humidifier is powered and turned on, the “On/Off” light is illuminated green.
During fill cycles, the “Fill” light illuminates green.
When the humidifier is turned on, any time the ADHC sends a call for humidity, the Steam light illuminates green.
Any time the drain valve is activated, the “Drain” light illuminates green.
During initial start up with a new canister, the humidifier may run through a series of fill/drain cycles until the conductivity of the water is in
a range that allows the humidifier to generate steam at the rated capacity. If the conductivity of the water is low, it may take a week or more
for the humidifier to generate steam at the rated capacity. The rated capacity is achieved when the humidifier is detecting a nominal current
of either 11.5 or 16.0 amps between the electrodes. If the humidifier has not reached capacity after 168 hours of operation, the Steam light
will illuminate yellow on a call for humidity. The humidifier will continue to operate with a yellow Steam light, and may satisfy the humidity
requirements. Once rated capacity is reached, the Steam light will illuminate green.
The internal controller adjusts water level in the canister to maintain the nominal current between the electrodes. As minerals build up on the
electrodes, their effectiveness decreases, so the controller will increase the water level to submerge more of the electrode surface. When the
water has reached the high level probe in the canister and the internal controller no longer detects nominal current, the Service light will flash
red indicating that the canister needs to be replaced.
If the humidifier attempts to drain the canister and cannot, the drain and fill valves will pulse on & off for four seconds to dislodge minerals
which may be blocking the drain valve ports. The Drain and Fill lights will flash on & off when this occurs.
Any time power is disconnected or humidifier is turned off, the internal timer for start-up and drain cycles is reset.
If the humidifier has operated 168 hours without a drain cycle, the drain valve will open and drain the canister. Normal operation will continue.
If the humidifier is operating and a power failure occurs, once power is restored, the “On/Off” light will flash green for one minute, then the
humidifier will turn on.
OPERATING MODES
END OF SEASON/PERIOD OF INACTIVITY SHUT-DOWN
The humidifier does not need to be turned off at the end of the humidification season. If 72 hours elapses without receiving a call for humidity,
the canister will automatically drain. The Drain light will remain lit for 24 hours. This may also occur during periods of inactivity during the
humidification season. The humidifier will resume normal operation when a call for humidity is made.
17

To turn humidifier off, push ON/OFF button once. Humidifier will enter four-minute drain cycle. Fill valve will open to temper drain water. The
Drain light will flash green for 15 seconds then turn green for four minutes while the canister drains. Once the Drain light turns off, the drain
cycle is complete and the humidifier is off.
SHUT DOWN PROCEDURE
DISPLAY PANEL
TABLE 5 – Display Panel
Indicator Light Function
Off Humidifier is turned off or power is disconnected.
Solid green Humidifier is turned on.
Flashing Green Humidifier is preparing to turn on. Occurs if power to humidifier was turned off when humidifier
was on. Humidifier turns on after light flashes for one minute.
Off Fill valve not energized.
Solid Green Fill valve is energized, filling or replenishing canister with water. (During drain cycle when fill valve
is open allowing cold water into canister to temper drain water, the fill light does not illuminate.)
Flashing Green Fill and Drain Valves are pulsing to dislodge mineral deposits from drain. Flashes 10 times in 4
seconds. Occurs if high water probe detects water during drain cycle.
Solid Red Humidifier cannot fill canister. Humidifier stops operating. Occurs after fill valve has been energized
for 40 minutes and high water probe does not detect water.
Off Humidifier is not producing steam
Solid Green Humidifier is turned on and receiving a call for humidity from the control.
Solid Yellow Humidifier is producing steam but at less than the rated capacity. Occurs if humidifier has operated
for 168 hours and does not detect nominal current between electrodes.
Off Drain valve not energized.
Solid Green Drain valve is energized, allowing water to drain from canister.
Flashing Green Humidifier is preparing to drain. Flashes for 15 seconds indicating fill valve is open allowing cold
water into canister.
Flashing Red
Canister has reached end of life. Humidifier continues to operate but at reduced capacity. Occurs
after humidifier has operated for 168 hours plus another 24 hours at less than 75% of the maximum
operating current level between electrodes.
Solid Red Humidifier is not operating and requires service.
Green lights indicate normal operation.
Yellow Steam light indicates humidifier is operating at less than rated capacity. Yellow Steam light also indicates humidifier is in Test mode.
Flashing red Service light indicates canister has reached the end of its life and needs to be replaced.
Solid red lights indicate humidifier has shut down and requires service.
Disconnecting power to humidifier resets internal timers.
18

MAINTENANCE
Inspect humidifier when servicing.
•Checksystemoperationandinspectallplumbingconnectionsandpipingforsignsofcracksorleaks.
•Inspectdrainlinetomakesureitisnotblockedandhasconstantdownwardslope.Cleanorreplaceifnecessary.
•Inspectsteamhosetomakesureithasnolowspotsandhasconstantupwardslopefromhumidifiertodispersiontubeinduct.Ifdispersion
tube is mounted below humidifier, inspect drip tee and drain.
Replace the canister annually and when prompted by the
“Service” light. Use Only Genuine Aprilaire Model 80 Canister.
1. Press On/Off switch to turn humidifier off.
2. Allow humidifier to drain. When the green Drain light stops
flashing, disconnect main electrical power to humidifier.
3. Remove front panel.
4. Pull three wires off posts on top of canister. (Two large electrode
conductors and one water level probe conductor.)
5. Loosen hose clamp at top of canister.
6. Slide hose off top of canister.
7. Slide canister up and out of drain assembly. Discard canister.
8. Remove O-ring from groove in drain assembly using small screw
driver.
9. Inspect drain assembly and remove any debris.
10. Insert new O-ring into groove in drain assembly. (O-ring is
provided with Model 80 canister.) Dampen O-ring with water
before inserting canister. Do not use oil, grease, or any lubricant
besides water.
11. Make sure strainer is inserted into bottom of new canister.
12. Insert canister into drain assembly. Position canister with label
facing outward.
13. Slip steam hose over top of canister and tighten hose clamp.
14. Reattach and fully seat three wires to posts on top of canister.
(Larger electrode conductors are interchangeable.)
15. Replace front panel.
16. Restore electrical power to humidifier.
17. Turn humidifier on and verify green On/Off light is illuminated.
18. See Start-up procedure.
TO REPLACE THE CANISTER
TO SERVICE THE FILL VALVE
If water flow from the valve is restricted:
1. Disconnect the inlet fitting and remove in-line strainer from the
inlet port using a small screw. Clean or replace strainer (part
#4004).
2. Disconnect the outlet fitting and remove, inspect and clean the
orifice.
CAUTION
• Allow humidier to drain and disconnect power before servicing.
• Service should be performed by a qualied HVAC technician.
TO CLEAN THE DRAIN VALVE
1. Turn unit off at membrane switch.
2. Unit will go through drain cycle – 4 mins – and turn off when
complete.
3. Disconnect main electrical power to humidifier at the circuit breaker.
4. Allow the unit to cool.
5. Remove front door.
6. Remove electrode wires, high water probe wire, steam hose and
canister.
7. With your finger swirl the fluid/precipitate mixture in the bottom of
the drain valve reservoir.
8. Using a sponge or paper towels soak up the water in the reservoir,
if necessary use a wet/dry vacuum to remove residue.
9. Clean the inside of the drain port (where coil projects out) by gently
swabbing with a bent cotton swab or other soft implement.
10. Rinse the drain valve reservoir with clean water and vacuum as
necessary.
11. Replace canister, reconnect steam hose and wires ensuring wires
are fully seated.
12. Replace door.
13. Restore power.
14. Turn unit ON.
15. Check for leaks.
19

CHECKING SYSTEM OPERATION & TROUBLESHOOTING
The following troubleshooting guide is intended to help diagnose and resolve general operational problems with Model 800 Humidifier. If a
problem persists, call Aprilaire Tech Support toll-free at 1-800-334-6011. Please be prepared to describe the exact nature of the problem.
For general operational problems, check to make sure humidifier is installed correctly.
CAUTION
Contact with electrical circuits can cause property damage, personal injury or death. Service and Troubleshooting must be
performed by qualified electrician.
TEST MODE
To check general function of humidifier and components, the following Test Mode procedure can be performed. Humidifier must be powered and
ADHC knob must be turned to OFF position. The humidifier should be plumbed to a water supply and the drain line should be connected. Test
Mode involves repeatedly pressing the On/Off button and listening for audible clicks as the various components are energized and de-energized.
The humidifier will remain in Test Mode for five minutes, then automatically return to the Off state. If the procedure is not completed in five
minutes, restart Test Mode. If the humidifier or components do not respond as indicated, investigate components being tested.
1. Press the On/Off button and hold it for 10 seconds until all display lights turn on. On/Off, Fill, steam and Drain lights will be green. Service
light will be red.
2. Press On/Off button again. All display lights will turn off.
3. Press On/Off button again. Fill light will illuminate red and Steam light will illuminate yellow.
4. Press On/Off button again. Red Fill light will turn off. Steam light will remain yellow.
5. Press On/Off button again. Listen for audible click as Power Relay is energized. If click is not heard, remove brown wires from terminals J7
and J8 and measure voltage across terminals J7 and J8. If 24 VAC is present, replace Power Relay. If 24 VAC is not present, replace control
circuit board.
6. Press On/Off button again. Listen for audible click as power relay is de-energized. If click is not heard, remove brown wires from terminals
J7 and J8 and measure voltage across terminals J7 and J8. If less than 1 VAC is present, replace power relay. If more than 1 VAC is present,
replace control circuit board.
7. Press the On/Off button again. Listen for a click as the fill valve is energized. Water should flow, filling the canister. If the valve does not
energize. measure voltage across the J6 FILL terminals on the control circuit board. If 24 VAC is present, replace fill valve. If 24 VAC is not
present, replace control circuit board.
8. Press On/Off button again. Listen for click as fill valve is de-energized. Water should stop flowing. If valve remains energized, check for
voltage across “J6 FILL” terminals on control circuit board. If less than 1 VAC is present, replace fill valve. If more than 1 VAC is present,
replace control circuit board.
9. Press the On/Off button again. Listen for a click as the drain valve is energized. Water should flow down the drain. If the valve does not
energize, remove the drain valve wires from terminals J3 and J4 on the control circuit board and measure voltage across the terminals. If 24
VAC is present, replace drain valve. If 24 VAC is not present, replace control circuit board.
10. Press On/Off button again. Listen for click as drain valve is de-energized. Water should stop flowing down the drain. If valve remains
energized, remove the drain valve wires from terminals J3 and J4 on the control circuit board and measure voltage across the terminals. If
less than 1 VAC is present, replace drain valve. If more than 1 VAC is present, replace control circuit board.
11. Press the On/Off button again. Listen for a faint click as the FAN PACK terminals on the control circuit board are energized. If the terminals
do not energize, (24 VAC measured across terminals) replace the control circuit board.
12. Press On/Off button again. Listen for click as FAN PACK terminals are de-energized. If the terminals fail to energize (more than 1 VAC
measured across terminals) replace control circuit board.
Exit Test Mode by disconnecting power to humidifier or allowing five minutes to elapse.
20