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Model GFX3 Humidistat Installation Manual
Testing The System
1. Re-assemble system and check all connections.
2. Restore power to the HVAC system.
3. Start HVAC system by raising thermostat setting.
4. Check to see that GFX3 display is on.
5. Set to TEST MODE by pressing “DROP” and “THERMO” together for 5 seconds.
The relay will close and the “+” will flash for 2 minutes or press a key to set to OFF MODE.
6. Set to OFF mode to verify humidifier operation ceases.
7. The GFX3 will stay in OFF Mode unless set to Manual or Automatic mode. See “Operation”.
Operating Modes
1. Operating Modes.
2. Press any button to light the display. Press the “DROP”
button to select the Operating Mode, Off, Manual, or Auto.
OFF Mode
The Humidifier is turned off.
MANUAL Mode
The GFX3 will work to maintain the single humidity selected. You can set your desired humidity
level by pressing “UP” or “DOWN”. The humidifier will turn ON or OFF according to your manual
setting. The humidifier will operate when the measured relative humidity falls more than 1% below
the set point until the measured relative humidity is 1% above the set point. When the humidifier
is operating, the “+” will display. Humidity may need to be lowered when weather is colder or if
condensation is suspected (see table at right). The GFX3 has a maximum operating temperature of
99°F.
PUSH
5 SEC.
BLINK !
At Outside
Temperature
Suggested
Setting
-20°F
-29°C
15%
-10°F
-23°C
20%
0°F
-18°F
25%
+10°F
-12°C
30%
+20°F
-7°C
35%
+30°F
-1°C
40%
AUTO Mode
The GFX3 will automatically raise the humidity as the outdoor temperature increases. This provides the highest possible humidity. The
GFX3 will automatically lower the humidity as temperatures drop. This minimizes the risk of condensation on cold surfaces like windows.
The Auto Humidity Index Set Point may be changed from 0 (low) to 10 (high) by pressing “UP” or “DOWN”. The Humidity Index is based
on the outdoor temperature and indoor humidity. The humidifier will switch ON/OFF according to the calculated auto Humidity Index set
point. When the humidifier is operating, the “+” will display. Lower Index settings are for older homes with less insulation and poor vapor
barriers. Higher Index settings are for newer homes with complete vapor barriers, triple pane windows and high R value insulation.
1-2 Older than 1950, no vapor barrier, little insulation.
3-4
Built 1950-1965, no vapor barrier, R6 insulation.
5-6
Built 1965-1975, craft vapor barrier, R11 insulation.
7-8
Built 1980-1990, craft vapor barrier, R19, double pane windows.
9-10 Built after 1990, poly vapor barrier, R38 insulation, foam exterior cladding, triple pane windows.
If condensation is seen or suspected, reduce index by 2 until condensation stops. The level bars indicate the humidity index; one bar for
two index points.
AUTO Mode Target Humidity
Humidity
Index
Outdoor Temperature F°
-20
-10
0
10
20
30
40
50
1
0
5
10
15
20
25
30
35
2
3
8
13
18
23
28
33
38
3
6
11
16
21
26
31
36
41
4
9
14
19
24
29
34
39
44
5
12
17
22
27
32
37
42
47
6
15
20
25
30
35
40
45
50
7
18
23
28
33
38
43
48
53
8
21
26
31
36
41
46
51
56
9
24
29
34
39
44
49
54
59
10
27
32
37
42
47
52
57
62
“DROP”
“UP”
“DOWN”
"DROP"
"UP"
"DOWN"
"BLINK"
PUSH
5 SEC.
USA: www.GeneralFilters.com Canada: www.CGFProducts.com
