Greenheck Fan VSU Make-Up Air Unit with Direct-Fired Gas Heater 470654 - Manual (Page 12)

12 Model VSU Make-Up Air
®
Vent Line Solenoid
To Burner
V
ent Line
To Outdoors
From Supply
Safety
Shut-off Valves
Optional Vent Line
WARNING
NEVER test for a gas leak with an open flame.
NOTE
The factory piping has been checked for leaks, but
should be rechecked due to shipping and installation.
Connect the Supply Gas Line
A manual shut off valve (gas cock), 1/8 in. plugged test
port and 6 in. drip leg must be installed prior to the gas
train. The valve and the test port must be accessible for
the connection of a test gauge. Supply gas connections
must be made by a qualified installer and are not
furnished by manufacturer.
WARNING
Reference the National Fuel Gas Code for additional
vent line requirements.
Test the System for Leaks
Check both the supply lines and the factory piping for
leaks. Apply a soap and water solution to all piping and
watch for bubbling which indicates a leak.
Installation of Building Pressure
Control (optional)
Mount Pressure Tap
Using the factory provided bracket, mount the pressure
tap to the outside of the
unit. Choose a location
out of the prevailing
winds and away from
supply or exhaust fans
to assure accurate
readings.
Run Pressure Tap Lines
Run a pressure tap line from the pressure tap on the
outside of the unit to the low pressure tap on the back
of the photohelic gauge. Run a second pressure tap line
from the high pressure tap on the back of the photohelic
gauge to the space. Fifty feet of tubing is supplied with
the unit.
Set the Building Pressure
The pressure gauge is used to set the desired building
pressure. The pressure is set by adjusting the knobs for
the upper and lower pressure limits. Typical settings are
0.0 in. wg for the lower and 0.10 in. wg for the upper
pressure setting.
Connections for Photohelic Gauge
Factory Wiring
High Pressure Tap
to space
Low Pressure Tap
to outside
Typical Photohelic Gauge Settings
Pressure Setting Knobs
Pressure Setting
Needles
Pressure Indicating
Needle
Pipe the Optional Vent Line
If an optional vent line is located between the safety
shutoff valves it must be piped to the outdoors.
To
Controls
Gas Cock
From
Gas
Supply
6 in. Trap
1/8 in. Plugged Tap
Ground Joint Union
Supply Gas Line