Installation manual
12
ENVISION AIR HANDLER INSTALLATION MANUAL
Hydronic Models
The water heater and hydronic air handler must be lo-
cated indoors and not subject to freezing temperatures. 
The water heater must be installed in accordance to local 
codes and its own installation instructions. The piping 
between the water heater and air handler should be kept 
to a minimum. Piping should be sized to allow for water 
velocities of 2’-4’ per second. At average water velocities, 
air bubbles should be carried along the piping to an air 
separator where they can be discharged from the system. 
Water velocities greater than 4’ per second could cause 
flow noise and should be avoided. If water lines pass 
through an unconditioned space they should be protected 
to prevent them from freezing. Valves should be installed 
to allow system isolation. All closed loop hydronic systems 
must be equipped with an expansion tank to allow room for 
the heated liquid to expand. A system is considered closed 
when a check valve or backflow prevention valve is installed 
in the cold water pipe upstream of the water heater. 
Once piping is complete all air must be purged from the wa-
ter lines. There is a dole valve at the top of the hydronic coil 
header that can be opened to purge air from the coil. There 
is also a plug at the bottom of the hydronic coil header for 
draining the coil.
Plug for coil drainage. 
Dole valve for air purging
Typical Installation. See the Hydronic Application Guide for other applications
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