Install Instructions for IMD

238-46299-00B REV 02/07
1) Install a properly sized expansion tank. An air separator and vent is recommended to eliminate air in
the system.
2) A pressure reducing valve is recommended for installation to maintain appropriate pressure in the
closed loop system.
3) The circulator should be installed to “pump away” from the expansion tank as shown.
4) Purge all air from the filled, closed system.
NOTICE
The Combi2 can experience condensation conditions longer than other water heaters as the hydronic
system comes up to temperature. These condensing conditions can extend for days in radiant floor
installations.
Figure 2 – Hydronic Piping with Zone Valves
Figure 3 – Hydronic Piping with Circulators and Flow Control Valves