14
VIII System Piping

Standard Piping

Figure 11 shows typical boiler system connections on a single zone system. Additional information on hydronic system
design may be found in Installation of Residential Hydronic Systems (Pub. #200) published by the Hydronics Institute in
Berkeley Heights, NJ. The components in this system and their purposes are as follows:
1) Relief valve (Required) - Mount the relief valve on the right side of the boiler as shown in Figure 1 using the 3/4 nipples
and elbow provided. The relief valve shipped with the boiler is set to open at 30 psi. This valve may be replaced with
one having a pressure up to the “Maximum Allowable Working Pressure” shown on the rating plate If the valve is
replaced, the replacement must have a relief capacity in excess of the DOE heating capacity for the boiler.
Pipe the discharge of the relief valve to a location where water or steam will not create a hazard or cause property
damage if the valve opens. The end of the discharge pipe must terminate in an unthreaded pipe. If the relief valve
discharge is not piped to a drain it must terminate at least 6 inches above the floor. Do not run relief valve discharge
piping through an area that is prone to freezing. The termination of the relief valve discharge piping must be in an area
where it is not likely to become plugged by debris.
2) Circulator (Required) - Although the circulator is shipped on the boiler return, it can be installed on the boiler supply. If
the circulator is moved to the supply it should be positioned just downstream of the expansion tank as shown in Figure
11.
3) Expansion Tank (Required) - If this boiler is replacing an existing boiler with no other changes in the system, the old
expansion tank can generally be reused. If the expansion tank must be replaced, consult the expansion tank
manufacturer’s literature for proper sizing.
4) Fill Valve (Required) - Either a manual or automatic fill valve may be used. The ideal location for the fill is at the
expansion tank.
5) Automatic Air Vent (Required) - At least one automatic air vent is required. Manual vents will usually be required in
other parts of the system to remove air during initial fill.

CAUTION

• INSTALL BOILER SO THAT THE GAS IGNITION SYSTEM COMPONENTS ARE PROTECTED
FROM WATER (DRIPPING, SPRAYING, RAIN, ETC.) DURING APPLIANCE OPERATION AND
SERVICE (CIRCULATOR REPLACEMENT, ETC.).
• OPERATION OF THIS BOILER WITH CONTINUOUS RETURN TEMPERATURES BELOW 120°F
CAN CAUSE SEVERE HEAT EXCHANGER CORROSION DAMAGE.
• OPERATION OF THIS BOILER IN A SYSTEM HAVING SIGNIFICANT AMOUNTS OF
DISSOLVED OXYGEN CAN CAUSE SEVERE HEAT EXCHANGER CORROSION DAMAGE.
• DO NOT USE TOXIC ADDITIVES, SUCH AS AUTOMOTIVE ANTIFREEZE, IN A HYDRONIC
SYSTEM.

DANGER

• PIPE RELIEF VALVE DISCHARGE TO A SAFE LOCATION.
• DO NOT INSTALL A VALVE IN THE RELIEF VALVE DISCHARGE LINE.
• DO NOT MOVE RELIEF VALVE FROM FACTORY LOCATION.
• DO NOT PLUG RELIEF VALVE DISCHARGE.
12