Operating instructions
14
• Install discharge piping from safety relief valve. See 
gure 5-2.
• Use ¾" or larger pipe.
• Use pipe suitable for temperatures of 375°F (191°C) 
or greater.
• Individual boiler discharge piping shall be independent 
of other discharge piping.
• Size and arrange discharge piping to avoid reducing 
safety relief valve relieving capacity below minimum 
relief valve capacity stated on rating plate.
• Run pipe as short and straight as possible to location 
protecting user from scalding and properly drain 
piping.
• Install union, if used, close to safety relief valve outlet.
• Install elbow(s), if used, close to safety relief valve 
outlet and downstream of union (if used).
• Terminate pipe with plain end (not threaded).
5.4 Trim Piping
• Temperature - Pressure Gauge. Install temperature 
pressure gauge using nipple, tee and bushing provided 
with boiler. See gure 5-3.
• Drain Valve. Install drain valve using nipple, tee and 
bushing provided with boiler. See gure 5-3.
5.5 System Piping
• See Table 3 for basic system piping congurations.
• Systems with automatic ll valves require back ow 
prevention device.
•  Single boiler system. See gures 5-4, 5-5, 5-6, 5-7A, & B 
for general guidance. Additional considerations:
• Boiler control is designed for single central heating 
pump. Installer responsible for integration of 
multiple central heating pumps.
• Boiler control allows domestic hot water 
prioritization. Function could be lost if central 
heating pump not directly connected to control 
system.
• Multiple boiler system. 
See gure 5-8A, B & C 
 for general 
guidance. Additional considerations:
• Control system requires equivalent water 
temperatures entering each boiler to properly 
sequence and adjust system supply temperature.
• Install multi boiler sensor kit. See "Parts, Kits & 
Optional Accessories" manual for part number.
• Heating system with existing primary loop, close internal 
primary loop ball valve.
•  Heating system without existing primary loop, leave internal 
primary loop ball valve open to use internal primary loop.
FIGURE 5-3 Temperature Pressure Gauge and Drain 
Valve Installations
Temperature Pressure 
Gauge shown at 
System Supply 
Connection
Check Local Codes 
For Maximum 
Distance To Floor
 WARNING
Burn and scald hazard. Safety relief valve could      
discharge steam or hot water during operation.   
Install discharge piping per these instructions.
! 
FIGURE 5-2 Safety Relief Valve Discharge Piping
Drain Valve shown 
at System Return 
Connection to Boiler
Safety Relief Valve
Gas Supply
5 - HYDRONIC PIPING










