Operating instructions
19
FIGURE 5-8B Multiple Boilers Using Primary/Secondary Pumping with Closed External Primary Loop
5 - HYDRONIC PIPING
Heating Load Heating Load
Heating Load
Existing closely spaced tees 
in primary system loop
12"/305mm 
Maximum 
Separation
Up to 16 
boilers
CH/System 
Pump
12"/305mm Maximum Separation
System  
Temperature 
Sensor
Size common piping 
per maximum heat 
capacity of entire 
system
All internal 
primary loop 
ball valves 
closed
Limit 
length to 
5' (1.6m)
3/8"/10mm Open 
End Wrench may 
be required to turn 
valve










