20
M
A
X
IM
U
M
O
F
12
”O
R
4
P
IP
E
D
IA
M
E
T
E
R
S
C
O
N
T
R
O
LL
E
R
S
E
N
S
O
R
5’
M
A
X
Reverse return piping is a proper method of manifolding multiple boiler hook-ups to ensure balanced flow through each boiler. Valves on
supply and return are needed to isolate any boiler, as required.
Fig. 25: Multiple-Boiler– Reverse Return Hook-Up—Models 133–4001