Amtrol OWB Series - Manual (Page 26)

Shutoff Valve
Circulating Pumps
Stem Thermometer
Supply to System
Return from System
Bypass A
S
R
Cold Water Feed
Drain Cock
Circulating Pumps
Adjust the two manual valves to maintain 160 degree F or more in the boiler while holding the supply water
temperature at the stem thermometer at 140 degree F or whatever minimum temperature system requires.
Figure 20.
NOTE
Bypass A shown in figure 20. above should not exceed 12 inches in length. If it
is not practical to maintain a 12 inch length or less then increase the pipe size of
the bypass by one size.
4. LARGE WATER CONTENT SYSTEMS------
Such systems as converted gravity systems, old systems with cast iron radiators, and
also newer systems that employ outdoor reset control present a potential problem with
low return water temperatures and condensation. The boiler must be protected from
condensation in such cases by using a by-pass as shown in Figure 21.
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Installation, Operation, And Service Instructions