Amtrol OWB Series - Manual (Page 22)

WATER PIPING CONNECTIONS
1. OWB-9, OWB-15, and OWB-25 boilers are shipped complete with circulating pump.
To make the piping connections to the boiler ready to connect to the system piping,
the following will also be required at a minimum:
1 – Air Purger (same size as supply pipe)
1 – Pressure reducing Fill Valve
1 – Expansion Tank (sized to system design requirements)
1 – Automatic Air Vent
2. The following accessories may also be required, depending upon overall system
design and code requirements:
1 – Low Water Cutoff may be required if boiler is located above radiation level.
Check requirements of state or local code bodies and insurance companies. If
required use a probe-type designed for water system use and install in tee in
supply piping above the boiler.
1 – Manual Reset High Limit----Required by some state or local codes. Also
required if system is to comply with ASME code.
1 – Backflow Preventer----- Required by many State and local codes.
3. Additional circulating pumps or zone valves may also be required if the system is to
be multi-zone or if it is to include a domestic hot water storage tank with coil.
WARNING
The expansion tank must be properly sized to system requirements. An under-sized
expansion tank will cause system water to be lost through the relief valve and make-up
water to be introduced through the fill valve. Continual introduction of fresh water into
the system will cause mineral build-up in the boiler sections and eventual section failure.
4. There are two types of expansion tanks used, the closed type and the pre-pressurized
diaphragm tank Most new installations use the diaphragm type tank, however some
installations still employ the closed type tank.
(a) Piping Connections with closed type expansion tank----See Figure 16. Piping
from tee in supply to tank should be 3/4 inch. If horizontal piping is
employed, pipe must be pitched up toward tank 1/4 inch per foot.
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Installation, Operation, And Service Instructions