Install Instructions

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109837-01 - 5/20
PVCG-C
Installation, Operating & Service Manual
6. Low Water Cut-Off (factory supplied) This boiler
is equipped with a low water cut-off (LWCO)
that prevents the boiler from firing if there is
inadequate water in the boiler. This LWCO is an
automatic reset type, meaning that it will allow
the boiler to restart automatically if the low water
condition is corrected. This LWCO satisfies the
requirements of most installation codes used
for residential installations, however some
jurisdictions may require a manual reset low
water cut-off which requires a reset button to be
pushed to restart the boiler.
If a manual reset LWCO is required, it must
be installed in the supply piping just above
the boiler in accordance with the LWCO
manufacturer’s instructions (the factory supplied
LWCO is left in place). No intervening valves
may be installed between an externally piped
LWCO and the boiler. Wire an external manual
reset LWCO to either break120VAC power to
the boiler, or break the external limit connection
shown in Section 9.
Figure 7.2: Standard Boiler Piping
7. Manual Reset High Limit (Required by some
codes) - This control is required by ASME
CSD-1 and some other codes. Install the high
limit in the boiler supply piping just beyond
the boiler with no intervening valves. Set
the manual reset high limit as far above the
operating limit setting as possible, but not over
240°F. Wire the control to break the 120 VAC
electrical supply to the boiler or the external
limit connection shown in Section 9.
8. Flow Control Valve (Required under some
conditions) - The flow control valve prevents
flow through the system unless the circulator
is operating. A flow control valve may be
necessary on converted gravity systems to
prevent gravity circulation. Flow control valves
are also used to prevent flow in circulator zone
systems through zones that are not calling for
heat.
9. Isolation Valves (Optional) - Isolation valves are
useful if the boiler must be drained, as they will
eliminate having to drain and refill the entire
system.
7 Water Piping (continued)