17
5. Flow Control Valve: Flow control valves such as the
TACO Flo-Chek or Bell & Gossett Flo-Control™ are
used to prevent gravity circulation by incorporating a
check valve with a weighted disc.
6. Pressure Reducing Valve: A pressure reducing valve,
such as the Bell & Gossett B-38 or a TACO #329, is
used in a hydronic system to automatically feed water
to the system whenever pressure in the system drops
below the pressure setting of the valve. These valves
should not be used on glycol systems unless close
supervision of the glycol solution is practiced.
7. Back Flow Preventer: A back flow preventer (check
valve) is required by some jurisdictions to prevent water
in the hydronic system from backing up into the city
water supply. This is especially important on systems in
which glycol solution is used as the heating medium.
8. Pressure Relief Valve: The boiler pressure relief valve
is shipped separately for field installation. The valve is
to be installed as shown in Figure 4.2.
Pipe the discharge of the relief valve to within 12" of
the floor and close to a floor drain.
Provide piping that is the same size or larger than the
relief valve outlet.
9. Low Water Cut Off: When installing a probe type
LWCO, locate the LWCO in the boiler supply above
the top jacket panel. Refer to Section 7. Electrical
Connection in this manual for wiring details.
10. Circulator: The boiler circulator is to be sized to
overcome the pressure drop of the system while
providing the flow required by the boiler.
a. If the boiler is piped in a secondary loop of a
primary/secondary heating system, the circulator
will need only to overcome the resistance of the
boiler and any fittings in that loop.
b. The circulator should be sized based on gross
output of the boiler. Table 4.3 shows the Boiler
Output as reported to the Hydronics Institute
Section of AHRI.
WATER PIPING AND CONTROLS
Figure 4.1: Piping Symbol Key
Do not operate this appliance without installing the
pressure relief valve supplied with the boiler or one
with sufficient relieving capacity in accordance with
the ASME Rating Plate on the boiler heat exchanger.
WARNING
Pipe the discharge of the relief valve as close as
possible to the floor and away from high traffic areas.
Pipe the discharge to a floor drain. Failure to do so
may result in personal injury and/or property
damage.
CAUTION
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