LAARS Mighty Therm LO-NOx PH (Sizes 250/400) - Install and Operating Manual - Manual (Page 14)

LAARS Heating Systems
Page 14
Flow
Switch
High-Limit
Dry Well
Pressure
Relief Valve
Figure 25. Pressure Relief Valve.
2.6.5 Chilled Water Systems
If the boiler is part of a refrigeration system,
include the proper valves to isolate the boiler from the
refrigeration system during times when the boiler is
not operating.
When the boiler piping is connected to heating
coils, which are close to refrigerated air circulation,
install flow control valves or other automatic methods
to prevent gravity circulation of the boiler water during
the cooling cycle.
2.6.6 System to Boiler Piping
1. Install gate valves at the inlet and outlet to the
boiler so it can be isolated for service.
2. Make sure the pressure relief valve (see Figure
25) has its outlet piped to a drain or floor sink.
Pay special attention to relief valve settings in
installations where the boiler is located on the
ground floor of a tall building, or where the
operating temperature of the boiler is above
210°F (99°C). In both cases, the static pressure of
the system is raised. This would bring raw water
into the system. The factory will furnish a 75 psi
(516.8 kPa) setting unless a special setting is
ordered.
Figure 24. One Boiler, Multi-Temperature System.
3. Install a low water cutoff device if the boiler is
installed above radiation level.
4. Install manual and/or automatic air venting
devices at high points in the system to get rid
of air.
5. Install a correctly sized expansion or
compression tank in accordance with the
manufacturer's instructions.
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