IBC Sl Series Installation & Operating Manual page 51

These boilers are designed for use within a closed loop, forced circulation, low pressure system.
A 30 psi pressure relief is supplied for field installation in the relief valve fitting on the boiler.
Relief valve discharge piping must terminate between 6 inches (15 cm) and 12 inches (30 cm)
above the floor or per local code.
Warning
During operation, the relief valve may discharge large amounts of steam and/or hot
water. To reduce the potential for bodily injury and property damage, install a
discharge line that:
Is connected from the valve outlet with no intervening valve and directed
downward to a safe point of discharge.
Allows complete drainage of both the valve and the discharge line.
Is independently supported and securely anchored, so as to avoid applied
stress on the valve.
Is as short and straight as possible.
Terminates freely to atmosphere where any discharge will be clearly visible
and is at no risk of freezing. terminates with a plain end which is not threaded.
Is constructed of a material suitable for exposure to temperatures of 375° F or
greater.
Is, over its entire length, of a pipe size equal to or greater than that of the valve
outlet.
Do not cap, plug or obstruct the discharge pipe outlet.
If piping from both sides at the same time,
a tee must be installed on either supply
outlet, immediately on exiting the boiler so
that there is no possibility of installing an
isolation valve between the pressure
vessel and the relief valve.
Pressure relief valve locations
(pick one)
No shut-off valve
Figure 35 Relief piping with dual side piping
connections
47
3.11.2 System piping