Pennco 3KW0.60 - Manual (Page 18)

18
RELIEF VALVE (provided)
Each low pressure hot water heating boiler is provided
with a safety relief valve for over pressure protection of
boiler and heating system. Safety relief valve opens when
pressure in boiler rises to 30 psig. Safety relief valve is
provided with lifting device for testing and should be tested
monthly during heating season. Provide discharge piping
from outlet side of safety relief valve to prevent scalding or
other hazardous situations. Discharge piping must remain
full size and terminate at safe point.
CONVENTIONAL EXPANSION TANK (not provided)
Size expansion tank correctly an improperly installed or
sized expansion tank may result in frequent lifting of safety
relief valve or other heating system problems. Install tank
higher than top of boiler. Connecting pipe from boiler to
expansion tank shall rise continuously up to expansion tank
so that air can rise into expansion tank.
Expansion tank is partially filled with air. Air compresses
as water expands, thus forming air pressure cushion. This
“spring-like” cushion serves to maintain correct operating
water pressure regardless of water temperature. This
assures “full measure” of water, even in highest radiation
unit of system. Tank also serves as trap for excess air in
system. Air causes noises in pipes and inefficient circulation
in radiators if left in piping system.
It is possible for a tank to become “waterlogged” (filled
with water). It can also become overfilled with air when
filling system with new water. Fittings provided on tank and
in line to tank are for bleeding off excess air and water.
DIAPHRAGM EXPANSION TANK (not provided)
Diaphragm type expansion tank takes the place of
conventional expansion tank. Read instructions packed with
your tank assembly. Size and correctly install expansion
tank, an improperly installed or sized expansion tank may
result in frequent lifting of safety relief valve or other
heating system problems.
Tank typically comes with 10-12 psig air charge. Same as
pressure produced in system by automatic fill valve set
to fill boiler to 10-12 psig with fresh water. When system
is first filled, tank fills partially with water. As water is
heated, and system pressure increases, water expands into
tank and compresses air in tank. Compressed air cushion
permits system water to expand as temperature changes
and assures “full measure” of water, even in highest system
radiation.
Mount diaphragm type expansion tank on air purger fitting
or any other convenient place in supply or return line.
Recommend locating diaphragm type expansion tank in
supply line with circulator located after expansion tank.
Configuration allows circulator to “pump away” from
expansion tank for improved air elimination and system
performance. Air eliminator fitting or air purger is not
provided. Use air eliminator fitting or air purger to help
remove air from system before it reaches radiators. Install
in supply line. Air left in system can cause noises in pipes
and inefficient circulation in radiators.
EQUIPMENT AND ACCESSORIES
WARNING
Burn and scald hazard. Safety relief valve could
discharge steam or hot water during operation.
Install discharge piping per these instructions.
!