provided with an appropriate transformer.
2.
Wire the heater and pump exactly as shown in
the wiring diagram supplied with the heater.
3.
The pump and heater must be electrically
interlocked so the heater cannot come on unless
the pump is running.
4.
All field installed electrical safety devices and all
field installed devices (draft switches, relays,
timers, outdoor temperature reset devices, etc.)
can be connected to the heater wiring at points
shown in the wiring diagram designated “Field
Interlock”.
2F.
Water Piping of System
1.
Be sure to provide valves at the inlet and outlet of
the boiler so it can be readily isolated for service.
A butterfly or similar type of valve is
recommended.
2.
The pressure relief valve installed in the tapped
opening provided in the outlet header (See
Figure 9), must be piped, but not fastened, to a
drain or floor sink. The drain pipe must be the
same size as the valve outlet and must pitch
downward from the valve.
Special attention must be given to relief valve
settings in installations where the heater is
located on the ground floor of a tall building. The
static pressure of the system is elevated and
could cause the relief valve to leak. Where no
special setting of the relief valve is ordered, the
factory will furnish a 125 psi setting. Never
reduce the relief valve openings.
Figure 10 – Tempering Valve Installation
9
Figure 9 – Pressure Relief Valve Location
Pressure
Relief
Valve
Hot
Water
Hot
Water
Storage
Tank
Floor
Automatic
Tempering
Valve
Cold
Water
Tempered Water
24"
3.
Pressure relief valve lever must be tripped at
least once a year to insure that waterways are
clean. When manually operating lever, water will
discharge through drain line. Precautions must be
taken to avoid contact with hot water and water
damage.
4.
The weight of all water and gas piping should be
supported by suitable hangers or floor stands.
5.
Check piping diagrams with local applicable
plumbing, heating and building safety codes.
6.
All two-temperature systems using temperature
valves must have forced recirculation in the low
temperature building loop.
7.
A check valve installed at the hot water inlet to
the tempering valve will prevent cold water from
being drawn in reverse through the tempering
valve into the hot water.
8.
When installing a tempering valve, place at
bottom of antithermosyphon loop at least 24" high
to prevent excessive hot water from entering
mixed water supply. Bring the cold water supply
up from the floor to the valve. (See Figure 10)
2G.
Water Expansion
When cold water is heated the water expands. If
no water is being used during the heat-up period the
expanded water will normally back up into the city
mains.
A water pressure reducing valve installed in the
incoming cold water line may act as a check valve
and prevent the expanded water from moving
backward. This will cause pressure to rise in the
heater, which will be relieved by the pressure relief
valve.
If the relief valve pops frequently a mineral
deposit may build up on the valve seat, causing it to
