30
Vented System Installation
The Maxim may be connected directly into an existing
hot water system, changing it to an atmospheric vented
system.
NOTE: Any changes in the existing boiler and/
or system should be done by a certified installer
in accordance with applicable codes. Be
sure the system water is properly maintained
with MolyArmor 350 (see Water Quality and
Maintenance section).
The hot supply line from the outdoor furnace can be
connected into the top of the existing boiler and returned
to the outdoor furnace from the bottom of the boiler
(see Fig. 38). Use one pump to continuously circulate
the water from the outdoor furnace through the existing
boiler and back to the outdoor furnace.
CAUTION
The outdoor furnace must NEVER be pressurized.
The vent cap must always be loose. Do not
extend the vent pipe. The outdoor furnace will be
damaged if it is pressurized.
When the existing system is connected to the outdoor
furnace as illustrated in Fig. 38, the circulating pump(s)
in the existing system must be located in the hot supply
line(s), not in the return line(s). A flow check or zone
valve will prevent thermal circulation and overheating
of building.
It is very important to eliminate all air and water leaks
(valve packings, bleeders, etc.) and purge all air from
the existing system.
1. After filling the outdoor furnace (see Initial Start-
Up Procedures section) and existing system with
water, purge the air from the indoor system by
closing the valves on the outdoor furnace; then
pressurize the indoor system with water from the
domestic water line.
CAUTION
Do not apply more pressure to the indoor system
than the pressure relief valve on the existing
boiler is rated for.
2. Bleed air from the pressurized indoor system; then
operate the circulating pump(s) on the indoor system.
Perform this procedure twice. If any auto float vents
are used in the existing system, they must be capped
off tightly after the air bleeding is completed. This
eliminates the possibility of allowing air to enter
after the system is depressurized.
3. When the indoor system is completely purged of air,
close the valve on the water line used to pressurize
the indoor system. If any air is trapped in the
system, it can reduce water flow. This will prevent
the system from heating properly.
4. Open valves on the outdoor furnace, turn on the
pump and proceed to start the fire in the outdoor
furnace.
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Flow check or zone
valve here will prevent
thermal circulation and
overheating of building.
It is recommended that
the circulation pump in
all hydronic systems be
located in the hot
supply line, not the
return line.
2-way
Zone Valve
Baseboard Heat Return
Existing
Boiler
Vented
Water
Heater
Circulating
Pump
Installer must comply with all applicable
codes and regulations.
Note
A pump must be installed in the hot
supply line between the outdoor furnace
and thermostatic valve.
Note
Outdoor furnace water
temperature setpoint should
be set at 185˚F minimum.
Note
Direct Connection to Existing Boiler
Fig. 38
Section 6 - System Installation
