Specifications
Legacy™ Model LRZM Pool/Spa Heater
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Installation and Operation Manual
Some of the servicing procedures for the Legacy
heater are hazardous because they involve fuel
gas, electricity, moving parts and procedures which
require testing or temporary bypass of safety con-
trols. For this reason, the heater must be serviced
only by a qualied professional service technician.
The Legacy heater incorporates unique design fea-
tures. Incorrect service of this heater can result in
property damage, personal injury or death. To avoid
such hazards, the heater must be serviced only by
a qualied professional service technician.
A qualied professional technician must
service the Legacy model LRZ millivolt pool heater
using Zodiac service procedures. Before calling for
service, however, the owner should check for obvious
problems. The other components in the pool system,
including pump, lters and strainers, water valves, gas
supply and time clocks have an effect on heater opera-
tion.
Conrm that the Legacy heater control switch is
set to 'ON' and that the temperature control knob is set
high enough to make the heater operate. Make sure the
pump is operating, that the lter and strainers are not
clogged, that there are no mis-positioned water valves,
that the gas is not shut off and that time clocks are
properly adjusted. Also be sure that there is no block-
age of the vent or louvers which supply combustion air
to the burners.
The Legacy model LRZ millivolt pool heater
has an atmospheric combustion system. This system is
illustrated in Figure 24.
As the heated exhaust gases rise out of the
combustion chamber, ow is created through the
system and fresh combustion air is drawn into the
heater through the louvers cut into the front and sides
of the heater. Gas is forced through an orice into
the open end of a burner. When the gas ows into the
burner, a “negative” pressure is created at the opening
of the burner. This negative pressure pulls air into the
burner with the gas and mixes the two together. As
the gas/air mixture ow through the burner ports it
is ignited in the combustion chamber. Hot combus-
tion products then rise through a highly efcient heat
exchanger. Combustion products then enter a ue
collector and are directed to the outdoors through the
grate top of the heater or a vent pipe and cap.
1. Gas Valve / Regulator - The gas valve controls
gas ow into the burner. It provides ow only
when the temperature controls require heat and
only if all safety controls enable operation. It is
also a positive pressure regulator. It regulates
the gas pressure in the burner to specications
addressed earlier in this manual. This is neces-
sary for proper operation of the burner system.
2. Temperature Control - The Zodiac Legacy
pool/spa heater is controlled by a mechanical
thermostat which controls heater operation to
bring the water to the desired temperature. The
desired temperature is set by rotating a knob on
the face of the control panel. To achieve accurate
water temperatures, the pool/spa water must be
monitored with an accurate pool thermometer.
3. Pilot/Pilot Ignition - The Legacy heater relies
on a standing pilot to ignite the burners when the
temperature control calls for heat. When lit, the
pilot receives a constant ow of gas from the gas
valve. If the pilot extinguishes, the gas valve is
automatically signalled to stop the ow of gas to
the pilot and the burners to prevent a gas build
up in the heater. Igniting the pilot is achieved by
means of a piezo spark igniter mounted on the
inner front panel of the controls compartment of
the heater.
4. Pilot Generator (Thermopile) - The pilot gener-
ator is a device, that when heated by the ame
of the pilot, generates a small electrical voltage
of approximately 750 millivolts. The voltage
is placed across the temperature controller and
safety circuit of the heater. If this current is
VENT TOP
FLUE COLLECTOR
HEAT EXCHANGER
COMBUSTION CHAMBER
BURNER
BURNER TRAY SHELF
EXHAUST
AIR FLOW