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L8124A,C,E,L and M
These immersion type controllers are used with forced
hydronic heating systems that include domestic hot water
service. All models provide high limit, low limit and
circulator control. Table 1 lists the various models and
These Aquastat® relays have a diaphragm powerhead
and MicroSwitch™ assembly that respond to
temperature changes in the boiler water. L8124 can
provide multizone control by using a separate circulator
and R845 Relay for each zone. L8124E and L have large
transformers and extra terminals for supplying power to
low voltage valves. L8124L includes a large transformer
and extra terminals for low voltage zone valves. L8124M
is for use in a wood-coal/gas-oil multifuel heating system.
Circulator is independently controlled by the thermostat.
Do not use these Aquastat® Relays where the pressure
can exceed 100 psi (690 kPa) on the bulb if inserted
directly or 200 psi (1380 kPa) when using an immersion
well, or where the ambient temperature can exceed
150°F (66°C) at the case or 265°F (129°C) at the sensing
Setting: 110°F to 220°F (43°C to 104°C), adjustable.
Differential: 10°F to 25°F (6°C to 14°C), adjustable.
Setting: 130°F to 240°F (54°C to 116°C), adjustable.
Differential: 10°F (6°C), fixed.
Can cause serious injury, death or property
Use this product only in systems with a pressure
Table 1. Model Descriptions.
Multizone control can be provided by using a separate circulator and R845 Relay for each zone.
Can Be Used For
No. of V8043 Zone
Burner Circuit Circulator Circuit
L8124A 120V Yes — Same as L8124A,C,L
120 Vac: 7.4A (full load),
44.4A (locked rotor).
240 Vac: 3.7A (full load),
22.2A (locked rotor).
L8124E 24V 2 1.25A at 24 Vac; 30 VA
(total load) B
L8124M 120V — Same as L8124A. None.