Water Heater Operating Cycle; Protection For The Water Heater; Gas Control; Water Temperature Protection - Lochinvar CH 100 G CE Installation, Commissioning, User & Maintenance Instructions

gis
2.3 Water heater
operating cycle
2.4 Protection for the
water heater
2.4.1
2.4.2
2.4.3
Instruction manual CH
The entire appliance is regulated by a control thermostat. The control
thermostat monitors the water temperature (T
cycle is activated as soon as T
(T ). The value for T can be adjusted using the control thermostat (±40°C to
set set
±70°C).
As soon as T drops below T
water
thermostat closes, causing the main valve on the gas control to open. The gas
mixes with the air it draws along. This mixture is ignited by the pilot burner and
the water is heated. As soon as T
thermostat opens again, and the heating cycle stops.
The control thermostat has a certain margin both when closing and opening. We
refer to this margin as the hysteresis. The hysteresis cannot be adjusted.
The burner control monitors the water temperature by means of thermostats
and ensures safe combustion. This takes place using:
• the

Gas control

• the Thermocouple
• the

Water temperature protection

• the Flue gas backflow safeguard
Gas control
The gas control has 2 valves for safety purposes:
1. The main valve, which controls the gas supply to the burner tray and which
is switched via the I/0/II switch circuit and the control, high-limit and flue gas
thermostats. This circuit is powered by the supply voltage.
2. The safety valve, which controls the gas supply to the pilot burner and which
is switched via the thermocouple circuit and the safety thermostat. This
circuit is powered by the millivoltage from the thermocouple that is located
in the pilot flame. Whenever the safety valve closes, the main valve also
closes.
Thermocouple
1. To prevent gas flowing when there is no combustion, a thermocouple is
fitted. As a result of the presence of the (permanent) pilot flame, the
thermocouple maintains a millivoltage which keeps the gas control's safety
valve open.
2. If the pilot flame goes out, this voltage disappears and the gas control's
safety valve closes, interrupting the gas supply to the burner tray.
Water temperature protection
To ensure a safe water temperature is not exceeded, the high-limit thermostat
sensor is installed at the top of the appliance. This is because stratification
('stacking') of the water temperature can mean that the temperature at the top
of the appliance can be considerably higher than the set temperature for the hot
water.
In the event that both the control and high-limit thermostats should fail, there is
also a safety thermostat.
The table explains how the high-limit and safety thermostats respond to the
sensors.
). The appliance's heating
water
falls below the specified threshold value
water
there is a demand, and the control
set
exceeds T , demand ceases, the
water set
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