A.O. Smith COF 199, Инструкция по установке, эксплуатации и обслуживанию

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1.2 Technical safety equipment
1.2.1 Control box
The temperature control for the water heater is
situated in the control box (see figure 1), which is
fitted to the heater cover.
The water heater has been fitted with three
thermostats:
- a control thermostat,
- a high-limit thermostat
- an overheating cut-out.
The control thermostat is the thermostat by means
of which the desired water temperature is set. The
high-limit thermostat acts as a safeguard against
excessive water temperatures at the top of the
heater, if as a result from a certain draining pattern
(frequently draining of small quantities), stratification
of the water temperatures in the heater occur. If both
the control thermostat and the high-limit thermostat
fail the overheating cut-out will automatically shut
down the water heater.
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1. GENERAL
1.1 Description of the heater
Construction of the heater is in accordance with the
European standards for gas-fired water heaters for
sanitary use (EN 89). The heaters therefore comply with
the European Guidelines for Gas Heaters and are
permitted to carry the CE mark.
They are atmospheric heaters suitable for both gas-fired
and oil-fired ventilator burners
(heater category B23).
The heaters are suitable for use with a working pressure
of up to 8 bar. The cylindrical tank is made from sheet
steel containing a number of vertically placed flue tubes.
For protection against corrosion, the inside of the tank is
glass lined. The tank is also fitted with a number of
magnesium anodes for extra protection against
corrosion. A thick PU insulating layer between the tank
and the steel jacket helps to reduce heat loss.
When the heater is completely filled with water, it is
under continuous mains water pressure. When hot water
is drained from the heater, cold water immediately
enters the heater. For effective heat transfer, flue baffles
have been included in the flue tubes. Heat from the flue
gases is transferred to the water by means of radiation
and convection.
1.2 Technical safety equipment
1.2.1 Control box
The temperature control for the water heater is situated in
the control box (see figure 1), which is fitted to the heater
cover.
The water heater has been fitted with three thermostats:
- a control thermostat,
- a high-limit thermostat
- an overheating cut-out.
The control thermostat is the thermostat by means of
which the desired water temperature is set.
The high-limit thermostat acts as a safeguard against
excessive water temperatures at the top of the heater,
if as a result from a certain draining pattern (frequently
draining of small quantities), stratification of the water
temperatures in the heater occur. If both the control
thermostat and the high-limit thermostat fail
the overheating cut-out will automatically shut down
the water heater.
The overheating cut-out interrupts the current supply
to the burner, as a result of which the gas valves of the
gas block will close.
Figure 1: Control box COF
Figure 1: Control box COF
The overheating cut-out interrupts the current supply
to the burner, as a result of which the gas valves of
the gas block will close.
The control thermostat can be set between 40°C
and 80°C by means of the temperature control knob.
The high-limit thermostat switches at 84°C, the
overheating cut-out at 95°C.
The control thermostat’s sensor is located in the
lower immersion well in the control box; the sensors
of the high-limit thermostat and overheating cut-out
are located in the immersion well at the top of the
heater.
If the overheating cut-out is activated, it must be
manually reset. This is only possible when the
temperature at the top of the heater has dropped
below 89°C.
The control box is fitted with an ‘ON/OFF’ switch
(‘I/0’). In position ‘I’ the ventilator burner is controlled
on the basis of the heat demand from the control
thermostat. In position ‘0’ the heater is switched off.