The Appliance's Heating Cycle - A.O. Smith GWV - 120 Installation And Service Manual

gis
Legend
1. Hot water outlet
2. Insulation layer
3. Electrical connector block
4. Aluminium strips
5. ThermoControl (electronic
controller)
6. Flue gas discharge
7. Jacket cover plate
8. Air supply
9. Gas controls
10. Fan
2.3 The appliance's
heating cycle
Instruction manual GWV
11. Drain valve
12. Pressure switch
13. Air distributor plate
14. Flame probe
15. Hot surface igniter/flame
probe connector
16. Injectors
17. Glow plug
18. Bar burners
19. Combustion chamber
20. Heat exchanger
21. Inspection glass
In this appliance, the cold water enters the bottom of the storage tank through
the cold water inlet (24). The system pump (22) ensures that the water flows into
the appliance. The water is heated by the heat exchanger (20) in the
combustion chamber (19).
The heated water leaves the appliance via the return valve (26) and then, once
heated, flows into the storage tank (32).
To prevent condensation from forming in the appliance, the water that flows into
it via the supply line (25) must not be colder than 30
the very first time, or after it has been shut down for a long period.
Once the appliance and the storage tank are completely filled with water, they
are permanently pressurised by the water pipes. As hot water is drawn from the
storage tank, cold water is immediately added.
Water flows into the appliance through the ribbed elements (20). This ribbing
ensures better heat transfer. There are aluminium strips (4) on these elements.
These slow down the flue gases, improving the yield. The air required for
combustion is forcibly delivered by the fan (10).
The appliance has two identical gas controls (9) of which one will be open
(partial load) or both (full load). Thanks to the modulated supply of gas and air
(8), the optimum gas/air mixture is always achieved. The flue gases are
removed via the flue gas outlet pipe (6). The air supply and flue gas outlet are
always in parallel.
The insulation layer (2) prevents heat loss. To protect against corrosion, the
storage tank is enamelled on the inside. Anodes provide extra protection
against corrosion.
For maintenance, the storage tank has an aperture for inspection and cleaning.
The appliance uses sensor T
set (T ) has been reached. When T
set
(T ), the electronic controller registers a "heat demand". This will switch the
set
system pump on and the flow-through switch (29) will give a signal to the
controller. The appliance will ignite and the water will be heated. Once T
above T , the demand for heat has been met and the electronic control stops
set
the heating cycle; the system pump (22) keeps running
pump running-on time") for a little while.
The electronic controller assumes a certain margin when ending a heat
demand. We refer to this margin as the hysteresis
hysteresis").
22. System pump:
23. Temperature sensor T
24. Cold water inlet
25. Inlet line
26. Return line
27. Return valve
28. Supply valve
29. Flow-through switch:
30. Temperature sensor T
31. Temperature sensor T
32. Storage tank
33. P-valve
o
C. This will only be the case
(23) to determine whether the water temperature
3
is lower than the set water temperature
3
(12.2 "Setting the
3
1
2
gets
3
(12.12 "Setting the
15