A.O. Smith SGE - 40, Installation, User And Service Manual

Page: 18 / 119

Instruction manual SGE 15
gis
• Hysteresis
The moment that T
1
falls below (T
set
- T
solar diff
- hysteresis), the controller
registers such a heat demand that the gas burner and the solar heating
system jointly heat the water. The solar heating system is only employed
when the temperature measured by S
1
is a certain (adjustable) value grater
than that of S
2
.
• T
solar diff
When T
net
exceeds (T
set
- T
solar diff
), the gas burner is shut off and the water
is heated by the solar heating system alone. When T
1
rises above T
set
(provided that T
set
= T
solar limit
), the solar heating system is switched off. The
value of T
solar diff
is adjustable (12.10.4 "Setting the solar difference").
• T
solar limit
Preset (12.10.3 "Setting the solar limit") water temperature at which heating
via the solar heating system is stopped.
Graphical representation of operating cycle
Note
T
1
can rise above T
set
. However, this is only possible if T
solar limit
is increased
via the service menu.
2.4 Protection for the
water heater
2.4.1 Introduction
The controller monitors the water temperature, helps ensure the safe use of the
solar heating system, and ensures safe combustion. This takes place using:
•
the Water heater water temperature protection
• the Gas control valve
• the Fan
• the Pressure switch
• the Flame probe
2.4.2 Water heater water temperature protection
The controller (4) controls and monitors the safety of the water heater by means
of sensors T
1
and T
2
. S
2
is also used for protection of the water heater.
However, this is primarily intended for control of the solar heating
system (2.6 "Protection for the solar heating system").
The table explains the functioning of these temperature sensors.
Legend
A = Gas burner on
B = Gas burner off
T
1
:
• = No heat demand, so water
is not heated
• = Water heated via solar
heating system
• = Water heated via solar
heating system and gas burner
t = time
T = Temperature
45
o
C = Minimum tap water
temperature
T
solar limit
T
set
Solar diff.
Hys.
T
min = 45 C