A.O. Smith SGS - 100, Installation & Service Manual

Page: 15 / 110

Instruction manual SGS 15
gis
fluid (S
1
) is a certain (adjustable) value higher than the temperature
measured at the appliance (sensor S
2
). As soon as (T
net
= T
set
= T
solar limit
),
heating via the solar heating system is stopped. There is one exception to
this rule, and that is when T
solar limit
is set to a higher value than T
set
.
• Hysteresis
The moment T
net
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 exclusively by the solar heating system. When T
net
rises above
T
set
(provided
Tset
= T
solar limit
), the solar heating system switches off. The
value of T
solar diff
is adjustable (12.8.5 "Setting the solar difference") .
• T
solar limit
Preset (12.8.4 "Setting the solar limit temperature") water temperature at
which heating via the solar heating system is stopped.
Graphical representation of heating cycle
Note
T
net
can rise above T
set
,. However, this is only possible if T
solar limit
is
increased via the service menu.
Note
T
solar limit
can be lower than T
set
; this will mean that T
net
can never be equal
to T
set
.
2.4 Protection for the
appliance
2.4.1 Introduction
The electronic controller monitors the water temperature, helps ensure the safe
use of the solar heating system, and ensures safe combustion. This takes place
using:
•
the Appliance water temperature protection
• the Gas valve
• the Fan
• the Pressure switch
• the Flame probe
Legend
A = Gas burner on
B = Gas burner off
T
net
:
• = no heat demand, so water
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