Rinnai ENERGYSAVER RHFE-308FTR Service Manual page 18

6. Filter Indicator
When the air filter becomes covered in dust and the temperature inside the appliance rises, the Filter
Indicator will glow.
7. Fuzzy Logic
a. The Purpose of Auto Comfort [Fuzzy Logic]
The main aim of the Auto Comfort function is to heat a room by controlling the flow of the warm air coming
from the heater. This increases heating efficiency as well as improving control over the flow of warm air
being discharged by the appliance.
In order to achieve comfortable heating, it is preferable to avoid cold drafts or draughts from the appliance.
Also, for increased efficiency it is important to reduce overheating in the room and concentrate heating in
the area where people are most often situated.
Fuzzy Logic is used in order to achieve the following improved heating pattern.
Standard Control Fuzzy Control
'Room temperature' and 'the time elapsed since the start of combustion' are the basis for fuzzy logic. Th
means of control is the speed of the convection fan and modulation of gas combustion.
b. Fuzzy Logic Summarised
In the case of a conventional fan heater, the convection fan operates normally from the time of ignition, and
a cold draught may accompany the flow of air from the appliance. To solve this problem, fuzzy logic
controls the speed of the convection fan after taking into consideration the room temperature at the time of
ignition. For example, in the case of the room temperature being low, the fan is made to rotate at a low
speed, raising the discharge air temperature. As the room temperature rises, the speed of the convection
fan is gradually increased. In this way it is possible to ensure a comfortable volume of warmed air whilst
decreasing the possibility of cold draughts immediately after ignition.
The fan speed increases proportionally as time passes and the room gradually heats up. This improves the
warm air distribution, assisting in a reduction of stratification throughout the room and resulting in more
effective heating conditions. The PCB then continually monitors the room temperature, and adjusts the fan
speed according to the conditions at the time.
8. Clock and Timer Setting and Operation
Refer to "Appendix" on pa ge59 of this manual.
9. Intelligent Timer [Pre Heat]
This function enables the room to be heated to the pre-set temperature prior to the time programmed in the
On Timer. See Intelligent Timer [Pre-heat]" on pa ge14 for more information.
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