Rinnai 46
Ducted Gas Heater IM
c.
Do not adjust the thermistor set temperature unless the system is NOT achieving the following temperature rises:
• Ceiling outlets: 25º to 30ºC, and
• Floor outlets: 35º to 40ºC.
These temperatures are calculated by measuring the temperature at the closest outlet to the heater,
then subtracting the return air intake temperature. The difference should never exceed 45ºC.
For example
, noting the maximum allowable floor outlet temperature rise is 40°C, with a return air intake
temperature of 20ºC, the closest floor outlet temperature rise must not exceed 60ºC.
Adjustments
If the desired temperature rise is too low or too high the following adjustments may be required.
a.
Increase the room temperature setting to maximum to turn the heater on, then wait until the thermistor temperature
until it stabilises.
Ideally, the fan speed setting will be sufficient for the heater to operate at full capacity when all of the
outlets are open and balanced as described previously. The gas rate will then be maintained at the
maximum rate during the initial heating cycle and will decrease (modulate) only when the supply air
temperature is reached on subsequent heating cycles. This will initially allow the heater to increase the
house temperature at a faster rate to maintain the customer’s desired room temperature.
b.
With a
floor outlet system
(which usually requires a low fan speed), as required adjust the thermistor set
temperature to achieve a 35º to 40ºC rise and avoid modulation. If the heater still reaches the thermistor set
temperature or the rise is greater than 40ºC, increase the fan speed.
c.
With a
ceiling outlet system
(which usually requires a higher fan speed), if the heater reaches the thermistor
set temperature and modulates (this is unlikely), increase the thermistor set temperature and/or increase the fan
speed to achieve a 25º to 30ºC rise and avoid modulation.
If the temperature rise is above 40ºC, investigate the reason. It may be due to the following:
• A low number of outlets on the system.
• Restrictive or poorly balanced ductwork.
• An oversized heater for the installation.
• Inadequate fan speed.
• Inadequate thermistor set point.
Adaptive Zoning
Systems that have zone damper motors operated from a networker (adaptive zoning) require the zone minimum
fan speed to be set to suit the duct system. This ensures optimum performance from the adaptive zoning functions
within the heater. Set the zone minimum fan speed as follows:
a.
Using the networker, close all but one zone.
• If the system does not have a common zone, select and turn on only the zone key that operates
the least number of outlets (ensure this zone does not have less than the minimum number of
outlets required for the heater size).
• If the system has a common zone then all zone keys can be turned off.
b.
Adjust the EHTG fan speed setting (H01 ID03) to provide the required amount of air through the remaining open
outlets, ensuring that the temperature rise does not exceed 45ºC. Do not adjust the thermistor set temperature
while setting up the EHTG fan speed.
