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Initially the fan will run at a low speed (approximately 500 RPM) and then ramp up to the preset fan speed for
heating (refer to Table 7, Item 1).
•
Wait for the heater to operate for at least 1 minute and then measure the gas inlet pressure. While all other gas
appliances are operating at full capacity, the gas pressure must not, at any time, fall below:
• 1.1 kPa for NG models
If the pressure cannot be maintained above these measurements, then the incoming gas supply is inadequate.
Check the supply pipe for blockages, and check the gas pipe and meter sizing.
•
Switch off the heater, remove the manometer, and tighten the captive screw at the inlet gas pressure test point.
THE GAS VALVE SHOULD NOT BE ADJUSTED UNDER ANY CIRCUMSTANCES.
IMPORTANT
If everything seems to be functioning correctly up to this point, please continue on with the commissioning
procedure. KUN4 & KUN5 heaters will automatically reattempt ignition a few times should the ignition process be
unsuccessful, so give the heater time to rectify itself. It may simply be purging any remaining air through the gas
components. In any event, the heater will cease ignition re-attempts and lock out with an error code if there is any
problem that it can't rectify itself. If the heater does lock out with an error code, please make a note of the code
then reset the heater (see the Owner's manual).
9.3.2 Heater Fan Speed and Temperature Settings
The next part of the procedure requires you to set the heating settings to suit the installation. The settings are
critical to provide adequate and efficient heating for the installation.
•
Ensure that the wall control is still set much higher than the actual room temperature.
•
Set the fan speed to suit the installation, adjusting it to provide sufficient but not excessive airflow. Remember,
typically the fan speed is less for floor outlet systems than for ceiling outlet systems. With down-vent type ceiling
diffusers, airflow in main living areas should be able to be felt down near floor level.
•
For new system installations (not changeovers) you should not need to adjust the thermistor set temperature.
This setting should only be adjusted if the system is NOT achieving the following temperature rise; ceiling
outlets: 25º to 30º C and floor outlets: 35º to 40º C. This temperature rise is measured from the closest outlet
to the heater, minus the return air intake temperature. (i.e. with a return air intake temperature of 20º C the
temperature at the closest floor outlet to the heater should not register more than 60º C). This temperature rise
should never exceed 45º C.
•
For changeovers, commission the new unit to best replicate the original units performance.
If the desired temperature rise is too low or too high the following adjustments may be required.
Increase the room set temperature to maximum to turn the heater on and watch the thermistor temperature until
it stabilises.
Ideally, the fan speed setting should 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 only decrease (modulate) the gas rate once the supply air temperature has been
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 temperature level.
So, with a floor outlet system, which usually requires a low fan speed, you may have to increase the thermistor
set temperature to achieve a 35º to 40º C rise and avoid modulation. If the heater still reaches the thermistor set
temperature or the rise is greater than 40º C, increase the fan speed.
With a ceiling outlet system, which usually requires a higher fan speed, it is unlikely the heater will reach the
thermistor set temperature and modulate. However, if it does, increase the thermistor set temperature and/or
increase the fan speed to achieve a 25º to 30º C rise and avoid modulation. If the temperature rise is above 40º C
investigate the reason:
•
Small number of outlets on the system.
•
Restrictive or poorly balanced ductwork.
•
Oversized heater for the installation.
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