OPERATING INSTRUCTIONS
HCV & HCVR Evaporative Cooling & Gas Heating
GENERAL OPERATION
1.
Ensure that all fuses on switchboard are in position.
2.
Ensure isolating switch for unit situated inside the heater section is in “ON” position.
3.
Set room thermostat to 21°C. This may be varied later if desired.
4.
The limit air thermostat will have been set during commissioning to give the desired comfort air off
temperature.
5.
Heat – unit operates and discharge dampers close to predetermined position to give design
temperature rises across unit or design L/sec air flow. Provided entering air temperature is below
duct thermostat setting, a gas control valve will vary the gas flame to maintain a controlled air off
temperature.
6.
Should the burner fail to operate and the red lockout light comes on, wait five minutes after
observing red light to ensure unit is venting and then press and release reset button. Unit should
relight and operate.
7.
When selector is turned “OFF” the fan may continue to run for up to five minutes to allow for cooling
down of the heat exchanger.
8.
Vent / Set selector switch to “High”. Fan motor only will operate. Heating section is de-energised.
9.
Set selector switch to “Low”. Dampers will close to same position as for heating and fan will operate
at reduced air volume. Heating section is de-energised.
10.
Cool – Unit operates on “High” or “Low” air output (damper opening as in high and low vent). Water
pump and fan operate. Heating section is de-energised.
11.
To shut down gas burners completely, close main stop cock at unit and turnoff isolating switch in the
heater section of the unit.
HCVR RETURN AIR MODELS
The HCVR Return Air Models are designed to allow full fresh air on cooling as per standard HCV, but then
allow economical return air heating during the heating mode. This is achieved by motorized dampers
automatically closing off the cooling fresh air section and opening a motorised return air heat damper at
the heating section of unit. Dampers can also be set proportionally to allow some fresh air during heating.
Standard control on Return Air Models is on/off gas control operated to a standard on/off room thermostat.
Optional electric Modulation is available to modulate burner operation in conjunction with a compatible 0-
10 volt Modulating room thermostat. Leaving air tempering is not required on Return Air models due to the
recirculated room air temperature.
IMPORTANT: If heater will not operate after carrying out instructions as detained above,
contact the installer or Aira for further advice.
During normal operation in cooling mode it is important that the water bleed-off is operating and is not
shut off or blocked. This bleed-off will prevent an accumulation of salts and solids in the unit. Bleed off also
ensures a constant supply of fresh water into the cooler. A Dump valve is also recommended to ensure no
water remains within cooler when unit not in use. Aira coolers have a very small water sump ensuring little
water is wasted in a dumping cycle.
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