REFCO LAC Extreme - Manual

HVAC/R
Service Products
REFCO Manufacturing Ltd. Telefon +41 41 919 72 82
Industriestrasse 11 Telefax +41 41 919 72 83
CH-6285 Hitzkirch (Switzerland) [email protected] www.refco.ch
INSTALLATION OPERATION
AND MAINTENANCE GUIDE
LAC EXTREME
Cooling only, Heat pump and Low Temperature Cut-Off Models
The HPC controllers modulate the condenser fan speed to maintain a cons-
tant condensing pressure in heat pumps, air conditioners and refrigeration
plant. This results in higher efficiency, shorter compressor running times,
and more-stable conditions on the evaporator. Over-condensing is elimina-
ted, and freeze-up of air conditioner indoor units is prevented.
COOLING OPERATION
Controlling air movement over the condenser by varying the fan speed
maintains a constant condensing temperature, therefore a constant head
pressure. The condenser temperature is measured midway through the cir-
cuit, where the hot gas is condensing. As the condenser temperature rises
and falls, the fan speed automatically increases and slows down to maintain
the head pressure at the set point level. When first powered in the fan runs
at full speed for 10 seconds before controlling to temperature. Note: low
temperature cut-off models need to measure within range before start up.
As temperatures drop the fan speed will fall to its minimum speed. Low
temperatures cut-off models switch off the fan if the temperature continues
to drop: a temperature rise will initiate a 2 second full speed re-start to get
the fan moving. Dual circuit systems are accommodated by the 2-sensor
model where controller responds to the higher of the two temperatures.
Fig. 1 Application Example