Chillers and Their Maintenance
This article will teach you how a chiller works and give you tips and maintenance measures that will help extend the life of your chiller.
IMPORTANCE OF SIZING A CHILLER CORRECTLY
Aquarium chillers are primarily designed for tropical fish applications where water temperatures are around 70 degrees F. Trout need water temperatures of 52 – 55 degrees F. Most applications – home and offices – have well controlled room temperatures between 68 and 72 degrees F.
In school applications, the room temperatures run much higher – many times as high as 80 – 85 degrees F. In most instances the room temperature is not within the control of the teacher.
Both of these conditions mean the chiller has to work a lot harder than it was designed to work. While a 1/6 HP chiller may be good for a 55 gallon tank of tropical fish in a home, it is not good for trout in a classroom. NJ uses a 1/3 HP chiller so that the chiller does not have to work as hard to cool the water.
Finally, the atmosphere in a classroom is dusty and dirty. As the dust gets into the chiller it quickly becomes less efficient. The less efficient it is, the harder it has to work. This is why you need to have your chiller at least 24 inches off the floor with a 10 inch clearance on all sides.
HOW THE CHILLER WORKS (Refer to Sketch)
An aquarium chiller operates on the same principles as a refrigerator or air conditioner. There is a temperature controller and temperature sensor on all chillers which allow you to set the optimum temperature for your water to be at – for TIC application 52 – 55 degrees F. (The controllers are designed to be accurate to plus or minus 2 degrees F.)
Chillers function using four main parts – a compressor, a heat exchanger, a radiator and a fan. The operation is based on the principles of gas expansion and contraction.
A refrigeration gas, in this case R-134, is compressed which results in a loss of temperature. This compressed gas (seriously cold at about minus 300 degrees F), flows through the heat exchanger where it picks up heat from the aquarium water being pumped through the heat exchanger.
The gas carries the heat back to the compressor but on the way encounters an expansion valve which allows the pressure to drop suddenly. As the temperature drops, the gas gives up heat to a radiator, which dispels the heat into the surrounding air with the aid of a fan. Hence the water returning to the aquarium will be at a lower temperature than when it entered the chiller.
The gas ultimately continues back to the compressor. The refrigeration system is sealed; the cycle is continuous.
Unfortunately the fan sucks air from the room in order to blow air on the radiator. Dust and dirt come in with the air and are blown at the radiator. The fins on the radiator get covered and clogged. Their ability to dissipate heat is reduced. The chiller’s efficiency gets severely compromised as a result of the dust and dirt.
AVOIDING EARLY FAILURES/ANNUAL MAINTENANCE
The chiller must be positioned well off the floor – like on a milk crate – and have at least ten inches of free air space all around it.
Every day someone should compare the temperature shown on the controller with the temperature of a good thermometer placed in the tank.
The Aqua Chill, Oceanic, and Prime chillers have easily removable front panels behind which are mesh filters. During the school year, these filters should be vacuumed or brushed weekly. (Also, see foam filter instructions below.)
Every chiller should be thoroughly cleaned at the end of the year. A compressor with a blow off nozzle is required. Most schools are equipped with a small compressor. The annual maintenance does not require a HVAC person. Anyone who can handle a screwdriver can do it.
On the Prime, Aqua Chill and Oceanic units:
• Remove the front panel.
• Carefully disconnect the connector(s) going to the temperature controller.
• Remove the screws holding the housing to the baseplate,
• Carefully lift the housing off the chiller. (Sometimes the handles get hung up on the heat exchanger)
• Blow 90 – 100 PSI air into the radiator from all sides – front, back and top – dislodging dust, dirt and other debris. Do it from all directions, several times, until you are sure the fins are clean.
• Re-install the housing and front panel. Make sure the mesh filter is completely clean before re-installation.
• Finally, tape a piece of 1/4 inch foam air conditioner filter material, cut to fit, over the air intake openings. 1/4 inch polyeurethane foam, Frost King part number F1524 is available at most hardware stores. This additional filter will minimize the dust intake without seriously compromising the chiller’s efficiency.
On the Polar Bear:
• Remove the (8) screws holding the housing to the base plate.
• Carefully lift the housing off, being mindful of the wires connecting the chiller and temperature controller.
• Blow 90 – 100 PSI air into the radiator from all sides – front, back and top – dislodging dust, dirt and other debris. Do it from several times from all directions until you are sure the fins are clean.
• Re-install the housing on the baseplate.
• Finally tape a piece of 1/4 inch foam air conditioner filter material, cut to fit, over the air intake openings.
Here are specific maintenance instructions for 5 different brands of chillers. Use the one for your chiller.