What Causes Fish Tank Heaters To Fail?

As the bimetallic strip bends toward and away from contact, an electric arc is created that eventually will pit and corrode the points. To prevent this, a condenser should be attached across the circuit, above the thermostat. Should the condenser short out, the current would bypass the thermostat, which would then not be operating. The heater, with no control on it, would continue to heat.

Better thermostats today have a fuse in series with the condenser. Should the condenser short out, the fuse will blow. The thermostat and heater, however, continue to function without the condenser and fuse assembly until they can be replaced.

Another cause of trouble is water in the thermostat tube. In this situation the heater continues to function but without any shut off control.
Occasionally, although not frequently, the silver points that are used today melt and fuse together. This prevents normal opening of the thermostat and is usually a possibility when the power source is direct current (D.C.). Cleaning the contact points occasionally with very fine sand paper will help correct this trouble.

The most common causes of heaters failing to heat is usually current failure, or improper contacts in the wall plugs. Occasionally the thermostat plug becomes disconnected without anyone realizing it. All that is necessary to restore its function, of course, is to plug it back in.Even more infrequent is a burned out heating oil, or a broken connection within the circuit itself.

Heaters fail to heat only a fraction of the number of times they overheat. It is hoped that the number of times the latter occurs will be lessened considerably by the use of proper fuses.

A magnetic snap action thermostat is a thermostat that operates on the same principle as the ordinary thermostat, but with the following addition. There is a small magnet at the end of the bimetal strip and a corresponding plate on the mounting. As the bending bimetal strip comes close, the magnetic attraction asserts itself, closing the contacts sharply with a snap—hence the name. This rapid closing eliminates the problem of the arc and the necessity for the installation of a radio condenser.

A Guide To Aquarium Hood, Heater, and Pilot Lights

A reflector is usually only 3-1 or 4 inches wide and covers only the front few inches of the aquarium. A hood covers the entire tank. Usually, although not always, the sockets in a hood is set in the center.

The hood, which requires more material and labor to make, is more expensive. It offers the advantage of protecting the tank from dirt and dust and preventing excessive evaporation.

A glass cover and a strip reflector are sufficient for covering and lighting your aquarium.

Commercial full hood is constructed of a light-weight unbreakable plastic. The front piece is hinged so that you can easily feed your fish.

A fish is physiologically suited to living within a certain temperature range. By exercising proper care one can safely bring it to the limit of that range—a limit which varies somewhat with individuals and their condition, as well as with species.

An electrically operated heater equipped with a suitable thermostatic control is the most inexpensive and trouble-free method.

A control unit employing a bimetallic strip which automatically responds to temperature changes and turns the heater on and off.

A pilot light is a small light which is hooked into the heater to indicate whether the current is on or off. It remains lighted as long as current is flowing through the heater. The pilot light may be installed inside the tube which holds a combination heater and thermostat; it may be in a separate tube with either the heater or the thermostat; or it may be the plug-in type that fits.

You should make it a habit to check all thermostats regular highly. If, in checking, you find that the tank temperature is higher than the thermostat setting and that nevertheless the pilot is still on, you have a strong indication that the thermostat has failed to shut off. It is entirely possible for the tank temperature to be higher than the thermostat striking the tank. However, when such external factors are causing the temperature rise, the thermostat connection should be open and the pilot light off.

It is also a sign of trouble when the temperature is lower than normal and the pilot light fails to indicate heating. This condition should be checked and corrected. Cheap heater-thermostat combinations can chill or cook your fishes.

Using Thermometers in Your Aquarium

By encasing the heater and thermostat in separate tubes, one is enabled to place the heater in one corner and the thermostat in another. This is supposed to insure a more even distribution of heat, since the heat must travel through the entire tank to reach the thermostat. In theory it is all right, but in actual practice it has hardly proven necessary. Water circulation itself distributes the heat readily enough.

Any type of thermometer can be used in a fish tank that is partitioned into several sections. Judge the wattage required by the capacity of the tank. Place the thermostat and heater in the center section or in adjoining sections. The end sections may be a few degrees cooler than the center, but the difference will not be appreciable.

To make sure that your thermometer is giving the correct reading, place your thermometer alternately in warm and cold water to see if it rises and falls properly. Wash the thermometer carefully, and place the bulb edge under your tongue. An accurate thermometer will read close to 98.6° F., which is body temperature. A variance of 2° or 3° is not important, however, since aquarium temperatures are not that critical.

Check a new thermometer for breaks or spaces in the mercury or “spirit” column. These often occur because of jostling during transit. To eliminate such breaks, place the thermometer on a piece of ice until the indicator has retracted completely into the bulb. When the indicator fluid is allowed to warm up, the column should be continuous.

Tips on Choosing an Aquarium Heater

A submergible heater is usually placed flat along the bottom of the tank. The theory is that as the warm water rises it will cause a mild circulation within the tank, insuring a more even distribution of heat. Whether this particularly benefits the fish in most home aquaria is doubtful. However, with the heat source at the surface of a tall tank, and with no aeration or filtration, you will note a considerable disparity in temperature between the upper and lower strata of water. Whether the difference, except in an extreme case, is enough to discomfort the fishes is problematical. In nature, fishes swim with no apparent signs of discomfort between the sun-warmed surface and the cooler depths. They appear quite capable of adjusting to this type of change with no noticeable signs of stress.

By encasing the heater and thermostat in separate tubes, one is enabled to place the heater in one corner and the thermostat in another. This is supposed to insure a more even distribution of heat, since the heat must travel through the entire tank to reach the thermostat. In theory it is all right, but in actual practice it has hardly proven necessary. Water circulation itself distributes the heat readily enough.
For the advanced hobbyist who can afford it, the most practical method for heating all your fish tanks is a tank room. The temperature in the room can then be thermostatically controlled and heated by the use of a commercial space heater, either gas or electric. A small fan can be used to assure an even distribution of heat within the room.

If this method is impractical, you have your choice of either of two methods, or a combination of both. The simplest way is to get a combination heater and thermostat for each tank. There are a number of low-cost combination units on the market which will give very satisfactory service.

An alternative method is to get a high-capacity individual thermostat. This is placed in the smallest tank of the series to be controlled with the single setup. Heaters with wattages proportionate to the size of the tanks they are put into are connected in series with the thermostat. For the average home, allow 5 watts to the gallon. For a 5-gallon tank, use 25 watts; a 10-gallon tank, 50 watts, and so on.

For example: a hobbyist with four tanks, a 5-gallon, a 10-gallon, and two 20-gallon tanks would use the following: a 25-watt heater in the 5-gallon tank, a 50-wa heater in the 10-gallon, and a 100-watt in each of the 20’s The thermostat to which all the heaters are coupled placed in the smallest tank. Why? Because the smaller the amount of water in a tank, the more subject it is to fluctuation. Should the thermostat be placed in the largest tank, the smallest one might show a drop of as much as 5 to 6 degrees before the temperature of the large one would drop sufficiently to activate the thermostat.

Aquarium Heaters for your Tropical Fish Tank

Heaters are no more expensive than any other small electrical appliance. Remember, heaters are using up electricity only when they are heating. Thermostats do not use up any current; they only conduct it or cut it off.

The warmer you keep your tanks in relation to the room temperature; the more electricity will be required. If you are concerned about the cost of electricity, keep your tanks in the warmest part of the warmest room - but not near a radiator - and maintain your tanks at the lowest safe temperature of 72° to 73° F.

Incidentally, it costs no more to operate a large heater when a small heater in the same size tank. The larger heater will simply heat up that much faster and shut off that much sooner. Many people are under the misconception that a heater gives off only the temperature at which the thermostat is set while heating. This is not so. A heater, once it starts heating, gets as hot as the resistance wire will allow, and stays at that high temperature until the thermostat shuts it off. Then it loses all its heat to the water. A heater does not feel hot to the touch while it is heating, because it is rapidly exchanging its heat with the water. The same heater in air becomes too hot to touch within seconds.

A test light can be wired to a heater, provided you know how to make the hook-up. If the test light goes on when the thermostat and heater are plugged in, turn the temperature control down until the light just flickers off. If the light fails to go on, turn the temperature control higher. The point at which the light flickers on or off is where thermostat is set for room temperature. A thermometer in the room will tell you what the room temperature is. From there it is a simple matter to turn the thermostat up or down.

If the light goes on and fails to shut off when the thermostat contact is broken, it is usually evidence of the failure of a condenser, which should be removed. The heater should then function normally. A new condenser should be put on as soon as possible, rather than operating without it. The absence of a condenser puts a strain on the contact points.

If the test light fails to go on, check the male plug and the contact points first; then look for a break in the element, or a black spot, which indicates a burned area.

Occasionally the points become so coated with carbon that they fail to make proper contact, or constant arcing may build up a high spot, preventing the contact from breaking properly. Fine sandpaper used carefully will remove those spots and return the unit to proper operating.

Tropical Fish Tanks - What is an Aquarium Heater?

A heater is the apparatus which provides the actual heat as opposed to the thermostat, which is the automatic switch for controlling heat. The majority of heaters made today are fabricated of nichrome resistance wire, which is wound around a ceramic core. Some are of nichrome which is wound on an asbestos backing, and a few have the resistance element imbedded in the ceramic. The tube may or may not be filled with sand.

Heaters are divided into two groups: those which are attached directly to a thermostat, either in the same tube or an adjoining one and those called combination heating unit, thermostatic control, condenser and pilot light. For convenience these items may be housed in the same tube with an attached hanger, or they may be located in two different tubes with a clip joining them and a hanger.

At the present time there is only one combination heater and thermostat that can be completely submerged in water. Most of them are designed to hang vertically on the aquarium, partly in the water. I specify “in the water” because I have found that a good many people, unless told otherwise, hang such heaters on the outside of the tank.

The water level should be one to two inches below the lip of the tube (or tubes) to prevent water from entering I lie heater. Always read and follow the manufacturer’s instructions carefully.

The cover glass (or hood), if used, should be cut away above the heater and/or thermostat to prevent condensed water from dripping into it.

The combination unit may have a knob on the top to adjust the temperature regulator. This is called an “outside-control.” An “inside-control” unit has the mechanism attached to the rubber cork stopper. Removal of the stopper lifts the unit, allowing the adjusting screw to be reached. It is advisable to unplug the unit before is removed for adjustment.

A word of warning: never put a hot heater into the water; it will crack. Always disconnect a heater before removing it from the water.

The heaters which are made independent of a thermostat may be sealed for submersion or may be hung on the side of the tank. These and the other types may be sand-filled.

How Does an Aquarium Thermostat Operate?

Aquarium thermostats all utilize the same principle with variations only in quality, construction and design. The basic principle behind a thermostat is that metal, when heated, expands; and that different metals expand at different rates. Two flat strips of different metals are bonded together. When heated, the metals’ unequal coefficients of expansion result in a bending of the strip. One end of this bimetallic strip is fastened rigidly in place and one end of the circuit is fastened to it. The other end is free and rests against a screw in a metal plate to which the other end of the circuit is attached.

As the bimetallic strip warms up, it curls away from the screw against which it is resting, thus breaking the contact and the circuit: With the circuit broken, the heater stops heating. As the water surrounding the tube cools, the drop in temperature is transmitted to the bimetallic strip, which - being cooled - straightens out again and re-establishes contact and turns on the heater.

The screw against which the lower end of the thermostat rests is threaded and may be turned to increase or decrease the distance between the points of contact. This varies the extent to which the metal must bend in order to make or break the contact. The metal always expands and contracts the same distance at given temperatures. Once the proper spacing has been reached for the desired temperature setting, it is only necessary to leave the screw setting alone.

The closer the contact points, the more heat is required before the circuit opens. The farther apart, the colder it must get before the contacts come together. In order to raise the aquarium temperature the adjustment screw is turned so as to bring the points closer together, and to lower the temperature, the points should be separated.

All adjustments should be made gradually and checked frequently with a thermometer to avoid sudden extreme changes of temperature. Usually a quarter turn is sufficient to raise the temperature 3° to 5°.

Some of the more elaborate thermostats have adjustment knobs projecting above the top. They are connected Icy means of threads or movable plates to the contact points. However, the principle remains the same: varying the distance between the contact points determines the temperature at which the circuit will open and close.

Some aquarium thermostats are sensitive to as little as 1 1°. However, such extreme sensitivity is not necessary; usually + 3° is adequate for aquarium use. Some cheap thermostats are even less sensitive and less satisfactory.

Most thermostats arc made to operate at an adjustment between 60° and 110°. Should you try to set the thermostat temperature lower than 60′, the adjusting screw would be at too great a distance from the bimetallic strip, and contact could not be established. Conversely, should you attempt to set the thermostat for more than 110° the screw would be pressed so tightly against the thermostat that the strip could not curl far enough away ever to break contact and stop the flow of electricity.