A faulty water-heater control valve may prevent you from having hot water. Whether your water heater runs on gas or electricity, it needs a controller to cycle the heat on and off, or the water in the tank would either be stone cold or perpetually boiling. The controller for a gas heater is called a thermocouple, while the corresponding one for an electric heater is called a thermostat. When the controller wears out and no longer signals the heater to turn on, it isn't difficult to replace. Water heater malfunctions aren't always caused by worn temperature controlling devices, however. There are a number of other possibilities to consider. Check the breaker controlling the heater. If it has tripped, reset it and make sure it stays on. If it won't stay on and you can confirm the breaker isn't faulty, turn it all the way off and look for loose connections on the heater. Tighten any you find with a screwdriver. If you can't find any loose connections, either the thermostat or heater element may be faulty.

Locate the heater elements on the outside shell of the heater. There may be one located near the bottom of the heater, or two: one at the bottom and one at the top. They usually are hidden behind metal plates you can pry off with a screwdriver. Each element is connected to a thermostat located just above or below it. Press the red reset button on the top thermostat if the circuit breaker is on but the heater isn't working. fish tank filter too slowIf the button goes in and stays in, the thermostat should start working again. fish tank heater battery backupIf you can't push it in, or it won't stay in, replace the thermostat. fish tank heater top finYou also should replace the thermostat if you can't find another cause for a tripped breaker.

Turn off the breaker and disconnect the wires from the thermostat, keeping careful track of their connection points. Unsnap the thermostat from the body of the heater. Snap a new thermostat in place and reconnect the wires. If the heater has two thermostats, replace both of them. Turn the adjustment nut on the new thermostat to 120 degrees Fahrenheit, then turn the power back on. Put your ear next to the heater and listen for a fizzing sound, indicating the heater element is working. Replace the heater element if changing the thermostat has no effect. Turn off the power and drain the tank. Disconnect the wires from the element and unscrew it from the tank with a wrench. Screw in a new element, reconnect the wires, refill the tank and turn the power back on. Check your gas supply. If you have a propane tank, the tank may be empty. Be sure all the valves between the gas source and the heater are in the "on" position. Turn the gas valve all the way off, then turn it to pilot and hold it in while you light the pilot.

Depending on the heater model, you either light the pilot with a lighter or by repeatedly pressing a spring-loaded button next to the gas control that generates a piezoelectric spark. If you have the latter type of heater, visually verify there is a spark when you press the button. Clean the pilot supply tube if you can't get the pilot to start. Disconnect it with a wrench and blow compressed air through it. You may buy compressed air in an aerosol can for this purpose. Hold in the gas valve for about 60 seconds after the pilot starts, then release it. If the pilot goes out, try again; this time, holding it a little longer. If you can't get the pilot to stay on after a few tries, the thermocouple is faulty and should be replaced. Purchase a thermocouple that fits your model and install it by consulting the owner's manual. Replacing the thermocouple isn't difficult -- it is held on by only one or two screws -- but the locations of the screws and the optimum orientation of the thermocouple can vary from model to model.

Replace the gas valve if the heater still doesn't operate correctly. Since it involves breaking and resealing important gas connections, this is a job best left to a professional. Things You Will Need Screwdriver Thermostat Water-heater element Lighter Wrench Can of compressed air Thermocouple Tip Warning Photo Credits Jupiterimages/liquidlibrary/Getty Images Suggest a Correction FREE Delivery in the UK on orders over £20. 12 used & new from This item can be delivered to your selected dispatch location in . Interpet Deltatherm Aquarium Heater - 100 W Dispatched from and sold by Amazon.DetailsInterpet Easy Read Aquarium Thermometer ( FREE Delivery on orders over . Save 20% when you spend £30 on selected aquariums and accessories. Here's how (terms and conditions apply) Visit the Tropical aquarium heating system The heater recommended will maintain a temperature up to 26⁰C in a well heated home. If the aquarium is in a cold location or over 26⁰C is required select the next highest wattage.

Ensure you get the correct size Deltatherm Heater for your aquarium: The Deltatherm heater is designed for indoor aquarium use only. The electrical cord and the glass casing are both integral parts of the unit. If these are damaged in any way, the whole unit must be replaced. Check the power supply requirements on the heater label before connecting to the mains. Disconnect any underwater appliances contained within the aquarium before carrying out any maintenance. It is recommended that for safety all aquarium equipment is connected through an earth leakage circuit breaker (RCD). Before installing your Deltatherm ensure the glass tube is not damaged Check that the voltage of the mains supply corresponds to the voltage shown on the heater. Fix the suckers to the heater and adjust the temperature control dial to the desired setting. The heater is set to 24⁰ the ideal temperature for most tropical fish. However, if you require a higher or lower setting this is easily achieved by adjusting the dial on the top of the heater.

You should never adjust the temperature by more than +/-2⁰C at one time if there are fish in the aquarium. Install the Deltatherm in the aquarium by attaching the suckers to the glass ensuring that the heater is completely submerged. The heater must not be in contact with the glass or any other material in the aquarium. It must not be buried or partly covered by the aquarium substrate. If removing the heater from the aquarium, turn it off and allow at least 15 minutes before taking it out of the water. This allows it to cool down. The heater should be placed diagonally in the aquarium rather than vertically or horizontally. Incorrect placement may result in inaccurate temperature control as the thermostat is at the top of the heater. When the heater is in operation, the red light will indicate when the heating is taking place. Once the desired temperature has been reached, the integral thermostat will turn the heater off. This can clearly be seen as the red light will turn off.

Pet TypeFish and Aquatic Compatible DevicesCompatible with 45 - 90 Litre Aquariums Specific UsesSuitable for Fresh Water^Suitable for Salt Water 2,247 in Pet Supplies (See top 100) in Pet Supplies > Fish & Aquatic Pets > Aquariums & Accessories > Aquarium Heaters Date First Available16 July 2010 Interpet Deltatherm heaters are made with high quality components and provides required heating for your aquarium. Featuring top view temperature control, Deltatherm heaters are easy to adjust with temperature control from 16-34 degrees Celsius (61-93 degrees Fahrenheit). An on/off light indicates when the heater is operating. The heater recommended for the correct aquarium size will maintain a temperature up to 26 degrees Celsius in a well heated home. If the aquarium is in a cold location or over 26 degrees Celsius, select the other high wattage heater.This double insulated heater is safe and fully submersible, and can easily be installed by attaching the suckers to the glass.

The heater must be fully submerged and should be placed diagonally in the aquarium, rather than vertically or horizontally. Incorrect placement may result in inaccurate temperature control as the thermostat is at the top of the heater.Note: Ensure you choose the correct wattage Deltatherm heater for your aquarium:25 W is suitable for 4-30 L aquariums or aquariums up to 46 cm in length50 W is suitable for 23-45 L aquariums or aquariums up to 46 cm in length100 W is suitable for 45-90 L aquariums or aquariums up to 61 cm in length150 W is suitable for 68-135 L aquariums or aquariums up to 76 cm in length200 W is suitable for 90-180 L aquariums or aquariums up to 91 cm in length300 W is suitable for 135-270 L aquariums or aquariums up to 122 cm in length This product is for animal use only and should under no circumstances be administered to any animal other than that which is stated for. See all Product description Best Selling • Lowest Price 4.0w Aquarium Adjustable Air Pump Twin Valve HD-603 with Accessories