water heater

[dan myers]

I have hunter 28, (1989) which I bought 3 years ago. It has an Atwood 6 gal water heater that currently is not connected to the fresh water supply. The boat is on the hard for the season. Is there an easy way to see if the water heater is functional or can be tested if removed from the boat?

 

[Randall]

Testing Water Heater

Water heaters generally heat with two methods. Electrical, and by running a heater hose from the engine through the water heater. The engine heating part is pretty foolproof, but if you try to test the electric side without having water in the tank, you'll burn out the element. They're not expensive - maybe $10 at any hardware store. It should be easy to hook up water to your tank, fill it and test the electrical side. If it's not heating, try putting a new element in. By the way, it's probably not connected because when you winterize the heater you should bypass it so antifreeze so it isn't filled with antifreeze. I guess the stuff stinks if you heat it up, plus you'd need 6 gallons of antifreeze to winterize the thing.

 

[Gord May]

HWT testing

There are generally 4 (or 5) things that can go wrong with a boat’s Electric/Heat Exchanger HWT:- Leaks (Storage Tank or Heat Exchanger) - also check for leaks in the boats plumbing system (CWS & DHW).- Electrical Supply (check @ top of thermostat, and at element - don’t forget to replace insulation around ‘stat’)- Element or Thermostat * if 120VAC at top of ‘stat but not @ element - replace ‘stat* If 120VAC at element - replace element- Some HWT’s have a red reset button (Hi Temp Cutout) - push to reset- Sediment in tank The Owners’ Manual for the Raritan “1700" HWT, including a good (generic) Installation & Commissioning Instruction, & Trouble-Shooting Chart:http://www.raritaneng.com/pdf_files/water_heater/L206waterheaterv0502.pdfFrom Allcraft:http://www.allcraft.net/Troubleshooting%20Guide.htmA Resistance measurement should be the best test of an electrical Heating Element - but it’s not that simple.The resistivity of most materials changes with temperature. For most materials, resistance increases as the temperature of the material increases. Electric Heating (Resistance) Elements are designed to deliver rated wattage (at rated voltage) only when hot.and:If actual voltage differs from rated voltage, the power delivered will vary as the square of the voltage. Remember a 1-% increase in voltage is about a 2% increase in wattage, and vice-versa, a 1% reduction in voltage is about a 2% reduction in wattage. The resistance of the heating elements will be lower at room temperature than when hotSo:In as much as the electrical resistivity of all heating element alloys will increase somewhat with temperature (by differing percentages for differing alloys), the resistance as calculated by the Ohm’s Law formulae should be considered the "hot resistance" necessary for a given wattage in a device when it is at operating temperature. The resistance of heating elements will also increase with age, due to the reduction in cross section by oxidation, and also, due to elongation of the loops.Mathematically Ohm's law is written as:I = E/RWhich may be transposed to:Ohms = Volt / Amps -or- Watts/Amps Squaredie:Ohms = 120V / 10A = 12 OhmsOhms = 1500W / (10A x 10A) = 15 OhmsRemember - When using an Ohmmeter - the Electrical Power MUST BE OFF (No Voltage)!!! In practice:A normal resistance reading will be somewhere between infinity and zero. The exact reading differs by manufacturer and model. If the Ohmmeter indicates infinite resistance, or moves to the other extreme of the scale (zero resistance) - then the element is damaged and should be replaced.Sorry, I cannot give more accurate resistance figures, without detailed engineering data for specific heating elements. FWIWGord