Saturday, September 19, 2015

Troubleshooting and Repair of a Standard Electric Water Heater


No Hot Water

"No Hot Water"

"Replacing A Heating Element"
It may take several hours for a newly installed electric water heater to reach normal operating temperature. If you don't have hot water after two hours (water not even warm), first check to make sure the water heater is getting electrical power. Not getting power is a common reason new water heaters don't work.
"Temperature Adjustment"

Checking for Electrical Power

You can check for power with a simple "circuit tester," but for a more complete diagnosis of electrical problems, you'll need a meter that measures voltage.
To check for power, turn the circuit breaker marked "water heater" off (or remove fuses). Remove the water heater's upper access panel. Carefully remove the insulation and plastic cover. Identify the power supply wires. Usually, these connect to the top two screws of the upper thermostat. Turn the circuit breaker back on and check for voltage on the top two screws of the upper thermostat.
The label on the water heater indicates what voltage the water heater requires. Most residential units are 220/240 volts (but some are 110/120 volts). Verify your water heater is getting the correct voltage. If it is not getting the required voltage, there are probably issues with your home's electrical system. A qualified electrician may be needed to fix your electrical problem. Turn the circuit breaker off, replace the plastic cover, insulation and access panel.
Testing Whirlpool Electric Water Heater Thermostat for Power with Voltmeter
Testing Thermostat for Power with Voltmeter
If the unit is powered with the correct voltage, and still does not produce any hot water, the upper heating element has probably burned out. A water heater must be completely full of water before electric power is applied or the upper heating element will burn out (this is called Dry Fire). The Installation Instructions require that a hot water faucet be opened and the hot water allowed to run full for at least three minutes before turning the power on. This is to make sure all of the air has been removed from the tank, and the tank is completely full of water. If the upper element has burned out, it can be replaced. Replacement heating elements are inexpensive and widely available. After the heating element has been replaced, make sure the tank is completely full of water before turning the power back on.
"Water Leaks"

Some Hot Water, but Not Enough (New Installation)

If a new water heater produces some hot water, but not as much as you're used to or not as much as you need, the thermostats may need adjusting. The Installation Manual has temperature adjustment instructions for your unit as well as important safety information about scalding. Water heater manufacturers recommend a temperature setting of no higher than 120ºF. Higher temperatures increase the risk of scalding injuries. Read and follow the temperature adjustment instructions and safety notices in the Installation Manual that came with your new water heater. Remember, higher temperatures (above 120ºF) can cause serious injuries.
Another possibility is that the water heater is not getting the correct voltage (see Checking for Electrical Power above). It is also possible that the water heater is too small or that your usage has increased.
"Water Drips"

Water Leaks

With a new water heater, most leaks are caused by leaking connections at the hot water outlet or cold water inlet. Occasionally, leaks can be found coming from a fitting (such as around the Temperature and Pressure Relief Valve) or around one of the heating elements. Leaking fittings can often be tightened or repaired. It is extremely rare for a new tank to leak.
"Electric Thermal Expansion Tank"

Water Drips

If drips are noticed coming from the discharge pipe of the Temperature and Pressure Relief Valve, the home's water pressure may be too high or a thermal expansion tank may be needed.
Note - If large quantities of hot water are coming from the discharge pipe, turn electrical power off and consult a qualified technician. Do not cap or plug the discharge pipe.

Water Pressure

Check your home's water pressure with a gauge. The recommended water pressure is 50 to 60 PSIG. If the pressure is higher than that, install a Pressure Regulating Valve (or adjust your existing pressure regulating valve if you have one). For water pressure issues, consult your local water utility or a qualified plumber. Most plumbing codes require a Pressure Regulating Valve if the water pressure is above 80 PSIG.

Thermal Expansion Tank

When water is heated, it expands. In older homes, the expanded water pushed back into the water main. Today, most homes have backflow prevention valves which stop the water in your home from reentering the water supply. These valves can be inside water softeners, pressure regulating valves or the water meter itself. Backflow prevention valves (also known as "check valves") prevent the expanded water from reentering the water main. Since the expanded water now has nowhere to go, the water pressure in the house's pipes can increase dramatically, often to the point where the Temperature and Pressure Relief Valve discharge pipe drips. A thermal expansion tank has an internal air bladder which can absorb the expanded water, protecting plumbing, appliances and the water heater. For these reasons, most homes now need a thermal expansion tank (and a properly adjusted pressure regulating valve). Not having a thermal expansion tank is the most common reason for a dripping discharge pipe.
WARNING! Do Not Cap or Plug the Temperature and Pressure Relief Valve Discharge Pipe. Explosion Hazard.

Wednesday, September 2, 2015

Electric motors are relatively simple mechanical devices, but rewinding the coils on a DC motor is a precise task that should only be undertaken by those who with experience in mechanical or electrical repair. A mistake or poorly-performed rewind job will result in a motor that doesn’t work. At that point, your only options are to buy a new motor or to take it to a professional shop for repair. Given the variety of motors and types of windings, this can only be a general article on rewinding. If you don’t understand the terminology, you shouldn’t be rewinding a motor; once you start removing the original coils, there’s no going back.
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Steps

  1. Rewind an Electric Motor Step 1.jpg
    1
    Clean your work surface to make sure it’s free of dirt and dust.
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  2. Rewind an Electric Motor Step 2.jpg
    2
    Remove the motor housing to reveal the armature, stator, and the windings.
  3. Rewind an Electric Motor Step 3.jpg
    3
    Document the present configuration by taking notes or photographs. You may even wish to videotape your deconstruction so that you can precisely recreate the original winding pattern and connections.
  4. Rewind an Electric Motor Step 4.jpg
    4
    Take the wire from the tabs on the brush pads. Bend the tabs gently (and as little as possible) and completely remove the wire from the tabs before cutting the coils of the wind.
  5. Rewind an Electric Motor Step 5.jpg
    5
    Cut the coils in the wind free from the armature and/or stator. The easiest place to cut is at the tops of the coils at the top of the armature and/or stator posts. Count the number of winds in each coil so that you can rebuild the motor to its original configuration.
  6. Rewind an Electric Motor Step 6.jpg
    6
    Check the insulation that lines the actual steel laminate areas of the stator before you rewind an electric motor. If it’s in good shape, you can put it back in place before beginning your rewind. You can replace burned or damaged insulation with similar material or insulating tape.
  7. Rewind an Electric Motor Step 7.jpg
    7
    Rewind the armature and/or stator using the same gauge and type of magnet wire that was on the original motor. If you’re more experienced, you may wish to upgrade your wire’s quality, substituting a nylon-and-polyurethane-coated wire for the original enamel-coated wire, for instance.
  8. Rewind an Electric Motor Step 8.jpg
    8
    Recreate the exact winding pattern and number of coils around each winding. Take great care to make each coil tight and precise for the best performance.
    • When beginning your first winding, leave the end of the first winding free but long enough to reach the first tab. The last winding will attach to the same point.
    • Crimp all the other windings down as you work to hold the wire in place. You do the winding with one long wire, so don’t cut anything as you go.
    • Before you crimp the wire down behind the tabs, use a sharp knife or sandpaper to remove the insulation from the wire at the point where it makes contact with the tab. Make sure you only remove as much insulation as is necessary to create good contact.
  9. Rewind an Electric Motor Step 9.jpg
    9
    Connect the end of the last winding and the loose wire you left in the first winding to the tab where you began.
  10. Rewind an Electric Motor Step 10.jpg
    10
    Check to make sure that none of the wires connecting to the tabs are touching.
  11. Rewind an Electric Motor Step 11.jpg
    11
    Reassemble the motor housing.
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