DIY Water Heater Repair Guide: How to Fix Electric and Gas Water Heaters
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DIY Water Heater Repair Guide: How to Fix Electric and Gas Water Heaters

You rise early. It is a cold December morning but you are comfortable in your humble abode heated to a toasty 70 degrees. If you are anything like me, the first thing you do is start a pot of coffee, then head for your morning shower. That is when you discover that there is not any hot water flowing from the taps or the shower head. What to do? Well the thing to not do is panic. Most hot water heater problems are easy to fix.

There are two types of hot water heaters used in residences - electric and gas fired. Before we get into the troubleshooting procedures applicable to each, I want to spend a moment or two talking about the tools and test equipment that you will need to troubleshoot and service your hot water heater. Many of my readers may be tired of hearing me say this by now but it is a point worth repeating - when buying tools or test instruments, but the highest quality tools or instruments that your budget will allow. Good tools will not only last you a lifetime and are a joy to use, they are also safer to use.

The first test instrument that you will need is a good Digital Multimeter to measure voltage, current, resistance, and continuity. If you are on a tight budget, you can get a digital meter for under $20 from Radio Shack and it will do the job but if you can afford one, I recommend getting a Beckman, Fluke, or some other professional quality meter. Besides the meter, you will need:

  1. a flat blade screwdriver
  2. a Philips head screwdriver
  3. needle nose pliers
  4. side cutting pliers
  5. I/4” or 3/8” drive socket set and
  6. A pair of 10” Channel-Lock pliers.
  7. Plumbers Teflon tape

Troubleshooting an electric water heater

1. If you have an electric hot water heater, the first things you need to check are the fuses or circuit breaker. Most residential hot water heaters operate on 220-volts so there will be a double pole circuit breaker or two fuses controlling the circuit. Most likely, the CB (circuit Breaker) or the fuses will be rated At 30 a (Amperes). If your home still has a fuse panel, the fuses will probably be glass, Edison Based, screw-in fused. As a rule, you can tell when one of these fuse have blown by the telltale black spot on the glass but if there is any doubt check their continuity with your new meter. Set the meter on its lowest Ohms scale and place one probe on the screw shell and the other probe on the brass button. If the fuse is good, it will read zero ohms. Actually, you may get a reading from 0.0 to3.0 Ohms because a good meter will read its own internal fuse resistance. If the fuse is blown, you will get an O.C. (open circuit) or an infinite resistance reading. You did read the instruction manual that came with your new meter-right? If not, read it now before using your meter for your own safety and for the safety of your meter.

2. If the CB has tripped, reset it or replace the blown fuse(s) and wait to see if the water gets hot. If the CB or fuse(s) were ok, or after resetting the CB or replacing the fuse(s), you still have no hot water, we need to start our troubleshooting at the water heater itself.

3. Remove the cover on the front of the water heater. Beneath this cover, you will find a circuit diagram that show the electrical connections for the upper and lower thermostats, the upper and lower heating elements, and their respective current overload protectors. If you had warm water but not hot water, your problem most likely is with the upper thermostat, overload, or heating element. If you get hot water for a very brief time, the problem most likely is with the lower thermostat, overload, or heating element.

4. Setting you meter on a 250-volt AC or higher AC scale, check for voltage at each of the element by placing a probe on each of the screws where the wires attach. You should get a nominal 220 - 240 volts AC reading across each of the elements. If there is a zero reading on either or both elements, check for a voltage reading on the line side of the thermostat(s), if there is voltage on the line side of the thermostat(s) check the respective thermostats for the proper setting. Also, try resetting the thermostats overload by pressing in on the red button. Recheck for voltage.

5.If there was voltage across each of the elements when you checked the first, or if there still is not any voltage across the elements after readjusting and resetting the thermostats and their overloads, it is time to turn the power off at the circuit breaker or fuse panel.

6. If there was voltage across the elements when you checked, but no hot water, you need to check for a burned out element or elements. To do this, making sure that the power is really off by taking another voltage reading; remove one wire from each of the elements. To check a hot water heater element, set your meter on the 1 K (K stands for Kilo or 1,000) Ohms scale and place a probe on each of the screws. No continuity through the element means that the element is burned out and you need to replace it.

7. To replace a burned out element, turn off the cold water coming into the tank, drain the tank and then remove the old element. Most elements screw in but some may be held in with four screws or bolts. Take the old element along with the wattage data off the hot water heater’s spec plate to the home center for a replacement.

8. If there was voltage on the line side of a thermostat but not on the element, it controlled, then you have a bad thermostat or its overload protection device. Mark the wires so you can replace them in the proper places, remove the thermostat and replace it with a new one.

9.Turn the power back on and if everything went according to plan, you will have hot water after a half hour or so.

Troubleshooting a gas fired hot water heater

1. The first thing to check is the thermostat setting. Gas hot water heaters, unlike their electric cousins, only heat from the bottom and only have one thermostat.

2. Is the pilot light lit? If not, following the instruction for your heater, attempt to relight it. If it lights but goes out again, the problem is most likely a bad thermocouple. The thermocouple controls the opening and closing of the pilot light valve. Replacing the old one is a relatively simple procedure but make sure you note the physical position of the old one before removing it and heading to the home center for a replacement.

3. If the pilot light is lit but the burner does not light when you turn the thermostat all the way up the problem could be a fouled burner or a bad valve. Before condemning the valve, shut off the gas, remove the burner and pilot light assembly, and clean it toughly. After cleaning, blow some compressed air through it. If the air passes freely through it, reinstall it.

4. Turn on the gas and relight the pilot light. If the burner still does not flame to life, the gas valve is defective and you need to replace it.

5. Replacing the valve is a simple procedure but make sure that you check all the fittings for gas leaks after you finish. A solution of soap and water works just fine as a leak detector. If there are no bubbles bubbling up, there are no leaks.

I will cover when you should replace a hot water heater and how to do it in another article.

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Comments (4)
Chicago Furnace Repair » DIY water heater repair guide: how to fix electric and gas water heaters

[...] link [...]

This is very good information to know. Thank you very much.

You are very welcome LadyM.

Heating Repair

This is very helpful information. Thanks for sharing.