Water Heater Repair, Maintenance and Troubleshooting Q&A

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Dear NH,

Is it okay to my drain water heater and shut off gas to it if the house is going to vacant for 4-5 months? I am always afraid of water leaks.



Most people just turn the water off unless they are concerned with freezing.  Then you should drain down the entire system.  However, there is a potential problem with draining down the water heater for a long period of time that you might want to consider... rust!

Water heaters are made from steel, which can rust.  Even though modern heaters are lined with a non-corrosive glass-like ceramic.  However, this is not 100% effective because it is impossible to coat 100% of the tank and the material is prone to cracking during transportation and installation.

The rust is stopped by the use of a sacrificial anode, a long rod of magnesium, aluminum or zinc that is put into the top of the tank and extends a few feet into the water.  These materials dissolve away more quickly than steel through a electrochemical reaction (like a common car battery) and the steel is not affected as long as the anode lasts.

Here is the problem.  Draining the water stops the sparing action of the anode and exposes the steel to the water vapor left in the closed tank.  This can cause increased rust and may decrease the life of the tank.

Though it is not unheard of for leaks to occur in the owner's absence, they are minimized if you turn off the water to the whole house when you leave so there is no pressure in the system.  Of course, if a visual inspection of your water heater shows evidence of corrosion or leaks anywhere, you should have it checked BEFORE you hit the road!

Dear NH,

What is the proper way to test the heating element(s) in a water heater? I have heard they can be tested with the power either on or off? Is one way better than the other?



To directly test the element, the electricity should be off.  The heating element in an electric water heater works the same as the heating elements in ovens, toasters and the stove top. The elements heat up because they highly resist the flow of electricity. This "resistance" can be likened to friction, causing an increase in heat.

If the element is broken... meaning the electricity does not have a compete path to follow through the element... the element will not heat up.  Technically speaking, a broken element has "infinite resistance" to the flow of electricity and zero continuity.

Resistance and continuity can easily be checked with an inexpensive multimeter or battery powered continuity tester, available at most hardware stores or Radio Shack.  Turn off the electricity, disconnect either wire from the element's terminals and test across the terminals for continuity.  If there is no "beep", or no movement of the pointer on an analog multimeter, you can be sure that the element is defective and needs replacing.

You can test across the terminals of the element for voltage (with the electricity on and all wires connected), but the reading you get may or may not indicate a problem with the element.  An "off" or broken circuit breaker, a defective thermostat or even a loose wire may be the culprit, not the element itself.

Dear NH,

My situation is this: My electric water heater is not working. I get 240V at the heating element and also at the thermostat. What test can I perform on the heating element or the thermostat to determine which is faulty without removing them?


If you are getting electricity at the heating elements, then the elements are most likely burnt out. To test them, first turn off the electricity. Now you must isolate them by disconnecting them from their thermostats. Set your voltmeter to continuity test, or if that's not an option, set it to test resistance. If you test infinite resistance, or if the continuity test reads open circuit, then the element is bad. This is the same test you would use on a kitchen stove burner or oven element.

If they do prove to be inoperable, chances are you have been heating your water with one heating element for a while, since it would be unlikely that both would fail simultaneously. You should notice a dramatic increase in the speed and efficiency of your water heater after the repair.

If the terms continuity or voltmeter or open circuit don't mean anything to you, perhaps you should pick up a really great book on appliance repair.

Dear NH,

What do you think about tankless water heaters? I love the idea. When you turn on your hot water knob, the unit heats water as it enters your house. There is no tank to collect sediment, or constantly heat water you may not use.  Do you recommend them?  Have they been on the market long enough to be proven reliable?  My local Home Depot doesn't carry them. Who would I call, a plumber? Can you recommend any particular brands?

MD from Venice, FL

I think tankless water heaters are great but have some limitations that make them unsuitable for some users.

They were originally designed to be used in situations where a tank is undesirable and/or inefficient, such as a building with very minimal hot water demand. They are more commonly used overseas than in the US, probably because we are not as attuned to the economy and space saving attributes of these water heaters.

Since the water is heated as needed, there can be tremendous savings over tank units that by design keep the water hot 24/7. And there are other more conventional alternatives that may be as good or better. For example, the energy (and dollar) savings are diminished or even nonexistent if the alternative is a hot water system integrated into your gas or oil heating system. If the price of gas or oil is especially low in your area, a standalone tank unit using these fuels may be competitive if you take the extra effort to superinsulate the tank (via wrapping the tank with insulation) and keep the temperature down to under 120 degrees.

There is a trade-off you must understand before making a purchase decision on a tankless water heater. Tank-type water heaters can supply enough hot water to run multiple hot water appliances or showers at the same time, provided you buy a unit with sufficient tank size for your projected usage and the size of your household. Tankless heaters, on the other hand, have large drop offs in water temperature as the flow through them increases. This is because of the way they work. The elements in a tankless water heater can heat water up to an adjustable maximum temperature, based on an assumption of the water flow through it and the temperature of the water coming into it. As the incoming water temperature drops, so does the outgoing temperature of the heated water. Of course, you can install more than one tankless water heater in your home, to serve different "zones", to solve volume problems.

One the positive side, with a tankless unit you never run out of hot water. We all know the frustration of having the stinking hot water tank run out of heated water during that critical final rinse! You know... the one that really counts!

There are a number of companies online that sell these units. I cannot give a product recommendation, but I suggest that you get the written manufacturer's performance stats on a number of them before making a purchase decision. Another possible source of information would be a hardcore plumbing supply house, rather than a home store.

Dear NH,

What are the signals that a water heater would give that it is time to replace it. I built the house in the spring of 1985 and I still have the original water heater. This water heater has never been drained, shortly after it was installed the pressure valve leaked and was replaced, and I have been the only person living in the house up until Sept 1997 when my mother moved in with me.

For about the past 3 months I have noticed that the pressure valve has been leaking a little water, so when my brother came up for Xmas I asked him to change it because it appeared it was slowly getting worse. Both the pressure valve and the galvanized metal nipple showed a considerable amount of junk in them. I replaced both.

The only noise I have ever heard from the water heater is a rumbling when a faucet is turned on while the water heater is heating water.

BO in the Mojave Desert, CA


There is no tried and true way to know precisely when a water heater needs replacement. Obviously, a leak in the body of the heater requires immediate replacement. If there is a major malfunction, such as complete or partial loss of hot water supply, leakage around plumbing fittings, or the appearance of excessive corrosion on the heater body itself or at the heater's plumbing connections, AND the unit is over 8 years old, replacement may be preferable over repair (if a repair is possible, that is). I would leave this up to your budget and repair skills.

All the active parts and most of the plumbing parts… the heating elements, thermostat, anode rod, and the various valves… are designed to be replaceable. The main obstacle to disassembly is corrosion. A water heater corrodes more quickly than other plumbing fixtures because of the constant higher than room temperature it operates at, and the fact that sometimes the water heater acts as an electric ground, accelerating this corrosive process. Corrosion makes replacing any parts chancy, since the replacement may leak, necessitating the replacement of the entire heater.

So, like a conscientious Boy Scout, be prepared for the possibility of replacement even when the repair seems simple and straightforward. So it goes with plumbing!

In your specific case, with a water heater over 13 years old, repairs are probably not cost effective, since the life expectancy of a water heater is only 8 to 12 years. As they age, they become less efficient. This is true for all heaters, but more for electric types. Modern water heaters have better insulation and are more efficient "out of the box", so you may notice dramatic savings in fuel and/or electric costs by replacing it.

Dear NH,

I have a 40 gallon gas water heater. It is leaking at the base of each pipe going into the top of water heater. Is this a problem with the water heater when there is no leaking from the bottom?

C.M. from Lees Summit, MO

Dear C.M.

From your description it appears that you are getting leakage around the threads for the in-and-out water supply lines into the heater. When this occurs shortly after installation, it is an installation snafu. However, most leaks that occur after years of service are caused by chemical corrosion that has "dissolved" the threaded fittings. The corrosion is softer than the original metal allowing water to seep around the threads. Eventually, the fitting will begin to spray water. Therefore, even though you are not in emergency mode as yet, this problem must be taken care of A.S.A.P. The leakage may or may not be correctable, depending on the severity of the corrosion. Be prepared… the only repair option may be replacing the water heater.

Most water heater connections are not designed to be taken apart without cutting the pipes so a rescue operation will involve pipe cutting, disassembly and examination of the fittings to determine whether or not they can be saved. It may take nothing more than wrapping the threads of the threaded connector with a few layers of Teflon pipe wrap and reassembling it. Then again, if the corrosion has deeply pitted the fixed connector on the water tank, it may leak when reassembled no matter what you do! Worst case… disassembly might even damage the tank!

Since reattachment of the pipes will be pretty much the same for an old or a new water heater, you should give some serious thought to replacing it now. If the heater is ten or more years old, you have reached the end of its useful life and would probably be better off getting a new one. Old water heaters, even if they don't leak, tend to be less energy efficient. Even if you have been diligent in draining the heater annually to remove energy-stealing sediment from the tank, buildup of hard scale in the tank still robs you hard-earned money 24 hours a day!

Over a few years a new heater will probably pay for itself in energy savings... with the added benefit of you NOT having to clean up the soggy mess of a major water heater failure.

Dear NH,

My pilot light won't stay lit on my hot water tank and I've been told it is the thermocouple. I am very handy with most things around the house and would like to try and install this myself. It is only a $6.00 part and yet they want $40 to install it! Could you tell me the steps to installing a thermocouple. I have the bottom cover off the tank and am familiar with where the pilot light is. Could you please walk me through this?


Dear K,

This is one of the less dangerous gas appliance repairs since you do not have to disconnect any gas lines. As a disclaimer, I am hesitant to encourage inexperienced people to do their own gas appliance installations and repairs because of the danger involved. Plumbers have special safety procedures and tools to minimize the risk of explosion or fire.

First things first… turn off the gas at the main shutoff. If the heater has been running let it cool for at least 20 minutes.

The thermocouple is located near the pilot light. It is designed as a safety feature that automatically turns off the gas supply should the pilot go out. It works by generating a small amount of electricity when heated, keeping the gas valve open. The gas control valve is essentially a "dead man switch"... if the electricity stops flowing, the switch opens and the valve closes.

I cannot tell you the exact location or appearance of the thermocouple, but if you purchase an exact replacement you should be able to visibly find it, since it will be in plain view behind the inspection plate.

There is a tube attached to the thermocouple that must be disconnected from the gas control valve. Once you unscrew the nut holding the tube in place, you will be able to slide the thermocouple out of the bracket on which it rests. If there is another fastening method, it should be obvious by visual inspection of the old thermocouple.

The new thermocouple is installed by the reverse procedure... slide it in place and then attach the thermocouple tube to the gas control valve.

If the new thermocouple does not attach exactly like the old one, stop the repair and call or visit your parts supplier to be sure that you have the correct part!

Hope this is helpful... and be careful!

Dear NH,

I watched the installation of a "Hot water Circulation Pump" on a TV handyman show. I would like to procure one or two, but can't find a source. Would you have any info on this device? The device is a small pump installed under the sink of the bathroom furthest from the hot water heater. It is connected to an electrical switch mounted under the counter. It comes with flex hoses for easy connection into the water lines. When the switch is pushed the pump circulates the hot water back to the cold water side for a few minutes. This eliminates having to waste water for several minutes until it is hot enough to use.

DB from Winter Park, FL


I heard of this type of recirculation system at least 20 years ago, though not as a kit, in the days of the (shudder) energy crisis! Its availability was proportional to the creativity of the plumber...in other words, an improvisational job. I have wanted to try this project myself, as I have a similar problem to yours. Having a very adequate well system in my own home, I never felt pressured to institute extensive conservation measures (even if the project seemed like fun). However, I know everyone is not as fortunate as I am in this regard.
Let's walk through the concept, and see how you could build one yourself with commonly available parts, and then discuss the "kit" .

First, the pump. The choice of the pump is critical. In a long ranch-style home with one floor, the "head"... the height the water has to be raised by the pump... is not very critical. However, a large multi-floor dwelling will need a pump that can push the water from water source to the second (or third) floor. This rise can be over 16 feet. The pump also must be able to handle very hot water. Not all pumps are designed to handle water over 120 degrees. So the pump of choice would probably be a solar hot water system pump. These run from $100 to $200.

The real trick in this project is to lace your return piping back to the cold water inlet side of the hot water heater. This will require some ingenuity and probably some minor demolition!
The connection is not extremely difficult but does require some plumbing skills and electrical skills. The pump (outlet side) would be installed on a T-fitting on the cold water line to the hot water heater, regardless of the type (tank or furnace-fed). One pipe would have to be run from the faucet side of the hot water shutoff all the way to the inlet side of the pump, forming a loop. The pump acts as a one-way check valve so cold water can't be drawn up to the hot faucet.

As far as the electrical wiring goes, these pumps draw around one amp at 115 volts, meaning you should be able to connect it to an existing circuit in the bathroom. I would put a switch near the pump as a shutoff. The pump documentation should help you determine the type of wiring necessary for the switch you locate under the bathroom sink. Also, I would use a standard electrical wall-type switch in an electrical box under the sink. You will get better service life than a push-type switch. Also, you will be able to tell if the pump is on or off at a glance! If you wanted to get really exotic, and also protect yourself from having the pump run too long... which would be a real waste of hot water... you could use a timer switch instead.

There is a company on the web that sells this system in kit form. It is called the Metlund Hot Water D'MAND System at http://www.gothotwater.com/ .  There are advantages to this kit over a pure D-I-Y job. They supply a flexible copper tubing to speed installation and temperature sensitive relays that automatically turn off the pump when the hot water reaches the faucet. This system can also be used at intermediate faucets on the line (such as in the kitchen or other bathrooms) by installing a separate switch and relay under each sink. It has a low voltage switch system, making the additional wiring easier because of the smaller wire size used, along with reduced shock hazard at the remote bathrooms... a good idea if you have kids.

They have a great schematic of the layout of these systems at the web site, that is worth looking at if only out of curiosity!

Dear NH,

I own a condo that is about 11 years old and my water heater is located upstairs and I'm worried that it may burst and do some serious damage to my place. I have had a few neighbors have their water heaters burst and had to replace them. Would it be wise to replace mine?


Dear JH,

The average life expectancy of a water heater is 8 to 12 years, though some units last significantly longer. If I were you, I would begin shopping for
a new one before you pay for it twice! I must also stress the importance of having a drainage pan installed under the new hot water heater. The pan functions as a catch basin for any leakage. Many contractors install water heaters in attic spaces in condos, especially in smaller units where living space is minimal and basements are nonexistent. Unfortunately, they often do not install the pan, so any leakage can be damaging or even catastrophic for the homeowner.

The pan has a drain built into it, which can be run into your plumbing drain system or even to the outside of your home. This would be determined by the code requirements for your area.

Dear NH,

Our house is 4 years old. Recently we have been having problems with our hot water heater. Sometimes the water is not hot. The pilot light is on, the temperature is set correctly. Is it possible we need to replace our hot water heater already? Someone told me there may be sediment in the bottom of it. How do you take care of this without getting into major expenses. Looking forward to your answer. Thank you

KD from a distant star


There is an article at the site on draining sediment out of water heaters at https://www.naturalhandyman.com/iip/infwaterheater/infwaterheater.html. Draining the tank in a gas water heater will improve the efficiency of the heater if you have a significant accumulation of sediment. The layer of sediment acts like insulation, slowing down regeneration… the speed at which your water heats up.

It should be noted that sediment does not have a significant effect on the efficiency of electric water heaters because the heating elements are located above the bottom of the tank.

If draining the sediment does not improve the function of your water heater, you should bring in a service person to examine it. I do not encourage do-it-yourselfers to experiment on gas appliances.

Dear NH,

I have a problem with the temperature of the water in my home. I have a hot water heating system, and my water is heated by the same furnace. I do not have a hot water tank. Instead, the water comes directly from the furnace. According to my oil burner company, I must keep the temperature of the water in the furnace above 140 degrees or my heating system will not work properly. This seems to be extremely hot and I am concerned that my little one (when he is old enough to reach the faucet) may burn himself. Should I insist he lower the furnace temperature?

PB from Scranton, PA


You are without-a-doubt correct to be concerned about your water temperature. Back in the good old days, it was not uncommon for water heaters to be set at 160 degrees, more than hot enough to cause immediate severe scalding burns! Nowadays, the standard setting for hot water is between 110 and 120 degrees.

However, I would advise against changing the water temperature of your furnace. Your furnace guy (or gal) is absolutely correct… lowering the temperature will radically change the built-in efficiency of your furnace and of your heating system as a whole.

Think about it… if you lower the temperature of the furnace, the temperature of the water circulating through your radiators will likewise be lowered. This will in turn increase the amount of time it will take for your home to be heated. All things being equal, it takes the same amount of oil to keep your home at a certain temperature regardless of how hot the water is. Therefore, your oil burner will have to cycle on and off more often to maintain this lower temperature because it will take longer for the temperature to rise. This will cause increased wear and tear on the furnace without any gain (or even a loss) in efficiency. The most inefficient moment in your furnace's operation is when it first starts up!

So instead of focusing on the furnace as the culprit, you can take measures to lower the faucet hot water temperature AFTER it leaves the furnace. This is done through the installation of a "mixing valve". A mixing valve is a simple thermostatically-controlled mechanism that mixes a little cold water with the hot water to lower the temperature. Mixing valves are adjustable to product the desired water temperature, but it is wise to use a thermometer to verify the temperature at the tap. Installation does require some plumbing skills such as pipe cutting and soldering, but the end result is worth it!

Dear NH,

I have a gas hot water heater and I am having a problem lighting the pilot light. For some reason the pilot does not stay lit when I turn the switch from "pilot" to "on".

CP from Plainfield, IL

Dear CP,

There is a safety device called a "thermocouple" in all gas furnaces and water heaters that utilize a pilot light. The thermocouple generates an electrical charge when heated, opening a valve which fuels the pilot flame. Should the pilot light go out, the thermocouple cools quickly and the pilot valve closes, preventing your home from filling with gas. The pilot position on your valve switch essentially overrides the thermocouple, allowing you to light the pilot.

There should be specific instructions for lighting the pilot light somewhere on the unit, but if not, here is the generic procedure. First, turn the manual gas control knob to "pilot". This position allows gas to flow to the pilot so you can light it. You will notice that the knob is spring loaded and turns off as soon as you release it. Once the pilot flame ignites, hold the knob in the pilot position for about 30 seconds so that the flame thoroughly heats the thermocouple. If the thermocouple is working properly, when you release the manual valve, the pilot will remain lit. Turn the knob to the "on" position so that gas can now flow to the main heating elements.

If this procedure fails, try holding the control knob open for up to a minute. If the pilot light still refuses to stay lit, you may need to either adjust the pilot light or replace the thermocouple. Both of these procedures are fairly easy, safe and do not require you to disconnect any gas lines.

Dear NH,

I have hear that there are products on the market that you can attach to your shower head to produce instant hot water. Can you tell me some manufacturers that make such a product and where they are located?



Instant hot water showers are available in many parts of the world. Actually, the concept is ingenious. Instead of the intricate plumbing and wasted water normally associated with showers, only one pipe... cold water... leads to the heating unit which is conveniently located right inside the shower enclosure. All adjustments for temperature are made at the heater which means instant and fairly consistent water temperature with no wasted water or electrical power!

They are not available worldwide, though, in part due to a low product demand in water-and-electrically-rich countries. For example, Alpha Electric, one of the links below, currently exports to Australia, Singapore, Thailand, Indonesia, Philippines, Vietnam, Fiji and United Arab Emirates. I could not find a company that exported to the Americas.

These units currently aren't engineered to meet the strict electrical codes in some countries. In the US, for example, electrical codes current don't allow for any household-current electrical devices within shower enclosures. To get these "instant showers" approved and the applicable electrical codes changed would undoubtedly be a costly political battle. Also, the voltage requirements may not be compatible with your own local power grid.

Here are three links to companies on the Web that offer these specialty heaters.



This sort of sensible alternative to central water heating will only occur when governments... spurred on by public opinion... start encouraging reasonable conservation through the use of these and other energy-saving devices.

Dear NH,

For the first time in 10 years my gas water heater is dripping a small amount of water out the relief valve discharge line onto the basement floor. Is this ok or do I need repairs?

KO from Newnan, GA

Dear KO,

Consider this little drip a polite warning sign that some repairs may be in order. If you have not noticed any other changes in the system... unusual increase in the temperature of the water, for example... then the valve is most likely the culprit.

The only way that a water heater can become dangerously overpressurized is if the thermostat(s) did not turn off the heating elements (in an electric unit) or gas flame (in a gas unit) at the temperature setting of the water heater. This can cause the water in the tank to overheat or even boil!. The valve is supposed to open under these extreme conditions to protect the damage to the tank or to your plumbing fixtures by relieving the pressure.

By your description, this does not sound like an emergency situation but it could eventually turn into one. I would suggest having the pressure relief valve replaced at your earliest convenience.