Debugging a water heater

About a month ago, Debra and I started noticing that hot water pressure was lower than normal.  At first I thought it was my imagination, but it steadily got worse.  My first hypothesis was sediment in the tank, which fit with what others online will say.  So I hooked up a hose, drained the tank, flushed it a bit, and then refilled it.  Still low pressure.

My next thought was to verify that the problem was with the water heater and not somewhere else in the pipes.  So I connected the cold water input directly to the hot water output, removing the water heater completely from the system.  The resulting high pressure from the hot water side confirmed that the problem was indeed with the water heater.

It took a little looking around, but I finally found the problem:  the 3″ brass nipple that connects the water heater with the hot water pipes in the house was clogged with sediment.  It was so clogged that I’m surprised any water was coming out.  I’m a little embarrassed that it took me so long to check that out.  But since I had so much time in the project and it looked like I wouldn’t have to replace the water heater, I decided to refurbish it a bit.

Electric heating elements for my water heater are about $10 each.  Those and two replacement nipples, plus gaskets for the input and output, and the special tool for removing the elements set me back a total of about $25.  It was a pretty big time investment, though.  Draining the water heater takes a long time.  A few things to keep in mind (some of which I learned from experience):

  • Before you drain your electric water heater or do any other work on on it, turn off the circuit breaker.
  • If you don’t open a hot water faucet somewhere in the house, or open the T&P valve on the water heater, it’ll take almost forever to drain.  (I knew this one before, but thought I’d throw it in because a friend of mine ran into this problem.)
  • Do not try to remove the elements with pliers or a pipe wrench.  Pay the $8 for the element removal tool.
  • If the screwdriver you’re using as a handle for the element removal tool starts to bend, stop.  It’s likely you’ll break the screwdriver before the element comes out.  Find a longer and stiffer piece of metal to use as a handle.  Or dispense with the handle and wrap a pipe wrench around the element removal tool.  Works wonders.  (I was smart enough to stop when I saw the screwdriver shaft flexing.)
  • Be absolutely sure the water is below the level of the element before you try to remove it.  You will not believe how fast water can come pouring out of that hole, and you will not be able to screw the element back in with the water pouring out.  And the water is hot. (Yes, I’m guilty of this one.)
  • You can clean corrosion from heating elements by soaking them in vinegar.  If you decide to re-use your elements after cleaning and inspecting them, be sure to replace the rubber gasket.  Otherwise they will almost surely leak and you’ll have to drain the water heater again to remove and replace them.  The way I figure it, if I’m going to the trouble of draining the water heater, I’ll just replace the elements.

One other thing.  Electric water heaters contain a sacrificial anode rod that helps prevent corrosion of the tank.  The idea is that the anode, being a more active metal than what the tank is made of, will corrode first.  As long as there’s a more active metal than the tank’s metal, the tank won’t corrode (or will do so much more slowly).  Water heater warrantees are typically based on how long the manufacturer thinks the anode rod will last.  You can replace the anode rod.  I haven’t tried it yet.

Most manufacturers recommend that you drain a few quarts from your water heater every three months (some say every month).  That will prevent sediment buildup in your tank.  They recommend draining the tank and inspecting the elements annually.  They also recommend an annual inspection of the anode rod.

By the way, elements that are covered in corrosion don’t work very well at all.  They require a lot more electricity to generate the same amount of heat as new elements.  Especially if you have very hard water, you’re probably money ahead if you replace the elements annually.  The money you save in electricity will more than offset the cost of the new elements, and your water will heat much faster.

Most people (myself included, usually) never think about their water heater until they have no hot water or they notice a leak.  That’s too bad, because with a little periodic maintenance a water heater can last 15 or 20 years rather than the five or so years that they typically last these days.  Considering the cost of a replacement water heater and installation (sometimes over $1,000) and the aggravation of a leaking heater or no hot water, you’re much better off with the periodic maintenance.

If you’re having a problem with your water heater, a good place to look for a solution is  Whereas it’s true that they’re trying to sell you things, they have very good information about common problems and simple solutions.  Oh, and in case you’re interested in how this stuff works: How Water Heaters Work.