Remember your home inspection report? Somewhere in there it says that the expected lifespan of a water heater is 10 years. That estimate is based on actual age-at-replacement numbers, and takes into account the ones that fail in 5 years, as well as the ones that last much longer. My guess is that a lot of water heaters get dumped before really necessary, for reasons that I will go into here. You can make it last a lot longer than 10 years!
The first question is, do you want to? A new 40-gallon gas-fired water heater costs $300-400, installed, or about $170 at Home Depot. How much maintenance are you willing to do to gain a few more years, at $40 per year? That question you have to answer for yourself.
The most basic maintenance of a water heater is flushing the tank once a year. This takes only a few minutes, and can add considerably to the lifespan. All you need is a garden hose and a pair of work gloves.
Mineral sediment from the water supply, (even the city water supply), gets deposited in the bottom of the tank. This layer acts as an insulator, so the metal tank bottom must get hotter than normal to hold the water at the set temperature. This extra heat is what shortens tank life. In extreme cases, the sediment can get so thick that the water at the very bottom turns to steam. When you hear a tank 'crackling', you are hearing this steam bubbling up through the sediment layers.
Flushing means that you connect one end of the garden hose to the drain valve on the tank, which should be at the bottom, possibly behind the cover. Take the other end of the hose to the laundry tub or sump pump. Don't try to do this using the floor drain; water will be coming out of that hose faster than most floor drains can accept it. If there is no handy place in the basement to run the hose to, lead it outside. Now, open the valve. All the way. The idea is to move water as fast as possible out through that drain, and hopefully it will take the sediment along for the ride. DON'T close the inlet valve on the cold water pipe over the tank. Close the drain after 2-4 minutes of running, and you are all done.
The possible hitch in all this? If the water heater temperature is set really hot, the hose will become too hot to handle, and you could get scalded. To avoid this, turn the thermostat on the water heater all the way down a few hours before you do the flush. This will allow the water in the tank to cool down. When you turn it back up after the flush, the water vapor from the gas flame will condense on the cold tank bottom, and may drip back onto the burner, making a hissing sound. Don't worry, this isn't a leak, and it will stop as soon as the water is warmed up again. (This condensation drip will also happen when you first fire up a new water heater.)
Ok, now that the sediment is flushed out, what else can you do? There is another maintenance step that I hesitate to recommend, because it often results in a minor repair. If you feel handy, go ahead and try this.
On the side or top of every water heater made since 1970, there is a pressure-temperature relief valve, often called a pop-off valve. It should have a small handle attached, and an extension tube that points to the floor, ending 4-6 inches above floor level. This valve is the reason we don't hear about water heaters blowing up any more. If the water gets hotter than 170 degrees, or the pressure goes over 150 psi, the pop-off valve pops off, discharging water or steam to release the extra energy. This can happen if the built-in thermostat fails, and the burner forgets to shut off. Ideally, someone should open that valve manually every year, to make sure it isn't stuck. All you have to do is put a bucket under the extension tube and pull up on that little handle. Watch your feet, the stuff coming out of that tube will be hot! Let it go for a second or two, then release the handle, allowing the valve to close itself. Here's the problem: If the unit is more than a couple of years old, and nobody has ever done this before, there could be mineral crust on the valve seat. The valve won't quite close all the way. Drip, drip, grrr... The next step is to turn off the gas, turn off the inlet valve, (the one on the cold water pipe just above the tank), and head for the hardware store for a new pop-off valve. Figure 10 bucks. Don't forget the teflon pipe wrap, 2 more bucks. Once back home you will have to drain the tank to a level below the valve, disassemble the extension tube, screw the old valve out and the new one in. Then re-open the inlet valve, open a faucet for a minute to get rid of the air, turn on the gas and relight the burner. Put the extension tube back on. Not a huge job, but it can be a pain if you're not ready for it. If you test the pop-off valve once a year or more, the minerals shouldn't be a problem, and the whole process gets easier.
Have you heard about the infamous "dip tube problem" in water heaters? You might. Here's the story. Every water heater needs an internal pipe to take incoming cold water from the fitting at the top of the tank and deliver it to the bottom where the flame is. This pipe is called a dip tube. Between August 1993 and December 1996, millions of water heaters were made with defective plastic dip tubes. The brand of water heater hardly matters; nearly all of the manufacturers were buying dip tubes from the same source, and they were nearly all bad. So what's the result? Several things can go wrong. As the tube falls apart, the water finds a shorter path from the inlet to the outlet side, and may not get hot, or even warm. This is causing people to replace water heaters when they really only need a new dip tube. Also, as the plastic pieces get into the water system, they can clog things up. On each kitchen and bathroom faucet, you have a small removable screen called a strainer. If you take it off and look into the screen, you may see white plastic flakes. These are the remains of the dip tube. Cleaning this kind of strainer is easy, but here's the catch: You also have strainers on the inlets for your clothes washer and dishwasher. They are much harder to get at, but if they get filled with dip tube remains, the appliance will malfunction. You can see why the lawsuits have started to fly - lots of good water heaters, dishwashers and clothes washers are getting landfilled because of a defective part that cost the water heater makers a few cents. How much more would they have had to spend to put in good ones?
So here's what you can do. First, check the faucet strainers for plastic chips. No chips, no worry. Next, flush the water heater as described above. If either process shows chips, or if you are having performance probems with hot water-related appliances, then it's time to replace the dip tube. I haven't been able to find them at retail outlets, but plumbing suppliers carry them. You may want a plumber to do this. Some of the manufacturers have realized how much hot water the're in, and have entered into a settlement. Check www.hotwater.com for info on A.O. Smith and others. If you want to know more about maintenance on water heaters, (yes, there's lots more to know!) check out this site: http://www.waterheaterrescue.com Lots of good information.
The Monthly Nag: For all of you lucky enough to have central A/C, it's time to change the furnace filter again. And if you're using a wall or window A/C, it has a filter too, usually just behind the front grille. This can be removed and washed, or replaced. Soon it should be cool enough for crawlspace vents to be opened. Late summer is a good time to check the sidewalk and other walkways around your house for low-hanging branches. Public walkways require about 7 feet of overhead clearance. On private property, use your own judgement, but keep in mind that you may have guests using that walkway in the dark.
This newsletter is a 2-way street. If you have any questions or concerns, please use this Sherlock Homes Inspection, Ltd.
copyright 2000 Matthew J. Bezanson