Why do water heaters drain?

Question

My water heater is draining water nightly. It seems to occur more frequently and is louder than normal. Could it be that it is the summer time and I am not using as much hot water as I would in the winter? It is a gas (not electric) water heater.

I read that the heater does it if the water gets too hot. How can I tell that the reason it is draining is OK or when should I start to worry?

Thanks!

Answer 1

Draining water? Do you mean it is coming from the pop off valve? You have a problem. Either you temperature setting is WAY too high, or you have a bad pop off valve.

This is the little brass thing with a handle on the side at the top of your heater.

First, turn down the temp. If it is still "draining", replace the pop off.

Answer 2

Do not open the drain valve because it may not close completely and drip.The drain valve on a water heater is not the highest quality and the hot water ages the seals.The best plan is to remove the original valve when the heater is new and install a brass ball valve.It has a large handle and is easy to tell from the standard valve. One important thing to do is to replace the stop valve when you replace a toilet.It is easy to replace when the toilet is off but very difficult when the toilet is seated.I needed to reseat my toilet because the stop valve was frozen.I sprayed the valve with liquid wrench and heated it with a torch and it came off because I had room for leverage. If you replace the hoses on the washing machine just shut off the water main and do not touch the valves because they could drip out the handle stem and need a rebuild or replacement.Spray oil onto stems when tightening and do not leave open full stop back it closed a quarter turn. Replace plastic with metal.Water hammer from my icemaker made the supply hose twitch which broke the plastic joint at the supply and flooded my kitchen.A plastic ballcock cracked and flooded my bathroom.Both times it was in the middle of the night and I was standing there which is about the limits of good luck.Plumbers charge $100 an hour so every hour you spend under the sink is a pay raise.

Answer 3

Along with all the information Jim B provided you, another problem may be a faulty gas valve. When it goes bad , it will not shut off even after reaching the temperature that you set the heater at, thus heating the water above the t&p rating. Set the heater for no more than 120 degrees. After the heater has run thru a cycle and shut off, run water out of a faucet for 3 minutes then draw a glass full and check the temperature with a thermometer that will read up 200 degrees or higher. If the water in the glass is significantly higher than the heater setting, then suspect the the valve may be bad.

Answer 4

If this has just recently started happening then you should take some action very soon. The only thing on your water heater that should open and close on its own and release water is the Temperature Pressure Relief Valve (TPR valve). This safety valve releases water (and thus relieves pressure) if either the temperature or pressure in the tank gets too high.

These valves are very important. Water heaters can become bombs if the pressure gets too high and these valves fail to work. Since yours is opening and closing then chances are it will not stick shut and allow pressure to build up to a dangerous level. You do need to be careful if you are around your water heater when it chooses to open because it may spray out scalding hot water.

There are at least three reasons for your TPR valve to be opening periodically. The valve could be old and weak and starting to open at lower pressure or temperature. The supply water pressure may have increased or may be experiencing surges in pressure and popping the TPR valve open periodically. Or the water temperature is getting too hot and causing the TPR valve to open because of high temperature.

High Water Temperature:
The first thing you should do is measure the water temperature and see if it is getting too hot. Over 160 to 180 F is too high. There's a chance the thermostat got bumped up accidentally or it may have failed and is letting the water get too hot and should be replaced.

Old TPR valve:
The TPR valve may just be old and weak and needs to be replaced. The TPR valve is an inexpensive device, but it can be a pain to unscrew. You may also need to replace the overflow pipe when you replace the TPR valve. Sometimes they are threaded on and the threads can get messed up when they are separated.

High Water Pressure:
You can chack the supply pressure with a $10 pressure gauge available at the hardware or building supply store. If it goes over about 80 psi then you should contact the water supply company and see if they can correct the water pressure problem. There may be a faulty pressure regulator on your water main that they need to replace. If they say there is nothing they can do about it then you can install a backflow valve or check valve and an expansion tank in the water supply line. I suppose you may already have a backflow valve and expansion tank on your water line if the house is newer because many localities require these on new construction. If that's the case then it may have failed and should be replaced.

Frankly, any of these would be best taken care of by a plumber both because you don't want to take a chance on messing up this safety device and because they can be a pain to determine the exact problem and replace/install the necessary parts.

Good luck.

Answer 5

You mentioned "more often at night". That is when the pressure of the civic water system is higher because of low usage. This may be because your valve may be getting older. Replacement is easy. There should be a drain tube directing the flow to a drain.

Answer 6

I totally agree with BARE B's answer. You do have a problem with the heater. It is building up too much pressure, because it is boiling the water and letting the pop off valve flow out the excess, or the valve itself is bad and leaking.

They aren't too expensive to replace and just screw on. Be sure to get some teflon tape to wrap the threads before you replace it, if necessary. good luck.

Answer 7

call a plumber to come and check the pop off valve
very common problem
really the valve is a safety feature to keep the heater from becoming a rocket in your closet

Answer 8

Give Bare 10 points and go to http://appliancequickfix.com/
for more information on appliances.