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Robert Lamoureux: Water heaters can be dangerous

Your Home Improvements

Posted: July 23, 2010 10:36 p.m.
Updated: July 24, 2010 4:55 a.m.

Hi Robert,
I’ve got a problem with my hot water heater. A part mounted on the outside of the heater, near the top, is leaking water. What’s causing this? I’ll come home and the floor around the heater is wet. This started to happen about a month ago and now there is always water on the floor. It is a 50 gallon water heater — only about 2 years old. Please provide your recommendations. Thank you,
Cliff H.

Hi Cliff,
The device that’s leaking is your T & P valve — temperature and pressure relief valve — which needs to be checked at least once a year. This question brings up a good point regarding home safety. It’s important to pay attention to all the warning labels around your home and understand what they mean.

There is probably a warning plate affixed to the water heater that reads: “WARNING. Explosion Hazard. If the temperature and pressure relief valve is dripping or leaking, have a licensed plumber repair it. Do not plug valve. Do not remove valve. Failure to follow these instructions can result in death or explosion.” Whenever you see a warning like this, know explosions have happened, people have been killed and their deaths necessitated the use of the warning. 

The purpose of a T & P valve is to relieve excess temperature or pressure inside the tank to prevent an explosion. An exploding hot water heater is like a bomb. It can take out the entire garage and could rip half of your house apart. 

Open field testing has been performed using a faulty T & P valve with the thermostat stuck in the ON position. The resulting explosion launched the metal tank at a velocity of 900 feet per second. The tank landed 400 feet away. 

The three main reasons why your T & P valve may be leaking are:   
1. Too much pressure
2. Too much heat
3. Defective T & P valve

When opening the lever on the valve for a check, sediments from the tank can sometimes become stuck in the seat and hold it partially open, causing the valve to leak. 

Check the water pressure in your house with a gauge. You can find this type of gauge at a hardware store for about $10. Attach the gauge to a water bib after the PRV — pressure regulator valve. The PRV valve is normally located outside your house. You can also get an adaptor so you can attach the valve to your sink faucet.

Most municipalities have between 100 lbs. and 120 lbs. of pressure coming in from the main.  Personally, I set my pressure at 70 lbs. Most people are more concerned with volume of water, not pressure. You don’t need more pressure than this — although code says you can go up to 80 lbs. More pressure is a  waste of water. Remember, we’re in the desert, homeowners should be conservative.

Another reason to avoid excess water pressure is that it puts unnecessary stress on the pressure fitted angle stops. If the pressure exceeds 80 lbs. the PRV needs to be adjusted down.  

Too much water pressure can cause serious damage to your house. We have seen a homeowner’s upstairs flex lines blown, which caused an entire living room ceiling to collapse from the weight of the water. Imagine 500 to 600 sq. ft. of ceilings down on the floor and everything soaked. Water is very destructive. Second only to fire.

I would also recommend you find the shut off valve to your house. People ask us often “How do I turn my water off?” It’s good to know where it is in case of emergency and it’s also good to exercise the valve — turn it off and on again, very slowly, to keep it functioning properly. Also, inspect the angle stops and the lines. If anything is corroded, replace it. 

There are also alarms available that will sound if water is detected. You can place these under sinks, behind toilets, under washing machines, etc. There are also systems which sound an alarm and shut the water off. 

Occasionally the PRV’s will bounce. This means you can check it and everything looks fine — then a few minutes later it reads at a higher pressure. Watch it for a few minutes. If you get different readings, if it bounces, it’s faulty and has to be replaced. 

If the water temperature gets too hot it will cause the T & P to blow open to relieve the pressure. The U.S. Consumer Product Safety Commission (CPSC) recommends water heaters be set at 120 degrees. In addition to preventing accidents, this decrease in temperature will conserve energy and save money. If you are unsure how to adjust the temperature, call the electric or gas company for instructions for your particular heater. For example, most electric heaters have two thermostats. Each must be set the same before the temperature can be regulated. 

Hello Robert,
Sometimes I smell a very faint gas smell in my garage but can’t find any holes in the hose or know where it’s leaking. Would a soapy water test be the best to find this type of leak? Thank you,
Emily P.

Hi Emily,
Call the Gas Company immediately and tell them you have a leak. Don’t wait and don’t play around with this. This is dangerous. 

The Gas Company will arrive with a gas sniffer and tell you where the problem is. It may be your problem or it may be their problem, but either way, they are the professionals so let them find out what is wrong. That smell is mercaptan. It’s a chemical with an unmistakable scent added to the otherwise odorless natural gas. When you smell this, you have detected a leak. 

This is where your leak finding comes to a close. You don’t need to check the lines. The Gas Company will take care of that. Open the garage door to allow as much ventilation as possible until they arrive.

If you know where your gas shut off valve is, turn the gas off. If not, ask the Gas Company technician to show you. Then, if there is a problem in the future, you will know how to shut off the gas to your home. 

We have designed a custom, full-color The Signal/Your Home Improvements T-shirt we will give you if we answer your question. The T-shirt will be available for pickup at our Valencia office.

Robert Lamoureux has 25 years experience as a general contractor, with separate licenses in electrical and plumbing contacting. He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor, after that contractor has made a thorough visual inspection. Send your questions to


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