The Hidden Danger of Water Heaters and Boilers

You don’t hear about it happening very much (thankfully!) but tank-based water heaters and boilers can (and do) explode, often with catastrophic results. Water heaters and boilers are designed to be safe, and are installed in literally millions of homes in the United States. Water heaters and boilers include failsafe devices to prevent the build–up of dangerous pressure levels inside the devices. Occasionally however, the failsafe devices fail.

This slow-motion video, compliments of the Mythbusters television show on the Discovery Channel, demonstrates (safely) what happens when a water heater pressure and temperature valve fails. Although the demonstration involves a hot water tank, the same thing can happen with a boiler. And in this case, size matters! The larger the device is, the more damage it can do!

The failsafe for a water heater or boiler is a device called a pressure-and-temperature valve (PT valve). Some people call them T & P valves – they’re the same thing. The valve usually sits on or near the top of the water tank or boiler and is designed to open when a set pressure or temperature inside the tank is achieved. Some tanks are outfitted with a pressure valve, which opens only when a higher pressure is detected, regardless of the temperature in the tank.

Basic physics says that temperature and pressure in a closed system have a direct relationship. That is, when the temperature goes up, so does the pressure, and vice versa. Turning up the heat on your hot water tank or your boiler control will increase the pressure in the system.

These systems are designed to handle “modest” changes in temperature and pressure. Manually adjusting the temperature upward on your water heater or boiler should never produce catastrophic results. So what can go wrong? Usually a combination of things!

Regulators and thermostats are designed to keep the operating temperature of a device within a specified range. When the temperature drops below the specified range, the regulator turns on the heater to heat the water in the system. When the temperature rises to the top of the range, the regulator turns off the heat. If the regulator or thermostat in the system goes bad, one of two things can happen: no heat at all, or heat all the time!

If the regulator or thermostat gets stuck “on” and heats the system constantly, the T & P valve or pressure valve is supposed to open and relieve pressure build up in the tank. It’s supposed to prevent the tank from ever reaching the point where an explosion is imminent.

Here’s the bad news. T & P valves and pressure valves can fail. Unlike the regulator or thermostat– whose erratic behavior will indicate a failure – there’s no way to know that a PT valve is going bad or has failed without testing it. Fortunately, testing is simple and homeowners should test the PT valves on their water tank(s) every month or two.

The valve (shown in the picture accompanying this post) can be lifted or flipped into the “open” position by hand. If the valve opens and closes smoothly, it’s still doing its job. If it doesn’t open, or opens and closes only with difficulty, it should be replaced. As a rule, PT valves on boilers and water heaters should be replaced every three years, whether they’re working or not. A PT valve is an inexpensive item, and the peace-of-mind is worth every penny.

Don’t underestimate the amount of damage a defective water heater can do to your home. Depending upon its size, a water heater or boiler can build up more than 100,000 pounds of pressure before it explodes. An exploding tank may lift off its base at a velocity of 350 MPH, and will easily shatter the foundation, floors and roof of a home. Unimpeded, a fully pressurized 50-gallon water tank can achieve an altitude of more than 500 feet!

Pressure aside, a hot water tank is also carrying 40 or 50 gallons of potentially scalding hot water, which will be distributed over the tank’s exit path. And then there’s gravity – what goes up must come down! An empty water tank can weigh between 75 and 200 pounds, and when it returns, it may come back down in one piece or it may split into multiple pieces.

Boston Standard Plumbing & Heating can help you perform regular maintenance on your hot water tank and/or boiler, show you how to test your PT valve and provide valve replacement services as needed. Water heaters and boilers can be operated safely in a home, but these devices do require regular professional inspections and maintenance.

Give us a call at (617) 288-2911 anytime to schedule an appointment. Call us if you experience any operating problems with your water heater or boiler – including over- and under-temperature conditions, and pilot light or electronic ignition problems.
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Test The Pressure Relief Valve On Your Water Heater

Last week, I gave you a procedure to use for draining your hot water tank. You should perform water heater maintenance annually to ensure that it operates safely and efficiently, and does not accumulate sediment that can cause your water tank to fail prematurely.

As part of your annual water heater maintenance routine, you can also test the pressure relief valve on your water heater. The pressure relief valve is a safety device that prevents the dangerous buildup of pressure in a hot water tank. If the pressure increases significantly in the tank, the relief valve is designed to let water (and pressure) escape safely. The pressure relief valve will be on or near the top of the tank and will operate in a closed position.

The pressure relief valve has a hinged handle or stem that normally sits in a flush position against the valve cover. To test the valve, lift the handle upward (or outward) to a 90° position and allow a little water to escape. The water in the tank will be pressurized and hot, so make sure everyone (and everything) is clear of the valve before you open it.

If your pressure valve normally leaks a little water, or shows signs of leaking when the valve is closed, this could indicate a problem with pressure build-up in your hot water tank. If the valve shows signs of mineralization or cannot be opened for testing or does not close properly after testing, this could indicate that the pressure-relief valve is malfunctioning. In either case, you should consult with a licensed plumber to determine the nature of the problem.

A plumber can correct either an over-pressure situation or a bad valve easily, but since the pressure relief valve is a safety device, any problems should be corrected immediately to keep your home, family and plumbing system safe! If you have a problem with the pressure relief valve on your water heater, give us a call at Boston Standard Plumbing & Heating at (617) 288-2911 anytime. We’ll be happy to examine your system for problems and make repairs if needed.

How To Drain Your Water Heater

Water heaters can give you years of trouble-free service, but a little water heater maintenance can help extend the life of your tank beyond its minimum rated service period. Many water tanks suffer from lack of maintenance, which can deteriorate the tank and cause it to fail prematurely.

To help keep your hot water tank operating properly, make a maintenance plan that includes draining the tank annually. This will discourage the build-up of sediment in the tank and will help extend the tank’s life. To drain the tank, you’ll need a standard garden hose and a safe place to put 40 gallons or more of hot water.

If your water heater is electric, cut the power to the tank at the breaker box before you do anything else. If your tank uses natural gas, turn the temperature control to the “pilot” setting, or to “off” depending upon how the control is marked.

Once the power/fuel is cut, attach the hose to the tank’s drain valve. The drain valve looks like a hose spigot, may be made of plastic or metal, and is threaded to accept a standard garden hose. Don’t open the drain valve yet – just get the hose attached to the valve.

Run the hose to a working floor drain, sump well or to the outside, if the tank is on the first floor of your home. Remember, the water that drains from the tank will be hot, so be sure to dispose of it safely!

Turn off the cold water supply to the tank, and open a hot water tap on one of your faucets. This will allow air to enter the tank and push the water out through the drain. Finally, open the drain valve on your hot water tank. Monitor the tank as it drains to prevent accidental flooding and to verify that the tank is draining.
When the tank is drained, open the cold water supply and begin refilling the tank. Don’t close the drain valve; the goal here is to flush any accumulated sediment out of the bottom of the tank.

When the water runs clear from the drain hose, close the open hot water tap and the drain valve. Allow the tank to refill. Once the tank is refilled, reapply power or re-ignite the gas and allow the tank to begin heating again.

Next week, I’ll discuss the pressure relief valve on your hot water heater, and show you how to test the valve for proper operation. In the mean time, if you have trouble with your water heater, or would like Boston Standard Plumbing & Heating to perform maintenance on it, please give us a call anytime at (617) 288-2911.

New Water Heater? Boston Homeowners Get A Tax Credit For That

As I mentioned last week, the federal government has extended the tax credit available for the installation of non-solar water heaters in Boston homes. The credit, which applies only to certain high-efficiency water heaters will put as much as $300 back in your pocket, if you claim the credit by December 31, 2011. What qualifies? Any gas, propane, or oil-fired water heater with an energy factor of at least .82 or a thermal efficiency of at least 90% (including tankless models) qualifies for the break. Electric heat pump water heaters with an energy factor of at least 2.0 also qualify. This program falls under the federal cap of $500 for energy efficient improvements made between 2006 and 2011, so if you’ve already claimed certain expenses under this program, your credit may be reduced or eliminated.

Note that standard electric water heaters and solar water heaters are specifically excluded from this program, so check the rules at before you buy. As with last year’s tax credit program, even highly efficient electric water heaters don’t generate enough energy savings to qualify for the credit. Solar water heaters are also exempt for the same reason, but if you want to install a solar water heater and you can go without the tax credit, contact us and we’ll be happy to talk about your options.

To claim your credit, you’ll need to put the device in service in 2011 in your primary residence. New construction, rental properties and second homes don’t qualify. You’ll also need to file IRS Form 5695 when you prepare your taxes next April. Don’t forget to save your receipt(s) and the Manufacturers’ Certification Statement with your records!

If you’re ready for more tax-friendly home improvements, consider adding a natural gas, propane or oil furnace. You can claim a tax credit of $150 if the furnace you install has an Annual Fuel Utilization Efficiency (AFUE) rating of 95 or better. If your home uses a boiler, you can get the same $150 credit for any gas, propane or oil boiler with an AFUE rating of 95 or better.

Of course, the experts at Boston Standard Plumbing & Heating are ready to help with any repair, installation or maintenance issues you may encounter with your home heating, cooling or plumbing systems. Whether you need an emergency repair or just some good advice, contact us at (617) 288-2911 and we’ll be happy to help.

Boston Water Heater Replacement Can Earn You A Tax Federal Credit

Right now, the federal government is offering homeowners a federal tax credit on the installation of new, high-efficiency gas, oil, propane and electric heat pump water heaters. Not all water heaters qualify for the credit, but if you’re considering updating a home in Boston, water heater replacement can save you money both up-front and over the life of the appliance.

To claim the credit, which amounts to 30% of your cost up to $1,500, you’ll need to install a water heater with an energy factor of at least .82 or a thermal efficiency of at least 90%. The tax credit will cover installation costs in addition to the cost of the water heater. This credit is significant because a hot water heater can account for between 15% and 25% of your total energy expenditures each year. Reducing energy consumption for hot water heating will produce a noticeable change in your monthly heating bills. This credit expires on December 31, 2010, so time is of the essence if you’re planning to upgrade your hot water heater.

Hot water heaters don’t have an indefinite life span. If your hot water heater is making noise (like crackling sounds), has aged beyond its original warranty, is not performing as expected, shows outward signs of rust, produces hot water with a foul odor, or releases white particles when you open the drain valve at the bottom of the tank, you may want to consider replacing your hot water heating system.

At Boston Standard Plumbing, we can perform hot water heater maintenance, and evaluate the condition of your hot water tank. We can also install a tankless hot water heat system that integrates with your existing boiler, or operates independently and provides unlimited, instant hot water for your home and appliances.

Contact Boston Standard Plumbing today at (617) 288-2911 for more information about this tax credit and how you may be able to take advantage of it.