How To Install Pressure Relief Valve For Water Heater' title='How To Install Pressure Relief Valve For Water Heater' />1 This water heater design has been certified by the Canadian Standards Association for installation in recreation vehicles. This water heater is not for use in. Water Pressure issues including leaks, pipe damage, and wasted water. The Temperature Pressure Relief Valve The ASHI Reporter. The most important part of your clients domestic hot water systemThe steam powered tank hurtled across the busy intersection at First Avenue South and South 1. Street over at least six lanes of traffic before landing more than 4. Pizza Hut. This excerpt from a July 2. Seattle Post Intelligencer describes what happened when a water heater with a capped Temperature Pressure Relief TPR valve overheated and exploded. According to a November 1, 2. WSOC TV Web site, a water heater landed 7. Kannapolis, North Carolina, home and did an estimated 2. According to the report, the heater lacked a TPR valve altogether. High limit controls. Water heaters have thermostatically controlled devices that keep them from overheating. Both gas and electric water heaters have temperature limiting devices that shut off the energy source when their regular thermostat fails. Electric heaters have a high limit switch that interrupts the power when overheating occurs. Many of us have seen and perhaps reset the device by pushing a small red button under the cover plate and just above the thermostat dial. Thermostatically controlled gas valves found on most residential gas water heaters have a safety shutoff built into the gas valve itself. When they react to excessive temperature, the gas flow to the burner is stopped. Generally not resettable, the entire control valve has to be replaced to get the water heater up and running again. Water-Heater-Blast.jpg' alt='How To Install Pressure Relief Valve For Water Heater' title='How To Install Pressure Relief Valve For Water Heater' />These devices are the first line of protection against water heater explosion. Should they fail, a temperature pressure relief valve, which should be installed within the top 6 inches of the tank, should prevent the heater from suddenly becoming a bomb or launching like a rocket. In both of the explosion events described earlier, it appears a properly installed TPR valve would have prevented the carnage. Photo Electric thermostat with high limit. Photo Camco Manufacturing, Inc. Photo A thermostatically controlled gas valve. Pressure relief vs. Temperature Pressure Relief. The two contributing factors that cause water heaters to explode are excessive water temperature and a failing in the tank itself. The failing or weakness could be in the design or could be caused by a defect from extensive corrosion or just normal wear. Experts note that as long as the water temperature within the tank remains under 2. F, excessive pressure alone will not cause a water heater to explode. Water under excessive pressure will exploit a weakness within the tank and cause it to leak. Water will drip, spray or gush from the tank, but the violent burst we would call an explosion will not occur. When heat energy is added to the water, especially when reaching temperatures in excess of 2. F, everything changes. As the temperature climbs, additional stress is put on the tank. Water inside the tank is under pressure, and this pressure will allow the water to be superheated or heated beyond the atmospheric boiling point. Where to install your water heater. You must install your water heater in an accessible location. A minimum of 24inch continuous width is required for access. Water Safety Flow Control Support Helpful Tools and Resources. Home Water Safety Flow Control Support Temperature and Pressure TP relief valves. In some cases, temperatures can exceed 3. F. When the tank opens or splits at a weak point, the superheated water will rapidly escape, expanding in volume many times as steam, creating an explosion and often propelling the tank like a rocket. In the past, water heaters and hot water storage tanks were merely protected by a pressure relief valve. You still occasionally see them installed in water lines near water heaters at older properties. Over the years, we learned how extremely inadequate pressure relief alone was for protecting water heaters from an actual explosion, and today combination temperature pressure relief valves are required. The standard for the industry is set to open at 2. F 9. 9C andor 1. TPR valve basics and installation concerns A properly installed TPR valve allows water to discharge through the device when conditions of excessive pressure, excessive temperature or both occur. When the valve opens, pressure from the tank, along with hot water, is released. As the water moves from the tank, the pressure drops and the exiting water is replaced with new much cooler water. This lowers the water temperature within the tank. When a safe level is reached, the safety valve should shut off. How To Install Pressure Relief Valve For Water Heater' title='How To Install Pressure Relief Valve For Water Heater' />Unless the cause for overheating is corrected, a good TPR valve will continue to trip or open repeatedly each time the unsafe conditions are reached. As stated earlier, temperature and pressure relief valves should be installed within the top 6 inches of the tank. Ghost Hidden Object Games Full Version on this page. Because of temperature stacking, this is where the hottest water in the tank is found. Hot Water Heater Relief Valve How to install, check and replace temperature and pressure relief valve and why it is important. From time to time, I find the TPR valve installed in the hot water piping away from the tank. Though standard storage tank water heaters have an opening specifically for the safety valve, some water storage tanks do not. In this situation and on the rare occasion the valve opening is used for something else, manufacturers recommend that a tee be placed at the hot water outlet and that the TPR valve be screwed directly into the top of the tee. The heat sensor thermostat of the TPR valve should pass through the tee and be submerged in the upper 6 inches of the tank water. The side opening of the tee is fitted and piped to deliver hot water to the house. On water heaters with very thick insulation, youll sometimes encounter an issue with the TPR valve that is related to the insulation itself. Because of the depth of the insulation, the threaded opening is somewhat recessed within the jacket placed around the tank. How To Install Pressure Relief Valve For Water Heater' title='How To Install Pressure Relief Valve For Water Heater' />Installers sometimes add a nipple and a coupling to the end of the TPR valve to bring it out beyond the insulation and jacket. This can cause the thermostat on standard length TPR valves to line up inside the nipple, where its unable to truly sense the water temperature. Special TPR valves with an extended shank should be used for this application. It not only gets the valve out beyond the insulation, but it is designed with an extended thermostat that keeps it well inside the tank surrounded by water. The extended shank is part of the valve itself, and no nipple is needed. In recent years, many water heater manufacturers have relocated TPR valve openings. They have moved them from the top to the side of the tank. When older heaters are replaced with similar height units, installers occasionally will turn the valve so it can be realigned with the original discharge pipe that extends from the wall. This often results in the trapping of the valve, preventing it from draining by gravity. If the valve drips, mineral deposits can collect at the opening and create a mineral plug. This can restrict or block the opening altogether. Neither the TPR valve nor the discharge piping should ever be trapped and should always drain completely by gravity. Illustration Watts. Photo Watts L1. XL is their model TPR valve for heavily insulated tanks. Photo Watts. Photo Trapped TPR valve. Photo by K. Hart. Photo Discharge pipe too short. Photo by K. Hart. Photo Camco runoff tube. Photo Camco Manufacturing, Inc. Discharge pipe issues. When it comes to water heater installation, Cash Acme, a manufacturer of TPR valves, states, The most common problem is the absence of or an incorrectly installed drain line from the TPR valve. As a plumber and home inspector, I agree. My personal observations lead me to believe that most installers understand the purpose of the device, but have no comprehension of just how dangerous the discharged water is when it leaves the tank.