Water Heater Facts and Fallacies
I've put together some information and pictures to demonstrate some of the issues that turn up during my home and commercial property inspections in San Diego and Temecula Valley. This is not intended to be an installation checklist, or a complete set of requirements for an approved water heater installation. These are just the observations of one home inspector.
Closed Loop System
Most newer homes have a Pressure Reducing Valve to keep water pressure at an optimal pressure for residential construction, which is usually between 50 – 80 psi. And many jurisdictions in San Diego also require a backflow device. A backflow prevention device is used to protect potable water supplies from contamination or pollution due to backflow. In water supply systems, water is normally maintained at a significant pressure to enable water to flow from the tap, shower, or other fixture. The PRV and the backflow device will only allow water to go in one direction, this makes your home's plumbing system a “closed loop system”.
Water Heater Expansion Tank
When water is heated, it causes expansion and increased pressures in both the hot and cold water piping system. In an open system, water can only push back into the street, provided that the street pressure is less than the expanding water pressure. If the water is taking up more space and has nowhere to go, as in a closed system, the pressure will increase and possibly damage the system, generally at its weakest points, until a leak or even a burst pipe results. The TPR is designed to relieve this pressure and act as the “weakest point”, thereby preventing damage to the system. The TPR is NOT an expansion device. The required expansion tank is designed to relieve the stress, thereby increasing the life of the components in your entire system. Expansion tanks work by equalizing the pressure throughout the system. Many jurisdictions in San Diego now require expansion tanks for the above mentioned reasons. Even if not required for your area, nearly every manufacturer recommends them. Most warranties for plumbing fixtures and water heaters become null and void when the products are subjected to excessive pressure.
Temperature Relief Valve
Relief valves (TPR) located inside a building shall be provided with a drain, not smaller than the relief valve outlet, of galvanized steel, hard drawn copper piping and fittings, CPVC, or listed relief valve drain tube with fittings which will not reduce the internal bore of the pipe or tubing (straight lengths as opposed to coils). The drain shall also slope to drain naturally and not trap water in the pipe.
The drain shall extend from the valve to the outside of the building with the end of the pipe not more than two (2) feet (610 mm) nor less than six (6) inches (152 mm) above the ground or the flood level of the area receiving the discharge and pointing downward.
Natural Gas Sediment Trap
A sediment trap is required to be installed at water heaters. Sediment traps help prevent debris in the gas system from clogging the inlet screen on the gas control valve and help prevent debris from damaging the control valve. Most warranties are null and void if it is determined that debris caused damage to the gas control valve.
Water Heater Exhaust Vent
The vent connector must be fastened to the draft hood, at each joint and to the first B-vent fitting. Three sheet metal screws or more are typically needed to hold the joint rigidly in place. Gas combustion water heater produce carbon monoxide gas as part of the combustion process. The exhaust vent expels the combustion gases to the exterior of the home. That is why it's important that the vent is properly installed. Carbon monoxide is a deadly gas. The exhaust vent should be sloped up towards the "B" vent 1/4" per foot. Anything less can cause dangerous back-drafting.
Water Heater Seismic Strapping
Experience has shown that water heaters can move or tip over during an earthquake if not properly anchored to the walls. Movement of or to the water heater may cause leaks in gas piping, which in turn may pose a fire hazard. Water leaks from broken water lines may also cause damage to floors and walls. Because of this recognized potential for damage, Assembly Bill (AB) 1890 was passed into law on September 27, 1989. AB 1890 requires all new and replacement water heaters sold in California on or after July 1, 1991, to be braced, anchored or strapped to resist falling or displacement due to earthquake motion. This applies for installation of all new water heaters and when water heaters are replaced or relocated. The California Plumbing code (CPC) states, water heater strapping shall be at points within the upper one-third of the water heater vertical dimensions. At the lower point, a minimum distance of four inches shall be maintained above the controls with the strapping. The upper strap is generally installed nine inches below the top of the tank. In depth information about water heater bracing is available on the State’s website. http://www.seismic.ca.gov/HOG/waterheaterbracing_08-11-04.pdf
Recirculating Hot Water System
Hot water recirculation pumps and systems are a convenient way to ensure that you have immediate hot water from the tap. These systems slowly pump hot water through your hot water pipes and back to the water heater through either a dedicated line or through the cold water line. The pump itself is typically installed near the water heater, and controlled by a timer. The timer should be set to turn the pump on only during times that you are likely to be using the hot water.
The Water Heater Data Plate
The water heater data plate has all of the information about the water heater. The manufacturer, the date of manufacture, the size (in gallons), the gas type, and sometimes will include warranty information. If the actual date of manufacture is not noted, there are many websites that will help you decode the serial number to determine the date of manufacture. For the water heater to last any longer than the warranty is a blessing. You should plan on replacing an out-of-warranty water heater at any time.
Gas-Fired Water Heater Combustion Air
If the combustion air supply for the gas-fired water heater is insufficient, it may cause incomplete combustion which can produce excessive amounts of invisible, odorless, tasteless, toxic gases like carbon monoxide. This is why you do not block the ventilation vents for a garage installation water heater. The garage vents were designed to supply combustion air for the gas appliances ins the garage. Pictured below are the blocked vents typical of what I find many times on home inspections.
Asbestos Exhaust Vent
Many older homes used asbestos material for venting gas appliances. Although asbestos is considered to be a known carcinogen, it is not considered to be a health hazard unless it is in a form in which it can be inhaled. Disposing of asbestos can be expensive and you would be required by law to disclose your knowledge of its presence should you decide to sell the home. The only way to confirm that the suspect material is actually asbestos is to have it tested in a laboratory.
Do I need A Water Heater Blanket?
If your water heater was manufactured within the last ten years, then probably not. In fact, manufacturers nowadays discourage adding insulation and most state that it will void their warranty if you do. The blanket also makes it very difficult to visually assess the condition of the water heater. And it makes it nearly impossible for me to find the data tag during the home inspection.
If you have an older water heater, then the the Department of Energy believes you can possibly save $20-45 dollars a year. But probably not in California (that's my opinion).
The intent of this article is to provide homeowners a general reference for the code requirements in many areas of San Diego. This information is for storage type water heaters only. This article does not cover all the code requirements found in the plumbing code. Most jurisdictions require obtaining a permit to replace a water heater. Be sure to check with local jurisdictions for adopted local amendments and code updates. For more detailed information on water heater installation in California, go here.
About the author: Frank Rotte is the Owner of Certified Inspection Services, LLC in Bonsall, CA. Comments are always welcome! Please visit us on Facebook at https://www.facebook.com/homeinspectionsandiego/