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Last month, Part 1 of this article discussed the requirement for a permit for an inspection if you replace a water heater. In most cases, a permit is required because a water heater is one of the most dangerous appliances in a building and there are many things that can go wrong if a water heater is replaced and there is an error in the installation. There can be water leaks that can cause water damage and mold, there can be gas leaks that can cause explosions and fires, there can be flue gas leaks that can lead to carbon monoxide asphyxiation or a fire, and there are hot water temperature controls that can cause scalding or allow Legionella bacteria growth.
In Part 2 of this article, I include a checklist for water heaters. The checklist was compiled from requirements in various codes and standards and from years of experience inspecting water heaters.
Applying for a permit triggers an inspection. An inspection of a water heater should include the following safety checks because water heaters are dangerous appliances for many reasons. The following items on a water heater, which can be dangerous/deadly, an inspector should be looking for.
Water heater inspection checklist
An inspection of a water heater should include the following safety checks.
Water heater fuel gas piping
q Check the fuel gas piping to see if the gas piping holds pressure. (Leak test per 2015 IFGC section 406.)
q Check the gas pressure regulator to verify the supplied gas pressure is within the gas pressure range on the appliance gas regulator.
q Check the fuel gas on the appliance label to make sure it is the same fuel as the fuel gas supplied within the building (Natural Gas, Propane, Butane, Methane, Manufactured Gas).
q Check to make it is installed properly (in accordance with the code) the piping must conform to the piping requirements in the fuel gas code with listed and labeled pipe, fittings, isolation valves, unions, and flexible connectors installed so as not to leak and cause an explosion or fire hazard.
q Check to make sure there are sediment traps or drip legs to catch sediment or moisture in the piping to prevent debris or moisture from making its way into the burner and that it is installed in accordance with the requirements of the fuel gas code.
Water heater combustion gas exhaust flues
q The flue pipe should be inspected to see if it is properly labeled and that the flue materials are listed in the code as materials for use as flue gas materials, Check the flue vent pipe manufacturer’s Installation manual to see if the material is installed in accordance with the listing.
q For plastic flue vent piping check to make sure the pipe, the fitting and the solvent are all listed for use in systems for venting combustible gasses. Temperature limits for various materials are: PVC limit is: 140-149°F; CPVC limit is 180°F: Polypropylene manufactured specifically for venting combustion gasses. Limit is 230°F.
q Check to see that the flue clearances from combustibles is sufficient.
q Check to make sure flue joints are installed to prevent leaks which could cause a fire.
q Check to make sure flue joints prevent leaking of combustion products which could lead to carbon monoxide poisoning and death.
q Check to make sure the relief valve is the proper capacity/size, pressure/temperature rating of the relief valve for the BTU/hr rating of the Water Heater it is installed on.
Relief valve discharge piping
The relief valve discharge piping should be installed in accordance with applicable codes.
q Check to make sure the relief valve piping is not be directly connected to the drainage system.
q Check to make sure the relief valve piping discharges through an air gap located in the same room as the water heater.
q Check to make sure the relief valve piping is not smaller than the diameter of the outlet of the valve served and discharges full size to the air gap.
q Check to make sure the relief valve piping only serves a single relief device and should not connect to piping serving any other relief device or equipment that can cause a back pressure on the relief valve that could affect its operation.
q Check to make sure the relief valve piping discharges to the floor, to the drain pan serving the water heater or storage tank, to a waste receptor or to the outdoors in accordance with the local code.
q Check to make sure the relief valve piping discharges in a manner that does not cause personal injury from hot water or steam discharge or structural damage.
q Check to make sure the relief valve piping discharges to a termination point that is readily observable by the building occupants so that they know when it is operating there is a problem.
q Check to make sure the relief valve piping is not be trapped. Water trapped in the discharge can reduce the discharge capacity and cause water hammer damage in downstream piping. Water trapped in a discharge pipe is like a bullet in the chamber.
q Check to make sure the relief valve piping is installed to drain or to flow by gravity so that no water can collect it the piping and cause corrosion, freeze or become an obstruction.
q Check to make sure the relief valve piping does not terminate more than 6 inches (152 mm) above the floor or waste receptor. Higher relief pipe terminations can expose building occupants or maintenance workers to sudden discharges of hot water or steam which can cause injuries.
q Check to make sure the relief valve piping does not have a threaded connection at the end of such piping to discourage the addition of valves or hoses which can be trapped and may have hose spray valves.
q Check to make sure the relief valve piping does not have valves or tee fittings.
q Check to make sure the relief valve piping is constructed of those materials listed in the code for water distribution or materials tested, rated and approved for such use in accordance with ASME A112.4.1.
Water heater thermal
q The water heater inspection should also include checking to see if there is a thermal expansion tank when the water system includes a water heater and is provided with a check valve, backflow preventer, pressure reducing valve or any other device that prevents relief of thermal expansion pressure during periods of non-use. Thermal expansion tanks or other approved devices having a similar function to control thermal expansion in domestic water systems should be approved for use in potable water systems. They should be listed, and adequately sized for the anticipated temperature rise and volume of the entire hot water system served.
q A check valve, pressure reducing valve or other normally closed device will create a closed system which requires an expansion tank or other means of relieving thermal expansion pressures. (Pressure relief valve, etc.) Inspectors should require a means to relieve thermal expansion when a check valve or pressure reducing valve is present in the water system with the water heater. The inspector and a commissioning agent if one exists should determine if the system is closed at non-obvious locations through the use of pressure gauges to show there is no relief of pressure build-ups when all faucets are closed. Items such as water meters and water softeners and pressure regulators or reducing valves typically have built-in check valves that can create a closed system and allow thermal expansion pressures to build up when water is heated in a water heater. Check for a closed system by pressurizing by putting a pressure gauge on a hose connection to see if the pressure dissipates.
q The water heater inspection should also include checking the size and installation of a thermal expansion tank to prevent over pressurization of the system which should not exceed 80 pounds per square inch. In installations without thermal expansion tanks the pressure often reaches 150 psi where there are intermittent discharges of the temperature/pressure relief valve which could cause tank damage leading to a leak and damage to the structure of the tank or a leak which could cause property damage. In areas with hard water, an intermittent leak of the relief valve could cause the relief valve to be coated with calcium/mineral deposits which could cause the relief valve to stop functioning and lead to a steam explosion which could injure or kill people.
q Check to make sure there is adequate combustion air to the water heater in accordance with the fuel gas code. Inadequate combustion air opening size could starve the water heater and cause incomplete combustion (sooting), which can plug up the flues and cause flame roll out and a fire or it could cause combustion products to roll out and cause carbon monoxide asphyxiation of the building occupants.
q Check to make sure the water heater is properly installed and secured to prevent it falling over and ripping loose the gas line or combustion flue in the event of an earthquake. Water heaters should be anchored or strapped to resist horizontal displacement due to earthquake motion. Strapping should be at points within the upper one third and lower one-third of its vertical dimensions. At the lower point, a minimum distance of 4 inches should be maintained above the controls with the strapping. Earthquake restrain strapping should not cover important safety and warning labels on the water heater. Water heater manufacturers should provide locations for earthquake restrains where the warning labels are not located. I have seen many warning labels covered by earthquake restraints. The water heater manufacturers should adjust where the labels are located and provide an indication of where the straps should be located to allow for a 2- 3 inches wide space for earthquake restraint straps at the noted locations. If warning labels are covered, make sure copies are posted showing: lighting instructions. Fire/explosion hazard warnings and scald hazard warnings are clearly visible.
Elevated water heaters with
ignition sources in garages
q Water heaters can be the source of ignition for combustible gasses that often are heavier than air and pool on the floor. In Garages, Water heaters should be elevated at least 18 inches above the floor. Unless they have sealed combustion and flame arrestors/Flammable Vapor Ignition Resistant (FVIR) technology.
Elevate electric water heaters
q Check to make sure electric water heaters installed in residential garages are installed so that the bottom of the tank is located at least 18 inches above the garage floor. Electric water heaters do not have mandated Flammable Vapor Ignition Resistant (FVIR) technology and may cause a small spark when the contacts call for heating. Electric water heaters should be placed on a stand unless documentation is provided by the manufacturer that the water heater is constructed with flammable vapor resistant construction.
q Installers and Inspectors should check the hot water temperatures flowing from fixtures after an installation of a water heater to assure the water heater installation does not create a scald hazard at the fixtures identified in Chapter 4 of the model plumbing codes as having temperature limits (Showers, Bathtubs, Bidets, etc.).
q This is especially important where the new walk-in bathtubs are being installed in place of showers or bathtubs in many older homes. Most walk-in bathtubs have non-code compliant two-handle faucets with a hand held shower. In this case an ASSE 1070 type temperature limiting valve should be installed on the walk-in bathtub. Even better would be a code compliant shower valve to prevent thermal shock.
q Check to see that temperature limit stops on showers, bathtub/showers and other fixtures with mixing valves and limit stops are adjusted to reduce hot water temperatures in accordance with the temperature limits identified in the plumbing codes. Note there are also warning labels on the water heater about water temperatures over 125 degrees causing scalding or death. The temperature limit stops on showers or tub/shower valves should be adjusted to comply with the maximum allowable temperature in the model codes.
Replacement water heaters
q If the installation of the water heater is in an existing building with two handle faucets or other styles of non-pressure compensating or non-temperature compensating shower controls, there should be some other means of temperature limits other than the water heater thermostat. Water heater thermostats cannot accurately control the outlet temperature of a water heater to prevent scalding.
One of the following temperature limiting means should be employed:
Limit stops on the shower or faucet fittings should be set at or below 120°F to minimize the chance of scalding in accordance with the requirements in the ASSE 1016 standard or if not all fixtures comply with this,
q A Master mixing valve should be installed at the water heater and should be adjusted to deliver a maximum hot water temperature of 120°F at fixtures to minimize the chance of scalding in accordance with the requirements in the ASSE 1017 standard.
q A Point-of-use mixing valve should be installed near the point of use fixture(s) to limit the hot water to a maximum of 120°F to minimize the chance of scalding in accordance with the requirements in the ASSE 1070 standard or
q A temperature actuated flow reduction valve should be installed on all sinks/lavs/tubs/showers and installed in accordance with manufacturer’s installation instructions and ASSE 1062.
Licensing and permitting requirements
q Check to see if the local code or any local ordinances have language stating that installers pulling a permit for a water heaters must have a master plumber license. This language is common in many states with exceptions for homeowners to install their own water heaters with a permit for inspection to assure a safe installation. Many jurisdictions make it unlawful for any person to install, remove, replace or cause to be installed, removed, or replaced any water heater without first obtaining a permit from the Authority Having Jurisdiction. The permit triggers an inspection by the local authority to look for many of the safety related things covered in this checklist.
Installation and operating instructions
q Check to see if the installer has left the manufacturer's installation, operating, and maintenance instructions in the plastic pouch on the side of the water heater or in a location on the premises where they will be readily available for reference and guidance for the Authority Having Jurisdiction, service personnel and the owner or operator.
q Check to see if the plumbing systems are installed in a manner conforming to the local code, applicable standards, and the manufacturer’s installation instructions. Where the code, applicable standards, or the manufacturer’s instructions conflict, the more stringent provisions should be followed.
Water heater accessories
q Temperature & Pressure Relief Valve - Check to make sure that temperature & pressure relief valves are installed in the top 6 inches of the water heater tank. The temperature probe activates at about 210°F and will be ineffective if installed in uninsulated piping downstream. The temperature probe should be installed in the hottest water or in the water heater discharge piping at the heater or in accordance with the manufacturers installation instructions.
q Vacuum Relief Valve - Check to see if the installation of a vacuum relief device may be needed and if so that they are installed in accordance with the terms of their listings and the manufacturer’s installation instructions. Vacuum relief valves are needed when there is a possibility of siphoning the contents from the hot water tank because of backsiphonage or backflow. Some water heaters have a small hole in the dip tube to allow an air break to prevent siphoning. If the cold water pipe connects near the bottom of the water heater it could siphon the contents. Siphoning the contents could allow a water heater to fire or the electrical element can energize without the presence of water and it can damage the water heater or the heating element.
q Automatic Gas Shut-Off Valves - Check to see if the installation of automatic gas shutoff devices are required and if so, are they installed in accordance with the terms of their listings and the manufacturer’s instructions.
q Earthquake Valves - Check to see if the installation of earthquake valves are are required and if so are they installed in accordance with the terms of their listings and the manufacturer’s instructions.
q Excess Flow Valves - Check to see if an excess flow shut-off valve is installed. Excess flow shut-off valves must be sized properly. Excess flow shut-off valve operate by having a ball or disc in the valve that shuts when the flow of gas causes enough flow to push the ball up into the port or the disc onto the seat. If an excess flow shut-off valve is too small the high velocity flow through the valve will trip the device and it will shut-off unnecessarily during peak flows. If the excess flow shut-off valve is too big, the flow velocity will not be enough to cause it to shut-off. The installation of excess flow valves should be installed in accordance with the terms of their listings and the manufacturer’s sizing and installation instructions.
q Temperature Actuated Master Mixing Valves (At the Water Heater) - Check to see if the installation of Temperature Actuated mixing valves are installed in accordance with the terms of their ASSE 1017 listings and the manufacturer’s installation instructions.
q Temperature Actuated Master Mixing Valves (with circulating pumps) - Check to see if the installation of temperature actuated mixing valves that are installed in a circulated domestic hot water system in conjunction with circulating pumps and circulating piping have a piping arrangement that split the hot water return piping after the circulating pump to flow to both the cold water inlet (or hot water return connection) on the mixing valve and the cold water inlet of the water heater in order to allow circulated flow through the mixing valve during periods when there are no faucets open in the building.
q Circulating Pump Rotation - Check the rotation of the circulating pump to verify that it is rotating in the proper direction. When circulating pumps are wired backwards, the pump can spin backwards. There is usually some flow, but often not enough to satisfy the temperature maintenance requirements.
q Circulating Pump Direction of flow - Verify that the pump is installed with the flow in the proper direction with the suction connected to the hot water return piping and the discharge flowing to the cold water inlet of the water heater and the cold water inlet of the mixing valve if a mixing valve is used.
q Check Valve on Circulating Pump Discharge - Verify that there is a check valve on the discharge of the circulating pump and verify that the check valve is installed in the proper direction of flow. To prevent cold water from short cycling back through the circulating pump to nearby fixtures. Domestic hot water circulating pumps are often fractional horsepower pumps that can allow cold water to flow backwards through the pump when nearby fixtures are used without a discharge check valve on the circulating pump.
q Flexible Gas Connectors - Check to see if flexible gas connectors are listed and labeled. Flexible gas connectors should comply with CSA Z21.24 Standard for Connectors for Gas Appliances.
q Flexible Gas Connectors Installation - Verify that the flexible gas connectors are installed in accordance with the terms of their listing. According to the requirements of the CSA standard that governs appliance gas connectors, the connector and fittings are design for use only on the original installation and are not to be reused for another appliance or at another location.
q Flexible Gas Connectors Location - Verify that both ends of the flexible gas connectors and the shut-off valve are installed completely in the same room as the appliance. The gas supply outlet must be in the same room as the appliance and the connector must not be concealed within or run through any wall, floor or partition. Flexible gas connectors can only be used above ground.
q Flexible Gas Connectors Length - Verify the length of the flexible connector does not exceed 6 feet. CSA certifies gas connectors up to 6 feet (72 inches). Joining two or more connectors is not permitted by product standards.
Water heater size
q Check to make sure that the water heater is sized adequately for the application. Water heaters should be sized in accordance with recognized industry guidelines like the HUD, ASPE Plumbing Engineering Design Handbook or the ASHRAE Handbook chapter on service water heating. Other sources of sizing information is the manufacturers sizing guidelines. Remember, when sizing water heaters a building owner has never had someone call up a six o’clock in the morning to say, “I have too much hot water.” Some states and local jurisdictions have sizing requirements for water heaters.
Protection of water heater from physical damage
q Water heaters located in a garage should be located or protected so they are not subject to physical damage by a moving vehicle. A pipe bollard should be installed to prevent vehicle contact with mechanical equipment located in a garage. A common protection barrier is a bollard design consisting of 3 inches or larger schedule 40 steel pipe, embedded 3 feet into the ground, encased in a 12-inch diameter footing and filled with concrete. Flanged bollards, fastened with anchor bolts to a concrete floor, wheel stops and elevating the water heater may also be solutions to protecting the water heater from damage.
Structural support for water
heaters in attics
q Check to see if water heaters installed in attics have adequate structural support for the weight of the water heater.
Drain pans for water heaters
q When a water heater is located in an attic, attic-ceiling assembly, floor-ceiling assembly, or floor/subfloor assembly where damage could result from a leaking water heater, a watertight pan of corrosion-resistant materials should be installed beneath the water heater with not less than 3⁄4-inch diameter drain to an approved location. Some codes have allowed tankless heaters to be exempt from requirements for drain pans.
q This requirement was because someone said, “tankless heaters don’t have very much water in them, so they don’t need a pan”. When tankless heaters fail, the entire municipal water system can drain out the hole in the side of a tankless heater’s heat exchanger. If they are installed in a location where a leak can cause water damage, it’s a good idea to have a drain pan. If the tankless heater is in toilet room under a lavatory counter and the floor in the toilet room is an impervious floor material and there is a floor drain, it should be OK to not install the a drain pan because a leak will drain to the floor drain and be readily observable. Use common sense and check with the authority having jurisdiction for what is required in your area.
Access to water heaters in attics
q Check to make sure where an appliance or water heater is installed in an attic there is adequate access through an opening and passageway that is large enough for the largest component of the appliance. The access opening should be a minimum of 22 by 30 inches.
q Access to Water Heaters in Attics - Where the height of the passageway is less than 6 feet, the distance from the passageway access to the appliance should not exceed 20 feet measured along the centerline of the passageway.
q Access to Water Heaters in Attics - The passageway should be unobstructed and should have solid flooring not less than 24 inches wide from the entrance opening to the appliance.
q Access to Water Heaters in Attics - A level working platform not less than 30 by 30 inches should be provided in front of the service side of the appliance.
q Power near Water Heaters in Attics - A permanent 120-volt receptacle outlet and a lighting fixture should be installed near the appliance.
q Light and Switch Near Water Heaters in Attics - The switch controlling the lighting fixture should be located at the entrance to the passageway.
Water heater clearances
Check for clearances around the water heater to verify the adjacent walls or equipment do not interfere with:
q Combustion air for the water heater;
q Draft hood clearance on top of the water heater;
q Relief valve discharge;
q Make sure there is accessibility for servicing.
q Water heaters should be third party listed and labeled for their intended application.
q Listed water heaters should be installed in accordance with their listings and the manufacturer’s installation instructions.
Fuel gas shut-off valve
q Water heaters connected to a fuel gas piping system should have an accessible, approved manual shut-off valve with a non-displaceable valve member, or a listed gas convenience outlet installed within six (6) feet (1.8 m) of the appliance it serves. Where a gas appliance connector is used, the shut-off valve should be installed upstream of the flexible gas appliance connector.
Drip leg/sediment trap
q Where a sediment trap is not incorporated as a part of the gas utilization appliance, a sediment trap should be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical at the time of appliance installation. The sediment trap should be either a tee fitting with a capped nipple in the bottom outlet, or other device recognized as an effective sediment trap. A sediment trap is required at water heaters. Sediment traps are just a tee with a dead leg where the gas changes direction in the tee allowing debris to fall into the sediment trap. Many years ago they were called drip legs when there was a higher moisture content in natural gas. The sediment traps catch rust, dirt and debris that may have been left in the gas piping and prevent it from getting into the appliance gas regulator, clogging the inlet screen on the appliance gas control valve, or clogging the jets in the appliance burner assembly. Warranties can be voided by manufacturers if it is determined that debris caused damage to the gas control valve. If drip legs are installed on wet gas systems (Methane or Manufactured Gas), the drip legs should be protected from freezing. Freezing could split the pipe and cause a gas leak.
Conversion from other fuels
q When an additional or replacement appliance is installed and the appliance is converted from the fuel gas it was using to another fuel (natural gas, propane, butane or other fuel gas) , the location in which the appliance is to be operated should be checked to verify the following.
q Check to make sure the proper fuel jets or nozzles are installed in the appliance for the fuel. The appliance label should identify the fuel type for the burner assembly on that appliance. Different fuels have different caloric values or heat contents per cubic foot. Natural gas is generally around 1000 BTU/Cubic foot of gas. Propane is about 2,500 BTU/Cubic foot of gas. Butane can be as much as 3,200 BTUs/Cubic foot. Methane gasses are becoming more popular as gasses are being recovered from landfills and sewage treatment processes to run generators to create power locally. Manufactured gasses can have various BTU/cubic foot values and the designer should check with the source for a caloric value. The caloric value is what determines the size of the burner opening or opening size in the burner nozzles. For example a natural gas nozzle will typically be 2.5 times larger in area than a propane nozzle because the BTU content is lower. If the wrong burner is installed for the fuel that is supplied, it can cause problems that could lead to a fire or carbon monoxide asphyxiation.
q Check to make sure air openings or ducts for combustion air and ventilation are provided where required, in accordance with the provisions of the fuel gas code. Where existing combustion air openings are not adequate, they should be upgraded to the requirements in the local fuel gas code.
q Check to make sure the installation components and appliances meet the clearances to combustible material.
q Check to make sure that the installation and operation of the additional or replacement appliance does not render the remaining appliance unsafe for continued operation.
Metal flue joints
Joints between sections of connector piping and connections to flue collars or draft hood outlets should be fastened in accordance with one of the following methods.
q By sheet metal screws.
q Vent connectors of listed vent material should be assembled and connected to flue collars or draft hood outlets in accordance with the manufacturer’s instructions.
q Other approved means.
q Note: 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.
q Type B vents should extend in a generally vertical direction with offsets not exceeding 45 degrees, except that a vent system having not more than one 60 degree offset is sometimes permitted. Check with the local code. Any angle greater than 45 degrees from the vertical is considered horizontal. The total horizontal distance of a vent plus the horizontal vent connector serving draft-hood-equipped appliances should not exceed 75 percent of the vertical height of the vent to maintain the draft in the flue.
q The maximum horizontal length of a single-wall connector should be 75 percent of the height of the chimney to maintain the draft in the flue or vent except for engineered systems.
q The maximum horizontal length of a Type B double-wall connector should be 100 percent of the height of the chimney or vent, except for engineered systems. The maximum length of an individual connector for a chimney or vent system serving multiple appliances, from the appliance outlet to the junction with the common vent or another connector should be 100 percent of the height of the chimney or vent.
q A gas vent should terminate in accordance with one of the following:
q Above the roof surface with a listed cap or listed roof assembly.
q Gas vents 12inches in size or smaller with listed caps should be terminated in accordance with the distances identified in the local fuel gas code, provided they are at least eight feet from a vertical wall or similar obstruction.
q A Type B or a Type L gas vent should terminate at least five feet in vertical height above the highest connected appliance draft hood or flue collar.
q Electric water heaters are required to have an electrical disconnect within sight of the water heater or have a breaker that is of a locking type.
Ron George, CPD, is president of Plumb-Tech Design & Consulting Services LLC. Visit www.Plumb-TechLLC.com.