There might be some minor discrepancies between jurisdictions which will in most (probably not all) cases concern seismic areas water heater installations. I’ll cover it within this water heater inspection manual but I would highly recommend to obtain a water heater installation permit from your local building department (usually required) and verify plumbing code requirements in your particular area.
There must be a water shutoff valve installed ONLY on a cold / inlet line of the water heater. This is required for the emergency and servicing purposes; so the water flow can be easily turned off in case of a leak or appliance servicing.
The water shutoff valve must be installed at or near the water heater / only a full-bore valve type is permitted for this purpose.
Water supply and distribution line material requirements vary between jurisdictions. They might be copper, plastic, galvanized, or even lead in older buildings.
While performing water heater inspection check for union connectors; they are required within 12″ from the water heater’s inlet and outlet side. Their type will depend on the water pipe material in your home. Dielectric and brass unions are safe for all types of water pipe materials (required for copper water pipes) because they provide required separation for different metal types to prevent their corrosion. Galvanized unions can be used for galvanized and plastic water pipes only.
Some jurisdictions will require / some forbid final water pipe connection to the water heater to be flexible. Also, some will require heat traps / heat loops on those flexible lines. I believe that most of the new water heaters will have heat traps built in, if not, a curved flexible line directly above the appliance servs the same purpose; allows cold water to flow into the hot water heater’s tank and prevents hot water convection / mixing with cold water and flowing out of the tank when not in use.
Installed water heater lines union connectors should be checked for leaks during the water heater inspection.
If you jurisdiction adopted UPC (Universal Plumbing Code), minimum R4 thermal resistance value insulation might be required on hot and cold water pipes withing 5′ from the water heater’s inlet and outlet.
Some water heaters have a hot water recirculating loop installed, which guarantees instant hot water at the furthest faucet from the water heater. Unfortunately such installation wastes significant amounts of energy and all of the recirculating hot water pipes might require to be insulated.
Most newer water heaters include integral R12 or higher value insulation and do not require additional external blanket insulation installation. However, in case the water heater has a lesser value integral insulation or it has been installed in an unheated area, extra layer of insulation is recommended and might be required.
Water heater thermostat temperature setting is a serious safety issue but not a code requirement. The most recommended setting is under 125°F (48,88°C). But continuous exposure of a child’s skin can even at that temperature result in 2nd or 3rd degree burns.
Tank type water heater installations in areas where leakage could cause damage require protective watertight drip pan underneath. This requirement also applies to a cabinet / under the countertop installations.
Since this is an extremely important water heater inspection topic and serious safety issue, please follow this link to a dedicated article: water heater pressure relief valve
An expansion tank would be required if a check valve / back flow preventer has been installed on a cold water supply line creating what is referred to as closed water system.
Sufficient amount of combustion air MUST be provided for the water heater to operate properly and to prevent incomplete combustion which might result in producing elevated levels of Carbon Monoxide gas. For explanation of this subject and examples follow this link – “Water heater combustion air“.
Water heater inspection – gas connectors
Some states (including Illinois) require heavy wall gas pipes or CSST (Corrugated Stainless Steel Tubing) as a water heater’s final gas connector. No appliance type (commonly used for gas ranges and clothes dryers) flexible connectors are permitted in Illinois.
However, there are jurisdictions where flexible connectors might be recommended or required in water heater installations (seismic areas). Therefore, while performing water heater inspection, gas connector type should be verified with a local building department, and / or gas lines servicing utility company.
Common requirements for a gas flexible connector are that it cannot run through or be concealed inside any wall, floor, or other partition. Also, gas flexible connector should not come in contact with objects like metal wall studs, electrical wiring, copper or iron piping, paneling, sheet metal, etc.
Maximum length of a flexible water heater gas connector is 3 feet.
Water heater must have a dedicated gas shutoff valve installed within 6 feet from the appliance, in the same room as the WH, and upstream of the union connector. Where a flexible connector is used, the valve must be installed upstream of the connector.
A union or flanged connection is required between the gas shutoff valve and the water heater. Flexible connectors already include flanged connector so no extra union is needed when using one of those. This is to allow removal of the water heater or its controls without removal of the shutoff valve.
Water heater gas supply line should have a sediment trap (also known as a drip leg) installed to collect moisture and prevent possibility of gas valve / thermostat contamination. It should be installed as close to the water heater’s gas valve / controller as practical at the time of equipment installation. Gas line’s drip leg can be in a form of a tee fitting with a capped nipple in the bottom or another device approved as an effective sediment trap. Again, this may not be required everywhere.
Garage water heater inspection
Follow this link – garage gas water heater – for explanation of such installation.
Based on the UPC (Uniform Plumbing Code) section 510.5, water heaters located in seismic zones 3&4 require strapping and / or anchoring to resist horizontal displacement caused by an earthquake. If you’re not sure about your seismic zone, use this US Seismic Zone Map (please let me know if the map is gone at that link) to determine it or call your local authorities.
The following general requirements stated in UPC might vary in your area: “Strapping shall be at points within the upper one-third (1/3) and lower one third (1/3) of its vertical dimensions. At the lower point, a minimum distance of four (4) inches (101.6 mm) shall be maintained above the controls with the strapping”
Follow this link for detailed California Guidelines for Earthquake Bracing of Residential Water Heaters
Water heater draft hood’s diameter depends on the size / BTU’s of the appliance. Residential size water heaters have usually 3″ or 4″ diameter draft hoods, some accept both sizes; the collar of the draft hood will have a profile that allows for different diameter vent pipes installation (picture).
A 3″ diameter draft hood should only have a 3″ diameter vent pipe directly attached to it. 4″ diameter vent pipe can be used as well but only with a reducing coupling.
New, 4″ diameter draft hood water heater installation in place of an old one that utilized 3″ diameter draft hood and a 3″ diameter galvanized vent pipe requires entirely new 4″ diameter vent pipe connector. No part of the old, smaller size water heater vent pipe can be re-used!
Although there is no UPC code that would mandate water heater’s vent connector having 12″ vertical rise above the draft hood, the Gama venting tables that are required for proper vent pipe / chimney calculations start with a 12″ minimum vent connector rise.
All water heater single wall vent pipe connections must be secured with 3 sheet metal screws each (unless some other form of fastening has been approved in your jurisdiction) which includes draft hood connection. Using metallic duct tapes is generally not permitted on water heater vent pipes because it limits monitoring and prevents spotting corrosion and leakage signs, which should be investigated by a professional ASAP .
B-vent type water heater vent pipes require no screws on their joins because they utilize twist and lock connections. The only area that requires screws is the first joint with a single wall vent pipe or draft hood connection.
Venting a furnace that utilizes induced draft motor and a natural draft water heater into a common vent requires “Y” shaped connection. This is required to prevent exhaust gases from the furnace from being pushed back into the house through the water heater’s vent pipe / draft hood.
Click – water heater venting – for an article dedicated to this subject.
Tank type water heaters utilizing power vent must have its PVC vent pipe joints sealed / glued using appropriate PVC cement that creates air tight joint. Using silicon for this purpose is not permitted.
The PVC vent pipe’s first connection to the power vent assembly collar is usually made with rubber sleeve / coupling and two clamps, which quiets vibration and minimizes its transfer onto the PVC vent pipe joints.
Water heater’s PVC vent pipe must be properly supported along its entire vertical and horizontal run to prevent sagging and dipping. Manufacturers span support recommendations vary between 3′-6′ with the first support / strap located immediately adjacent to the first 90° elbow. This might be further regulated by you local authorities.
The diameter and the minimum / maximum length of the water heater’s PVC vent pipe must be verified using the water heater’s installation manual. It usually depends on the appliance’s tank size, power vent motor, BTU’s, and the number of elbows along the entire run.
Click the following link - water heater PVC vent pipe - for additional material covering water heater’s PVC vent pipe. You need it to complete this power vent water heater inspection .
Water heater drip pan, TPR valve and discharge pipe requirements are the same as above.
Electric water heater requires in-sight or lockable disconnect, 220V circuit breaker should be labeled accordingly.
Electrical conduit must be secured to the connection box with a listed type connector and wiring performed / concealed inside the compartment / protected with a cover.
Electrical conduit must not touch metal water pipes.
Electric water heater requires grounding – a ground terminal is usually located inside the connection box or in its vicinity.
Green color wire or green tape marked wire must be attached to the WH grounding terminal and to the electrical service ground terminal.
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This article was written by Dariusz Rudnicki
I'm a retired Illinois home inspector, founder and editor of checkthishouse.com, a blog which attracts around 2 thousand readers daily and is dedicated to answering the many questions of home owners and home buyers. Connect with me on Google+ Find me on Google+ Local