CNI-036 Water Heaters

Version 08/30/2023

This handout is to inform building permit applicants of the specific codes that may be required when replacing an existing water heater with another water heater or heat pump.

There are special code requirements for ALL water heaters. Permit Sonoma offers auto-issued water heater permits and it is important to understand what the code implications are. For example, on-demand tankless water heaters require substantially more natural gas than standard storage tank water heaters. The existing gas line(s) may not be properly sized to provide the required volume of fuel and may require larger gas line(s) to handle the additional demand (See Figure 1).

On-demand tankless water heaters require special venting to comply with specific manufacturers’ requirements. The entire existing water heater venting system may need to be replaced based on specific manufacturers’ requirements. For example, a stainless-steel vent may be required, and the existing combination venting system may not be allowed (See Figure 1).

Costs associated with the installation of different water heaters such as going from a storage tank water heater to a tankless can be more expensive overall. Installing new vents that comply with manufacturers’ specifications, and upsizing of existing gas supply line(s) are the main reasons for the increase in costs. Some costs may be reduced by prior planning of the proposed location of the replacement unit. Careful consideration may help decrease some of the costs associated with replacing a standard heater with an on-demand tankless type.

Figure 1: Proposed Condition with On Demand Water Heater

Plans are not required for building permit issuance. However, at the first inspection, the applicant may need to provide the Building Inspector with the manufacturer’s specifications and an isometric drawing showing gas pipe sizes and load calculations from the meter to the most remote gas-fueled appliance, in accordance with the current edition of the California Plumbing Code (See Figure 2).

Figure 2: Required Isometric Diagram of Proposed Condition

Additional code requirements are listed below.

Note: If a new gas line is being installed, a pressure test and inspection will be required.

Gas – Tank Water Heater (See Figure 3)

1. Installation water heaters shall be installed as per the manufacturer’s installation instructions and current California Plumbing Code and California Energy Code. Requirements The inspector will be looking for the following minimum requirements: (Refer to the illustration for itemized references)
2. Elevated Platform: Gas-fired water heaters located in a garage shall be installed so that burners and burner-ignition devices are located not less than 18 inches above the floor unless listed as flammable vapor ignition resistant. (CPC 507.13)
3. Seismic Bracing: In order to prevent the water heater from toppling over during an earthquake, it must be secured to the wall in an approved manner. (CPC 507.2)
   • Two straps required. Strapping must be located at points within the upper one-third and lower one-third of the water heater and must wrap completely around water heater and back to wall.
   • Lower strap must be at least 4 inches above the controls.
   • The third strap is required for water heaters exceeding 52 gallons and the ends of all straps must be secured to a stud with a minimum ¼- inch x 3-inch lag bolt with a washer.
   • (Please note that plumbing tape is not permitted as strapping material).
4. Appliance Vent: That portion of the venting system, which penetrates the ceiling floor, attic or roof systems must be of type B, BW, type L, or other listed assembly approved by the Building Official. The appliance vent shall extend in a generally vertical direction with offsets exceeding 45 degrees.
   • For new water heaters, a category III, IV, or Type B vent with straight pipe between the outside termination and the water heater space will be required. (CEC 110.0(b)1.150.0(n)1)
5. Vent Connector: That portion of the appliance vent, which is within the same room as the appliance. Vent sections must have a minimum rise of ¼-inch per foot. Clearance from the vent connector to any combustible construction must be at least 6 inches for single wall pipe and 1 inch for double wall pipe.
6. Clearance of Combustibles: The clearance from the appliance vent to any combustible construction must be at least 1 inch. In order to maintain clearances from combustible insulation in attics, a metal sleeve shall be provided around the vent pipe, extending 6 inches above insulation and maintaining a minimum of 1 inch around vent. (CPC Table 509.7.3)
7. Vent termination: Vents must be extended above the roof surface a minimum of 12 inches and terminated in an approved vent cap. The minimum total height of the venting system is 5 feet from vent collar to termination. Termination must be a minimum of 4 feet from any opening into the building. (CPC 509.6 & Table 509.4 509.6.2)
8. Temperature & Pressure Relief Valve & Drain Line: All storage-type water heaters must be equipped with a listed temperature and pressure relief valve and drain line. The drain line should be equal to the outlet size, but in no case be less than ¾-inch copper or galvanized pipe and must extend from the valve to the outside of the building. The end of the pipe should not be more than 24 inches or less than 6 inches above the ground and point downward. If you cannot drain to the outside, other locations for termination shall be approved by the Building Official. (CPC 504.6 & 608.5)
9. Combustion Air: Combustion air shall be provided in accordance with Section 506 of the CPC.
10. Gas Connection: The gas supply must have a shut-off valve adjacent to the water heater. An approved flex connector may be used for the final connection to the water heater. Maximum length for the flex connector is 3 feet. A shut-off valve must be located ahead of the flex connector and before the sediment trap (drip leg) per manufacturer’s instructions. (CPC 1211.5) For new water heaters, the gas line shall be sized to allow a capacity of at least 200,000 BTU/hr.
11. Noncombustible Collar: A metal collar shall be placed against the ceiling to seal the gap between the sheetrock and the vent.
12. Pipe Insulation: The first 8 feet minimum of both cold and hot water inlet and outlet piping must be insulated. (CEEC 120.3)
13. Pipe Bollard: If the water heater is located in the path of travel of a vehicle, a bollard will be required to be installed so as to protect the water heater from damage.
14. The water system shall have an approved, listed and adequately sized expansion tank or other approved device having a similar function to control thermal expansion over 80 PSI. (CPC 608)
15. Bonding of Piping: Water and gas pipes shall be bonded. (CEC 250.104) 15. Electrical Outlet when applicable: Per manufacturer’s installation instructions and the CEC a dedicated 125-volt, 20-amp electrical receptacle.

Figure 3: Typical Installation of Tank Gas Water Heater

Gas – Tankless Water Heater

1. Installation water heaters shall be installed as per the manufacturer’s installation instructions and current California Plumbing Code and California Energy Code. Requirements The inspector will be looking for the following minimum requirements: (Refer to the illustration for itemized references)
2. Seismic Bracing: Per manufacturer’s instructions. (CPC 507.2) 
3. Appliance Vent: That portion of the venting system, which penetrates the ceiling floor, attic or roof systems must be of type B, BW, type L, or other listed assembly approved by the Building Official. The appliance vent shall extend in a generally vertical direction with offsets exceeding 45 degrees. 
   • For new water heaters, a category III, IV, or Type B vent with straight pipe between the outside termination and the water heater space will be required. (CEC 110.0(b)1.150.0(n)1)
4. Vent Connector: That portion of the appliance vent, which is within the same room as the appliance. Vent sections must have a minimum rise of ¼ inch per foot. Clearance from the vent connector to any combustible construction must be at least 6 inches for single wall pipe and 1 inch for double wall pipe.
5. Clearance of Combustibles: The clearance from the appliance vent to any combustible construction must be at least 1 inch. In order to maintain clearances from combustible insulation in attics, a metal sleeve shall be provided around the vent pipe, extending 6 inches above insulation and maintaining a minimum of 1 inch around vent. (CPC Table 509.7.3)
6. Vent termination: Vents must be extended above the roof surface a minimum of 12 inches and terminated in an approved vent cap. The minimum total height of the venting system is 5 feet from vent collar to termination. Termination must be a minimum of 4 feet from any opening into the building. (CPC 509.6 & Table 509.4 509.6.2)
7. Temperature & Pressure Relief Valve & Drain Line: All storage-type water heaters must be equipped with a listed temperature and pressure relief valve and drain line. The drain line should be equal to the outlet size, but in no case be less than ¾-inch copper or galvanized pipe and must extend from the valve to the outside of the building. The end of the pipe should not be more than 24 inches or less than 6 inches above the ground and point downward. If you cannot drain to the outside, other locations for termination shall be approved by the Building Official. (CPC 504.6 & 608.5)
8. Combustion Air: Combustion air shall be provided in accordance with Section 506 of the CPC.
9. Gas Connection: The gas supply must have a shut-off valve adjacent to the water heater. An approved flex connector may be used for the final connection to the water heater. Maximum length for the flex connector is 3 feet. A shut-off valve must be located ahead of the flex connector and before the sediment trap (drip leg) per manufacturer’s instructions. (CPC 1211.5) For new water heaters, the gas line shall be sized to allow a capacity of at least 200,000 BTU/hr.
10. Noncombustible Collar: A metal collar shall be placed against the ceiling to seal the gap between the sheetrock and the vent.
11. Pipe Insulation: The first 8 feet minimum of both cold and hot water inlet and outlet piping must be insulated. (CEEC 120.3)
12. Pipe Bollard: If the water heater is located in the path of travel of a vehicle, a bollard will be required to be installed so as to protect the water heater from damage.
13. The water system shall have an approved, listed and adequately sized expansion tank or other approved device having a similar function to control thermal expansion over 80 PSI. (CPC 608)
14. Bonding of Piping: Water and gas pipes shall be bonded. (CEC 250.104) 15. Electrical Outlet when applicable: Per manufacturer’s installation instructions and the CEC a dedicated 125-volt, 20-amp electrical receptacle.

Electric – Tank Water Heater

1. Installation water heaters shall be installed per the manufacturer’s installation instructions and current California Plumbing Code and California Energy Code. Requirements The inspector will be looking for the following minimum requirements: (Refer to the illustration for itemized references)
2. Seismic Bracing: In order to prevent the water heater from toppling over during an earthquake, it must be secured to the wall in an approved manner. (CPC 507.2)
   • Two straps required. Strapping must be located at points within the upper one-third and lower one-third of the water heater and must wrap completely around water heater and back to wall.
   • Lower strap must be at least 4 inches above the controls.
   • The third strap is required for water heaters exceeding 52 gallons and the ends of all straps must be secured to a stud with a minimum ¼- inch x 3-inch lag bolt with a washer.
   •  (Please note that plumbing tape is not permitted as strapping material).
3. Clearance of Combustibles: Per manufacturer’s instructions.
4. Temperature & Pressure Relief Valve & Drain Line: All storage-type water heaters must be equipped with a listed temperature and pressure relief valve and drain line. The drain line should be equal to the outlet size, but in no case be less than ¾-inch copper or galvanized pipe and must extend from the valve to the outside of the building. The end of the pipe should not be more than 24 inches or less than 6 inches above the ground and point downward. If you cannot drain to the outside, other locations for termination shall be approved by the Building Official. (CPC 504.6 & 608.5)
5. Pipe Insulation: The first 8 feet minimum of both cold and hot water inlet and outlet piping must be insulated. (CEEC 120.3)
6. Pipe Bollard: If the water heater is located in the path of travel of a vehicle, a bollard will be required to be installed so as to protect the water heater from damage.
7. The water system shall have an approved, listed and adequately sized expansion tank or other approved device having a similar function to control thermal expansion over 80 PSI and adequately secured. (CPC 608)
8. Bonding of Piping: Water and gas pipes shall be bonded. (CEC 250.104) 15. Electrical Outlet when applicable: Per manufactures installation instructions and the CEC a dedicated 125-volt, 20-amp electrical receptacle.

Electric – Tankless Water Heater

1. Installation Water heaters shall be installed as per the manufacturer’s installation instructions and current California Plumbing Code and California Energy Code. Requirements The inspector will be looking for the following minimum requirements: (Refer to the illustration for itemized references)
2. Seismic Bracing: Per manufacturer’s instructions. (CPC 507.2) 
3. Appliance Vent: That portion of the venting system, which penetrates the ceiling floor, attic or roof systems must be of type B, BW, type L, or other listed assembly approved by the Building Official. The appliance vent shall extend in a generally vertical direction with offsets exceeding 45degrees.
   • For new water heaters, a category III, IV, or Type B vent with straight pipe between the outside termination and the water heater space will be required. (CEC 110.0(b)1.150.0(n)1)
4. Vent Connector: That portion of the appliance vent, which is within the same room as the appliance. Vent sections must have a minimum rise of ¼-inch per foot. Clearance from the vent connector to any combustible construction must be at least 6 inches for single wall pipe and 1 inch for double wall pipe.
5. Clearance of Combustibles: The clearance from the appliance vent to any combustible construction must be at least 1 inch. In order to maintain clearances from combustible insulation in attics, a metal sleeve shall be provided around the vent pipe, extending 6 inches above insulation and maintaining a minimum of 1 inch around vent. (CPC Table 509.7.3)
6. Vent termination: Vents must be extended above the roof surface a minimum of 12 inches and terminated in an approved vent cap. The minimum total height of the venting system is 5 feet from vent collar to termination. Termination must be a minimum of 4-feet from any opening into the building. (CPC 509.6 & Table 509.4 509.6.2)
7. Temperature & Pressure relief valve and drain line. The drain line should be equal to the outlet size, but in no case be less than ¾-inch copper or galvanized pipe and must extend from the valve to the outside of the building. The end of the pipe should not be more than 24 inches or less than 6 inches above the ground and point downward. If you cannot drain to the outside, other locations for termination shall be approved by the Building Official. (CPC 504.6 & 608.5)
8. Combustion Air: Combustion air shall be provided in accordance with Section 506 of the CPC.
9. Gas Connection: The gas supply must have a shut-off valve adjacent to the water heater. An approved flex connector may be used for the final connection to the water heater. Maximum length for the flex connector is 3 feet. A shut-off valve must be located ahead of the flex connector and before the sediment trap (drip leg) per manufacturer’s instructions. (CPC 1211.5) For new water heaters, the gas line shall be sized to allow a capacity of at least 200,000 BTU/hr.
10. Noncombustible Collar: A metal collar shall be placed against the ceiling to seal the gap between the sheetrock and the vent.
11. Pipe Insulation: The first 8 feet minimum of both cold and hot water inlet and outlet piping must be insulated. (CEEC 120.3)
12. Pipe Bollard: If the water heater is located in the path of travel of a vehicle, a bollard will be required to be installed so as to protect the water heater from damage.
13. The water system shall have an approved, listed and adequately sized expansion tank or other approved device having a similar function to control thermal expansion over 80 PSI. (CPC 608)
14. Bonding of Piping: Water and gas pipes shall be bonded. (CEC 250.104) 15. Electrical Outlet when applicable: Per manufacturer’s installation instructions and the CEC a dedicated 125 volt, 20 amp electrical receptacle.

• Base plate 8 inches X 8 inches X 1/2 inches
• 5/8 inch anchor (5/8 inch X 4 inches wedge anchor or concrete screw anchor 1600 lb minimum allowable tension at 2-3/4 inches embedment)
• 4 inches schedule 40 steel pipe ¼ inch minimum fillet weld to base minimum 36 inches
• Reflector strip existing
• 4 inches minimum slab grade commercially available