Tankless Water Heater Plumbing code installation

Tankless water heater is becoming more and more popular nowadays, most of my water heaters inspections are tankless water heaters.

Tankless water heater takes less space and can be installed indoor and outdoor. This blog will have all information related to the plumbing code requirements installing Tankless water heaters.

Does replacing the Tankless water require a plumbing permit?

Local jurisdictions (cities , counties) require a plumbing permit to install a new tankless electric water heater and gas water heater as well.

The local jurisdictions will require one Final inspection to inspect the water heater after all work has been completed. (CPC 503.0).

If a new gas line being installed to relocate the water heater. An additional Gas test inspection will be required prior final inspection.

Read more: Benefits of replacing your old water heater.

Who can apply for a plumbing permit?

Per CSLB a C-36 – Plumbing Contractor. However, if the homeowner is doing the work himself/herself, the local jurisdictions will allow him/her to obtain the plumbing permit.

Plumbing code requirements replacing Tankless water heater

Tankless water heater Location

The location of the tankless water heater per the plumbing code is not listed. The manufacturer of the water heater specify if the water heater is suitable for installation indoor or/and outdoor, so I recommend reading the manufacturer specs before purchasing if you have specific location in mind.

But mainly most of the tankless water heaters are approved for indoor and outdoor. If you planning to relocate the water heater to outside location, check with the local planning departments for location approval.

Gas-fired water heaters, which depend on the combustion of fuel for heat, shall not be installed in the following locations: (CPC 505.0)

  1. A room used or designed to be used for sleeping purposes.
  2. A bathroom.
  3. A clothes closet.
  4. In a closet or other confined space opening into a bathroom or bedroom.
    Exception: Direct vent water heaters. (CPC 505.1).

Read more: Why my water heater makes sounds and how to stop it.

Tankless water heater clearance

Another thing, the plumbing code, is not mentioning is the tankless water heater clearance, and it also up to the every manufacturer to set the clearance from combustible and non-combustible materials.

tankless water heater clearance
Tankless water heater clearance

Temperature and Pressure (T & P) Relief Valve & Discharge Line Water

Minimum ¾ inch T&P drain to terminate “outside” of the building no closer than 6 inches or further than 24 inches from grade.

T&P line must be looking downward with no threads on the end. Water heaters located in the garage may terminate on the garage floor with the same distance requirements. (CPC- UPC 505.6 CPC & 505.4, 508.5 & 608.5). T&P does not discharge into a water heater drain pan. (CPC- UPC 508.5).

Gas line sediment trap (drip leg)

Sediment trap (T, 3” minimum nipple and cap) installed on water heater’s gas supply. (CPC- UPC 1212.7).

Gas connectors sized for the BTU input rating of appliance. Does not exceed 3 feet in length and is connected downstream of approve shut of valve.

tankless gas water heater rough installation
Replacing tankless gas water heater

Water lines shutoff

A full bore shut off valve is required on cold water side only, but preferably on cold and hot water lines.

Water heater vent

Venting system sized and constructed per manufacture’s specifications (CPC 510.10.3). Vent termination shall be per manufacturer’s installation instructions.

Distances to building openings, floors, overhangs etc. must be maintained. Wall vents shall not discharge through walls located 5 feet or less from any property line.

Combustion Air for tankless gas water heater

For combustion, ventilation, and dilution of flue gases for appliances shall be obtained by application covered in (CPC 506.2 through 506.7.3).

Metallic Piping bonding

Continuously with copper bonding wire and bonding clamps to cold, hot, and gas lines to tie systems together at water heater, using a #8 for 100 amps service and a #6 for 200 amps service. (C.E.C. 250.104. 2016).

Only if the water lines (Hot & Cold) inside the house are metallic, if PEX or non-metallic materials are being used, bonding is not required.

Electrical outlet (Receptacle)

110/120V receptacle installed within 3 feet of equipment. Attic or basement installations will require a switched luminary at or near the equipment for service.

The switch for the luminary must be located adjacent to the attic or basement access. all new electrical work is required an electrical permit.


Reference Codes – Uniform Plumbing Code (UPC) – California Plumbing Code – National Electrical Code