Just imagine: water heaters sometimes enter zones of extreme temperature and pressure, and building code helps prevent costly mistakes.
If the TPR valve and discharge piping isn't up to par, it can lead to burns.
Or if the water heater isn't protected from cars, it can result in severe damage.
And if you are in an earthquake or seismic zone, straps need to be installed in case of disaster.
In this HomeInspectorSecrets.com guide, you will learn:
- A catch pan is needed if there is water damage risk
- Discharge piping is required that goes to the TPR valve
- Where exactly discharge piping should terminate
- A few locations where you can't install a water heater
Keep reading to learn our list of the top 10 water heater installation codes!
What Are Water Heater Installation Code Requirements?
Water heater installation code requirements improve home safety and help prevent water damage.
A water heater is a compact tank full of pressurized hot water. Water heaters have even been known to explode on occasion. And of course, water heaters can cause significant water damage if it leaks in a finished area.
The International Residential Code
Water heater installation code is clearly laid out in the IRC or International Residential Code in Chapter 28 - Water Heaters.
The IRC is known as a model code, and many U.S. states and countries have adopted it. Your local state may have some variation to the IRC or exceptions.
And don't forget, your local county or state will likely require a permit for a water heater installation and for it to be installed by a licensed plumber.
This article covers the most important water heater install codes in the IRC, but always check your local state because it has priority.
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10 Water Heater Installation Code Requirements
- A Pan Needs To Be Installed If There Is Water Damage Risk
- Catch Pan Should Be Made of Approved Material
- Prohibited Install Locations Of Water Heaters
- Water Heaters Need To Be Protected From Damage
- Water Heaters With Ignition Sources Should Be Raised
- Water Heaters Should Be Protected From Earthquakes
- TPR Valve Is Required
- Discharge Pipe Should Be Installed Onto TPR Valve
- Discharge Pipe Should Terminate To Pan, Outside, or Floor Drain
- Shutoff Or Check Valves Are Prohibited
Code #1. A Pan Needs To Be Installed If There Is Water Damage Risk
A catch pan should be installed underneath the water heater where leakage will cause damage.
A catch pan will collect any leaking water and prevent drywall, subfloor, wood flooring, and any other finish materials from getting damaged.
If the water heater is installed in a finished area, there should be a pan installed. If the water heater is in a garage, unfinished basement, or outside, then a catch pan is not required.
Also, if the water heater is in the attic, the water heater needs a catch pan because it may leak onto the finished ceiling below.
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Code #2. Catch Pan Should Be Made of Approved Material
The catch pan should be made out of No. 24 galvanized steel, plastic at least 0.9-mm thick, or other approved materials by the manufacturer.
If the catch pan is made out of plastic, and the water heater is gas-fired, then the plastic pan needs to have a flame spread index of 25 or less. Also, the smoke developed index should be 450 or less.
Code #3. Prohibited Install Locations Of Water Heaters
Water heaters are prohibited from being installed in any area if it is being used as a storage closet.
Water heaters are prohibited from being installed in bedrooms or bathrooms unless it is in a sealed enclosure. Also, combustion air cannot be taken from the adjacent bedroom or bathroom.
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Code #4. Water Heaters Need To Be Protected From Damage
Water heaters need to be protected from getting hit by cars.
If the water heater is in a garage or some area where there is risk of car damage, then it needs to have a barrier.
Code #5. Water Heaters With Ignition Sources Should Be Raised
Water heaters need to be raised above the floor on a platform if it has an ignition source.
If you have a gas or oil-fired water heater with an ignition source (open flame or spark), then the water heater needs to be raised at least 18-inches above the floor.
Sometimes flammable vapors get released by accident in homes (especially garages), and the vapors tend to stay near the floor. If the water heater creates a spark or flame, it may ignite the flammable vapor, which is why this code is required.
One exception to this code is if the water heater is flammable vapor ignition-resistant as stated by the manufacturer.
Code #6. Water Heaters Should Be Protected From Earthquakes
The water heater needs to be protected from earthquakes if it is in a seismic zone.
There should be at least two straps on the top 1/3 and the bottom 1/3 of the water heater.
Each strap should be able to handle horizontal forces of at least 1/3 the weight of the water heater. For this building code, it only applies to homes in Seismic Categories of D0, D1, D2, and townhomes in C.
Code #7. TPR Valve Is Required
A TPR valve (temperature pressure relief) is required on water heaters to prevent an explosion.
If the pressure becomes too great in the tank, or if the temperature rises too high, then the TPR valve will release water and steam.
It can be a single 'combo' TPR valve, or the water heater is allowed to have a separate temperature relief valve and pressure relief valve.
Code #8. Discharge Pipe Should Be Installed Onto TPR Valve
The TPR valve needs a discharge pipe.
Sometimes when I inspect homes, the water heater is missing a discharge pipe.
This is dangerous because if the TPR valve is released, and if someone is in the room, they can get severely burned.
Code #9. Discharge Pipe Should Terminate To Pan, Outside, or Floor Drain
The discharge pipe for the TPR valve should go outside, to a catch pan, or a floor drain.
If it terminates on the outside, the discharge pipe should be visible to homeowners.
The discharge pipe should also be adequately sloped so it will drain by gravity.
The discharge pipe needs to terminate a maximum of 6-inches above the floor, and a minimum of 2x the pipe diameter.
Here are a few other code requirements for discharge piping:
- Should not be directly connected to drainage system
- There should be an air gap
- Pipe size shouldn't be smaller than the TPR valve
- Only a single pipe allowed (it shouldn't serve another system)
- P-trap is not allowed
- Threaded end is not allowed
Code #10. Shutoff Or Check Valves Are Prohibited
Check valves and shutoff valves are not allowed to be installed between the TPR valve and the termination.
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Final Thoughts On Water Heater Install Codes
Water heater installation codes are essential guidance for safety.
Water heaters are pressurized tanks, and have the explosive potential to destroy an entire home. And if they leak, water heaters may cause significant flooding damage.
Probably the most important codes has to do with the requirements for the TPR valve and discharge piping. The TPR valve is an essential safety device, and the discharge piping will also prevent burns to a nearby person.
I hope you enjoyed our guide on water heater installation code.