How to Replace a Mobile Home Water Heater

Choosing and Installing a New Unit for Your Home

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Project Overview
  • Working Time: 2 - 3 hrs
  • Total Time: 2 - 3 hrs
  • Skill Level: Advanced
  • Estimated Cost: $500 to $800

Water heaters in mobile or manufactured homes are very similar to conventional water heaters used in site-built homes. But there are differences between a mobile home water heater and a regular water heater; you can't just put a house water heater into a mobile home when it's time for a replacement. Most importantly, the type of water heater that goes in a mobile home must be rated for mobile home use. All mobile home heater installations must include sufficient space and ventilation for the equipment, and the heater tanks must be secured to prevent movement.

The following how-to steps outline the basic procedure for replacing a standard (not sealed-combustion) water heater in an exterior compartment of a mobile home. Specific installation steps and requirements may vary by area and your particular water heater.

Choosing a New Mobile Home Water Heater

In most cases, water heaters are replaced with new units that use the same fuel source as the original. The most common fuel types are electric and gas, but there are also some fuel-oil units. Since a mobile home's size is limited and the location of a water heater is usually in a closet, you will typically have the choice of a 30- to 40-gallon size water heater.

HUD and Code Approval

Mobile home water heaters must meet specific standards established by the U.S. Department of Housing and Urban Development (HUD). All heaters approved for use in manufactured homes carry a label indicating HUD compliance. Using a standard, non-compliant unit in a mobile home will likely run afoul of the local building code and can lead to other problems. Home insurers may not honor claims related to non-compliant water heaters, and non-compliant heaters can create roadblocks when selling a home.

Water heaters designed for manufactured homes typically have a few specific features:

  • Side-mounted cold water inlet (sometimes the hot water outlet is also at the side of the tank)
  • Meets HUD standards for insulation and energy efficiency
  • Non-adjustable temperature-and-pressure relief (TPR) valve
  • Smaller overall size than comparable standard units (in some cases)
  • Gas heaters are sealed-combustion if installed indoors

Water Heater Fuel Types

Gas heaters may use propane or natural gas, depending on the home's supply. It can be costly to convert to a different fuel type as part of a replacement project, but it is possible.

Electric units must have sufficient capacity in the home's electrical panel and typically require a dedicated 240-volt circuit, while gas heaters need a gas supply and special accommodations for combustion air and exhaust.

Installing new circuits or plumbing connections for a different fuel type usually requires a permit and may need to be performed by licensed professionals, significantly increasing the cost of replacing a water heater.

Water Heater Location

Regardless of whether you have a single- or double-wide mobile home, the location of a mobile home water heater is especially important if it is a gas unit. A water heater located inside a mobile home, such as in a closet or alcove with no outside access, must be a sealed-combustion unit so that there is no connection between the heater's intake and exhaust and the home's ambient air. A gas water heater that is located in an exterior compartment—with an access door only on the outside of the home—can be a standard gas water heater that is approved for mobile home use.

Before You Begin

Close the shutoff valve on the cold water supply line feeding the water heater. Turn off the gas valve on the water heater's gas control unit, then close the shutoff valve on the gas supply line feeding the heater. Let the water heater cool completely.

What You'll Need

Equipment / Tools

  • Garden hose
  • Adjustable wrenches, pipe wrenches, or tongue-and-groove pliers
  • Drill and attachments for driving screws or anchors
  • Drip pan and drain (as needed)


  • New water heater of appropriate size
  • Fasteners for tank brackets or strapping (as needed)
  • Sheet metal screw
  • Discharge tube for TPR valve (as needed)
  • Thread-seal tape for plumbing connections
  • Gas-rated thread-seal tape for gas connections
  • Gas-leak testing solution


Installing a New Unit for Your Home 

  1. Drain the Tank

    Attach a garden hose to the drain valve on the water heater tank. Extend the hose to a suitable drainage point, such as a landscape drain or a planted area. Open the drain valve completely to drain the water from the tank. Also, open the temperature-and-pressure relief (TPR) valve on the water heater to allow air into the system and prevent suction. When the tank is empty, close the drain valve and disconnect the garden hose.

  2. Remove the Old Water Heater

    Disconnect the flexible gas line from the gas control valve. Disconnect the hot and cold water lines from the tank outlet and inlet, respectively. Then, disconnect the vent duct from the draft hood on the tank. Remove all strapping or bracket fasteners securing the tank to the home's structure. Remove the tank from the water heater compartment.

  3. Install a Drip Pan

    Install a corrosion-resistant drip pan and drain for the new water heater, if necessary. You can reuse an existing pan if it is in good condition and is appropriately sized for the new heater.

  4. Add the TPR Valve

    Install the new temperature-and-pressure relief (TPR) valve onto the new water heater, following the manufacturer's directions.

  5. Place the New Water Heater

    Fit the new water heater into place on the drip pan. Position the heater so it is properly aligned with the existing gas supply, water piping, and vent duct. Secure the heater tank to the wall and floor, as applicable, using the brackets or strapping provided by the heater manufacturer. Be sure to follow local code requirements.

  6. Complete the Vent Connection

    Install the provided draft hood onto the new heater tank, as directed by the manufacturer. Typically, the hood snaps into place with a few tabs and may include screws. Fit the vent duct over the outlet on the draft hood, and secure the vent to the draft hood with a sheet metal screw.

  7. Add a TPR Discharge Tube

    Install a copper or CPVC pipe onto the TPR valve so the pipe drains to the home's exterior. You can reuse the old discharge tube if it is a suitable material, in good condition, and an appropriate size for the new TRP valve.

  8. Connect the Water Lines

    Connect the cold water supply pipe to the cold water inlet on the heater tank, using an approved supply connector and thread-seal tape for plumbing connections. Connect the hot water outlet on the tank to the hot water piping with an approved connector.

  9. Make and Test the Gas Connection

    Connect the gas supply tube to the gas control valve on the water heater as directed by the manufacturer, using gas-rated thread-seal tape. Turn on the gas supply to the water heater, and test all gas connections with a gas-leak testing solution to confirm there is no leaking.

  10. Fill the Tank

    Confirm that the drain valve on the heater tank is closed. Turn on the cold water supply to begin filling the tank. Open the hot water tap at the nearest faucet in the house. Let the tank fill until water flows at full force out of the hot water tap (indicating the tank is full), then close the faucet tap.

  11. Check the Installation and Start the Tank

    Confirm that all connections are secure and there are no water or gas leaks. Start the pilot light on the heater following the manufacturer's directions.

  • What is the standard-size water heater for a mobile home?

    A 30-gallon water heater is commonly installed in a mobile home, though there are 40-gallon tanks that can fit in a mobile home, as well. In addition, there are smaller HUD-approved 28-gallon tanks that may be able to suffice for the needs of one person living in a mobile home, though any water heaters smaller than that are designed for specific dedicated uses and not for whole homes.

    A 30- and 40-gallon tank services one to four people, respectively. There is limited room in a mobile home, so a 50-gallon tank (which services four to six people) would typically not be possible to install. Keep in mind that one shower usually uses 20 gallons of water.

  • How long does a mobile home hot water heater last?

    Whether you live in a mobile home or conventional home, your hot water heater won't last forever. Both mobile home and traditional homeowners may find they need to replace a hot water heater after eight to 12 years on average.

  • Can you use a tankless water heater in a mobile home?

    Yes, there are tankless water heaters that are mobile home-compatible. You would use a tankless electric water heater if you need more than a 30-gallon capacity, for example. If you want a gas tankless water heater, confirm that it will use your type of gas, likely propane, rather than natural gas used in a traditional home.