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Can you Put a Water Heater in a Crawl Space?

Frequently houses have a crawl space under the house. Some homeowners have been very clever and used it as a place where to install their heating system. Let’s see how good of an idea that would be for you!

Let’s make sure you have all the info about placing the water heater in the crawl space before you start this project.

A water heater can be placed in a crawl space. Local building codes, climate, and environmental features need to be taken into consideration.

Permanent light

Crawl space must have at least one fixed light in order to install a water heater.

According to building code N 210.8(E) crawl space lighting outlets must be protected by a ground fault circuit interrupter (GFCI).

Even if it is much more convenient to use a headlamp in a crawl space you still need to have a fixed light to make sure to pass the building inspection. Some plumbers might even refuse to carry out maintenance when there is no light in the crawl space.

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Electrical outlet

When installing the water heater, don’t forget to wire an additional electrical outlet in your crawl space when doing the wiring.

Crawl space needs to have an electrical outlet according to most building codes. This will be used by your HVAC technician to perform regular maintenance.

If you are specifically looking to install a tankless water heater, then perhaps my article on Can a Tankless Water Heater Be Installed in a Crawl Space would be more helpful to you.

Make sure that the crawl space wires are protected from pests and are secured, so nobody can pull them down and hurt themselves.

Make sure you use an outlet that is meant for outdoor use and connect it to a GFCI. They are usually rated IP44 or higher.

AFCI breaker & outlet and GFCI receptacle and outlet illustration


There needs to be access to your water heater. It will be used for maintenance and repairs. And eventual replacement of the water heater.

There needs to be a minimum of a 24″ clearance in front and sides of the water heater. (Some places require up to 36″, so check your local building codes).

Distance From Ground

During home improvements around the house, you must follow building codes. This ensures that you will not be fined, or worse denied an insurance claim.

Related article: Is it OK To Transport A Water Heater Horizontally?

When you decide to fix things by yourself make sure you have the correct info. The most reliable place to get up to date building code details is the local building officials. The name of the place will vary from state to state, so it is best to call your local city hall and ask for building codes.

Gas water heater

FVIR(flammable vapor ignition resistant) water heaters eliminate the need for the space between the ground and ignition. Sometimes building codes are not updated to reflect their benefits.

When installing a gas water heater with open combustion chambers(non-FVIR) by code it needs to be raised at least 18 inches from the ground. The height needs to be measured from the pilot or lighting mechanism. 

Related article: Can a water heater be placed directly on the floor?

Many people think it is impossible to install the water heater in the crawl space because there is not enough space. They often measure 18 inches from the bottom of the water heater, not the pilot light.

For example, if the pilot light is 3 inches from the bottom of the water heater, then the distance between the ground and the water heater can be 15 inches.

Elevated water heater by 18 inch in the crawl space illustration

Before installing a gas water heater make sure to check the local building codes to make sure you comply with all of the regulations.

Electric water heater

When installing an electric water heater the distance from the ground depends more on where you live.

By code it is not necessary to raise the electric water heater.

Why Do Water Heaters Need to Be Raised?

Water heaters need to be raised off the ground to prevent damage from flooding. Additionally, gas water heaters with open combustion chambers need to be elevated to prevent igniting other combustible materials under the water heater. For example, spilled gasoline.

During heavy rainstorms, there can temporarily be some water in your crawl space. You do not want your water heater sitting in a pond of water under your home.

When your water heater is in contact with water for a long time it may cause all kinds of different problems.

Water is a life source for rust and oxidation of electrical connections. While most water heaters have been made so that they will last between 8 to 12 years, this time will be decreased significantly, if the water heater has been in standing water.

Should I Put My Water Heater on Blocks/Bricks?

Quite often in life, we need to make sure that we have a good foundation before we start to do something. This is especially important with a water heater since the water heater tipping over would be disastrous.

When installing a crawl space water heater, it can be placed on blocks or bricks. It is important to remove all loose dirt so that the underlayer is strong and stable.

An even better solution would be to make a concrete pad for the water heater. This way you can be sure that nothing moves and the heater is secure.

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In states subjected to regular earthquakes it is necessary to have strapping around the water heater to make sure it will stay in place during seismic activity.

Strapping down the water heater can be a good idea even in non-earthquake affected areas. It will ensure that it will stay upright even when there is a problem with the foundation.

Related article: Can a Water Heater Be Installed Horizontally

Increased Energy Consumption

By placing the water heater in an unconditioned space such as a crawl space you will most likely increase your energy bill.

Depending on where you live, at certain times of the year, the outside temperature will drop significantly lower compared to the indoor temperature. This means that the energy required to keep the water at 120f is increased.

Extra insulation placed around the water heater will reduce the heat loss and in turn reduce your energy bill.

Placing insulation around the water heater is only one of the ways you can reduce the energy consumption of the water heater.

Consider Frost Risk

The temperature can change quite a lot in different places.When living in area where there is risk for frost it is important to protect the water heater and pipes from frost damage.

As you know, water expands when frozen. The freezing process creates so much pressure that the metal pipes and fittings will burst. Often the weakest points are ball valves and elbows. But it can happen anywhere.

I have an entire article dedicated to how to prevent pipes from freezing. So I won’t go into more detail about how to do this.

Related article: Can You Put a Water Softener in a Crawl Space?

At what temperature do pipes freeze in crawl space?

Water freezing temperature is around 32F°(0C°). However, most crawl spaces are not completely open and the heat from the house and the ground will keep it warmer than the outside. This means that outside temperature must drop lower than 32F°(0C°) for the pipes to freeze.


The temperature where it starts to give you headaches depends a lot on how well the crawl space and the pipes are insulated, the amount of ventilation, the temperature of the house, and many other factors.

Generally, pipes in a crawl space start to freeze when outside temperatures drop below 20F°(-6C°)

For peace of mind it is a good idea to have a wireless thermometer next to the pipes, then you can monitor the crawl space temperature from inside the house.

Here is a wireless thermometer from Amazon that would work perfectly.

Is It Normal to Have a Little Water in a Crawl Space?

Water is something without what, there would be no life. Sometimes it can also give life to some things that will make our life more difficult, such as mold, rust and moisture damage.

The perfect crawl space is dry, with a good vapor barrier, and has proper ventilation.

Black plastic sheeting on the floor in the crawl space illustration

Actually, dry crawl space is more important than you can imagine. There are already many articles about it. so I will just go through it quickly.


If you have excess moisture, or even worse standing water in your crawl space it will affect your water heater tank, not to mention metal building elements such as nails, screws and rebar.

Moisture is metal’s greatest enemy, they will battle until one of them wins. And you can be sure that your expensive water heater tank will never win.


All that extra moisture will evaporate and find its way into your home.

It takes more time to heat up air that is damp, so your HVAC system needs to put in extra work, and that will lead to a bigger electricity bill.

Places that lack good ventilation and are extra damp, usually also have air that has a special kind of odor. And not a good kind of special.

So when it will sneak inside your home the air quality will be affected.

A family member with allergies, breathing problems, or other health issues can be easily affected by that.


Nobody wants to have uninvited guests. But mold is something that does not care. If the environment is good, it will be there before you notice.

Mold underneath your house is not a small problem it can cause you really serious health problems, not to mention damage to the building itself.


We have an article here on how to fix mold problem in your bathroom.

It is hard to believe how fast mold can grow and spread. That means it will find its way inside your home. When it has found its way in, it will be only a matter of time until it will also be in the air you are breathing.

Inhaling the air where also tiny mold molecules are mixed in can make people very sick.

Here you can read what are the different kinds of molds and what kind of health issues they can cause.

If mold problems are not treated it can even damage your house. It can lead to collapsing falls, floorboards, or even ceilings because mold feeds on organic materials(paper, wood). Plus unattended it can develop into a black mold which can lead to serious health problems.

Related article: Can You Put a Junction Box in a Crawl Space

Related article: Can You Put a Furnace in a Crawl Space

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