Can A Water Heater Sit Directly On A Concrete Floor?

A water heater can only be installed in one of the two popular methods of installation.

  1. One method entails the bottom of the heater sitting directly on your concrete floor.
  2. The other style is characterized by a bottom raised slightly above, about 2”, with air space between the concrete floor and the bottom of the heater.

Some first-time homeowners are often split between these two methods.

Choosing between the two is never easy. Without proper guidance from a qualified plumber, you are likely to install your water heater the wrong way.

(Let’s Get This Out Of The Way..) Can A Water Heater Sit Directly On A Concrete Floor?

Yes, but it depends on an array of factors. For example, not just any type of heater would work perfectly when installed directly in contact with the ground. GE Gas Water Heaters, for example, cannot be installed directly on the ground. It has nothing to do with preference most of the time, the source of energy alone can determine whether it should be left on the bare concrete or raised.

Factor 1: Fuel – electric water heaters can; gas heaters can’t

Yes, only electric water heaters can be installed directly on the concrete ground/floor.

But, why can’t gas-powered water heaters be installed this way?

It has something to do with the risks that come with using gas – the gas is ignition-prone because the heater’s pilot flame will be too close to the ground/floor.

The pilot light is used to describe the small gas flame (produced by normally LPG –liquefied petroleum gas – or natural gas) which functions as a source of ignition for a more powerful flame on a gas burner.

Initially, a pilot flame would remain permanently ablaze, but this has been found to waste a lot of gas.

Still, no water heater (regardless of type of fuel) should be installed directly on concrete or “dirt,” by default, but should be raised slightly to remove the danger of “exploding”, energy wastage, and damage (more on these later).

But, who/what decides how electric/gas heaters should be installed?

Enter the Uniform Plumbing Code:

Uniform Plumbing Code

The Uniform Plumbing Code – a model code created by IAPMO (International Association of Plumbing and Mechanical Officials) to govern all installations and inspection of all plumbing systems as a way of promoting health, welfare, and safety which sets up standards nationwide – requires that the sparking or flame mechanism in your gas water heater must be at least 18” off the ground. It means that the accurate measurement for the right installation can’t be based on the total distance between the bottom of the floor and the water heater.

The same code also dictates how the installation of electric water heaters should be carried.

Water heaters should only be raised (as per the code) if they’re powered by an ignitable fuel (propane, gas, etc.).

The code suggests that only the device’s ignition mechanism should be raised. For that reason, if your heater is electric or a heat pump, you don’t need to elevate it.

The second, and important as well, is the location factor.

General placement is more popular. That’s why most heaters are placed in basements or garages.

You might want to install your heater close to an outer wall so that you can make enough space for the flue, but the heater should be off the floor if it’s gas-powered as the code.

You should also locate the heater in such a way that it’s that it can be refreshed constantly with water from a faucet or direct feeder pipe of cold water.

Factor 2: Energy wastage

It is always a good idea to install your water heater off the ground to prevent energy wastage.

Whether you choose an electric or gas heater, build a support slab that will raise the rest of the unit off the floor. Still, you need some padding material between the slab and the heating element of the heater.

Truth be told, any heater placed directly on concrete floor stands to lose a lot of energy to the cold surface (or bare earth, no major difference).

Concrete can get remarkably cold even during warm seasons.

Even electric heaters, which are normally installed on bare concrete with no worries, can turn out to be energy inefficient with time because part of the generated energy would be absorbed by the concrete.

The amount of heat energy absorbed by the concrete can be considerably higher during cold seasons. It’s not uncommon for homeowners to discover that about 10 percent of the heating cost was never used to heat the water.

Factor 3: Damages

In terms of the health and durability of your water heater, regardless of the type, placing it on the ground would simply be unadvisable.

If you do, the bottom of your heater will deteriorate fast, especially if it is an electric heater.

This may mean frequent repair and maintenance or complete replacement in a short time.

The best approach is to let your electric heater sit on a thick catch pan (lots of manuals recommend this) or some sort of padding material that won’t be too vulnerable to cold or moisture encroachment.

What does the manufacturer say?

Check the manufacturer’s installation specifications for your particular model of the water heater. Manufacturers provide all the information you need to install and use their products. Install it as directed.

Summary

To install the water heater on the ground or not?: this is the first question you could ask yourself immediately you acquire a new water heater especially if you have never dealt with these appliances before.

Fortunately, the job of installation is normally a reserve of qualified plumbers, so your professional will make most of the decisions for you.

Still, you need to understand which type of water heater is fit for ground installation and which isn’t. Of course, several other factors must be put into account.

Gas waters should never be installed directly on the ground. They need to be elevated because flammable fumes tend to fall to the lower 4” to 6” from the floor (air freshener, hair spray, etc…flammable products!).

Distance requirements for heater installation are mainly based on safety rather than functionality.

For example, the least distance off the ground you could factor is intended to avert explosions and fires in case any flammable substance (say, petrol and your heater is nearby) is spilled on your floor.

This requirement applies mostly to gas heaters, not electrical types. There are plenty of factors to consider:

Health and durability-wise, regardless of the type of your water heater, placing it on bare concrete would simply be unadvisable.

The bottom of your heater will deteriorate fast, especially if it is an electric heater, meaning you’ll have to do frequent repair and maintenance or need to make a complete replacement way too early.

The best approach is to let your electric heater sit on a thick catch pan or some sort of padding material that won’t be too vulnerable to cold or moisture encroachment

The manufacturer will recommend the best installation method for their heaters plus any other information you may need – read the manual of your heater to find out whether it’s safe to place it on concrete or not.

Energy efficiency is another factor – it is always a good idea to install your water heater off the ground to prevent energy wastage

Whether you choose an electric or gas heater, build a support slab that will raise the rest of the unit off the floor.

You also need to add some padding material between the slab and the heating element of the heater

A water heater placed directly on concrete floor stands to lose a lot of energy to the cold surface (or bare earth, no major difference).

Concrete can be considerably cold even during warm seasons.

Even electric heaters, which are normally installed on bare concrete with no worries, can turn out to be energy inefficient with time because part of the generated energy would be absorbed by the concrete.

The amount of heat energy absorbed by the concrete can be considerably higher during cold seasons.

Risk of damage is another factor

The bottom of your heater may deteriorate fast if installed on bare concrete, especially if it is an electric heater

Damages may mean frequent repair and maintenance or complete replacement in a short time.

The best approach is to let your electric heater sit on a thick catch pan or some sort of padding material that won’t be too vulnerable to cold or moisture encroachment

The type of fuel used by your water heater can determine how it should be installed.

Only electric water heaters can be installed directly on the concrete ground/floor.

Gas-powered heaters can’t be installed on bare concrete because they are equipped with a gas is ignition-prone – the heater’s pilot flame would be too close to the ground/floor

The Uniform Plumbing Code – a model code created by IAPMO to govern all installations and inspection of all plumbing systems as a way of promoting health, welfare, and safety which sets up standards nationwide – requires that the sparking or flame mechanism in your gas water heater must be at least 18” off the ground.

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