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Can a Water Heater Be Installed Horizontally

Sometimes it would be nice to turn an appliance this way or that in order to find the best fit for a space. Water heaters can be rather big if they have a storage tank. So, if you have found yourself eyeing that horizontal space you have and wishing the heater could be put there, well, you are in luck.

Some water heaters are manufactured for horizontal installation and therefore are entirely compatible with that orientation and violate no code regulations. You need to heed the manufacturer’s directions; otherwise, you will encounter difficulties in terms of relief valves as well as the general function and safety of the heater, regardless of its type.

Water heaters manufactured to support horizontal installation can be installed thus. Building code allows this installation if it accords with manufacturer instructions. There will be no issue with the heater’s relief valve, function, or safety, if they have been designed to fit with that orientation.

The Legality of Horizontal Installation

Code Says Manufacturer Instructions Apply

Section M2005.1 of the International Residential Code (IRC) says:

“Water heaters shall be installed in accordance with Chapter 28, the manufacturer’s instructions and the requirements of this code.”

This means that if the manufacturer’s instructions allow for horizontal installation and you follow the other code rules, you will be up to regulation.

If the manufacturer prohibits horizontal installation, you will not be able to install in such as manner without breaking code. This would impact your product warranty and any potential insurance claims involving the heater.

Stamp with text Not Recommended,vector illustration

Manufacturer warranties generally specify that they are only valid if the product is installed according to the product instructions, as well as if the installation is code-compliant. You will void your warranty for any faulty components or needed repairs on the heater.

In terms of insurance, your provider is going to base their willingness to compensate you for any insurance claims on the assumption that you are following code regulations. If your water heater is installed incorrectly according to the manufacturer’s directions, you risk your insurance claim being denied and you being liable for the costs.

It may even result in trouble with your insurance in general, as not only will insurance not cover damage to the water heater, but you are likely going to be denied claims on damages as a result of the heater, such as water damage to the house.

Would It Affect Relief Valve Code Requirements?

Section P2804.3 of the IRC says:

“Pressure relief valves shall have a relief rating adequate to meet the pressure conditions for the appliances or equipment protected. In tanks, they shall be installed directly into a tank tapping or in a water line close to the tank.”

For a tank designed to allow for horizontal installation, the pressure relief valve positioning and the working pressure of the heater should be accounted for in the manufacturer’s directions and instructions for installation.

Section P2804.4 states that:

“Temperature relief valves shall have a relief rating compatible with the temperature conditions of the appliances or equipment protected. The valves shall be installed such that the temperature-sensing element monitors the water within the top 6 inches (152 mm) of the tank.”

If the water heater is intended to support horizontal installation, then you should be able to install the valve so that the element is in the top 6” of the water in the tank. If this is achievable, then there will be no effect on the function of the temperature relief valve.

Section P2804.6.1 provides the requirements for the discharge pipe serving the heater’s relief valve. If the discharge pipe can still flow with gravity, terminate at an appropriate height, and can discharge without structural or personal harm, along with the rest, then there should be no interference with the discharge of a horizontally installed heater.

Provided you are not taking a heater intended for vertical installation and flipping it onto its side, then you should have no trouble with where the components are positioned.

Is Function Compromised by Horizontal Installation

A correctly installed electric, gas, or tankless water heater will encounter no troubles when in optimal condition. This means that a horizontal water heater will function as well as a vertical heater as this is how it was made to work.

I cannot say the same for a heater that someone has merely tipped over, and if you have found a water heater that appears to be incorrectly installed in your home, I would call a professional immediately.

Be aware that many water heater warranties have a fine-print caveat that it is only valid via professional installation.

Electric Water Heater

Electric water heaters with storage tanks function by means of a heating element and thermostat. Bigger tanks often have two heating elements.

Hot water leaves through the top of the tank and cold water enters at the bottom. When cold water enters the tank and cools down the element, the thermostat turns on the heating element. This will heat the water to the preset temperature.

It is important to keep heating elements covered by water; otherwise, when they turn on (dry-fire), they will burn out. This actually means that the element will break.

In a dual-element heater, if the lower element breaks, your water heater cannot effectively heat water. For the upper element, a breakage means that power is cut to the lower element, and no water will heat. A broken single element will, of course, also result in no hot water.

This is the major problem of turning a vertical electric water heater onto its side.

Considering that the heater’s water flow is intended for a different orientation, this would impact how efficiently the water heater could supply and pull water.

Gas Water Heater

A gas water heater with a storage tank works on the principle of different water temperatures rising and sinking naturally.

The water circulation for a vertical heater comes from the heat at the bottom from lit gas, and the heated water rises while the cool water sinks and then gets heated too.

If your water heater is on its side, this will interfere with the circulation of the water. In addition, this may cause ignition problems with the pilot light and the gas if the flame cannot be lit properly or is in the wrong position to catch the gas.

The gas release on a gas heater is triggered when the thermostat measures the water as being below temperature but will only be allowed through if the sensor measures that the pilot light is on.

With the effect of gravity on a flame, the gas may then continuously release because the water is cold and the flame is on, but the gas may not be ignited. This would result in unburnt gas being leaked.

A gas water heater requires proper clearance and elevation for its combustion chamber. A vertical heater installed horizontally may lack the proper space at the (true) bottom.

This can result in insufficient combustion air (air needed to light the gas), resulting in an incomplete combustion process and the release of carbon monoxide.

The internal flue of the gas heater can also be impacted as the airflow may be compromised. If the warm waste air from the combustion process cannot effectively rise and be emitted, this may cause backdraft problems.

Tankless Water Heater

A tankless water heater uses the same methods for heating water as the versions with storage tanks. However, the heating element or gas burner works as water passes through a pipe as the water is needed instead of heating water stored in the heater.

A tankless heater has one to two heat exchangers that heat water as it passes through the system. The heating element or gas burner is activated when the system is in use and shuts off when you are done with it. This is how you get the more economical water-on-demand version of a water heater.

You might find that you have more flexible installation methods with a tankless heater. This, however, doesn’t mean that you can just install any old vertical tankless heater in a horizontal position.

The water pressure in the system may be impacted by incorrect installation, which could result in damage to your heater and insufficient heated water. There is still a process for heating the water that needs to be considered and a manufacturing design that provides a functional purpose.

While you may encounter fewer problems in the short term with an incorrectly installed tankless water heater, you will be voiding your product warranty, negatively impacting your insurance, and you will be causing damage to the heater as it is functioning in less-than-optimal conditions.

If you have just bought that tankless heater, I’m pretty sure your wallet will prove how much you don’t want to shorten its lifespan!

Safety Implications of Horizontal Installation

For the safest installation of your water heater, I would recommend hiring a reputable professional to install the appliance. AS mentioned, many water heater warranties have a fine-print caveat that it is only valid via professional installation.

Like with the functionality, any water heater should be safe if it is installed properly and in accordance with all the necessary safety procedures according to the IRC and your local codes.

By calling in a professional, you would also be assured that all the appropriate and necessary safety protocols are in place, such as seismic bracing.

Electric Water Heaters

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White, 20.2

The electrical components on a water heater are not intended to get wet. If you install a vertical water heater in the wrong orientation, you may cause leaking, and this would not only risk structural damage but may also cause short-circuiting by wetting the wiring and controls system.

The heating element inside the tank may also be partially exposed, instead of being fully submerged in the water, which then becomes a safety risk as the water heater casing will be heating up, instead of the water.

An electric water heater tipped onto its side, if your elements burn out from dry-firing, may mean you may have a fire and electrocution hazard on your hands.

A broken element is not supposed to allow electricity to pass through it. However, there is still a chance that this may happen (especially if you keep using the heater). The broken elements may cause an electrical grounding problem and cause short-circuiting. This would potentially make it dangerous should you touch your metal storage tank.

Water and electricity do not make a good team unless they are each appropriately contained. With a compromised electrical connection directly into the water system from the electricity-heated elements, you are at risk of electrifying the water in your house. And where there is electricity, there can be fire.

Gas Water Heaters

water heater in modern boiler room

Section G2406.2 of the IRC requires that gas heaters installed in living spaces be direct-vented or properly enclosed with the approved door sealing and a self-closing door hinge to prevent the enclosure from not sealing. You can read more in my article: Can a Gas Water Heater Be Installed in a Bathroom.

If you can meet these conditions with a gas water heater that is produced for horizontal installation without compromising the manufacturer’s directions, then everything should be up to code and safe. If not, you are facing potentially serious health and safety risks.

With an incorrectly installed gas heater, the major risks are the combustion by-products and the fire risks associated with the gas cylinders.

The combustion process by-products must be vented to the outdoors. This is because the main by-products are carbon dioxide and water vapor. While not necessarily harmful, these could affect the air quality of your home.

The real problem comes when the combustion process goes wrong.

Carbon monoxide is highly poisonous and is colorless and odorless, which makes it difficult to detect. This is supposed to be what happens when something goes wrong with your gas heater. However, by intentionally compromising a vertical heater, you may be risking high leaves of carbon monoxide due to the installation.

Along with the direct health risks, carbon monoxide is also highly flammable.

A side-lying gas water heater will not be able to vent properly as the vertical flue relies on the hotter by-product air to rise and exit through the necessary direct vent. If this is not happening effectively, you find yourself with combustion (complete and incomplete) by-products leaking into your enclosure.

Now, you are already dealing with the risks of a gas cylinder. But when you include a supply of highly flammable gas that isn’t venting properly, well, the fire risk becomes too high. And with all the gas, you are likely to have an explosion along with a fire, which will only further the damage and potential for injury.

Tankless Water Heaters

Rinnai V53DeN Natural Gas Tankless Hot Water Heater, 5.3 GPM

You will probably find that the tankless heaters are slightly more forgiving of the incorrect orientation. This may make it less noticeable at first but will still result in problems and is against code regulations if the manufacturers do not allow horizontal installation.

You will likely experience trouble with your water pressure and heating, but beyond damaging the heater itself, there are far fewer risks associated with these heaters in general.

Tankless heaters generally have shut-off mechanisms that prevent overheating, and the gas version tends to stay away from pilot lights.

Hiring a professional to install a tankless water heater is recommended. This is because there are several considerations, including safety, that must be considered, and these professionals can provide an optimal installation based on these factors.

Strapping Horizontal Heaters

The IRC Section P2801.8 outlines strapping as needing two straps, one in the upper and one in the lower third of the appliance. Horizontal heaters still need to be strapped, whether electric, gas, or tankless. A professional will be familiar with the code regulations for a less typical orientation.

This may be more difficult for your horizontal heater, though. Section P2801.8, specifically says that strapping must be done to:

“… resist a horizontal force equal to one-third of the operating weight of the water heater, acting in any horizontal direction, or in accordance with the appliance manufacturer’s recommendations.”

Here is both your problem and your solution.

To brace your water heater as described in the IRC, you need to place the straps horizontally. This, however, will not effectively prevent the horizontal movement in the way the code requires.

Therefore, you are going to need to pay attention to that very last point. The manufacturer’s recommendations. This is where you will find the requirements for strapping a horizontal heater and this will allow you to legally strap in a different method.

Water Heaters Designed for Horizontal Installation

Horizontal water heaters are not as plentiful as the vertical variety; however, it is possible to find some models that support horizontal installation.

You’ll probably have an easier time finding electric options with tanks, although you will be able to find both gas and electric options for tankless heaters.

Funchic has a 13-gallon, wall-mounted, low-noise horizontal water heater model.

Funchic Electric Hot Water Heater, 50L 13 Gallon Wall Mounted Low Noise Tank Water Heater 110V Quick Heating with Leak-proof Plug for Home Shower Bathroom
  • ⭐【Four Safety Protections】- Funchic electric hot water heater applies multiple safety protection devices for boil dry protection over-temperature protection, electric leakage protection and high...
  • ⭐【Full-automatic control】- This electric water heater can keep automatically adding cold water, automatically heating and automatic temperature control, Pre-thermostat knob and indication light...
  • ⭐【Long Service Life】- Adopts ceramic liner, anti-rust, anti-corrosion, anti-scale, anti-leakage to extend service life. Thicken overall polyurethanes foam to keep good temperature control...
  • ⭐【Special Sewage Outfall】- Simple liner cleaning, time-saving and labour-saving. Liner anode protector is mounted at sewage outfall to facilitate checking and replacing anode protection...

Last update on 2024-05-30 / Affiliate links / Images from Amazon Product Advertising API

Then Bosch has a heater with a 360° installation orientation, meaning that you can install it horizontally without problems.

Bosch Thermotechnology 7736505867, 3.6kW, Bosch US3-2R Tronic 3000 Electric Tankless Water Heater, 3.6 kW, 6.6" x 12.8" x 2.9", White
  • NEW LOW ACTIVATION FLOW RATE: A new lower activation flow rate of only 0.3 GPM allows for use with newer, low flow faucets
  • ELECTRIC TANKLESS WATER HEATER: 3.6 kW under-sink tankless water heater designed to provide an endless supply of instantaneous hot water to one or more sinks
  • FLEXIBLE INSTALLATION: Can be installed in a 360 degree orientation so you can position the unit in tight under counter spaces for a flexible, worry-free setup. Due to the amperage requirement this...
  • EFFICIENT DESIGN: Ultra compact and lightweight design with 98% efficiency and no stand-by heat loss plus does not require a temperature or pressure relief valve

Last update on 2024-05-30 / Affiliate links / Images from Amazon Product Advertising API

These are heaters that you can find online. You will be able to find heaters through your local plumbing supply shops, plumbing companies, and some large franchises like Walmart or Target.

Here are some reputable brands to look at when you source your own heater:

  • A.O. Smith Water Products.
  • Rheem.
  • Bosch.
  • EcoSmart.
  • Kenmore.
  • American Water Heaters.
  • American Standard.
  • Bradford White.
  • Stiebel Eltron.

Can a Water Heater Be Transported on Its Side?

A water heater can be transported on its side, despite sales assistants saying otherwise. This is mainly done for delivery service promotion. However, many plumbers say that it is safe to transport your heater horizontally, a practice they employ themselves.

You might even say that it is safer. Water heaters can be large, and not many people have a vehicle with the space to transport them vertically, but there is also the matter of what damage could occur if that large heater fell over.

As long as you place the heater on a flat surface to prevent damaging the shell, with the right side up (indicated on the box or packaging) to protect the components and use straps to secure the heater, then you should have no problem if you drive safely.

If the heater does not have protective packaging, the same principles apply, but you will just have to be a little extra cautious that nothing will damage the heater.

You can use blankets to provide a layer of padding and support to the heater during transport if needed. I would recommend reading this article Is it OK to Transport a Water Heater Laying Down? for the full story on transporting water heaters horizontally.


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