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In many cases, water heater malfunctions have nothing to do with the water heater itself and everything to do with the air (or lack of air) in the surrounding area. Much like a lighted candle in a jar with a closed lid, your water heater’s burner assembly will not stay lit if it doesn’t have access to enough air.

Gas appliances, including most water heaters, require a certain amount of air to use for combustion. In this article, we’ll explain what you need to know to make sure your water heater has a sufficient air supply.

How Much Air Does My Water Heater Need?

The amount of air required for a water heater depends on the amount of energy the water heater uses.

As a general rule, water heaters need 50 cubic feet of air per 1,000 BTUs/hr. For example, a water heater with an input of 40,000 BTUs/hr should be in a room (often the garage) with at least 2,000 cubic feet of air. If the room isn’t large enough to provide enough combustion air, you will need a ventilation system of some sort to bring in air from the outdoors or another part of the house.

Keep in mind that if there is another gas appliance in the same room, such as a gas furnace, you will need to calculate the amount of air needed based on the combined input ratings of both appliances.

What If My Water Heater Is In A Small Room Or Closet?

If the water heater needs more air than is available in the room, you will need vents or a louvered door connected to another part of the house or the outdoors.

In most cases, you will need two vents, one located within 12 inches of the ceiling and another within 12 inches of the floor. The proper vent height and size depend on where the air is coming from and whether there are grills or screens covering the vents. An HVAC contractor can determine the best ventilation setup for your home.

What Else Should I Know About Water Heater Airflow?

Even if there is sufficient combustion air in the room with the water heater, you may still experience issues if there is too much clutter surrounding your water heater. Clutter reduces the amount of air available and can impact water heater function. Ideally, you should keep all the space within two feet of the water heater clear.

Water heaters can also be impacted by lint and debris in the air. Commercial water heaters in laundry rooms often malfunction if lint is sucked into the burner. Even if your water heater is in a residential home, you should keep the surrounding area clean.

It’s also a good idea to have your water heater regularly inspected by an HVAC professional. A professional can help you ensure your water heater is getting enough air to operate efficiently and help catch any issues that may arise.

If you live in Snohomish or King County and are looking for assistance with water heater installation or maintenance, reach out to Paragon today. Our office is open from 8am-6pm Monday-Friday and 8am-1pm on Saturdays.