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FVIR WATER HEATER CLEANING INSTRUCTIONS

To perform the cleaning instructions below the following tools 
are needed: 
• 

Vacuum cleaner with hose attachment.

• 

Flame arrestor cleaning attachment.

• Flashlight
• 

Small mirror approximately 2”x3”.

• 

3/8”, 7/16”, and 3/4” open end wrenches.

• 

3/8” nut driver

• 

Small container of soapy water and an applicator.

Like other appliances, your water heater will need occasional 
servicing to maintain peak performance. Suffi cient air fl ow 
is crucial to the proper operation of your water heater. This 
publication addresses one possible cause of restricted air 
fl ow, and the procedure for its prevention and correction. 
Signs of restricted air fl ow are yellow fl ames, pilot outage, 
sooting, or unstable fl ame. Before starting, consult the 
sections of your owner’s manual dealing with condensation, 
air requirements, gas supply, venting, and cleaning the air 
intake screen. Also, make sure that your heater is properly 
sized for your home. An undersized heater may result in 
condensation which can drip onto the fl ame causing a pilot 
outage. Your water heater is built to the current industry 
safety standard and meets all FVIR (fl ammable vapor ignition 
resistant) requirements. This assures that any fl ammable 
vapors drawn into the combustion chamber and ignited can 
not ignite remaining fl ammable vapors on the exterior of the 
heater causing a fi re or explosion. This design includes a 
fl ame arrestor and one or two air intake screen(s), see Figure 1. 

Figure 1

These screen(s) prevent larger particles of dust or lint from 
entering the heater, thus restricting air fl ow and causing 
improper combustion. The owner’s manual asks you to 
visually check and clean the screen(s) as necessary. Smaller 
particles may pass through these screens and lodge in the 
fl ame arrestor.

This document will cover 2 levels of cleaning. The first will 
cover the steps necessary to clean under the water heater, 
where combustion air is drawn in through the air intake 
screen(s) and flame arrestor. The second will cover the steps 
necessary to clean the combustion chamber. 

Procedure: Level 1

1.  Turn the water heater gas control knob to “off” and allow 

the burner area to cool, see Figure 2.

GAS CONTROL KNOB

TOP 

VIEW

Figure 2

2.   Remove the plastic air intake screen(s) and use a small 

mirror and flashlight to view the bottom of the flame 
arrestor. 

3.  Using the flame arrestor cleaning attachment, vacuum 

all dust and other particles from beneath the heater, see 
Figure 3.

4.  To clean the bottom of the flame arrestor, turn the flame 

arrestor cleaning attachment over and insert it through 
the air intake opening at the base of the heater, and use 
a gentle sweeping motion to clean the entire base, see 
Figure 3.

FLAME ARRESTOR 
CLEANING ATTACHMENT

AIR INTAKE
OPENINGS

Figure 3

5.  Re-insert the air intake screen when finished.
6.  At this point, relight the pilot, and check heater for 

operation. Allow an entire heating cycle to complete to 
assure proper operation.

NOTE: If the original fi lter screen is missing or damaged, or you 
have an installation that frequently gets lint or dust buildup, we 
recommend the installation of a larger capacity fi lter screen. If 
you have questions, contact Residential Technical Assistance 
referencing the number in your manual.

186210-000

FVIR-Cleaning.pdf

Applies to AO Smith line of products

http://waterheatertimer.org/troubleshoot-flammable-vapor-on-gas-water-heater.html

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