spa parts, hot tub parts and repair help
spa parts, hot tub parts and repair help
spa parts, hot tub parts and service help
spa parts, hot tub parts and repair help
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Gas Heater Cleaning, Heat Exchanger

Note that the purpose of this section is to show you how to clean a gas heater that has a dirty or clogged heat exchanger. This condition will normally be found on gas heaters that are more than 5-8 years old, however, depending on environmental conditions, can happen more often.

Safety Warnings!
Remove Power from the spa/hot tub, AND the gas heater (if powered from outside sources), BEFORE performing this procedure.  Failure to comply with this requirement, can lead to electrical shock and/or electrocution!

Turn OFF the GAS SUPPLY to the heater! Failure to comply with this safety requirement may create a fire or EXPLOSION HAZARD!


The instructions here are intended for general reference only. Many gas heaters are different from the one depicted here, and may require more or less mechanical effort or knowledge in order to achieve the desired results.

Typical Gas Heater Installation  This is a typical gas heater installation. While it does work, and has worked well for many years, you can see that there is a safety problem with running the gas line over the top of the heater. 

In order to maintain continuity, we will only address the heat exchanger cleaning. Usually, the only tools required for this job are a 1/4" and/or 5/16" nut driver.

Clogged Heat Exchanger

This particular heat exchanger is clogged very heavily, and does not allow for the proper flow of heat from the burners to escape to the ventilator.

This is typical heat damage due to a clogged heat exchanger.

Determine which tool is required to remove the top of the heater, and remove the screws that attach the top vent to the main heater housing. Typically, there will be 8 screws. Be careful with the sheet metal, it can cut you!
Ventilator Removal

With all of the screws removed, carefully lift up the ventilation unit it separates from the base. On certain heaters, it may require a bit of force to get it off. If all else fails, recheck to see if there are any screws that you may have missed.

Removing the internal flute With the top off of the heater, you'll probably encounter something that looks like this... There may or may not be screws attaching it to the top of the heat exchanger. If so, then remove them to gain access to the entire heat exchanger.
This is what you should see, the top of the heat exchanger with the heat containment shields on top. There is usually a wire that holds them in place, (used primarily for shipping reasons), that you can probably just pull off with your fingers or cut with a pair of wire cutters. Once the wire is removed, take note of where the shields are located (for replacement), remove them and put them aside.
Heat Exchanger Top View

Shield Removal Shield Removal

Heat Exchanger Look very closely at the grids (fins) of the heat exchanger, and you'll probably see quite a bit of built up "gunk" inside them. This is what causes the heater to over-heat... it literally chokes itself.

Using a directed pressure stream of water, clean the exchanger thoroughly. This normally will only require about 30 seconds to do. DO NOT USE A PRESSURE WASHER! You could permanently damage the heat exchanger! 

Also, keep the stream directed straight DOWN... so to prevent the saturation of the insulation inside the heater. This is quite critical, particularly in older heaters that use conventional hard fire-brick.

Cleaning the Exchanger Cleaning the Exchanger

Reassembly is simply the reverse of disassembly. 

For safety reasons, you should let the heater "dry out" for about 24 hours before putting it back into operation. Because of the possibility of water entering the burners, it can create a fire hazard because the gas will be blocked from its normal path. It is recommended that you use some type of air blower to blow out all water and other foreign matter from the burner area before igniting the heater and pilot light (if equipped) again.

Metro Atlanta Spa/Hot Tub Service
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