How to clean a gas heater


Learning how to clean a gas water heater is a very useful skill. As you surely know, a hot water heater that is not properly cleaned suffers from diminished performance, increased fuel bills and pollutant gas emissions, not to mention the accumulation of bacteria that can be passed on to the water. For all these reasons, today we have decided to prepare this tutorial on how to clean a gas water heater in the simplest and most effective way.

How do you service a gas water heater?

One of the main symptoms that your heater needs cleaning is the quality of the flame. Given an accumulation of dirt, the flame may become small (if there is clogging it may be minimized), or it may be the wrong color, or have excess residue. When these things happen, you’d best clean the heater.

How do you clean a gas water heater? How do you maintain a gas water heater? These two questions seem to be dealing with the same problem. But this is not necessarily the case. To “clean” is to sanitize the heater, while “to do maintenance” refers to a more in-depth procedure that requires checking the parts and circuits of the heater, and even the repair or replacement of parts that could later cause real breakdowns, but which, when tackled in time, can help to prevent more serious problems.

However, here we will refer to maintenance in the sense of cleaning. To clean, flush and in general to maintain a gas heater, necessarily requires partial or total disassembly of the equipment. If you do not know how to do this, we recommend that you call a technician. There are many parts and they can be complex to disassemble and reassemble.

Gas heaters are very similar, and this tutorial will help you regardless of which brand you own. For example, it will help you to know how to clean a butane gas heater, be it Junkers, Cointra, Vaillant Saunier Duval, Ariston, Baxi, or most of the most popular brands. So: How to maintain a gas water heater? You can do it following these steps:

1. Shut off gas and water supply

Turn off the tap of the gas cylinder or tank you are using, and also turn off the water inlet of the water heater.


2. Open the cover of the heater

Remove the front cover of the heater. It may have some metal or plastic tabs screwed on, so remove the screws. The control knobs must be removed before the cover can be removed. The front cover is removed by first pushing it up while pulling towards yourself along the bottom edge.

3. Locate and clean the nozzle

The nozzle (also called “injector” or “atomizing nozzle”) can get dirty often and is one of the main reasons why the flame of the heater does not work the way it should. A small device that is part of the burner, which has the function of supplying air for combustion, is called “nozzle”. Since it’s constantly subjected to flames and combustion residues, it tends to get dirty and clogged easily. It can be cleaned with a toothbrush (or any similar tool). Remove all dust and residue from the gum. If you know how to unscrew the nozzle, you will be able to clean it better under the pressure tap, and it will be as good as new.


Warning: never use a needle to clean the small hole in the nozzle. The orifice is actually smaller in diameter than a needle, and inserting a needle will enlarge the orifice and cause excess gas flow, resulting in poor combustion.

4. Cleaning the ignition system

The ignition is produced by the so-called electric-component igniter (also called “spark plug”), a component that also requires cleaning. Sometimes if the glow plug does not ignite, it may not be a malfunction, but rather that this part is dirty. Hence the importance of cleaning it during maintenance.

Locate the electric-component igniter and clean the dust off it with a toothbrush, small brush or a similar tool. Clean the regulator knob in the same way. If the electric-component igniter is faulty, it would be better to replace it with a spare. Purchasing a new one is fairly inexpensive.

5. Performing a general cleaning of the inside of the heater

Having already cleaned the 2 most important parts (the nozzle and the electric-component igniter), it’s time to perform a general cleaning of the inside of the heater. Shake and clean all the internal parts of the heater that are visible and have dirt, whether they are metallic, plastic or wires. The cleaning of the coil will be the subject of a separate section in a moment.

6. Check the flexible piping and regulator

It’s advisable to include this step in the cleaning-maintenance of the heater: check the condition of the flexible pipe that connects the gas cylinder to the heater, as well as the condition of the regulator. Especially the flexible pipe should have an expiration date, at the end of which it is better to replace it for safety reasons. Also make sure that the regulator is working properly.


How to clean a gas heater coil

Cleaning a gas heater involves cleaning such an important part as the coil. That is why we’ll deal with it here in a separate section. Now we will explain how to clean the coil of a gas water heater inside and out. These steps will help you to know how to clean the coil of a butane or propane gas heater.

The gas heater coil is a copper pipe designed in the shape of a spiral that surrounds the burner or burners of the heater, and whose function is to increase the temperature of the water as it circulates inside the heater.


To clean the inside of the coil we will use hydrochloric acid (although you can use any other anti-limescale product that is effective). The hydrochloric acid is the key to answering the question: How to remove scale from a water heater, that is, how to remove water-related mineral buildup. Hydrochloric acid is very effective in removing limescale from a water heater. But before we start, let’s go over these:

IMPORTANT SAFETY MEASURES WHEN USING HYDROCHLORIC ACID: Hydrochloric acid is an aqueous solution of hydrogen chloride gas or HCl. It has different names depending on the region: strong water, bad water, muriatic acid, hydrochloric acid, marine acid, salt spirit, salt acid, etc. Hydrochloric acid is highly acidic, corrosive and harmful to surfaces, skin and respiratory tract. Therefore, when using it, you should take care to wear high rubber gloves, use a mouth guard (even if you avoid breathing it directly), and that you also take all precautions. Again we recommend: it may be best to seek a technician.


Now let’s go over the steps to clean the coil:

1. Disassemble, use hydrochloric acid and let it stand.

Disassemble the coil from inside the heater, and carry it to a spillway, bathtub or any place with drainage where the acid can be poured without damaging the floor or anything like that.

2. Use hydrochloric acid or other products to get rid of limescale

Pour the hydrochloric acid carefully into the coil, and let it stand for as long as possible, so that the acid can do its job thoroughly.

3. Throw away the acid and rinse the coil with clean water

Now throw away the hydrochloric acid with the waste that has been removed from the coil, and then rinse the coil with plenty of running water until the water runs clear.

4. Clean the outside of the coil with a wire brush.

To remove the soot from the overall outside area of the coil, use a wire brush. Try to remove only the soot, taking care not to scrape too much of the coil material.

5. Put the coil back in its right place

When the coil has been cleaned both inside and out, put it back in place exactly as it was originally, and then replace the heater cover.


How to purge a gas heater?

So far we’ve talked about how to clean a gas heater in the sense of servicing it, not purging it. If the question is “How can I purge a gas heater?” the answer is that it depends.

If it’s a gas heater with a tank, it’s very likely that it will come with a purge valve. But if it’s a flow or instantaneous heater (without water tank), not all of them have a purge valve, because it is assumed that not having a tank, they do not accumulate mineral sediments from the water.

We’ve already put out a couple of guides on how to purge: one about how to purge a heater and another about how to purge radiators. Please check these articles, because although they do not deal with how to purge a gas heater, they can give you some useful general tips.

Now let’s talk specifically about how to purge a gas heater. You can do it by following these steps:

  1. Shut off the cold water and fuel supply to the heater. This is an important safety precaution.
  2. Connect a hose to the drain valve on the heater, and point the outlet end towards a drain, the garden, or any place where hot water can be drained without causing damage.
  3. Open the overpressure valve on the heater, and only then open the drain valve, and let the heater drain until all the water in the tank has drained out. This may take a while.
  4. When no more water comes out of the hose, close the purge valve, remove the hose and close the overpressure valve.
  5. Open the cold water inlet faucet to the water heater, as well as the hot water faucets in the house. As water starts coming out of the faucets, turn them off.
  6. When you have turned off all the hot water faucets, open the gas tap on the water heater. All done.

What should the flame of a heater be like?

A side comment. If you have ever asked yourself “How should the flame of a heater be?” the answer is that it depends on the type of fuel the heater uses. If you’re using an oil heater, the flame will always be a little orange naturally, while producing more combustion residue than gas.

On the other hand, if you’re using a gas heater, the flame must be very blue. But the truth is that it also depends on whether the combustion is being done properly, with gas/air balance. If everything is going well and the combustion is being done properly (with a well-balanced mixture of fuel and air), you will always see an elegant blue flame.


Buy all the spare parts for heaters you need from Suner

If, during gas heater cleaning and maintenance, you discover that some parts have broken down and need replacement parts, count on Suner’s store to supply them. And the same if you run a business that continually needs replacement parts for heaters and boilers.

Make us the spare parts supplier for your business, and we guarantee an uninterrupted supply of original parts of the highest quality, as well as easy purchasing, fast and secure shipping, and an after-sales service that adapts to the real needs of each customer.


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