Repair of the gas boiler – an overview of the main faults and methods of elimination

Oftentimes the unsung hero of home comfort, a dependable gas boiler keeps us warm and comfortable. But over time, boilers can have problems just like any other appliance, leaving us in the cold—sometimes very literally. Knowing how to troubleshoot gas boilers and being aware of common issues that they may encounter can help you save time and money. In this post, we’ll examine the common problems that gas boilers can encounter in more detail as well as possible solutions.

Gas boilers are complex systems made up of many parts that operate together to heat our houses. Every component, from the heat exchanger to the burner, is essential. Even the best-maintained boilers, nevertheless, are susceptible to malfunctions. Loss of heat or hot water is one of the main issues that homeowners can face. It becomes critical to comprehend the possible causes of unexpectedly cold indoor temperatures or icy showers.

A broken thermostat is one of the most frequent causes of a gas boiler that isn’t working properly. The thermostat is the heating system’s control panel; it sets the temperature and tells the boiler when it needs to run. Inconsistent heating or perhaps the boiler failing to start at all may result from a malfunctioning thermostat. Fortunately, recalibrating the thermostat, checking the settings, and replacing the batteries are often simple steps in the troubleshooting process.

Low water pressure is another common issue that gas boilers have. A drop in water pressure can cause the boiler to shut down as a safety precaution or reduce the amount of heat it produces. Adequate water pressure is necessary for the heating system to operate efficiently. Finding the source of the low water pressure—be it a system leak or a malfunctioning pressure relief valve—is essential to getting the boiler operating at its best again.

Furthermore, problems with the ignition system or pilot light can also affect gas boilers. You might be left in the dark if the boiler doesn’t fire up at all due to a broken pilot light. Similar to this, homeowners may experience discomfort and frustration when their boiler is unable to start due to issues with the ignition system. Quickly restoring warmth to your home can be facilitated by knowing how to safely relight the pilot light or troubleshoot ignition issues.

Brief information about the device of the system

One-circuit and two-circuit gas boilers are distinguished from one another based on how hot water is prepared. The coolant that circulates in the heating circuit is heated using the first kind. The second type is a more complicated device because it heats water for the kitchen and bathroom in addition to maintaining the heating system. Therefore, troubleshooting a single-circuit heating system won’t be a problem if you become proficient in the repair of two-circuit gas boilers.

The following components make up the gas heating boiler:

1. Body with a pipe for gas combustion products outlet. Inside it there is a frame or metal panel, to which the main components of the gas boiler are attached.
2. Furnace chamber. There is a gas burner and a heat exchanger in which the water-heating medium is heated.
3. Circulation pump pumping the coolant through the heat exchanger in the furnace.
4. Gas and water supply control system with a set of sensors and a three-way valve.
5. Electronic control board and flame ignition unit with a thermocouple.

A second heat exchanger is also present on two-circuit gas boilers in order to prepare hot water. It can be bithermal, as in the case of Ariston models, and heat the water as it flows at the coolant’s expense.

A separate heat exchanger that is integrated into the furnace and used to heat the water in the built-in boiler is utilized in certain boilers. For instance, in the Baxi brand’s equipment.

The furnace design of wall-mounted boilers varies; it can be either closed or open, or atmospheric in nature. In the first instance, the chimney pipe’s draught allows air to enter the combustion chamber. In the second, an electric fan or smoke evacuator provides the air flow.

What you need to know about the operation of the gas boiler for successful repair

The great majority of gas-powered heating appliances made today have a closed chamber and a street-side air intake. In this instance, the gas boiler’s body is positioned against the wall, at least 70 centimeters from the ground. The maintenance and operation of this setup are made easier. Combustion products exit the building through a wall-mounted chimney. Wall-mounted gas boiler repairs are carried out in more comfortable settings.

In the past, floor-mounted boilers were situated beneath window openings. These systems didn’t require a pump or extra hot water heat exchanger; they were self-flowing. could continue to work even without electricity. The water was heated to 90–95 °F while the burner ran continuously. Fuel made of gas burned inefficiently. Repairing the heat exchanger wasn’t the most enjoyable task because of the possibility of soot buildup and burnout caused by air gaps.

The majority of today’s wall-mounted gas boilers run in pulse mode. With this plan, you can precisely dose the gas so as to prevent the heat exchanger from overheating. Furthermore, having a pump enables you to "remove" more heat exchanger energy. However, the inclusion of electronic control boards, fans, and electric valves makes repairs more difficult.

Modern gas boilers come with touchscreen or push-button controls, though touchscreen controls are more common. The LCD screen shows the water’s temperature, pressure, and—most importantly—the error code in the event that something goes wrong.

For instance, the Vailant boilers require you to press the "i" and "+" buttons on the control panel in order to obtain information. When you press both at once, "d.0" and a list of potential issues will appear on the screen. After navigating the list, choosing the option that best matches the description, and pressing "i," the problem’s details will be shown.

You can get Ariston’s details from the table.

Toggle control and one or two arrow indicators indicating the system’s temperature and water pressure were features of models produced more than fifteen years ago. Because older boilers lacked an electronic indication unit, repairs were somewhat easier.

However, no matter how serious the breakdown, only a qualified specialist should perform the necessary repairs on a boiler like Proterm "Lynx." Models with condensing units are challenging to modify and even harder to fix.

Causes of breakdowns

A gas boiler can generally be regarded as high-quality if it has operated for at least a year without any issues or minor repairs (like replacing the handle or repairing the board). Within six months, reconditioned and fake apparatuses typically "fall off."

Thus, there could be two reasons for the breakdown and subsequent repair if the boiler is original, bought from an authorized dealer, and has undergone pre-start preparation and adjustment.

• problems with the quality of water, gas or electricity supply;
• hidden defects and errors made during the installation of the gas boiler.

Service managers frequently add incorrect gas equipment operation, including unapproved interference with boiler unit operation, to the list of additional causes.

Any attempt to "work" the boiler automation by the service technician during the initial service or repair will be identified if the gas boiler is still covered under warranty.

Poor water quality

Two issues might arise. The heat exchanger and pressure sensor’s inner walls accumulate lime scale as a result of the high concentration of magnesium and calcium salts.

When dealing with hard water, masters typically advise adhering to two guidelines in order to prevent costly repairs:

• operate the gas boiler at one-third capacity – hot water in the secondary heat exchanger should not be heated above 60 ℃. At this temperature, the rate of lime deposition decreases by an order of magnitude;
• periodically give the heat exchanger to the service center for flushing.

The only options for repair in the event of a burnt or leaking heat exchanger are part replacement or fistula soldering. While the primary heat exchanger should only be repaired by a master with pressure testing, you can solder the secondary heat exchanger on your own.

The second is that a lot of microscopic abrasive particles in water might not be caught by the filter-dirt collector. Iron oxide is typically what "eats" away at the circulation pump’s plastic impeller. An excellent magnetic filter must be installed on the gas boiler inlet to prevent repairs.

Quality of power supply

Electronically controlled gas boilers are excessively susceptible to spikes in voltage within the electrical grid. The electronic control unit of the operating modes and the ignition board malfunction as a result.

The board and unit of older gas boilers (10–15 years old) can be fixed by hand; on more recent models with digital controls, repairs are made by swapping out broken parts.

Incorrect installation of the equipment

Installation-related infractions may be one of the causes of the gas boiler breakdown. For instance, the instructions state that the chimney on a wall-mounted model with a chimney outlet through the wall should be installed at a negative angle of five degrees to the horizontal axis.

Condensate that should have flowed down the pipe to the outside will collect inside the sandwich flue if the installation conditions are broken. Improper installation allows moisture to enter the combustion chamber. The boiler’s gas burner and heat exchanger will need to be repaired after a year of use.

The absence of grounding is the subject of another infraction. The sensor control unit will therefore need to be fixed or replaced.

Non-compliance with operating conditions

Repairs are frequently necessary due to issues with poorly operated boiler equipment.

The most typical situations

1. Connecting a gas boiler into a socket without a mains filter. In this case, the refrigerator, washing machine, electric fryer when switched on create a current and voltage surge in the network. As a result, it will be necessary to repair the control unit.
2. Installation and connection of the gas boiler through an uninterruptible power supply unit. Not all uninterruptible power supplies can be used to protect modern two-circuit boilers. In this situation, the circulation pump fails. The fan motor may need to be repaired.

These days, input voltage stabilization schemes are standard on all gas boilers. Boiler automatics can function flawlessly between 180 and 250 V. There is no benefit to installing a manual or relay voltage stabilizer. The transistor or stabilizer on the gas boiler block will burn out if the relay is switched on at the same time as the refrigerator is included. Although it is not difficult to repair, there is a chance that the control unit could burn out.

The most hazardous infraction for a two-circuit boiler is the removal of hot water at a reduced flow rate. From a structural point of view, the gas burner can run at least 500–700 W of heat output. At a water flow rate of no more than 100 ml/s, the faucet opens and the heat exchanger enters a near-boiling mode. The typical course of action for repairing overheated heat exchangers is to replace them with new ones.

Poor quality of gas fuel

The use of contaminated gas could be another reason for repairs. Standard gas fuel is primarily composed of carbon dioxide, methane, and a trace amount of nitrogen. It is transported centrally through pipes. However, the composition of the gas will contain propylene and ethylene if it is not thoroughly cleaned. These additives create an oily, viscous deposit on the metal surface when they burn. Filters, nozzles, and valves become clogged as a result.

It will be necessary to replace the filters, lubricate the valve stems, and flush the gas appliance with an alcohol and acetone mixture in order to make repairs.

The gas meter can also be stopped due to contaminated gas. Therefore, before fixing the boiler, it makes sense to have a gas service technician inspect and maintain the inlet filter upstream of the meter.

Nuances of diagnostics

The level of service experience directly affects the success of the repair. For this reason, it may be beneficial to speak with service technicians more frequently. A typical user lacks diagnostic tools such as gas pressure meters, testers, and chimney vacuum degree sensors. The majority of issues must be diagnosed by feel, the electric motor’s or burner device’s operation, and occasionally a good sniff will help.

Things to be mindful of:

• on the sounds produced by the moving parts of the boiler when switching on. Ringing sharp noises usually indicate that the three-way valve or fan impeller needs to be repaired. A constant humming noise can indicate bearing problems;
• odors. If the gas fuel is not burning properly, there will be an odor of burning and burnt paint. The appearance of a specific gas odor indicates a leakage. Urgent repairs to the boiler inlet are required.

It is essential to pay attention to the nature and length of the burner operation. A gas boiler typically operates its burner for 10 to 30 seconds at regular intervals to start and stop. The burning period’s duration is the only variable. If the boiler remains stationary for an extended period of time, or if the duration of combustion is excessive, the control board might require maintenance.

Never attempt to test individual electronic board components or change the boiler’s settings directly. The board is de-energized, earthed, removed from the boiler, and inspected in accordance with the instructions using a specialized tester connected under load if the unit has failed and repair is necessary.

Maintaining a warm and cozy house throughout the winter requires fixing a gas boiler. Many common problems with gas boilers that homeowners may experience range from broken thermostats to malfunctioning pilot lights. Your heating system will operate more efficiently if you are aware of these problems and how to fix them.

A broken pilot light is one of the main problems gas boilers give homeowners. When you least expect it, a pilot light that won’t ignite or won’t stay lit can leave you without heat. Cleaning the pilot assembly or adjusting the pilot light’s position can often solve this problem. If the issue continues, though, it can point to a more serious problem with the gas valve or thermocouple that needs to be looked at by a professional.

One other typical issue with gas boilers is a broken thermostat. Inconsistent heating or the boiler not starting when it’s needed are two possible effects of a broken thermostat. Checking the thermostat settings, changing the batteries, or recalibrating the thermostat are common steps in the troubleshooting process for this problem. If none of these easy fixes work, there might be a wiring or sensor problem that needs to be fixed by a professional.

Gas boilers can also have problems with temperature control and water pressure. While variations in water temperature can cause discomfort and inconvenience, low water pressure can lead to insufficient heating. These problems could be caused by issues with the circulating pump, expansion tank, or pressure relief valve. Changing the pressure settings, bleeding the radiators, or doing any necessary repairs or component replacements could be necessary to resolve these problems.

To ensure the longevity and efficient operation of gas boilers, it is imperative to perform routine maintenance and timely repairs. A comfortable living space can be maintained year-round and expensive repairs can be avoided by homeowners who are alert to warning indications of trouble and take quick action when necessary. It is advised to seek the diagnosis and repair of complex problems or those requiring specialized tools and knowledge from a licensed heating technician.

We’ll go over the typical issues homeowners have with gas boilers and how to resolve them in this guide. Although gas boilers are necessary for heating homes, they can experience problems such as malfunctioning thermostats, pilot light failures, or strange noises. We’ll take you step-by-step through every issue, providing workable answers that you can either apply on your own or with an expert’s assistance. Understanding these typical issues and being able to troubleshoot them will help you keep your house toasty warm throughout the winter without having to pay astronomical amounts for repairs.

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