Gas boilers are reliable equipment supplying our country houses and part of city apartments with heat and hot water. Unfortunately, they cannot work completely without breakdowns. And among the violations, valves often appear - protection devices and supply of fuel to the units.
We will tell you how and what kind of repair of a gas boiler valve can be done with your own hands. In detail we will analyze the situations that signal the occurrence of related violations in work. Let’s show you whether it’s worth making your own efforts or is it better to turn to gas workers.
In our article, you will find step-by-step guides on restoring the functionality of gas boilers by repairing or replacing a gas, safety, and three-way valve.
Varieties of valves in a gas boiler
The normal operation of gas equipment intended for heating sanitary water and preparing a coolant is ensured by a wide range of systems, parts, devices, each of which clearly fulfills the important function assigned to it.
In the design of gas boilers there are the following types of valves:
- Gas valve. A component of the gas system, which is responsible for the proportional supply of blue fuel to the gas burner, ensuring a stable combustion process in accordance with the instructions of the electronic board. This electromagnetic device also includes shut-off and control valves.
- Safety valve. A component of the hydraulic system, designed to discharge excess coolant from the heating circuit in case of exceeding the standard pressure values.
- Three way valve. Detail of the hydraulic system of only double-circuit boilers. Redirects the flow of heated water from the heating circuit to the DHW during its consumption for hygiene purposes. Depending on the class of the boiler, it happens with and without a servo drive.
All of the listed types of valves involved in the operation of the gas boiler can be replaced or repaired in the event of a breakdown.
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Wall mounted boiler without front panel
Circulation pump and expansion tank
Gas valve of the heating unit
Safety and three-way valves
Let's get acquainted with the technology for restoring their performance. Having mastered simple repair principles and techniques, you can significantly increase the life of the boiler itself.
Typical failures and repair methods
The types of valves listed above perform ambiguous functions and vary in design. The reasons why they become unusable and the ways to eliminate the breakdown differ.
Gas valve malfunctions
The main purpose of the gas valve is to regulate the pressure of the gas supplied through the nozzles to the burner. You can adjust the flow so that 25 to 100% of the flow enters the chamber. It all depends on what type of gas to be used in the operation of the equipment, how much air will flow for normal combustion.
In fact, this is an electromagnetic device, the main work of which is carried out only with the connection to the power supply. However, when its electromagnetic coils are de-energized, the gas valve acts as a safety part. In this case, it tightly overlaps the channels through which the gaseous fuel moves.
A lit ignitor acts on the working part of the thermocouple, which begins to generate current. Generated electricity is transmitted to the gas valve coil, which attracts a metal washer and opens the way for blue fuel
The charge generated by the thermocouple of the gas water heater or heating boiler falls on the electromagnet (coil) of the gas valve, as a result of which the metal washer of the shut-off valve is magnetized to the coil. The washer opens the membrane so that the gas can pass to the igniter and nozzles of the burner block.
When the flame attenuates or decreases below the standard values, the thermocouple stops generating electricity. As a result, there is a demagnetization of the coil holding the washer. The blue fuel supply channels are closing.
If no current flows to the coils of the gas valve, the device hermetically closes the channel for supplying blue fuel to the burner. In addition to the shut-off valve, the gas valve design also has adjusting devices with which you can configure the minimum and maximum gas flow
The need to take action will be reported by a drop or increase in static pressure, i.e. inlet pressure when the boiler is idle. For units that process main gas, it must be at least 17 mbar. For boilers powered by liquefied fuels - not lower than 35 mbar.
The list of typical gas valve breakdowns includes:
- Violations in the electrical circuit supplying the electromagnetic device. In this case, all wiring and contacts in the connection areas should be checked with a multimeter. If a break is detected, it is eliminated in a commonplace way: by replacing a damaged wire, stripping and tightening the contacts.
- Clogged gas valve. The channels of the device can periodically become clogged with mineral particles coming together with low-quality gas, elemental carbon deposits and calcium salts formed in the event of condensation in the supplied fuel. The simplest mechanical cleaning saves.
- Thermocouple failure. Often requires a complete replacement due to complete burnout of the working edge. At the same time, no current is transmitted to the electromagnet at all, as a result the boiler does not light at all or is blocked after a couple of minutes of operation.
- Mechanical damage to the gas valve. For example, the above washer. It either ceases to be pressed tightly and ensures tightness, or does not respond to adjustment, due to which an uncontrolled volume of gas enters the chamber. To eliminate this, either a valve or a damaged part is replaced.
- Short circuit to the body of the coil of the electromagnetic coil. Most often, it occurs due to short-term overheating and subsequent melting of the plastic sleeve, on which coils of the electromagnet are wound.
It is clear that the list of all breakdowns can be divided into two groups: violations in the electrical part and mechanical damage to parts.
Gas boilers go on sale with factory-made settings for the consumption of main gas. They are changed in case of adjusting the flow of gaseous fuel or in the case of transferring the boiler to work from a liquefied gas mixture
We immediately warn that when carrying out any repair measures for which it will be necessary to remove the unit body, it automatically deprives the owner of the right to use the warranty from the manufacturer. In addition, neither the company nor the organization with which the service contract is concluded will bear the slightest responsibility for a negative result.
It happens that instead of learning how to correctly fix the electromagnetic valve of a gas boiler, the unit owner is trying hard to turn it on. At the same time, continuously presses the button of the gas supply device, trying to start the burner. This is absolutely impossible to do.
If you independently open the path to the gas flow, the boiler burner will still not ignite. But the gas will flow into the room uncontrollably, while the owner will hold his finger literally "on the trigger." What does this threaten? At best, light poisoning, at worst - explosion.
The following selection of photos will introduce the steps to restore the electromagnetic coil of a gas valve:
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As an example, we will analyze an electromagnetic locking device of the simplest design from the boiler Rostovgazoapparat AOGV
In working condition, the metal valve washer must be magnetized to the coil when a current of 1.5 V from the battery is applied to it. Due to a short to the winding body, it did not magnetize
We examine the electromagnetic part of the gas valve, look for the closure of the coil, each of which includes 6-7 turns of thick wire
Disconnect the threaded sleeve soldered to it from the body, heating the connection point with a soldering iron
Remove the polymer sleeve that insulated the winding wire. It deformed and became the cause of the closure of the valve winding
Instead of a damaged and deformed sleeve, we put a new part. If you could not buy it, a couple of pieces of PVC pipes threaded into each other will do.
We put all the parts that were separated from the gas valve body into regular places in the reverse order to that performed during disassembly
After assembling the parts of the gas valve, weld the threaded sleeve back to the gas valve body
Step 1: Disassembling the gas valve
Step 2: troubleshooting the valve
Step 3: Finding a Coil Damage Area
Step 4: Detach from the hub body
Step 5: Removing the Insulation Sleeve
Step 6: Replacing a Damaged Plastic Sleeve
Step 7: Reassemble the Gas Valve
Step 8: Soldering the threaded sleeve
Repairing the gas boiler valve is not too easy, but it is much cheaper than buying and installing new equipment for the preparation of coolant and hot water.
Having completed the repair, for the purpose of prevention, all components of the gas system should be cleaned of contaminants. Flux should be removed from the solder sites using a suitable solvent. Next, you need to check the operability of the valve by supplying it with a 1.5V battery.
Relief Valve Problems
The design of a wall-mounted gas boiler of a new generation must have at least one safety valve. In gas columns and old floor units for heating, it was not provided. It was believed, after all, that this protective device was to be mounted on the pipeline after the boiler.
Double-circuit units that process the heating system and sanitary water supply branches can be equipped with a pair of safety valves. One of them is put on heating, the second - on the DHW pipeline. In both cases, this device is ajar from excess pressure in the system and releases excess water. Then it closes automatically.
It makes no sense to repair the safety valve, since in most cases its breakdown is associated with the appearance of a crack on the body or thread breakage, which violates the tightness. This device is just changing
Problems with the safety valve to the owners of the gas boiler will be reported by a leak in the area of this protective device. It is located at the bottom of the unit, not far from the circulation pump. A technical passport will familiarize you with the exact location.
If there is a serious breakdown, it does not make sense to repair the safety device. Only a replacement is made. If a grain of sand is stuck under the seal or in the mechanical part, there is a reason to tear apart the device and assemble it again.
Maintenance valve problems
We repeat - only double-circuit boilers are supplied with three-way valves.Their task is to redirect the flow of water from the heating to the hot water supply and vice versa. More precisely, at the command of a three-way valve, water enters the plate heat exchanger for its subsequent supply to the water points or to the main heat exchanger associated with the heating system.
Violations of the three-way valve can be determined:
- To reduce the temperature of the coolant in the heating circuit.
- By cold water entering the plumbing fixtures when the heating equipment is running.
- By the absence of a switching effect, i.e. for heating either only coolant, or only sanitary water.
The most common cause of a three-way valve failure is the appearance of mineral deposits on the inside walls of the device. This happens because of the simplest clogging, because the filter was not installed on the water supply in front of the gas boiler.
The servo drive burns out much less frequently or its individual components fail. If a drive problem is found, the three-way valve will have to be replaced completely. It is selected according to the specification specified in the data sheet by the manufacturer of the unit.
However, mercilessly throwing away the switching device in case of failure does not need to work. You can try to restore the operability of such a device in order to leave it as a backup device.
The steps for repairing a three-way valve are detailed in the following photo gallery:
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If the three-way valve of the double-circuit gas boiler has stopped redirecting the flow of heated water from heating to the hot water supply, it means that it needs repair. In addition to the device, the master will need a Phillips screwdriver, soldering iron and multimeter
We study the condition of the inlet. In most cases, mineral deposits and rust are visible on it.
In order to disassemble the three-way valve of the gas boiler, we unscrew the four screws, using a Phillips screwdriver
With a multimeter, we check the operability of two microswitches located inside the case.
Unscrewing two more screws, remove the three-way valve engine to check its condition
We inspect all the internal parts of the disassembled three-way valve, clean it of rust and mineral sediment
We test the performance of the valve motor. We check the resistance between its terminals. If the tester readings are measured in units of ohms, change. The resistance of the working motor should be 15 kOhm or so.
If the valve repair did not give the expected results and the wiring connecting the three-way valve valve to the wiring turned out to be in order, the problem is in the electronic board. Theoretically, it can be repaired, but it is better to change
Stage 1: Preparing the maintenance valve for repair
Stage 2: Inlet Inspection
Step 3: Loosen the screws from the valve body
Step 4: Verify Micro Switch Performance
Step 5: Disconnect the valve motor
Stage 6: Cleaning the interior of the sediment
Stage 7: Testing the operation of the crane engine
Step 8: replacement electronic circuit board
Do not forget that the water redirection device is connected to the power supply. So, if the valve itself is not damaged, there may be problems in the wiring. They are eliminated in an elementary way: first, the wiring is checked, they ring, then the damaged wire is changed.
If everything is in order with the wiring, then you need to check the contacts. All joints are checked with a multimeter. For prevention, they need to be disconnected, wiped with an alcohol-containing composition, reconnected, tightening with effort.
It happens that the failure of the three-way crane to do the job is not to blame for himself or the wiring, but the electronic board sending the commands. In the workshop, of course, they can restore it, replace the burned-out resistor. But most often they change completely to a similar model.
The following video will introduce the gas valve device, the causes of malfunctions and repair methods:
Solving the problem with a three-way valve of a gas heating unit:
Dismantling and cleaning the safety valve:
Repair of valves of gas equipment will significantly extend the operational life of units. Repairing them is much simpler and cheaper than buying a new model. Not all repair operations are recommended to be carried out independently, but the simplest actions are quite accessible to home masters.
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