Hot water does not flow from the boiler – causes and their elimination

Storage tanks, also commonly referred to as water heaters or boilers, are frequently installed in buildings without access to centralized hot water or where there is a high likelihood of service interruptions. This technology has maintained its importance since ancient times to the present day. Thus, the credit for the invention of the boiler goes to the ancient Greek mechanic Geron of Alexandria during the latter half of the 1st century AD. Geron’s creation involved using steam to heat cold water. While this knowledge was eventually forgotten, it had to be redeveloped in the late 17th to early 18th centuries. However, similar to other household appliances, even an enhanced water heater can experience malfunctions due to various internal or external factors, as well as regular wear and tear on its components. This article will cover all the possible reasons why a boiler fails to produce hot water and provide solutions to rectify them.

Device and principle of operation

• electric water heaters;
• indirect boilers;
• gas water heaters.

All these devices share a similar design and operate based on the same principle. Their only difference lies in the heat sources utilized for water heating. A heating element, a coil connected to a heat carrier (such as a boiler), or a gas burner can all serve as the heating source. Structurally, all boilers consist of a wall-mounted tank with insulating material covering its interior surfaces. Cold water enters the tank through a lower pipe, while the heated liquid is extracted from the upper part of the tank.

In an interesting twist!

Both the inlet (cold water) and outlet (hot water) pressures in the tank are equal, ranging from 4.5 to 6.8 bar. Consequently, if there is no flow of cold water into the tank, there will be no hot water at the outlet. The water supply is regulated by a pressure regulator (reducer) incorporated into the tank, safeguarding the boiler from potential damage caused by sudden pressure fluctuations within the domestic water supply system.

Causes of lack of hot water and how to eliminate them

Although boilers are known for their reliability and long lifespan, there are instances where hot water may not flow from the tap. Typically, this is caused by minor issues, including:

• clogging of the inlet filter, pipes, and spigots;
• accumulation of scale and salt deposits on the heating element;
• malfunction of the pressure regulator, check valve, or thermostat.

Hint! Oftentimes, the issue of not getting hot water from your faucet or having a weak flow can be attributed to a clogged faucet mesh in your kitchen or bathroom. So, the first step is to check and clear any blockage in the mesh (also known as an aerator) located inside the spout of your faucet.

Here is the step-by-step process for cleaning the mesh. First, close the faucet and unscrew the spout from the mixer’s main body. Carefully remove all the parts and give them a thorough washing. If any of the elements are heavily soiled or have salt deposits, soak them in a solution of washing liquid. Once the cleaning is done, ensure that all contaminants have been removed. Then, place the parts back inside the spout’s body and reattach it to the mixer. Finally, open the faucet and check if the issue has been resolved.

Another potential cause for a lack of hot water production in the boiler could be the failure of one or more valves responsible for the cold and hot water intake. Before diagnosing the boiler’s components, it is crucial to check the functionality of these valves. If any of the valves are faulty, they should be replaced.

Clogging of the inlet filter, pipes and connections

In order to safeguard the internal components of the boiler from any potential debris in the public water supply, a coarse filter is fitted before the inlet connection. Excessive accumulation of particles on the filter element can result in the interruption of the cold water supply to the tank, consequently leading to a shortage of hot water at the faucet.

Resolve the dysfunction by completely cleansing the mesh filter component. For this task, utilize a specialized wrench to unscrew the plug within the filter container and extract the mesh component from the bulb. It should be thoroughly rinsed under a powerful stream of water. In the event of substantial grime, the mesh ought to be cleansed with dishwashing soap. Once the filter component has been washed from dirt, it can be reinstalled in its original position. To expedite the process, it is advisable to have a spare mesh on hand.

Helpful hint! For effectively cleansing the filter element from stubborn contaminants, it is recommended to apply dishwashing detergent onto a sponge and then utilize it to wipe the grid. However, experts advise against soaking the grid in a cleaning solution.

Dirty water frequently leads to blockages in both the main filter and the water pipes and/or supply connections. The centralized water supply system often contains various deposits and foreign entities that cause debris to accumulate and impede the water flow. This is most likely to occur at bends in the pipes. The only way to resolve this issue is by replacing the old plumbing with plastic pipes. If a blockage occurs, it is also advisable to replace the supply valves.

The slow heating of cold water in the boiler or the lack of hot water in the faucet is frequently caused by the accumulation of scale and salt deposits on the surface of the electric heater. These deposits can not only block the water inlet of the boiler, but also cause damage to the heating element.

In order to prevent the negative consequences of tap water of poor quality, it is important to regularly clean the heating elements. This can be done by following these steps:

1. Begin by draining the water from the boiler.
2. Proceed to remove the protective cover.
3. Then, disconnect the boiler from the main power source and detach the electrical wires connected to the heater.
4. Before starting the cleaning process, it is recommended to ensure that the heating element is functioning properly. This can be done by using a multimeter to measure its resistance. A properly working heating element should display a resistance reading of several tens of ohms. If the multimeter indicates zero resistance (short circuit) or infinite resistance (break), it is necessary to replace the heating element.
5. After finishing the cleaning process, it is essential to reinstall all the parts smoothly.

Before proceeding with the installation, it is advised to clean the inside of the tank thoroughly and assess the condition of the magnesium anode. If required, it should be replaced.

When it comes to the components that facilitate water heating through an indirect method, they are also cleansed utilizing cleansing solutions containing citric acid.

It is imperative to avoid utilizing hydrochloric, sulphuric, or acetic acids for the purpose of cleansing heaters and other components within the boiler. These substances are ineffective against limescale and salt deposits, but they do react strongly with copper and copper alloys, which are extensively utilized in the fabrication of parts and components in any water heater.

Contrary to boilers equipped with heating elements, the heaters of gas-fired appliances and indirect water heaters necessitate partial and, in certain cases, complete disassembly before they can be cleansed.

Pressure regulator failure

The lack of hot water coming out of the heater can be caused by two things: either there is a weak water pressure or there is no cold water entering the boiler outlet, and there could also be a problem with the pressure regulator. To check if there is any cold water coming into the system, open the cold water faucet and see if there is any flow (if there is no flow, it means there is no cold water). If there is no issue with the water supply’s pressure, you should then inspect and attempt to adjust the pressure regulator. If the pressure regulator is found to be faulty, it will need to be replaced.

Breakdown of the check valve

A variety of factors can lead to the breakdown of the components installed within the boiler. One such example is the obstruction of the check valve caused by the entry of foreign materials, which may be present in improperly treated water. To address this issue, it is necessary to drain all the water from the boiler, disassemble it completely, and remove any debris located beneath the stem in order to thoroughly clean the valve.

Thermostat failure

If the water heater ceases to heat up water, a potential cause of this problem could be a malfunctioning thermostat. Typically, water heaters are fitted with either a mechanical (built-in) or electronic (surface-mounted) thermostat. To assess their functionality, you will need a multimeter to measure the resistance. If there are no changes in the multimeter reading, it indicates that the thermostat is defective and should be replaced. Unfortunately, thermostats cannot be repaired.

Remember to only check the thermostat once you have confirmed that the heaters are functioning correctly.

When it comes to carrying out procedures related to the dismantling of specific components of boilers, whether it’s partial or complete disassembly, it is advisable to bring in experts who have prior experience in carrying out such tasks on models from the same brand. This requirement stems from the fact that boilers from different manufacturers tend to have unique design attributes relating to the positioning, fastening, and interconnection of internal assemblies and parts.

For instance, Ariston, a well-known company, employs self-clamping clamps in their water heaters instead of nuts for pipe connections. Meanwhile, Termex boilers are equipped with heating elements that are inserted into a 60 mm diameter hole, making it impossible for any tool or hand to reach. This is why the original flanges are utilized to attach the heating element to the boiler body, with bolts that become firmly stuck to the nuts during operation, rendering them impossible to unscrew. Consequently, the fasteners (which can amount to 6 or 12, depending on the boiler’s capacity) have to be cut off using a bolt cutter.

Therefore, the absence of hot water from a household appliance like a boiler can be attributed to external factors that are beyond the user’s control, as well as internal malfunctions within the components of the device. In both scenarios, it is necessary to seek the expertise of professionals (except in cases where there is no supply of cold water), as attempting to clean the heating element without experience is not advisable – this could potentially cause irreparable damage to the boiler. However, by regularly performing preventive maintenance, the device will continue to function efficiently and without any issues.

The best-selling storage water heaters

On Yandex Market, you can find the Thermex Champion Silverheat ERS 50 V storage water heater.

If you are looking for a storage water heater, Yandex Market offers the Thermex Flat Plus Pro IF 50V (pro) model.

Gorenje OTG 50 SLSIMB6/SLSIMBB6 is another storage water heater available on Yandex Market.

Check out the Electrolux EWH 100 Centurio IQ 2.0 storage water heater on Yandex Market.

For those interested in a different Electrolux model, Yandex Market has the EWH 50 Magnum Unifix storage water heater.