Electric Boiler: An In-Depth Guide

What Is an Electric Boiler?

As opposed to the typical boilers, an electric boiler operates without using combustible fuel such as oil, gas, coal or biomass but rather use electricity to generate heat for your home or steam for your production process. When referring to an electric boiler, it implies that electricity is the type of fuel used to power the boiler.

An electric boiler can come in the form of an electric combi boiler, as they both operate on electricity. However, other types such as biomass boilers or gas boilers have a different fuel type.

The electric boiler system is highly efficient thanks to the conversion of electricity into thermal energy that produces an almost 100% efficiency rate. However, it depends how the electricity is generated — whether the electricity generation is efficient or not will influence your conversion efficiency rate.

You will often hear about electric water boilers: be careful, it is not the same as electric boilers! In fact, the first one concerns the small appliance you use to boil water when you want to make a tea or a coffee while the second one involves the device used to heat your home.

If you’re considering the installation of a boiler, we provide you with a free of charge and with no obligation service that allows you to request quotes and compare different systems, so that you can find the most suitable for you. Just fill in the form on the right to request offers.

How Do Electric Boiler Work?

The production of steam is a rather simple process. First, the electricity runs through a heating device that has a resistor property, therefore allowing heat to be created by the resistance phenomenon. Then, when the heat is created, the water comes via a pipe from the water tank to the heating device or close to it to get heated up. When the water is hot enough and starts boiling it produces steam that is used to heat your home via steam pipes.

We could then say that an electric steam boiler works in a similar way as an oil-fired boiler, the difference being the means by which the water is heated.

Pros of Electric Boiler

Several reasons make electric boilers good investments. We listed the main advantages of electric steam boilers:

No need for combustible fuel. Indeed, the use of electric boilers makes the use of a combustion fuel such as gas or oil obsolete. You can, therefore, decrease your energy bill by focusing on electricity rather than diversifying the energy used.

Save space. Because electric boilers don’t use combustion fuel, you do not need to add a fuel storage close to your boiler. Thus, this space left vacant can be used for other purposes.

Save money and energy. Thanks to an electric steam boiler, you benefit from a high-efficiency rate, as almost no energy is lost during the conversion of electricity into thermal energy. You, therefore save money on your energy bill compared to your bill if you possess a condensing boiler such as a fuel combustion one. You also have to install less equipment with an electric steam boiler, which can help you save money during the installation process.

Safe because you do not use fuel for electric boilers, your boiler is safer to use as you won’t experience fuel leaks.

Help conserve the environment. An electricity boiler benefits from a smaller carbon footprint than fuel boiler when it is running.

Reduce your maintenance costs. A combustion boiler needs to get its pipes replaced after some time, mostly when it concerns biomass boilers, wood pellets boilers or wood-fired boiler stoves. However, electric boilers don’t need as much maintenance which saves you time as well as costs.

Cons of Electric Boiler

When referring to the cost of new boiler, there are many factors to take into consideration:

In the previous section, we said that investing in an electric steam boiler is good for the environment. Be careful, this has to be nuanced! Indeed, the generation of heat from an electric boiler compared to a fuel combustion boiler generates less pollution. However, when it comes to producing electricity, it can be as costly for the environment as other fuel extraction such as gas or oil. So the impact of electric boilers on the environment is not always as clear.

This type of boiler operation depends on the generation of power (electricity). If there is a power shortage you might end up with no electricity during some time, making your boiler in-operational.

Your energy bill is mainly subject to the cost of electricity. Nowadays, this cost tends to rise making it more expensive to operate your electric steam boiler. Moreover, with the abandon in some countries of the nuclear power to generate electricity, it might be harder to obtain electricity and thus more expensive.

Boilers steam for Process Heating

Boilers steam is largely used for the purpose of process heating. Using Boilers steam for processing heating offers multiple benefits over other heating media. Numerous benefits, simplicity of the system and high efficiency and reliability make steam the first choice for process heating.

Steam can be used either for direct heating or indirect heating.

Direct Heating

In direct heating, Boilers steam is directly injected in the substance which is to be heated. Care should be taken that proper mixing takes place to ensure uniform heating. It is also essential to take care that no temperature overshoots are observed. Sparge pipes should be used to ensure that steam does not escape to the environment without heating the product.

In pharmaceutical or food and beverages industry, steam of highest purity (safe to be consumed by humans) should always be used for direct heating purposes.

Indirect Heating

The indirect method of heating uses steam to heat the product with the help of heat exchangers so that the product does not come physically in contact with steam. The indirect heating can be done through use of various heating equipment such as cookers, jacketed vessels, plate type or shell and tube type heat exchangers etc.

Boilers steam for Atomization

The process of atomization ensures a better combustion of fuels. The word atomization literally means breaking in to tiny particles. In burners, steam is used for the purpose of atomizing the fuel. This ensures a larger surface area of the fuel available for the combustion. As a result of atomization, soot formation is minimized and overall efficiency of combustion goes up.

Boilers steam for Power Generation

The very first commercial central electrical generating stations in New York and London, in 1882, also used reciprocating steam engines

For decades, steam is being used for the purpose of power generation in form of electricity. The steam power plants work on the Rankine Cycle. In Rankine cycle, superheated steam is generated and then taken to steam turbine. The steam drives the turbine which in turn generates the electricity. The used steam is again converted in to water using a condenser. This recovered water is again fed back to the boiler to generate steam.

The efficiency of the power plant is directly dependent on difference between pressure and temperature of steam at the inlet and outlet of turbine. Hence, use of high temperature and high-pressure steam is advisable. Hence, power generation plants are most efficient when superheated steam is used. As high pressure is involved, water tube boilers are used for Boilers steam generation.

Boilers steam for Humidification

Maintaining humidity is a crucial aspect of HVAC systems as humidity lower or higher than desired has adverse effects on humans, machines and materials. Humidity lower than desired might lead to drying of mucus membranes which ultimately results in respiratory distress.

Low humidity also leads to increased static electricity problems which might damage the costly equipment.

Boilers steam can be used for the purpose of humidification. Using steam for the purpose of humidification offers added advantages over other media. There are different types of humidifiers from evaporating humidifiers to ultrasonic ones to suit different applications.

Boilers steam for Drying

Product drying is another application of steam where steam is used to remove moisture from the product. Conventionally, hot air is used for product drying. Using Boilers steam to dry makes the system simple, easy to control drying rates and compact. The overall capital investment is also low.

On the other hand, use of steam is cheaper on operational basis compared to hot air. It is also a safer alternative. The use of Boilers steam for drying purpose also ensures a better product quality when compared with hot air.

Benefits of boiler system Maintenance

One of the most significant reasons why good boiler system maintenance is so important is because it helps prevent boiler system-related emergency shutdowns. Boilers are typically indispensable pieces of equipment at most industrial facilities. If the boiler fails then all operations at the plant can grind to a halt, stopping production and costing the plant in lost productivity. Following are the other befits of regular boiler system maintenance

Boiler Maintenance Increases the Efficiency of the Boiler

Scheduled Boiler Maintenance and Inspection Increases the Lifespan of Boiler

Regular Boiler Maintenance Helps Prevent Accidents

Certified Boiler Maintenance Saves Money

Good Boiler Maintenance is Needed for Compliance with Laws and Regulations

Boiler system maintenance Check list

Below are recommendations for daily, weekly, monthly, semi-annual and annual tasks. As always, follow your manufacturer’s recommendations for routine maintenance.

Daily Boiler system Maintenance

Blow down the bottom of the boiler system.

Blow down the water column(s) and open the drain slowly to prevent float damage.

Track boiler pressure and temperature, especially at the steady state to determine if it’s keeping up with the load.

Take a stack temperature reading to determine how efficiently the boiler is operating. A well-tuned boiler should have a stack temperature ranging between 50 – 100 degrees above the steam or water temperature.

Routinely check the gas pressure coming into the gas pressure regulator and also its downstream pressure.

For a hydronic boiler, monitor the supply and return temperatures, which are essential control variables that dictate load satisfaction based on the engineer’s design.

Look through the boiler’s sight port in the furnace and observe the flame for any evidence of impingement and possible sooting.

Observe the water softener, dealkalizer, chemical feed system and any other equipment that supports the boiler to ensure proper operation and required levels of salt and chemicals.

Take water samples on a regular basis and compare them to the recommendation.

Weekly Boiler system Maintenance

Conduct an evaporation test on the low water level control(s) to ensure proper operation and burner shutoff at the low water point.

Check the condition of the gauge glass on the low water cutoff for wear and etching.

Check the operation of the fuel supply valves.

Check the single point positioning system on the burner; if applicable, look for wear, slip and hysteresis.

Observe the operating and modulating controls, and while watching the pressure gauge, see if they are turning on and off at their respective set points.

Pull out the flame scanner to ensure the burner shuts off at the prescribed time.

Check the indicating or running lights and alarms to make sure they are functioning properly.

Assess the motors for noise and vibration.

Look for leaks of fuel, water or flue gas.

Check the high- and low-gas pressure switches and the combustion air proving switch.

Monthly Boiler system Maintenance

Check the burner’s diffuser for any deformation, burning or cracking.

Check the burner’s pilot tube that contains the electrode that provides the spark for pilot ignition.

Check the free movement of the air damper device or devices.

Check the entire outside of the boiler for signs of hot spots.

Semi-Annual Boiler system Maintenance

Remove and inspect the low water cutoff bowl and its interconnecting piping.

Pay close attention to the condition of the head assembly’s wiring and switches.

Check the pump alignment on all the base-mounted pumps in the boiler room, and reset combustion using a combustion analyzer for reading O2, CO and NOx emissions.

Annual Boiler system Maintenance

Properly shut down the boiler system and open the access doors to expose the fireside of the boiler.

Thoroughly clean the tubes and tube sheets.

Inspect the insulating materials, looking for any degradation.

Check the refractory. Cracks in the refractory insulation of 1/8” or less are okay.

On the waterside, look for heavy scaling and bridging of the tubes with scale.

Look for evidence of oxygen corrosion.

Check the gas valves and conduct the safety test recommended by the valve manufacturer.

Check the safety valve to make sure there is no sign of leakage.

On the control panel, ensure that all of the electrical connections are tight.

Inspect accessories such as the vented feedwater receiver, deaerator and chemical feed systems, if these are part of the boiler system.

Boiler Stack Loss and effect of Excess Air

Rising energy costs are forcing organizations and management to look in all areas of boiler facilities to improve the efficiency of energy-using systems. Because boiler plants use and waste huge amounts of fuel, managers need to seriously consider maintenance and operations procedures that optimize boiler performance and maximize the organization’s energy investment.

Boiler operators’ common mistakes

When there is too much air in the combustion process, additional fuel is burned to raise the temperature of this excess air to that of the combustion process. Excess air is a costly waste of fuel because it simply absorbs heat that goes up the stack, rather than into the process. How does one guard against these problems?

If there is not enough air being introduced into the combustion process, all fuel will not be burned and, consequently, it will be lost up the stack in the form of combustibles. Not only does this result in an obvious waste of valuable energy, safety and pollution hazards are created. For each increment of change, the energy lost due to excess CO in the flue gas is five- to ten-times greater than the energy required to heat the excess air. To avoid this condition, there is a natural tendency by operators to introduce excess air into the furnace.

Boiler Efficiency improvement

Obviously, some stack-gas heat losses are unavoidable, but lowering the gas temperature as close to the air temperature surrounding the boiler can improve overall efficiency. Boiler efficiency improves by 1 percent for every 11 degrees a boiler or heater’s makeup water is heated. Also, every 40-degree decrease in stack temperature results in a 1 percent improvement in efficiency.

Boiler efficiency is highly dependent on the excess air rate. So, operators should optimize excess air to increase system efficiency. To ensure combustion is complete, they also should provide more combustion air than theoretically is required for boilers. This tactic helps ensure safe boiler operation.

What boiler operators should do?

Technicians also should keep excess air levels as low as possible — about 15 percent excess air, equivalent to 3 percent oxygen — to reduce the quantity of air to be heated and exhausted at the stack. As a rule of thumb, boiler efficiency increases 1 percent for every 15 percent reduction in excess air.

Operators should be careful to prevent the excess air rate from dropping too low, since this can result in heavy buildup of carbon monoxide and possibly even smoke. Some burners operate at recommended excess air levels at high firing rates but increase for other firing rates, which results in an efficiency loss.

To correct excess air levels, operators should perform a tune-up at least annually, and in some cases they should do so more often. The tune-up frequency depends on how quickly the controls require adjustment. Oxygen-trim and carbon-monoxide trim controls can adjust automatically and continuously to compensate for variables inherent in the combustion process and improve the control and efficiency of excess air levels.

Boiler burner fine tuning

Burner performance also is critical to boiler efficiency. The burner essentially fixes the fuel and air quantities in proportions that result in flammability and continuous combustion. To provide optimum efficiency, operators should clean and adjust burners as required.

The most efficient burner mixes fuel and air to minimize excess air for the specific firing rate, ideally throughout the turndown ratio of the burner. Excess air tends to increase at lower turndown ratios.

The most common waste in boilers arises from improperly adjusted burners. Undesirable air and fuel adjustments are common over time, due to changes resulting from wear of cams, linkages and pins. The result is a loss in efficiency.