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You must know the boiler types for the right purchase. Orient Boilers discusses boiler varieties. So, you can make the right decision for home or industry. Diverse boilers have distinct features and serve distinguished purposes. They uniquely suit their objectives. Let’s explore different types of boilers.

What are the different types of boilers?

Typically, boiler heating systems and fuel differences offer a difference across boiler types. We discuss six different types of boilers in this write-up.

Steam boiler

Steam boilers offer steam-oriented heating systems. Multiple types of steam boilers manage steam by hitting the water to create energy. A heat exchanger, the boiler makes steam for outside usage. The boiler contains a combustion chamber and a water container.

The fine-tuned merger of heat and water produces steam. Radiation, convection, and conduction are three forms of heat to generate steam.

Construction, portability, tube type, fuel type, and pressure types define steam boilers. Initially, boilers were dangerous due to stark deficiencies of control mechanisms. 

Various fuels power steam boilers, including electricity, wood, natural gas, coal, and fossil fuels. Fuel selection relies on costs, eco-friendliness, and efficiency.

A pressure relief valve and a low water cutoff are mandatory for steam boilers. Sometimes, the machine carries a manual valve to add water as necessary. Boilers need occasional maintenance of the heating system.

Wet-back boiler

Wet-back boilers have the reversal chamber surrounded by water. Water surrounds the combustion reversal chamber. So, the heat in the flue gases goes through optimal use. 

The lowest radiation losses characterize these boilers. Because the combustion chamber lies hidden from the atmosphere with layers of water. It translates into insignificant losses and smaller fuel bills. 

Note: Modern boilers are mainly wet-back boilers.

Dry-back boiler

Water partially surrounds the reversal chamber in a dry-back boiler, unlike the wet-back boilers. The posterior part lies exposed to the atmosphere. Hence, increased radiation losses bring you enormous fuel bills. The atmosphere sucks the radiant heat dissimilar to the wet-back boilers. 

Note: The dry back was the earliest generation boilers with less fuel efficiency.

Hot water boiler

In hot water boilers, tanks transfer heat to water. Then, the water circulates for heating purposes. Hot water boilers use stainless steel, cast iron, aluminum, and steel. They can withstand high temperatures and pressure.

The heating systems rely on pressure, volume, and temperature to heat the radiators. The boiler uses multiple pumps to circulate heated water across the designated area.

Tube systems characterize the hot water boilers. In short, fire-tube hot water boilers immerse tubes in water. Heat moves through the pipes and warms up the water around them. Contrarily, water-tube hot water boilers push water through the tubes. As the water circulates, the hot tubes warm it up.

Note: Hot water boilers are not hot water heaters.

Natural gas boiler

Gas steam boilers use natural gas or propane. Typically, natural gas boilers guarantee high efficiency than others. An external source injects the fuel into the boiler via a direct pipe. Moreover, the heat distribution relies on your preferred configuration. 

These propane-based machines are the best industrial boilers that require low-pressure applications. A temperature gauge regulates natural gas circulation, whereas a thermocouple reduces fuel wastage. The gas flashes a pilot light. In turn, the light warms up the heating coils located in the boiler. Then, the coils allocate the heat to the water tank.

Electric boiler

Electric boilers use electricity to generate heat. They offer a clean, fast, and efficient heating system. This eco-friendly method avoids fossil fuel burning. Endurable electric boilers need less cleaning and maintenance. However, they develop scale in the water reservoir.

Highly popular electric boilers are incredibly efficient and eco-friendly. They dismiss the need for exhaust fumes carrying valuable heat into the atmosphere. They require no gas or fuel supply. Low installation costs and space efficiency make them highly desirable.

Oil boiler

Oil boilers come with water-oriented heating systems fueled by oil. You could spot them in rural areas with limited access to natural gas. 

The separate oil tank occasionally blends heating oil with domestic biodiesel. Then, it pumps the mixture into your oil boiler to heat the water. Afterward, the boiler sends hot air or water through the piping. 

Old oil boilers cost extra energy. Besides, you can detect the less eco-friendly boilers from their natural draft, continuous pilot light, or a heavy heat exchanger. Sometimes, retrofitting could allow a longer life span. However, you must eventually replace the entire unit.

Condensing boiler

Two separate heat exchangers define condensing boilers. They heat the water towards the radiator and reheat the water returning from the home piping. 

Typically, this boiler taps into the energy potential in exhaust gases to preheat the return water to the boiler. Improved energy efficiency marks it out against its non-condensing counterpart.

Low-pressure boiler

At a temperature of 300° F, low-pressure steam boilers relocate heat at pressures between 10 and 15 psi. 

They prohibit temperature fluctuations and facilitate the need for a consistent environment. Anyway, the rapidity of steam delivery boosts their massive popularity. They work much faster than high-pressure steam boilers.

High-pressure boiler

Extreme pressure of high-pressure steam boilers powers equipment and machinery. The force eventually derives from a pump that drives the steam at high pressure into the circulation mechanism. They produce pressure between 15 psi and 800 psi at 250° F+ temperatures. 

As types of industrial boilers, their safety and efficiency rely on regular inspections of the pressures and temperatures.

Water-tube boiler

Water tube steam boiler channels water through the boiler tubes. Fire lits up in the combustion chamber. Then, it burns around the outside of the tubes to heat the water passing through them. 

Tangential pressures in the tubes produce high-pressure steam, called hoop stress. Here, the pressure applies to the circumference of the tubes. The theory resembles the stress involving the bands of a wood barrel as it fills up.

Fire-tube boiler

What is a fire tube boiler?

Fire-tube boilers heat the tubes. Then, the water circulates the tubes. Coal or oil heats the gases to heat the inside of the tubes. After that, thermal conduction transfers the heat to the water to create steam.

Fire-tube boilers design involves low-pressure steam. Cochran, locomotive, and Lancashire are three dominant fire-tube boilers.

Combo boiler

Combo boilers merge a high-efficiency water heater with a central heating boiler. They contain no additional storage units and utilize the hot water straight from the tap. Hence, extreme energy efficiency defines them. They can momentarily heat the water. Being extremely compact, they are ideal for tight spaces. Combos are the types of boilers for homes

Shell boiler

Shell boilers enclose heat transfer surfaces in a steel shell. An intricate combination of tube layouts is crucial. The heat makes it through the tube layout before being discharged. 

Shell boilers have another name, flue boilers. They contain a long water tank with fire tubes. The furnace heat passes through these fire tubes to heat the water.


Now, you know different types of boilers.

Numerous options make it hard to select the right boiler involving some tricky insights. Luckily, at Orient Boiler, our seasoned boiler experts help you pick your perfect match. So, let’s get a free consultation to find yours.

A heating system characterizes boilers. Water heating generates energy. Several fuels empower a steam boiler to heat water — diverse combinations of heat and water prompt steam. 

The construction, portability, types of tubes & fuels, and the pressure define the boilers. The combustion engine releases heat as the boiler absorbs it. 

Radiation, convection, and conduction are the three heat transfer methods. Different types of boilers speak of discrete physical structures and purposes.

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