Millions of households throughout the U.S. remain warm, comfortable, and safe all winter long through the use of a boiler. Boilers are systems that use fluid to hold and distribute heat. Let’s take a closer look at what a boiler is and how it functions.
Hot Water and Steam
There are two main types of boilers used for residential and commercial applications: hot water and steam. They both use fluid to hold and distribute heat. The main difference is that hot water boilers never reach the boiling point. Steam boilers, on the other hand, heat water until it becomes vapor. Hot water boilers are more common than steam boilers and have been for many decades. This initially happened because hot water boilers were much safer. Modern steam boilers are very safe, but hot water boilers are still more common because they’re more efficient and allow for more precise control. That said, steam boilers are still available. One reason is backward compatibility with older plumbing installations. Another is that steam boilers don’t need pumps and require less maintenance.
Power and Fuel
For both hot water and steam boilers, there are two main configurations: electric and fuel-burning. The Department of Energy (DOE) measures boiler efficiency using the annual fuel utilization efficiency (AFUE) rating. AFUE indicates the percentage of fuel that a boiler successfully converts into heat. This rating is at or near 100% for electric boilers. Despite that difference in efficiency, fuel-burning boilers are more popular due to the cost of electricity. To compare electric boilers, look at the estimated annual operating costs found on the yellow EnergyGuide label.
Even most fuel-burning furnaces use some electricity for LCDs, control boards, and so on. Natural gas boilers are the most popular and affordable but require natural gas access. For homes that lack access, liquid propane and fuel oil are popular alternatives. The DOE minimum for gas boilers is AFUE 80. High-efficiency boilers have an AFUE as high as 98.5.
Storage Tank or Reservoir
Hot water boilers have a storage tank to store and heat water. Steam boilers have a reservoir with the main distinction being that it doesn’t have to be as large. Both systems have a cold-water inlet, which is where water enters the boiler from the plumbing. Boilers also have an outlet. In hot water systems, a pump forces the hot water through the outlet. In steam systems, pressure forces the steam through the outlet.
Steam and hot water boilers have a drain valve and a temperature and pressure relief (T&P) valve. The drain valve allows a plumber to flush the system, which is necessary because sediment and limescale may build up over time. Limescale and sediment accumulation causes inefficiency and component wear. The T&P valve allows the system to relieve pressure. The moisture exists via the valve and drains out of the home through a drainage system.
Heat Exchanger
Boilers generate heat and then transfer that heat to water via a heat exchanger. Both electric and fuel-burning systems typically achieve that heat transfer through coils. Manufacturers design the coil array to maximize surface area and allow for the most heat transfer.
Size and Capacity
The size and capacity of a boiler aren’t the same thing but are closely related. The HVAC and plumbing industries in the U.S. measure heating output in British thermal units (BTUs). You need a certain tank or reservoir size to achieve the required BTUs. How many BTUs do you need? That depends on many factors, including climate, location, building envelope, floorplan, square footage, ceiling height, and so forth. Your installer will take all these details into account via a load calculation. A rule of thumb is that you need 30 BTUs per square foot.
Heat Distribution
A boiler heats water either to the point of boiling or until it becomes steam. It then moves that fluid out of the boiler through pipes or tubes. These systems also require a mechanism through which the heat leaves the water and enters the home. The most common solutions are radiators and radiant panels.
Radiators
Households have used radiators as long as they’ve used boilers. These are reservoirs that hold water and allow heat to enter the living space through a finned design. Wall radiators were the earliest kind of radiator and are still in use today. As technology advanced, baseboard radiators became more popular. They take up less space and are lower to the ground, which allows for more even heating.
Radiant Panels
Radiant panels are a modern alternative to radiators for hot water boilers. These are panels that we install beneath the flooring and which have tubes to carry the hot water. Radiant panels provide even better floor-to-ceiling heating than baseboard radiators. They also heat the floor itself, which is very nice in bedrooms, bathrooms, and living rooms. You can install radiant heating panels throughout a home. You can also mix and match radiators and panels.
Exhaust
Fuel-burning furnaces create carbon monoxide (CO) and other toxic gases as a byproduct. Boilers that burn fuel need an exhaust system to vent those gases outside the home. You also need CO detectors in case there’s ever an issue that causes dangerous gases to enter the home.
Condensing vs. Noncondensing
In conventional boilers, heat energy escapes through the ventilation system, which is one of the main causes of inefficiency. The industry now refers to this conventional design as noncondensing. High-efficiency boilers are condensing systems. They have a second heat exchanger that reclaims much of the heat energy from the exhaust. This is what allows AFUE ratings as high as 98.5.
Thermostat Control
Boilers have at least one internal thermostat to regulate the system. Hot water boilers often have two: one for the upper part of the tank and another for the lower. There is also at least one thermostat within the home to provide convenient user control. It’s crucial to choose a thermostat specifically designed for boilers. Regulating heat from radiators and panels is quite different than a furnace or heat pump.
Zone Control
Modern boilers are well-suited to zoning. This is where we organize a home or commercial space into discrete zones. This formation allows, for instance, cozy bedrooms while the rest of the home has a more energy-efficient setting.
Combination Units
Combination systems or “combi” boilers provide hot water to the home as well. Traditional systems have a larger tank to store the necessary hot water for faucets, showers, and appliances. There are now indirect systems that provide hot water on demand. There are also hybrid systems that use a heat pump and supplement it with traditional water heating.
Boiler Services in Anoka
Liberty Comfort Systems is a family-owned and operated company that’s served Anoka, MN and the surrounding areas for over 20 years. We provide both residential and commercial services. Our NATE-certified technicians install, maintain, and repair all manner of hydronic heating systems. We provide these services for furnaces, heat pumps, air conditioners, and ductless mini-splits as well. Our indoor air quality team cleans ducts and installs and services air purifiers, UV lamps, humidifiers, and dehumidifiers.
Our licensed electricians perform inspections, maintenance, repairs, and installations, including solar. We also have plumbers available for drain cleaning, sewer repair, tank and tankless water heaters, water filtration, and water softening. Contact us today with any questions about our products and services or to book an appointment.
