If you’ve ever wondered about the differences between a water heater and a boiler, Aris Parviz of Able Air-1, Inc. is the just the right expert to break it down for you. His company services home heating and water heating systems of all types, including boilers, water heaters and some of the newest “combination” systems. Here Parviz shares his insider perspective on the major differences between water heaters and boilers.
No clue about the systems that heat your home and your water? You’re not alone. In the HVAC and plumbing industries, we find that many homeowners don’t know much about their major appliances. One major source of confusion is the difference between water heaters and boilers. It makes sense; it seems natural that something called a “boiler” would do essentially the same thing as something called a “water heater.” But the two are actually quite distinct, both in their function and in their use. More recent trends, however, have blurred the lines a bit between these two types of systems. For someone building a home or upgrading to a newer home heating or water heating system, understanding a few basic differences is important.
In terms of how they function, boilers and water heaters differ. In a basic sense, a boiler is essentially a sealed container in which water is converted to steam. In order to heat the water, fuel — coal, gas or oil — is burned.
A boiler is part of a “closed loop system.” This means that once the steam is produced, it is sent through a closed series of pipes to another point in the system at which it can be used to do something. The steam might be used to deliver heat, to power an engine, to sterilize something…the possibilities are nearly endless. When a boiler is used to provide heat, the steam usually travels through pipes to either radiators or convectors which give off heat to warm a space. The steam can also be used, secondarily, to warm water for domestic use, but the steam itself never leaves the system. As the steam cools, it returns to a water state and is returned to the boiler for re-heating.
In contrast, most water heaters simply use energy — either gas or electricity — to heat water to a higher temperature and then provide it to the interior of the home for domestic uses. Some newer water heaters, however, can also be used to heat spaces. Some water heaters are used as part of a heat pump system which heats air and then forces it through the home via ductwork.
Boilers and water heaters differ widely in terms of cost, with a boiler costing $1,000 to $10,000 and a typical water heater costing about $1000.
While both boilers and water heaters can used as domestic hot water sources, water heaters are used more commonly for this purpose. Conversely, water heaters are only occasionally used to provide heat. But some newer “combination” systems are gaining popularity. These systems deliver both residential heat and hot water, and can do so instantly.
The newer systems use a boiler or a high-efficiency water heater to supply heat for either a forced air or radiant heat system. They also provide on-demand hot water, which means that water is only heated as it’s needed. As a result, there is a limitless supply of hot water to the home. In addition, these new systems are generally more compact and more efficient to run than a boiler, a water heater or both.
These double-duty systems (“tankless” water heaters and “combination” boilers) are significantly more expensive than traditional residential boilers or water heaters. But, over time, they can pay for themselves in energy savings.
