Many buyers overlook the mechanical systems when buying a new home. Behind a mortgage, heating and cooling energy costs are the second-largest expense homeowners typically have. So, it’s important to know what type of heating system and cooling system exists in a house you’re looking to buy.
In the video above, Ask This Old House plumbing and heating expert Richard Trethewey, walks you through a house with a steam heating system.
What is Steam Heat?
Steam heat is created by converting water from a boiler into steam. Houses with steam heat can be identified by looking for radiators that are connected to only one pipe, not two.
A steam boiler is normally located in the basement and filled halfway with water. A flame underneath the boiler heats up the water, and as the water turns to steam, it expands to 1,700 times its original volume. The steam then travels up quickly through piping and works its way into radiators throughout the house. An air valve on each radiator allows air from the piping and the radiators to escape until steam is sensed and the valve closes. The steam gives off its heat to the room as it condenses back into water.
Should You Use a Steam Heating System?
Here’s what to what to consider when weighing your options with steam heat.
Pros
- A common question is, is steam heating efficient? A well maintained steam system can be comfortable and efficient.
- Steam boilers can last a very long time, so if the installation date on the boiler itself seems old, that does not necessarily mean it needs to be replaced. When checking out a home remember to also check the condition of the boiler. Boiler’s usually last a very long time, but it’s worth it to make sure everything is working, and that there aren’t any leaks, before you buy.
In one TOH project featuring an 1880s building, the original steam boiler was still operational. As TOH plumbing and heating expert Richard noted, the system had evolved over time — originally fueled by coal, the boiler had been updated with modern fuel sources while the fundamental steam distribution remained in place, heating the entire building through every single radiator.
Cons
- There can only be one zone (or one thermostat) controlling the heat for the entire house if it’s heated by steam heat, meaning some rooms can be hotter than others. This can be a disadvantage for some homeowners.
- Oftentimes, houses with steam heat will not have air conditioning, and that can be expensive to retrofit. Factor in if you need or want to add air conditioning into your costs.
- Steam radiators can also sometimes have very loud, clanking water pipes. This does not mean there is anything wrong with the system; it’s just annoying. You can test this during an open house by asking the realtor to turn the heat up in the house and listening to the pipes during the tour.
Pro Tip: As one TOH plumbing expert noted during a home evaluation: “It’s one zone, one thermostat for the entire house. So some rooms can be hotter than others.” When touring a prospective home with steam heat, take note of whether the radiators are consistently sized — mismatched radiators, often swapped out by previous owners to make room for furniture, can make the uneven heating problem even worse.
Overall, deciding whether or not steam heat will work for you boils down to comfort. If you don’t care too much about having air conditioning and you just want steady heat, there’s nothing wrong with steam heat.
One common complaint with steam systems is overheating. In one TOH visit, a homeowner demonstrated the all-too-familiar routine: first, trying to shut off the radiator by the handle — which, as she admitted, doesn’t really do much — then resorting to opening a window. In the industry, that’s known as the “double-hung thermostat.” If you’ve ever driven through a city and noticed top-floor windows cracked open in the dead of winter, chances are those buildings have one-pipe steam systems with limited temperature control.
