If you heat your home with steam or hot water, you’re in a very select group! Most of the 113.6 million homes in the U.S. rely either on natural gas or electricity for home heating. Only 6.9 million, however, rely on steam or hot water systems and of that number 4.3 million are located in the U.S. northeast.
That’s only 6.07% of all U.S, homes —pretty unique. But that also means that homeowners that rely on steam or hot water have pretty unique problems — especially when it comes to radiators. To keep them working at their highest efficiency, you need to be able to understand how to take care of them. So to help homeowners that rely on this unique and archetypal heating system, we’re going to explore some tips on how to keep your radiators working efficiently so you can stay warm and comfortable, and save money.
One-Pipe vs Two-Pipe Radiators
There are two types of home steam radiator systems; one-pipe and two-pipe.
One pipe systems carry steam up the the radiator. The steam heats the radiator and then cools, condensing into water. The condensed water then travels back down the same pipe to the boiler where it is reheated. One-pipe systems use automatic air vents on each radiator. These small cap-like vents are connected between the radiator and steam pipe. Inside the vent is a valve and a bellows filled with a volatile liquid. This liquid boils at 10°F below the boiling point of water. When the boiler isn’t being used, the valve stays open, letting in ambient air from the room. When the boiler is fired up, steam begins rising in the system. As the steam reaches a radiator, it push the air out of the radiator (called “bleeding”). When the steam reaches the valve, it heats the bellows. The liquid inside expands and closes the valve.
Radiator water contains lime scale and rust that can form sediments and over time clog the radiator air vents. Clogs can keep these vents stuck open so that steam escapes all the time and wastes the heat. Or clogs can keep the valve closed so that steam never enters the radiator, keeping the room cold.
It’s a good idea to test fire your system before the heating season starts. That way, you can identify what valves are causing problems. With the heating system shut down and cooled, these vents can then be disconnected from the radiator and boiled in vinegar and water to dissolve the clog. However, because the bellows that shuts the valve can also go bad, you should expect to periodically replace the vent.
One important detail is that radiator air vents need to be replaced with the same type and size to keep the system balanced. From smallest to largest, these are: #4, #5, #6, C, D and #1.
Two pipe systems have one pipe that carries steam up to the radiator. When the steam condenses into water, the condensate water drains down the second pipe to the boiler to be heated again. To keep steam from being forced down the drain pipe, two pipe systems use a steam trap. The trap contains a float that opens a valve. When water condenses in the radiator, it fills the trap. When enough water accumulates, it raises the float which then opens the valve and allows the water to drain back to the boiler. When steam traps go bad, they keep the valve open or closed — which can also throw the whole system out of balance by allowing steam and water into places that it shouldn’t. In that case, Energy.gov advises the best approach is often to simply replace all the steam traps in the system.
How to Fix a Knocking Radiator
Dr. Science once explained that a radiator knocks because pitiful creatures are trapped inside and are knocking, desperate to get out.
Actually, it’s water getting trapped. When it comes in contact with steam, the steam can condense suddenly and quickly, taking up 1700 times less space. This creates a sudden powerful vacuum that pulls in nearby water, slamming it against the insides of the radiator. Thermal expansion from hot radiators can wreak havoc with wooden floors. Over time, the heat and weight cause the flooring to warp or tilt— especially more so if a valve has been leaking water. Radiators can also sag. So, if the radiator is no longer in a position that lets the condensate drain back down to the boiler, then the water will get trapped and cause banging or hammering when it gets hot.
Adjusting the radiator’s pitch to allow the water to drain properly can be done using a few shims and carpenter’s level. Of course, if you’re unsure of your plumbing skills, call a trained professional plumber.
How to Fix a Hot Water Radiator
Hot water radiators are more common in newer homes. Their most common problem is air getting trapped into the system when fresh water is added, which causes them to work less effectively and efficiently. The fix here is to get the air out by turning on the system and then going to each radiator and bleeding off the air and hot water into a bucket until the bubbles are gone. Start at the top most floor and move lower floors until all the radiators have been bled.
Boiler Maintenance Tips
Keeping your boiler working well is important not just for energy efficiency but also for your family’s safety, too. Before heating season begins in earnest. don’t forget to:
- Drain some water from the boiler to clear sediments. This improves energy efficiency and increases the lifespan.
- Check the boiler water and add chemicals as needed to control deposits and corrosion.
- Check the boiler’s heat exchanger for signs of leaking water.
- On hot water systems, check the pressure relief valve.
- Be sure to have your boiler checked over annually to make sure its safety controls are in working order.