If you’ve moved into a house with a boiler or you’re thinking about switching to one, the first thing to understand is that this is a hot water system, not hot air. There are no ducts and no vents blowing heat across the room.
Instead, the boiler heats water and pushes it through a series of pipes that feed radiators, baseboards, or in-floor coils. The heat comes from the surfaces, not the air itself, which is why homes with boilers often feel more consistent and less drafty.
Most residential boilers are in the basement, usually near the water heater. When the thermostat signals for more heat, the boiler fires to warm the water and sends it through a loop. That water makes its way through the home, gives off heat in each room, then returns to the boiler to start the cycle again.
That’s the big picture. Here’s what makes it work.
What’s Inside the Boiler Room
A standard hot water boiler setup includes a few core components.
- The boiler itself is the central unit. It holds and heats the water. Most run on natural gas, propane, or oil. Electric models exist, but they’re rare in this region unless the home was built for it.
- A burner ignites the fuel to heat the water on older systems, which may involve a standing pilot. Newer ones use electronic ignition.
- The heat exchanger is where the water actually picks up heat. It’s a series of metal passages inside the unit. If this cracks or gets scaled up with minerals, the system loses efficiency fast.
- A circulator pump moves the heated water out into the system. If that pump fails, the boiler will heat but nothing will move, which is why cold radiators with a hot boiler usually point to a circulation issue.
- An expansion tank sits above or beside the unit. As water heats, it expands. The tank gives it room to do that without over-pressurizing the system.
- Relief valves and pressure gauges keep everything in check. Most systems run between 12 and 15 psi.
Radiators, Baseboards, and In-Floor Loops
You might have one, two, or all three of these.
- Cast iron radiators are slow to heat but hold their warmth for hours. They’re common in older homes and great for long, steady heat.
- Baseboard convectors run along the bottom of the wall. These respond faster and are easier to zone, but don’t stay warm as long as the system shuts off.
- Radiant in-floor systems are buried beneath tile, hardwood, or concrete. They’re quiet, clean, and efficient, especially in well-insulated spaces. They do take time to heat up and cool down, so they’re not great for quick temperature swings.
All of these rely on hot water, which makes a complete loop through the system and returns it to the boiler. If air gets trapped or the flow is restricted, the loop breaks and the heat can’t get through.
What Happens When Your Home Needs More Heat?
When the thermostat drops below the set temperature, it closes a circuit and signals the boiler’s control board. That triggers a chain reaction: fuel flow starts, the burner ignites, and the circulator begins pushing water through the loop.
As the water travels through the pipes, it loses heat to the room. By the time it completes the loop and returns, it’s cooled off enough for the cycle to begin again.
In steam systems, things work a bit differently: water is boiled into steam and rises through the pipes without the help of a circulator. Most homes in this region use closed-loop hot water systems.
Maintaining Your Boiler
Most boiler systems don’t need constant attention, but they do benefit from a good annual check—especially before the cold sets in. That means looking at flame quality, making sure the heat exchanger is clean, and checking the expansion tank to see if it’s holding pressure like it should. If the tank’s waterlogged, the system can spike in pressure every time it heats up.
Circulator pumps get tested too. If a pump’s failing or a zone valve is sticking, you might only notice one part of the house not heating properly. A tech will also check the pressure gauge to make sure the system isn’t running too high or too low. If it’s drifting out of the normal range, that usually means a valve issue, trapped air, or a problem with the fill system.
You might also need to bleed the radiators if they start heating unevenly or making gurgling sounds. It’s really simple and typically requires using a small key air out until water flows steadily. If you do it more than once a season, there could be a leak or an air-separator issue.
Signs There’s Something Wrong With Your Boiler
Most homeowners overlook an issue with the boiler until a room runs cold or the whole house starts to feel cooler than usual. Here are a few things that point to problems:
- The boiler is firing, but the radiators stay cool
- You hear banging, knocking, or rushing water sounds in the pipes
- The pressure gauge spikes or drops outside of the normal range
- Water is leaking from the relief valve or pipe joints
- The burner keeps cycling on and off rapidly
All of these are worth looking into before they snowball into bigger repairs.
Final Thoughts
A boiler system might seem old-school, but it’s incredibly reliable when set up correctly. As long as the loop stays intact and the system is clean and balanced, you’ll get quiet, steady heat without the dry air or dust movement of forced air.
If your system’s been neglected for a few years or you’re noticing minor performance issues, now’s the time to get ahead of it. Schwantes can take a look, check the pressure, clean the burner, bleed the radiators, and give you a clear sense of how your system’s holding up.
