When Your Boiler Is Telling You Something

A boiler heats a building quietly, which is a big part of its appeal. Hot water moves through pipes to radiators, baseboards or radiant floors, and rooms warm up without the air movement of a forced-air furnace. When something goes wrong, though, the signs are easy to miss until a cold morning makes them impossible to ignore.

Paul's AIR FX installs, replaces and services boilers, and lists five problems. Before going through them, it helps to know what's inside the system you're listening to.

How a Hydronic System Moves Heat

Hydronic simply means heat carried by water. The boiler heats the water. A circulator pump pushes it out through the supply piping to whatever releases heat in your rooms, and it comes back, cooler, through the return piping to be heated again. In larger systems you'll often see supply and return headers, the big pipes that gather and distribute the flow, with a row of branches coming off them.

Zones divide a building into areas, each with its own thermostat and its own valve or pump, so the shop floor and the office don't have to run on the same schedule. A small expansion tank sits on the piping to absorb the extra volume as water heats up and expands. Without it, pressure would climb every time the boiler fired.

Every symptom below traces back to one of those parts: the water, the pump, a valve, the tank, a control, or the burner itself.

No hot water or heat

Check the simple things first. Is the boiler powered, and is the thermostat calling for heat? If both are fine and the system is cold, the cause could be a lack of fuel or power, a safety control that has locked out the burner, a failed ignition part, or a pump that isn't running. A boiler also won't fire when its water pressure has dropped too low, which can be a sign of a leak somewhere.

If your boiler also makes your domestic hot water, losing that along with the heat usually points to the boiler itself rather than one zone. Don't keep pressing the reset button. Note any lights or codes and call. And if you ever smell gas, leave the building and call your gas utility first.

Strange noises

Boilers aren't silent, but they shouldn't bang, grind or scream either. Different sounds usually point to different causes:

• Banging or rumbling, often from mineral buildup on the heat exchanger that makes water boil in pockets
• Gurgling or hissing, usually air trapped in the piping
• Whining or grinding from the circulator pump, which may be wearing out
• Clicking at startup, which can be an ignition problem

Noise rarely fixes itself. Mineral buildup in particular gets worse with time and makes the boiler work harder for the same amount of heat.

The radiator is not getting hot

When the boiler runs but a radiator stays cold, the heat isn't reaching it. Trapped air at the top of a radiator is a classic cause. Others include a stuck zone valve, a circulator that isn't moving water, a closed or blocked valve, or sludge in the piping.

Where the cold is helps narrow it down. If only one radiator is cold, the cause is usually local to that radiator. If a whole zone is cold, look at that zone's valve or pump. Releasing trapped air changes the system's water pressure, so it's best to have a technician do it and check the pressure afterward.

The boiler turns itself off

A boiler that starts, runs briefly and shuts down is usually protecting itself. Safety controls shut the burner off for low water, overheating, a flame it can't detect or a blocked vent or air intake. A boiler that is too large for the building can also heat the water faster than the system can use it, then shut off and restart again and again.

That start-stop pattern is called short cycling. It wears out parts, wastes fuel and often means something upstream needs to be corrected. It's a good reason to have the system inspected before the coldest weather arrives.

Thermostat issues

Sometimes the boiler is fine and the instruction never reaches it. A dead battery, a thermostat sitting in a drafty spot or in direct sun, settings that reset after a power outage, or failing wiring can all cause problems. A bad zone thermostat leaves just one area cold while the rest of the building is comfortable.

If you're considering a smart thermostat, it needs to be compatible with your boiler's controls. Paul's AIR FX lists smart thermostat integration among its services, so ask before you buy one.

Boilers in Commercial Buildings

For business owners, a heating system that quits in a cold snap affects customers and employees as well as comfort. Paul's AIR FX handles boiler installation and replacement, and its chillers and boilers work covers commercial settings alongside chiller installation and repair. It also offers preventive maintenance plans for commercial systems.

Paul's AIR FX also services furnaces and boilers that run on gas, electric or oil, including cleaning, inspecting and repairing them. If your boiler is showing any of these five signs, call (509) 225-3420 or use the contact page.