A few checks resolve a meaningful share of boiler calls, and they take about five minutes. Pressure, power, thermostat, and the reset button account for most of what a homeowner can safely fix.

Start With System Pressure

This is the check unique to boilers and the one most homeowners have never made.

Your boiler has a pressure gauge on it. A cold system should typically read somewhere around 12 to 15 psi, though the correct figure for your boiler is on its label or in the manual.

Too low and the boiler will not fire, or will shut down on a low-water cutoff. Too high and the pressure relief valve discharges, which is what the puddle near the boiler usually is.

Low pressure has a cause. A system that needs topping up repeatedly is losing water somewhere, and finding that leak matters more than refilling it. Persistent pressure loss is a service call, not a routine task.

Power and Controls

Confirm the boiler has power and its breaker has not tripped. Many boilers have a separate service switch nearby — often a light switch on the wall that looks like it belongs to something else, and gets flipped by accident.

Check the thermostat: set to heat, calling for a temperature above the current room reading, and with working batteries if it uses them.

On a system with zone valves or circulators, one zone that is cold while others work points to a zone valve or circulator rather than the boiler itself.

The Reset Button

Most boilers have a lockout reset. If the unit has locked out on a fault, pressing it once is reasonable.

Once. If it locks out again, stop. A boiler that repeatedly locks out is protecting itself from something, and repeatedly resetting past a safety is how a manageable problem becomes a dangerous one.

Note any fault code displayed before resetting — that code is the most useful diagnostic information available, and clearing it without recording it throws it away.

Bleeding Radiators

On a hydronic system with radiators, air trapped in a radiator prevents hot water from filling it. The symptom is a radiator that is warm at the bottom and cold at the top.

Bleeding it is a homeowner task on most systems: open the bleed valve with the appropriate key until water appears, then close it. Check system pressure afterward, since bleeding lowers it.

If radiators need bleeding frequently, air is entering the system somewhere, which is a real problem worth diagnosing.

Gas Supply

If other gas appliances are also out, the issue is the supply rather than the boiler. On propane, check the tank level — it is a more common cause than people expect.

What to Leave Alone

Anything involving the gas valve, burners, or gas connections. The expansion tank, low-water cutoff, and pressure relief valve. The heat exchanger. Any electrical component beyond the breaker and service switch.

Boilers combine gas, high-temperature water, and pressure. That combination is unforgiving of experimentation.

Call Immediately If

You smell gas — leave the house first and call from outside. A carbon monoxide alarm sounds. You see water actively leaking from the boiler body rather than the relief valve. The pressure relief valve is discharging repeatedly. Or there is any burning smell or visible soot.

Boilers Are Less Common Here

Hydronic heating is relatively rare in the Hill Country compared to colder regions, which means fewer local contractors work on it regularly.

We service boiler equipment including brands such as Weil-McLain and Buderus, and the expertise genuinely differs from forced-air work — combustion, water chemistry, circulation, and expansion all behave differently, and a technician who only knows furnaces is not equipped for a boiler.

Annual Service Matters More on a Boiler

Water chemistry, expansion tank charge, low-water cutoff testing, and combustion analysis are all annual items that homeowners cannot perform.

Neglected boilers fail expensively. Scheduled service is covered under our Care Club maintenance plan, alongside our other heating work.

For anything beyond the checks above, contact 72 Degrees or call (830) 240-1835. Emergency heating repair is available around the clock.