BOILER REPAIR & HOT-WATER HOME HEATING
Cold house?
Find the real cause.
A boiler heats water. A pump sends it through floor tubing, radiators or baseboard heaters, which release heat into your rooms. The cooled water returns to the boiler and goes around again. This is called hydronic heating: heating with water.
The details around the boiler matter.
OWNER SAFETY NOTICE / CHECKED SEPTEMBER 8, 2026
Have a Triangle Tube?
Check its recall status.
Certain Prestige Solo, Prestige Excellence and AERCO Esteem gas boilers are recalled for a carbon-monoxide hazard. The recall reports two deaths.
Which boilers?
The 2025 recall covers specific models made from December 2011 through April 2019. Compare your model and serial number with the official list.
Check CPSC’s model & serial list ↗The company closed.
Triangle Tube ceased operations November 3, 2025. CPSC’s March 2026 update says the recall remedy is unavailable to people who had not already registered.
Don’t count on a new free factory repair. Existing registrations, repair history and parts availability need individual review.
Read the manufacturer’s current notices ↗What should an owner do now?
Compare the model and serial number with the recall list, follow CPSC’s alarm guidance and arrange professional service for an affected unit. Keep earlier recall and repair paperwork for the technician. Leave the boiler’s safety controls intact and stop repeated resets if it fails to light.
Triangle Tube also has older recall notices. Have the technician check the complete model/serial recall history.
Triangle Tube warranty or other claim?
The manufacturer’s current notice lists September 30, 2026 as the deadline for submitting warranty and other proofs of claim. This is separate from recall registration and does not guarantee a repair or payment. Read the official notice and forms ↗
START HERE / HOMEOWNERS & NEW TECHNICIANS
Learn the system.
One question at a time.
You do not need to know the part names. Follow these four lessons in order, or open the one that answers today’s question. Each ends with a question to test your understanding.
- 1 · Boiler basicsWhere does the heat go?
Follow the water around a system. Select a part to learn its name, its job and what a problem can look like.
- 2 · Water & antifreezeWhat is inside the pipes?
Learn why minerals, metal damage and diluted antifreeze can matter even when the system is full.
- 3 · Air & pressureWhy is the room still cold?
Separate filling the pipes, moving the water and giving warming water room to expand.
- 4 · Numbers with meaningWhat does the measurement tell us?
Work through heat, antifreeze and valve examples. Open each calculator with the case values already entered.
Here because something stopped working? Start with the symptom guide. You can return to the lessons after you know what to report.
What’s the house doing?
You don’t need to name the broken part. Pick the closest symptom.
Is the boiler unable to make heat—or unable to move it?
Useful things to tell us
Look at the thermostat’s normal display and the boiler’s visible error code. Note whether hot water at the taps still works. Don’t open covers or keep resetting a safety shutdown, sometimes called a lockout.
What we check and why
We follow the heating sequence: the thermostat requests heat, the burner lights, the pump circulates water, and the floor or radiator warms the room. Checking each step shows where heat delivery breaks down.
Start with the pipes and controls serving that room.
Useful things to tell us
Tell us which rooms are cold and whether the others heat normally. Note gurgling, a recent repair, or a thermostat change.
What we check and why
A zone is a room or group of rooms controlled together. We check its thermostat, water valve and pump, then look for trapped air. We also check whether enough water reaches its floor tubing, radiator or baseboard heater.
The safety valve may be releasing water because pressure is too high.
Useful things to tell us
Keep clear of hot discharge and wet electrical equipment. If safely visible, record the gauge reading when cool and when heating—without changing settings.
What we check and why
We compare pressure as the boiler warms, then check whether the expansion tank is accepting the growing water volume or the fill valve is admitting too much water. On systems that also heat tap water, a leaking internal coil can let higher-pressure tap water enter the heating loop.
The type of noise helps separate the causes.
Useful things to tell us
Describe where and when it happens: when the burner lights, when the pump starts, during warm-up, or all the time. A bang at ignition or suspected fumes calls for prompt safety attention.
What we check and why
Trapped air, blocked water flow, pipe movement and mineral buildup can cause different noises. A bang when the burner lights requires a burner and fuel-safety check. Record when the noise occurs to guide the diagnosis.
Repeated short runs can wear parts and signal a mismatch.
Useful things to tell us
Note approximate run times and whether it happens during mild weather or when only one room or small area needs heat.
What we check and why
We compare the heat that area needs with the least heat the boiler can produce. If the boiler makes heat faster than the water can carry it away, it may shut off quickly. We check water movement, temperature sensors and settings before deciding why it happens. This repeated starting and stopping is called short cycling.
The boiler may heat both the rooms and the tap water through separate paths.
Useful things to tell us
Tell us whether hot water is stored in a separate tank or made inside the boiler, and whether every tap is affected. A photo helps if you do not know the equipment type.
What we check and why
A combi boiler heats tap water inside the unit. An indirect water heater uses a separate tank warmed by boiler water inside a sealed coil. We check the tank or tap-water request, the temperature sensor and the water path used to transfer the heat.
More than a boiler.
See the whole system.
Warm floors, radiators, hot showers or a snow-free walkway. Choose a system, open the equipment and take a closer look at the parts.
Preparing the mechanical room…
CONDENSING BOILER + FLOOR HEATING
The floor becomes the radiator.
A boiler feeds the floor circuits. Each loop delivers heat, then returns the cooled water.
Quiet heat spread across the room.
Floor response depends on the construction and controls.
The complete system
Tap a component to see its job and zoom closer.
These cutaways show the water paths in common home-heating systems. The floor loops are shortened so their connections stay visible. Select a part to explore how it moves water, transfers heat or controls pressure.
What changes from one system to another?
How the boiler handles cooler water: a conventional cast-iron boiler can be damaged if returning water stays so cool that exhaust moisture turns to liquid inside it. A condensing boiler is designed to handle that liquid and recover its heat.
Where the heat goes: floor tubing and radiators warm rooms. An indirect water heater warms tap water in a separate tank: boiler water passes through a sealed coil, transferring heat through the metal without mixing the two water supplies.
Which liquids stay separate: the snowmelt example has water indoors and a water–glycol antifreeze mixture outdoors. A heat exchanger passes heat through metal plates between the two liquids while keeping them apart. Each side needs its own water movement and pressure control.
Indirect-water and snowmelt examples ↗ · Caleffi’s boiler piping concepts ↗ · Manifold components & dimensions ↗ · Wall-boiler reference & manuals ↗
UTAH WINTERS / DRIVEWAYS, STEPS & WALKWAYS
Snowmelt needs
a preseason check, too.
Warm liquid flows through tubing under the pavement to melt snow. The liquid, pumps, controls and drainage all have to be ready when the weather turns.
Keep the liquid protected
Glycol is the antifreeze ingredient mixed with the water. Plain-water top-ups dilute it, and the chemicals that protect system metals need periodic checks too. Test the installed heating fluid before freezing weather arrives.
Confirm the heat can travel
Check that liquid moves through each tubing loop and that its pump works. Check pressure and the expansion tank that makes room for warming liquid. If a heat exchanger separates indoor and outdoor liquids, check both sides.
Check the response
Test the snow sensor and controls that start the system. Cold pavement takes time to warm, and meltwater needs somewhere to drain without refreezing across a walkway.
The water is
part of the machine.
Your heating loop usually reuses the same water as it carries heat out to the rooms and back. Mineral deposits, called scale, can coat hot surfaces and slow heat transfer. Corrosion damages metal and sheds debris, while trapped air can interrupt flow. Repeated top-ups bring fresh oxygen and minerals into that loop.
Clean & compatible
Fill water is the water used to fill or top up the loop. Testing its mineral content and acidity helps select treatment that suits the boiler’s metal surfaces and water-quality limits.
Air under control
Removing trapped air when filling the pipes is called purging. An air separator keeps collecting small bubbles during use. Both need the right system pressure to work well.
Pressure that behaves
A fill valve adds water. An expansion tank gives warming water room to grow. A safety relief valve releases excessive pressure. Repeated top-ups or discharge means something needs checking.
See what happens when one number changes. Explore how water carries heat, how antifreeze gets diluted and why valves need pressure. Start with guided examples or enter your own measurements, with explanations in both views. Open the calculators ↗
A WORKED DIAGNOSIS / FICTIONAL TEACHING EXAMPLE
Follow a cold room’s heating circuit.
The boiler is running and the other rooms are warm, so the technician starts with the controls and pipes serving the cold room.
Start with the observation
The homeowner reports that the room has been cold since a recent service visit. The technician records when the problem began and what work was performed.
Check the request and the path
In this example, the technician confirms that the room’s thermostat requests heat and its water valve opens. The room’s pipes form one heating branch, also called a zone. Next, the technician checks water flow through that branch.
Find the interruption
The room’s branch contains trapped air. The technician directs water through that branch and out through its purge valve to carry the air out. With the air removed, water can circulate again.
Check the result
In this example, the room warms while its thermostat continues calling for heat. The technician checks for leaks and watches system pressure to find out how the air entered.
What the homeowner can contribute: which rooms are affected, when it started, recent work and visible display messages. The technician adds measurements and equipment tests.
The teaching method follows a request through heat production, water movement and room delivery. Read Caleffi’s professional troubleshooting process ↗
Learn the checks behind a cold-room complaint →UTAH LICENSING / ASK ABOUT THE ACTUAL WORK
A plumber’s license
isn’t always required for boiler work.
That makes boiler-specific experience worth checking. Ask who will diagnose your system and about their experience with your equipment.
Utah’s S410 specialty license permits specified boiler installations and related piping. Connections to drinking water require backflow protection, a device that prevents heating water from flowing backward into the drinking supply; S410 installation of that device has a specific training condition. Gas work has separate certification rules and recognized exemptions. Ask for the business license, the technician’s applicable credentials and experience with your boiler model.
Check the credentials
Check the contractor’s active license and ask who will work on your boiler. These questions help you learn how they diagnose and service your equipment.
Check a Utah license ↗Ask for evidence
- Do you service this exact make and model?
- Will you explain the burner’s exhaust-gas test results and compare them with the manual?
- Will you check water quality, water movement and the tank that handles expanding water?
- Will I get the findings and post-repair results?
Reference: Utah R156-55a-301y (S410) and R156-55a-308b (natural-gas technician certification). Read the current rule ↗
What a thorough boiler service checks.
A service visit follows the heat from the burner, through the water, and into the rooms. The model’s maintenance schedule supplies the cleaning methods and test limits for each part.
Burner, exhaust pipes & safety controls
Combustion means burning fuel. An exhaust-gas analyzer measures how the burner is operating; looking at the flame cannot replace that test. Check the gas supply, air intake, exhaust, ignition and safeties, then use an analyzer as the manual specifies. At Utah elevations, verify the altitude configuration and fuel requirements for the exact boiler model. Burner work and gasket changes need the required leak and combustion checks before the boiler goes back into service.
Water quality and leaks
Find where water is being lost before treating what replaces it. Test the fill supply and loop fluid against the equipment requirements. Inspect collected dirt and magnetic debris. Glycol is the antifreeze ingredient used in some heating systems. Identify the product and test its freeze protection and condition; color alone tells us very little.
Pressure changes, trapped air & moving water
Cold and hot pressure readings help reveal problems with filling and expansion. We also follow each thermostat’s request through its valve and pump, check for trapped air, and run zones together to see whether they affect one another.
The heat-transfer surfaces and their drain
A condensing boiler recovers extra heat by cooling moisture in the exhaust into liquid water, called condensate. That liquid needs a clear drain and a water-filled trap that blocks exhaust gas. A neutralizer uses material that reduces the liquid’s acidity; that material needs replacement when used up. The heat exchanger—the metal surface that passes burner heat into water—also needs the model’s specified cleaning method.
Controls and operation after repairs
Check the temperature readings and control settings while the boiler runs. Outdoor reset adjusts the heating-water temperature with the weather, lowering it on milder days while keeping the rooms warm. After repairs, run the affected zones and hot-water call, record the results and explain any remaining fault.
Repair or replace?
Ask what the next dollar fixes.
Repair a defined fault
A serviceable boiler, available parts and a clear cause can make a targeted repair sensible. Correct the condition that damaged the part.
Fix the system around it
Air problems, constant water replacement, poor piping, poorly arranged thermostat-controlled areas or wrong settings can follow a brand-new boiler. A replacement quote should address those findings.
Consider replacement
Unsafe or unserviceable equipment, unavailable critical parts, serious heat-exchanger damage or repeated costly failures warrant a replacement comparison. For affected Triangle Tube units, recall status and manufacturer closure belong in that decision.
Size the boiler for the house. A replacement needs a calculation of how much heat escapes the building in cold weather. The boiler must replace that heat. Its lowest heating output matters too: it should suit small heating requests without constantly restarting. Tap-water demand, exhaust piping and required water temperatures also affect the choice.
Discuss my boilerThe questions worth asking.
Does a boiler boil the heating water?
These systems heat liquid water and circulate it through floor tubing, radiators or baseboard heaters. The water gives up heat in the rooms, then returns to the boiler to be warmed again.
What pressure should my boiler run at?
Cold pressure needs to keep the highest pipes filled. As the water heats, the expansion tank takes in the extra volume and limits the pressure rise. Recurring pressure loss, a large cold-to-hot swing or a dripping relief valve gives the technician a specific problem to investigate.
Should I drain the boiler water every year?
A healthy closed loop can keep using the same water. Service includes checking its condition and any treatment chemicals. Cleaning or replacing the fluid is useful when test results, debris or a repair call for it, using the equipment’s service instructions.
Does a water softener protect my boiler?
Check the boiler’s water-quality limits first. A household softener exchanges hardness minerals for sodium, leaving dissolved salts in the water. Some boilers specify a minimum hardness as well as other water limits, so the fill supply needs testing before treatment is chosen.
Can I just bleed the noisy radiator again?
Recurring air deserves diagnosis. Low pressure, leaks, frequent filling or other oxygen-entry paths may be involved. Bleeding hot equipment also risks burns and pressure loss. Have the cause checked rather than repeatedly replacing water.
Is antifreeze a good idea in every boiler?
No. Glycol, an antifreeze ingredient, is useful where freezing is a concern, but the boiler must allow the product and concentration. It changes fluid properties and needs periodic testing. Do not add automotive antifreeze or mix unknown products.
How often should a boiler be serviced?
Many gas-boiler manuals call for annual professional service. The visit checks combustion, cleaning, water condition, circulation and safety controls. Glycol deterioration, recurring debris or an active fault may call for an earlier visit.
Can the boiler heat my showers too?
A combi boiler heats tap water inside the boiler. An indirect water heater stores tap water in a separate tank warmed by a sealed coil of boiler water. Metal surfaces pass the heat across while keeping the two water supplies apart.
CHECK YOUR UNDERSTANDING
Can you explain it?
The boiler is running, but one room stays cold. Where would you check next?
Try answering in your own words, then compare your reasoning.
Show the answer & why
Follow the branch serving that room. Check whether its thermostat is requesting heat and its valve opens, then whether water flows through its radiator or floor tubing. A closed valve or trapped air can interrupt that path while the rest of the house heats normally.
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