Common fault diagnosis and troubleshooting for wall-mounted boilers!

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Frequently Asked Questions

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Release date:

2026-10-21

概要： [Introduction] Flue gas safety for wall‑mounted boilers: Wall‑mounted boilers use a concentric double pipe; the inner pipe exhausts flue gases, while the outer pipe supplies combustion air and is connected to a sealed chamber, remaining completely isolated from the indoor space. All brands of wall‑mounted boilers feature forced exhaust (with a fan) and balanced draft (with a pressure switch), so both flue gas discharge and air intake occur outdoors, without consuming indoor air, ensuring a high level of safety. In recent years, all reported explosions have been caused by leaks in natural gas hoses; there have been no incidents involving boilers exploding.

　　Troubleshooting Common Problems with Wall-Mounted Boilers

　　Boiler troubleshooting: methods for addressing common issues such as flue gas safety concerns, reduced domestic hot water output, unusual noises during heating, and frequent water‑flow sounds.

　　How to drain water when cleaning the filter screen: To drain the heating water from the boiler, close the cold water inlet valve, open the filling valve, and turn on the domestic hot water tap; the heating water inside the boiler will then drain out. Performing the reverse sequence allows you to refill and resume operation. Simply unscrew it. For draining radiators, you can only use the radiator’s air vent.

　　Reasons for reduced hot water output from the wall‑mounted boiler: the faucet’s filter screen or the cold‑water inlet’s filter screen is clogged. Remove the corrugated hose at the cold‑water inlet to inspect; cleaning it will restore normal flow.

　　The wall-mounted boiler makes unusual noises during heating and heats water slowly: this may be because the filter screen at the inlet or outlet of the boiler is clogged—simply disassemble the corrugated pipe and clean it—or because the heating pipes are blocked.

　　Flue gas safety of wall‑mounted boilers: The flue pipe is a concentric double tube, with the inner tube exhausting combustion gases and the outer tube supplying air, both connected to a sealed chamber that is completely isolated from the indoor space. All brands of wall‑mounted boilers use forced exhaust (with a fan) and balanced draft (with a pressure switch), so both flue gas discharge and air intake occur outdoors, without consuming indoor air; thus, safety is assured. In recent years, all reported explosions have been caused by leaks in natural gas hoses; there have been no reports of boilers themselves exploding.

　　Common Fault Diagnosis for Wall-Mounted Boilers

　　Because wall-mounted boilers are highly sophisticated household heating appliances that integrate fans, water pumps, combustion systems, heat exchangers, electrical automatic controls, and complex mechanical structures into a single unit, and because they are closely linked to the heating and hot-water piping systems, it is essential to follow the boiler’s operational sequence when diagnosing faults in order to accurately analyze and resolve issues.

　　During each debugging and fault diagnosis session, the following essential procedures should be performed first.

　　① Inspect the gas system, including the type of gas, its composition, calorific value, supply pressure, flow rate, and related components such as gas pipelines and meters.

　　② Inspect the heating system, including all relevant details such as the heated area, type of heating, heated floor space, heating load, design room temperature, and building conditions.

　　③ Inspect the water supply system, including water supply pressure, water flow rate, and heating pipelines and valves, as well as hot water pipelines and valves.

　　④ Check the power supply.

　　⑤ Check the flue gas exhaust of the wall-mounted boiler.

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