10 Common Commercial Boiler Problems and How to Fix Them

Welcome to our comprehensive guide on the 10 most common commercial boiler problems and how to fix them. By familiarising yourself with these problems, you can prevent costly downtime and maintain a comfortable environment for your employees and customers.


For most cases, you need professional assistance to resolve the issue. To find a reliable commercial boiler repair service in London,  visit our page with  Plumbing and Heating services. Then, select the tab with Commercial Services and go to the Boiler tab.

Boiler Won't Start

There are several possible causes for this issue. First, check if the power supply is intact and the circuit breaker hasn't tripped. If the power seems fine, inspect the thermostat settings and ensure they are correct. In some cases, a faulty ignition system or a malfunctioning pressure switch could be the culprit.


Insufficient Heat Output

There are a few potential reasons for insufficient heat output. First, check if the thermostat is set at the desired temperature and adjust it if necessary. Next, examine the radiators or baseboard heaters to ensure they are not obstructed by furniture or other objects. If the issue persists, it could indicate a problem with the circulation pump or a buildup of sediment in the system.


Strange Noises

Common noises include banging, clanking, or hissing sounds. These sounds can be a result of an air-trapped system, a malfunctioning pump, or a buildup of mineral deposits. To resolve this, try bleeding the radiators. If this does not help, turn to a qualified technician.


Leaking Boiler

This is a serious issue that requires immediate attention. The cause to blame can be a faulty pressure valve, a damaged seal, or a cracked heat exchanger. Turn off the boiler and shut off the water supply to prevent further damage.

Boiler Cycling On and Off

A boiler that frequently cycles on and off is not operating efficiently and may indicate a problem. This issue, known as short cycling, can be caused by various factors. A malfunctioning thermostat, improper water flow, or a buildup of debris in the system can all contribute to this problem. Additionally, an oversized boiler or incorrect settings can also lead to short cycling.


Uneven Heating

Uneven heating is often caused by an imbalance in the system or obstructions in the radiators or pipes. Begin by checking if all the radiators are fully open and not obstructed by furniture or curtains. If the problem persists, you may need to rebalance the system or seek professional assistance to ensure proper heat distribution throughout your commercial space.


High Energy Bills

If you've noticed a significant increase in your energy bills, your commercial boiler may be operating inefficiently. Several factors can contribute to this problem, including a malfunctioning thermostat, poor insulation, or an aging boiler. Start by checking the thermostat settings and ensuring they are programmed correctly. Consider improving the insulation in your building to prevent heat loss. If the issue persists, it may be time to upgrade to a more energy-efficient boiler system, which can save you money in the long run.


Frozen Condensate Pipe

A common issue with condensing boilers during colder months. If you notice your boiler not functioning, it's possible that the condensate pipe has frozen. So, thaw the pipe using warm water or a hot water bottle. However, it's essential to avoid using boiling water, as it can cause the pipe to crack.

Boiler Keeps Losing Pressure

A boiler that frequently loses pressure can be a sign of an underlying problem. Low pressure can lead to inefficient heating and even damage to the system if left unaddressed. Checking the system for visible leaks - around radiators, pipes, or valves. Another cause here may be a faulty pressure relief valve or expansion vessel. 


Pilot Light Keeps Going Out

An extinguished pilot light can prevent the boiler from heating your building. The cause here can be a faulty thermocouple, a safety device that detects the presence of a flame and ensures the gas valve remains open. Over time, the thermocouple can become dirty or worn out, leading to pilot light failure.


In conclusion, being aware of these common issues commercial boiler problems can encounter is essential for maintaining a reliable and efficient heating system. By addressing these issues promptly and seeking professional assistance when necessary, you can avoid costly repairs and minimise downtime. Remember to schedule regular maintenance for your commercial boiler to keep it operating optimally and to maximise its lifespan.