13 Reasons why your boiler is not firing up for central heating and hot water

23 March 2022


The boiler of every home is the unsung hero of our cozy way of life. Whether it be singing under the shower, taking a hot bath, or your central heating system supplying the warmth you desire, the benefits of your boiler go beyond providing hot water. This explains why boiler problems cause a good amount of frustration when they occur. In this article we go over the most common reasons why your boiler stops working and how to fix it.

Why is my heating and hot water not working?

Your heating and hot water might not be working for the following reasons:

  1. Leaking boiler system
  2. No pilot light
  3. Gas problem
  4. Temperature setting
  5. Timer setting
  6. Reset your boiler
  7. Low boiler pressure
  8. Air in the radiators
  9. Frozen pipes
  10. Complete failure
  11. No power
  12. Corrosion
  13. Failure of the diverter valve

As you may be aware, boiler difficulties can result in life-threatening circumstances and carbon monoxide leaks, so act promptly and call a licensed plumber to repair your boiler.

1. Leaking boiler system

One of the most common causes of boiler problems is a leaking combi boiler. A leak can appear anywhere in the system and dramatically reduce boiler pressure. If it occurs after the boiler pressure gauge, it may not be detected by the readings. Examine everything that is exposed, including radiators and the boiler itself. If you don’t see any clear indicators, you may need to call a plumber and have them inspect the central heating system and boiler.

If the pressure in your boiler continues to drop after you’ve topped it up, it’s possible that you have a leak in your current system. These leaks can be difficult to locate since they require following your pipes from the boiler to every linked point throughout your home.

How much does an emergency plumber cost?

2. No pilot light

If you own a gas boiler and the pilot light is off, this prevents the boiler from heating everything that passes through it. The signal this sends is that your natural gas tank might be empty or that a tiny debris is obstructing the pilot’s jet.

3. Gas problems

These aren’t as frequent as they once were, but they’re still hazardous. To solve these issues, you’ll need a master plumber, who is certified and qualified to repair your boiler systems that use gas as fuel. Tiny leaks or build-up of volatile fuels can be caused by a broken valve, so don’t try to replace it yourself unless you have the certification to do so.

4. Temperature setting

The central heating will not turn on if the room temperature is higher than the thermostat setting. Check the thermostat temperature and raise it — many people believe that the optimal thermostat temperature is between 18 and 21 degrees Celsius.

5. Timer setting

The boiler’s timer may have reset after a power outage, resulting in the boiler not firing up when you expect it to. Examine the instruction handbook that came with your boiler to learn how to program the times when your boiler will automatically ignite.

6. Reset your boiler

Although all boilers feature a reset button, the location of the button and how to utilize it differ from model to model. Check the instructions that came with your boiler if you can’t see the button.

In most cases, once you’ve located the reset button, you’ll need to do the following:

  • Hold the button down (for somewhere between 1-5 seconds);
  • Watch for the boiler to light up (this could take several minutes);
  • Make sure not to hit the button more than once, as this could exacerbate the problem.

The flame will ignite, the problem code will disappear, and you may notice a green light, indicating that the boiler has reset (rather than red or orange). If the boiler hasn’t reset, you should contact a plumber to identify the problem. 

7. Low boiler pressure

The hot water pressure running around the central heating system is measured by boiler pressure. The boiler pressure in your home should ideally be between 1-2 bar, preferably 1.5 bar. The boiler pressure can be checked with the pressure gauge. If the boiler pressure is too low (below 1 bar), the boiler will not work.

On the other hand, if the boiler pressure is too high (above 2 bar), the boiler will be overworked and may break down. A boiler’s pressure will gradually reduce over time, but if it drops suddenly, it’s usually a sign that there’s a leak in the system or that the radiators require bleeding. Turn off the water supply and contact a plumber if you discover a leak, no matter how tiny.

8. Air in the radiators

When you switch on the central heating system, hot water circulates through the pipes, filling the radiators and heating the space. If you find that only the bottom of the radiator heats up, or that the radiator doesn’t heat up at all, there is air trapped in the radiator, preventing water from filling the radiator fully. Bleeding the radiators allows the trapped air to escape, allowing the water to be adequately heated.

9. Frozen pipe

The condensate pipe is an important component of condensing boilers, as it transports acidic waste water away from the boiler. Because condensate lines are exposed to the elements, they are subject to freezing, resulting in a blockage that stops water from exiting the boiler. If this occurs, the boiler will recognize that it is no longer safe to operate and will lockout until the condensate pipe has thawed.

If you’re reading this in the winter, your condensate line is probably frozen. Your boiler should display an error code to help you identify a frozen condensate line. If your condensate pipe freezes, you have two options: try to defrost it yourself or contact a plumber.

10. Complete failure

It’s possible that a boiler is simply broken beyond repair. Complete failure can be the result of a damaged internal circuit or as a result of water causing significant rusting on some critical components. In cases like this, you may have little choice but to consider the boiler a lost cause, especially if it’s old.

Boilers are built to be robust so you shouldn’t give up on your heating unit if only one component has been torn down. If you can replace that part, you might be able to rapidly resolve the problem. 

Water heater installation

11. No Power

Most boilers, especially newer ones that incorporate electronic smart technology, require electric power. You normally don’t have a boiler without power, and only a few of them can heat water without it. This implies that if you lose power, you’ll lose heat as well, and it won’t always be clear that the system isn’t working. 

This does not imply that you’ll lose electricity throughout your home; if a power cable is destroyed or a water leak damages the outlet to which the boiler is connected, the issue may be less with the boiler and more with the power source. Wet power lines can also damage circuits within the boiler, so make sure the system isn’t damaged to the point where it can’t take in power properly.

12. Corrosion

Corrosion is a frequent problem that many boiler models face, especially after they have been running continuously for several years. Like other types of damage, corrosion can affect a single element or the entire boiler, making some cases far more catastrophic than others.

If the problem is not addressed early, it might linger and cause a boiler to malfunction for years. When dealing with corroded pipes and boiler components, you’ll almost always have to replace them because you won’t be able to fix them yourself.

How do you test a pipe for corrosion?

13. Failure of the diverter valve

The diverter valve is a crucial component deep within the inner workings of your boiler. This component is in charge of directing water flow to the appropriate pipe. There will be a lack of hot water if there is a failure and the diverter valve fails. This problem will require the assistance of a plumber.

If the valve fails, a new one will be installed, and you’ll have hot water in no time. If your boiler is old and has additional faults that are expected to cost you money in the near future, a plumber may recommend that you replace it rather than pay for continuing repairs. Newer units are more powerful and efficient, which means you will save money on your energy bills.

Heating and hot water not coming on yet?

Plomberie Pro-Drain‘s experts will assist you with the best quality and value for your money. Our licensed plumbers will guarantee that the plumbing systems in your home or business are up to date and comply with all applicable legislation.

Plomberie Pro-Drain can assist you with a toilet, air conditioning, heating, plumbing steel pipes, or a shower redesign or repair. Our team of professionals has the resources, equipment, employees, and, most importantly, experience to ensure that all of your installations are stable, clean, and comply with all applicable standards.

Our plumbers provide timely, friendly, and personalized service throughout the greater Montreal area and its environs, whether you’re on the south or north shore. If you have an emergency or want to modify your boiler and heating system, don’t hesitate to call us!

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