BACKJAN 17, 2026
It’s one of the worst feelings: you wake up on a chilly morning, stumble to the shower, turn the handle, and are met with a stream of lukewarm—or worse, ice-cold—water. You touch a radiator, and it’s stone cold. Your boiler isn't working, and suddenly your cozy home feels more like an icebox.
Looking for more guidance? Take a look at our Repairs overview.
Don't panic! While a boiler breakdown is stressful, it doesn't always mean an expensive call-out is in your immediate future. Many common boiler issues can be safely diagnosed and fixed with a little DIY know-how. Boiler breakdowns are one of the most common home maintenance issues, but you'd be surprised how often the solution is something simple.
Here at Casa, we want to empower you to handle these problems yourself. Think of us as your friendly expert on the other end of the line, ready to walk you through it. This guide will help you troubleshoot why your boiler isn't producing heat or hot water and get your system back up and running.
To figure out what’s wrong, we first need to narrow down the symptoms. The most important question you need to answer is:
Are you having issues with BOTH your central heating and your hot water, or just one of them?
The answer to this question is your key to unlocking the problem.
Once you know the answer, you can jump to the right section below and start troubleshooting.
If your whole system is down, it’s likely a central issue. Let’s work through the most common culprits, from easiest to most complex.
Your boiler needs to maintain a stable water pressure to function correctly. If the pressure drops too low, a safety feature will often shut the boiler down to prevent damage.
How to check: Look for a pressure gauge on the front of your boiler. It’s usually a round dial with green and red zones. When the system is cold, the needle should be in the green zone, typically between 1.0 and 1.5 bar. If the needle is below 1.0 bar, or in the red, you've likely found your problem.
Repressurizing sounds technical, but it’s a straightforward task.
Once repressurized, try restarting your boiler. In many cases, this is all it takes to bring your heat and hot water back to life.
Sometimes, the simplest solution is the right one. It's possible your boiler is fine, but it hasn't been told to turn on.
Make the necessary adjustments, wait about 10 minutes, and then check a radiator or hot water tap.
If your radiators have cold spots, especially at the top, it’s a classic sign of trapped air in the system. This air prevents hot water from circulating properly, making your heating inefficient and sometimes causing the boiler to struggle.
The circulation pump is the heart of your heating system, pushing hot water from the boiler to your radiators and back again. If it gets stuck or fails, the water won't move, and you'll get no heat.
If the pump is very hot to the touch or makes loud grinding noises, it has likely failed and will need to be replaced by a professional.
If your radiators are toasty but your taps are cold, the issue is with the domestic hot water system. The fix depends on what type of boiler you have.
A combination (combi) boiler heats water on demand. A component called the diverter valve directs hot water to either your radiators or your taps. These valves can sometimes get stuck in the "heating" position.
A gentle tap on the valve's housing with the handle of a screwdriver can sometimes be enough to free it. You'll need to remove the boiler's front panel to access it. Always turn off the power to your boiler before removing any panels. If this doesn't work, the valve likely needs to be replaced by an HVAC technician.
If you have a conventional boiler with a separate hot water storage cylinder (tank), check the thermostat on the side of the cylinder. It should be set to at least 60°C (140°F) to ensure the water is properly heated. If it's set too low, just turn it up, wait 30 minutes for the boiler to reheat the water, and test a tap.
While many boiler issues are simple DIY fixes, some problems require an expert. You should call a professional if:
According to Angi, the average professional boiler repair costs around $425, with a typical range between $225 and $630. While it's an expense, it's a worthwhile investment in your home's safety and comfort.
Facing a boiler problem can be daunting, but by following a logical troubleshooting process, you can often solve the issue yourself and save hundreds of dollars. By checking the pressure, thermostat, and radiators first, you can knock out the most common culprits in under an hour.
For more easy-to-follow home maintenance guides, expert advice, and a direct line to vetted professionals when you need them, download the Casa app today. We're here to help you manage your home with confidence, one project at a time.
