Boiler won’t Turn Off – How to fix!

hand turning on electric water heater

What To Do When Your Boiler Won’t Turn Off

Boilers heat water for use throughout your home. In addition to this function, it also provides heating for your home, which is particularly useful for keeping your home warm during the colder months.

However, your heating system needs to work efficiently to be beneficial. That means your boiler should use the least amount of energy possible while providing adequate heating and hot water when needed.

Unfortunately, your boiler may develop issues, perhaps due to prolonged use, which can make the appliance overactive. In this case, your boiler won’t turn off, so your home becomes too warm, your water is too hot, it wastes energy, and you pay more in energy bills.

In this quick guide, we consider some of the most common causes of this problem and temporary solutions until you can contact a boiler engineer. By the way, do not hesitate to contact us if you ever need professional help.

Boiler not turning off? Investigate the Possible Culprits!

An overactive boiler calls for further investigation. As you already know, a boiler consists of several components, and any one or more of these parts can be responsible for the appliance not turning off.

The problem might be a faulty timer, pump, thermostat, heat exchanger, or a motorised valve. It is also possible for a malfunctioning programmer to cause issues of non-stop heating. In some cases, a blown fuse, faulty wiring, or problem with the circuit may be responsible for the problem.

For many homeowners, a boiler refusing to go off can be worrisome because it is inconvenient, could mean you need a replacement boiler as well as impact energy bills.

Thankfully, fixing this problem can be as simple as resetting your programmer, turning down the temperature level of your thermostat or simply turning off your boiler and turning it back on.

The following tips should help you troubleshoot your boiler if it keeps working even when you try to turn it off.

How to fix a boiler that you can’t turn off

1. Check the Thermostat

repairman for an electric boiler connects the wires to a thermostat

Boilers have thermostats that detect the water temperature and activate heating once the temperature is below the predetermined point. Also, the room thermostat cuts off the heating as soon as the water temperature is above a set point.

A faulty thermostat will not be able to sense when the water temperature has gone over or below the predetermined point, so your boiler will continue to operate way past where it should normally stop heating.

The first thing you should do is test the thermostat. Simply turn down the temperature levels of the room thermostat to see if anything changes and your boiler turns off. If this doesn’t work, consider turning off the unit and turning it back on to rest it.

In some cases, the issue could be weak batteries. Replace the thermostat batteries to see if anything changes.

We recommended getting in touch with a specialist to diagnose the problem if these solutions don’t work.

2. Check to See if the Programmer is Faulty

The next possible culprit to suspect if your boiler won’t turn off is the programmer. Usually, boilers feature a timer or a heating programmer. The former automatically turn your boiler on at a specific time every day, while the latter gives you greater control over the appliance beyond merely turning it on.

A boiler thermostat allows you to choose heating settings, schedule when the appliance should come on and off, as well as select hot water, heating, or both. This allows you to save on your heating bill while also reducing any negative impact boilers may have on the environment.

Regardless of the specific type of programmer on your boiler, it can override your thermostat instructions if it becomes faulty, and this will keep your boiler working continuously. On a heat-only boiler, the problem is likely from the two-channel programmer. On the other hand, the fault might be coming from a single channel programmer if you have a combi boiler.

One way to correct this problem is to reset the programmer. Simply turn off your boiler and wait for about 30 seconds before turning it back on. This will usually reset the controls, but if it doesn’t, you may need to consult the programmer’s user manual to learn how to reset it.

Usually, resetting the programmer should make your boiler work normal again if it is a minor issue. If this doesn’t solve the problem, consider getting professional help.

3. There Could Be Some Issues with the Valves

Valve designs include switches that regulate the pump and boiler. The switch becomes activated when the valve is open, and this, in turn, allows the boiler to start heating the water.

But when the valve develops issues, the switch remains active (or in the “on” position), even when the valve is closed. In other words, the pump and boiler won’t turn off, and heating will continue.

In other instances, the diverter valves or check valves may become damaged or jammed, causing hot water backflows and keeping hot water flowing through the appliance, even when you turn it off.

One way to correct this problem is to carefully release the valves if you can. Keep in mind that these valves are strong and may injure your finger if not handled with care. Fixing a new diverter valve may be a more permanent solution in some cases. For this reason, we recommend getting a qualified technician to release the valves or make any form of repairs.

4. It Might be a Wiring Problem

If your boiler won’t turn off after trying all of these potential solutions, the problem might be caused by faulty wiring. There are a few tips and tricks to confirm if the issue is really from the boiler’s wiring, but we’ll not advise you to perform any checks or tinker with the wiring of your appliance.

Your best bet, in this case, would be to invite a Gas Safe Registered engineer to examine the wiring and figure out what the fault is. The engineer will likely unplug the boiler from the power source and check the low-temperature switch. This switch tells the boiler to keep heating the water inside if it senses that it is not adequately heated.

Whatever you do, avoid tampering with fuses (blown or not), resetting circuit breakers, or the heating element. If you are not a licensed technician, it is best to leave wiring problems for the experts to handle. 

Before You Hire a Boiler Specialist

It is common for many homeowners to immediately think of calling a boiler specialist if their boiler won’t turn off, turn on, make weird sounds, or have some other issues.

Engineer adjusting thermostat for efficient automated heating system

While contacting a boiler repair specialist is generally a good thing, here’s what we recommend. Talk with your appliance manufacturer before reaching out to a boiler specialist or engineer, especially if your boiler is covered by a manufacturer’s warranty.

In many cases, the boiler warranty period can vary widely between brands. It is not uncommon to see warranty periods spanning anywhere from 2 to 12 years, depending on the manufacturer (although some brands do not offer a warranty at all).

If your appliance comes with a warranty, you may void it if you allow an independent engineer to carry out any repairs on your faulty boiler. This is why it is usually more prudent to first check to see if your boiler manufacturer can cover the repairs before inviting an independent specialist to attempt any repairs on your appliance.

As you probably already know, a boiler is usually a major investment, and you shouldn’t be spending extra money on avoidable labour costs and call-out fees. For this reason, we suggest that you first check out this guide to find out the best boiler warranty if you are thinking of a new boiler.

Consult an Expert Boiler Engineer to Fix Your Boiler

In most cases, the above-mentioned issues are usually responsible for an overactive boiler. However, if all of the solutions fail, you might want to reach out to a qualified boiler engineer to check your appliance.

Whatever you do, remember that you shouldn’t attempt any repairs on your boiler. The tips provided in this guide are simply to help you understand the possible reasons your boiler won’t turn off and ways to fix minor issues. Usually, it is best to contact an expert if turning your boiler off and back on doesn’t solve the problem.

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