Many homeowners notice that their heating activates when they only expect hot water. In this article we explore common causes for hot water and heating issues and explain how to fix them, as well as share information about our comprehensive boiler installation and replacement services.
Faulty motorised valve (diverter or 3-port valve)
One of the most common causes of hot water and heating issues is a faulty motorised valve, which controls whether hot water is sent to your radiators, hot water cylinder or both. There are two main types of motorised valves. The diverter valve (in combi boilers) directs hot water to either the radiators or taps, while the 3-port valve (in system and conventional boilers) directs hot water to the hot water cylinder, radiators or both. If the valve is stuck or faulty, hot water may be flowing into the radiators when you only want hot water for taps or showers.
How to fix it
Try manually moving the valve using the switch on the side. If the valve does not move or stays in one position, it may need repair or replacement by a heating engineer. A stuck or broken motorised valve should be fixed by a Gas Safe Registered professional to ensure safe operation.
Incorrect boiler or timer settings
Sometimes hot water and heating issues are due to incorrectly programmed heating controls. If you have a traditional programmer, check that the hot water and heating schedules are set correctly. Some older timers have settings that automatically activate the heating when hot water is requested.
How to fix it
Check your boiler and thermostat settings. Try adjusting the timer or reprogramming your heating schedule. If you are unsure, consult the boiler manual or contact one of our Essex Boiler Group heating engineers.
Faulty thermostat or room temperature
A faulty room thermostat can send incorrect signals to the boiler, causing the heating to turn on even when it is not needed. This can happen if the thermostat misreads the room temperature or remains stuck in the on position.
How to fix it
Check the thermostat settings to ensure it is correctly programmed. Replace the batteries in wireless thermostats if necessary. If the issue persists, it may need repair or replacement. Upgrading to a modern, smart thermostat can help prevent these issues and improve energy efficiency.
Gravity-fed heating system (older systems only)
In older gravity-fed heating systems, the design may cause radiators to heat automatically whenever hot water is being heated. In this setup, hot water rises naturally to the radiators when the boiler is running. The only way to stop this is by installing a motorised valve to control the flow.
How to fix it
One of our Essex Boiler Group heating engineers can install a zone valve to separate the hot water and heating circuits. Consider upgrading to a modern system boiler or combi boiler for better efficiency and control.
Boiler wiring or electrical faults
In rare cases, wiring issues in your boiler or heating system can cause incorrect signals, making the heating come on when it should not. Signs of electrical faults include the heating and hot water turning on and off unpredictably, the boiler failing to respond to thermostat settings, and fluctuating heating performance with radiators heating up unexpectedly.
How to fix it
Turn off your boiler and restart it to see if the problem persists. If the issue continues, contact a qualified heating engineer from the Essex Boiler Group to inspect the wiring and controls.
How to prevent hot water and heating issues in the future
Book an annual boiler service to check for faulty components. Test your thermostat regularly to ensure it is working correctly. Check the heating and hot water settings on your boiler and programmer. Bleed radiators if they are getting warm when they should not be. Upgrade an old heating system if it is outdated and inefficient.
When to call a heating engineer
If your heating turns on whenever hot water is used, if radiators heat up even when the thermostat is off, if you suspect a faulty diverter valve or motorised valve, or if your boiler or thermostat is not responding properly, it is best to contact a professional. Our Essex Boiler Group Gas Safe Registered engineers will identify the issue and provide a cost-effective solution to restore your heating system’s efficiency.
Why choose Essex Boiler Group?
We employ Gas Safe Registered engineers to ensure safe and professional service. Our fast, reliable repairs solve heating and hot water problems quickly, while our boiler servicing and system checks help prevent future issues. With competitive pricing and no hidden fees, our clear upfront quotes make us a trusted local business serving homeowners across Essex, Kent and London.
Book a heating system inspection today
If you are experiencing hot water and heating issues, do not ignore the signs. A small fault can quickly turn into a bigger, more expensive problem if left unresolved. Call us today to book a professional inspection. Let Essex Boiler Group restore your heating system to full efficiency and save you money on energy bills.
