What to do when you have hot water but no heating

How to solve the issue of having hot water but no heating

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Hot Water But No Heating? Don’t panic!

Having hot water but no heating is one of the most commonly occurring boiler problems and one of the most annoying. If your boiler system is giving you hot water but no heating, don’t panic! You can put the jumpers and blankets away as it most likely isn’t a major fault and can be fixed by some basic troubleshooting. The most common cause for this issue doesn’t stem from the boiler but actually the surrounding components such as a faulty thermostat, motorised valves or radiators. The main factors that will leave you shivering with hot water but no heating are:

Boiler settings

This may seem obvious but the settings of your boiler system are frequently overlooked. If a combi boiler is installed at your property, the problem may be resulting from having the system set to hot water and not heating. The heating aspect of your system may have even been switched off in the summer months when the heating wasn’t necessarily needed.

Alternatively, another setting which could be preventing your boiler from providing heating is the time of day the programme is set to. In either circumstance, you should refer to your user manual and adjust the settings on your control panel accordingly. We recommend getting in contact with the manufacturer of your system and quoting the model of your boiler if you have any difficulties operating your boiler or adjusting the settings.

Low boiler pressure

If the pressure gauge is showing that the pressure is below 1 bar in your system, then this could be the reason why you are getting hot water but no heating. When the boiler pressure is lower than it should be, it means that the boiler will struggle to distribute the water efficiently.

This means the system may not have enough pressure to transport enough hot water to the radiators in order to heat them sufficiently. Check out our article on low boiler pressure for further info


An unresponsive thermostat could be another factor to blame, when your heatings isn’t working but your hot water is running fine. If the thermostat was set to 0 when it was responding and has since become unresponsive, it then wouldn’t take effect when changing the temperature on the faulty thermostat. 

Always check that your thermostat has fresh batteries, is in range of your boiler system and the time on the thermostat correlates with the time on your control panel. Also always try fresh batteries and move your thermostat closer to your boiler just to ensure that this isn’t the cause of the problem. Check out this article for more information on unresponsive thermostats.


The radiators on your property are most likely the cause when you have hot water but no heating. If the radiators are hot on the bottom but cold towards the top then they will probably require bleeding, this means that air has become trapped inside your system and is blocking the flow of hot water inside the rads.

Bleeding the radiators is a simple procedure that normally just needs a radiator key, a bucket and some towels. Although the process is fairly similar for most radiators, it can still vary depending on the model and make of the boiler installed at your property. As a result we still recommend finding a tutorial video relevant to the model you own, or calling out one of our gas safe engineers to inspect the matter.

When the radiators feel warm on top but cold on the bottom, chances are they need to be power flushed. Rust and other forms of dirt often accumulate inside radiators and the pipework, this then builds up creating sludge. These blockages will prevent a sufficient amount of hot water entering the radiator, creating cold spots towards the bottom where the sludge sinks down to. 

We recommend having a professional perform a power flush as it’s a much more complicated process than bleeding your boiler system. Power flushes also require chemicals to help break down the sludge and other specialist equipment; conducting the work without this normally won’t get out all excess material and could damage your system further. Call 0207 9989 005 to book in your power flush with Flair Facilities today.

Motorised valves

Boiler systems have a variety of valves that need to be in a certain positions for your system to operate as it should. Some of these valves are motorised and change position to automatically align with your control system on your boiler. After a while the electrical components of these valves can wear down and get stuck in the same position. When this happens it could leave your system only producing hot water, or the opposite of only producing heating. 

The valve most likely to cause this to happen is the diverter valve as this switches the output and flow of your boiler system between hot water and heating. Due to the electric components of the valve needing to be replaced we recommend contacting a professional to fix this issue as it isn’t as simple as screwing on a new valve like some may think.

To clarify

As stated previously never carry out maintenance work on a boiler system yourself if it involves removing the case of the boiler or working on a gas appliance. Always get in touch with a professional if you are ever uncertain about a problem with your boiler system to ensure the safety of those within your property. 

Call Flair Facilities today if you have further enquiries or need to make an appointment with a gas safe engineer.

Check Out These Smart Thermostats!

Hive Thermostat for Hive Hub

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*Optional image or document upload. Details of current boiler such as photos of boiler/plant room and boiler plate with make and model no.