Radiators too hot is a common problem
A common problem I come across is that the customer thinks the radiators are too hot. They complain that they turn them down but they come on again just as hot as before.
There is a very simple explanation to this problem.
Radiator valves don’t control the temperature of the radiator
The customer is turning the thermostatic valve down expecting the temperature of the radiator to go down.
This is not how thermostatic radiator valves work.
They are a simple on off valve that opens and closes depending on the temperature of the room.
When the room gets hot the valve closes and the radiator slowly cools.
When the room cools down the valve opens again. This makes the radiator heat up to the same temperature as before.
Radiator temperature is set at the boiler
The temperature of the radiator is set at the boiler.
The boiler will have a control dial or buttons. This control changes the temperature of the water in the central heating system.
To make the radiators feel cooler turn the heating dial down. It will have a picture of a radiator beside it. The hot water control will have a tap beside it.
The oil boiler in the picture above has a temperature range of 55 at min and 81 at max. That is a big difference in how the radiator will feel.
Both will heat the house up in all but the lowest outdoor temperature.
What if my boiler thermostat is already turned down?
If your boiler thermostat is already turned down then there may be a fault with your boiler.
The two most common faults are:
- Passing diverter valve
- Broken control knob
- Faulty temperature sensors in the boiler.
Frequently asked questions
How can I make my radiators cooler?
Turn the temperature down on the boiler. Find the dial or setting with the radiator symbol.
Why does the valve not change the radiator temperature?
The radiator valve only turns off the flow of water from the boiler. It doesn’t change the temperature of the water. The temperature of the water is controlled at the boiler.
How can I safely reduce radiator heat in my home?
The radiator heat is controlled from the dial or buttons at your boiler. The temperature can be as low as you choose. If you select a really low temperature your house will take longer to heat up. In really cold periods it will not heat up to your required temperature.
Why are my radiators too hot to touch and how can I fix them?
The radiators are too hot because the control dial on the boiler is set too high. You can reduce the temperature by turning the flow temperature of the boiler down.
Can a faulty boiler cause radiators to become too hot?
Yes, a faulty boiler can cause the radiators to become too hot. If a diverter valve is passing the boiler can send heat to the radiators without it realising. If the temperature sensors are reading wrong the boiler may be sending water at the wrong temp to you radiators. If the control knob is broken then the dial may look like its in the right position but it isn’t.
All these faults need a gas safe engineer to check them.