Heat On Demand – How it Works (Dynamic Behaviour)

Answer

Heat On Demand is a short‑term request from your Hive Radiator Valve to your boiler, asking it to boost your heating. When you turn up the temperature on your Hive Radiator Valve, Heat on Demand asks your boiler to fire up and heat your room until it reaches its target temperature, then stop as normal.

Think of it as a one-off trigger that happens only when you need it. This trigger temperature needs to be higher than the target one, otherwise, the boiler won’t fire up. The important thing to remember is that the heating boost lasts only until your target temperature is reached. Then it’ll switch off – it won’t carry on until it reaches the trigger temperature. 

Heat on Demand doesn’t change your room’s target temperature or heat your home more than you’ve asked for. It just starts the boiler so the room can reach the temperature you want.

How It Works

Previously, Heat on Demand was set at a fixed temperature of 25°C, but we’ve introduced smarter, dynamic Heat on Demand logic in the Hive Hub. Now it’s activated automatically based on:

  • Your heating hardware
  • The current room and thermostat temperature
  • Whether your boiler supports OpenTherm

This means Heat on Demand always works efficiently across different boiler and thermostat setups, so you’re not using more energy than you need to.

How the new dynamic Heat on Demand works 

When a Hive Radiator Valve requests heat, the system temporarily raises the thermostat’s Heat on Demand trigger temperature just enough to fire the boiler. The exact temperature depends on whether your boiler is using OpenTherm.

In standard systems that don’t, when Heat on Demand is triggered, then we’ll make sure it’s 2.0°C above the current thermostat's actual ambient temperature. This is calculated dynamically every time.

Dynamic Heat on Demand in OpenTherm systems

OpenTherm boilers can vary their output (modulate) instead of running at full power all the time, so the trigger temperature will vary depending how close the room target is to the current room temperature. 

If the difference between them is more than 2°C, the Heat on Demand trigger is 2°C higher than the thermostat temperature.

If it’s less than 1.5°C, the Heat on Demand trigger is 1.5°C higher than the thermostat temperature. This means the boiler can stay in its more efficient modulating mode when only a small amount of heat is needed.

Why does OpenTherm have different triggers? 

OpenTherm boilers begin modulating efficiently when the difference between the target temperature and the current temperature is 1.5°C or less. By having different triggers, it means that the system can take full advantage of this capability to:

  • Deliver heat more smoothly
  • Reduce boiler cycling
  • Improve efficiency without affecting comfort

And it does all this automatically, so you don’t need to do anything.

What about the old 25°C value?

A failsafe default of 25°C still exists, but it’s only used very rarely, when the system can’t reliably calculate a dynamic value (for example, if temperature data isn’t available). So don’t worry if you occasionally see 25°C appear – it doesn’t affect your comfort or increase your energy use.

What happens to other rooms?

When the heating is on, all radiators receive hot water:

  • Hive Radiator Valves heat rooms to their set temperatures.
  • Manual radiator valves (non-smart) will continue heating until the boiler turns off.

Heat on Demand works best when you use Hive Radiator Valves on most radiators to avoid heating rooms unnecessarily and to maintain full control.

 TIP: Most homes have one manual valve (often near the thermostat) to ensure the boiler always has a radiator to heat. Do not replace this with a Hive Radiator Valve without consulting a plumber. 

How to Enable Heat on Demand

You’ll need:

  • A Hive Thermostat
  • A Hive Hub

To enable in the Hive app:

  1. Install and name each Hive Radiator Valve.
  2. During setup, you’ll be asked:
    “Would you like [radiator name] to turn the boiler on?”
    • Select Yes to enable Heat on Demand.
    • Select No to disable it.

You can change this later by:

  • Opening the Hive Radiator Valve settings (tap the settings icon)
  • Toggling Heat on Demand on or off

When Heat on Demand Won’t Trigger

Heat on Demand will not activate if:

  • It’s not enabled
  • Your thermostat is set to Off
  • Your thermostat is in Holiday Mode
  • Your thermostat is already heating
  • A boost is already running
  • Your thermostat’s target temperature is above 27°C
  • Is the Hive Radiator Valve less than 0.5° below its target temperature? Heat On Demand will only kick in when your radiator valve has dropped more than 0.5° below its target
  • The Hive Radiator Valve doesn’t need heat (room is already warm)

Turning Off Heat on Demand

To disable:

  • Go to the Hive Radiator Valve settings
  • Unlink it from the Hive thermostat

If disabled, Hive Radiator Valves will only heat rooms when the heating is already on.

Using Heat on Demand on Selected Radiators

Heat on Demand is managed per radiator.

To disable it for specific Hive Radiator Valves:

  1. Open the Hive app
  2. Tap the settings icon on the valve control screen
  3. Toggle Heat on Demand off

That radiator will still heat up when the boiler is on, but won’t be able to turn the boiler on by itself.

Does Heat on Demand increase energy use?

No, the amount of energy you use depends on the target temperatures and heating schedules you set. The temporary Heat on Demand trigger temperature isn’t a target, so your home will only heat to the temperatures you’ve set in each room and according to your schedules.