Knowledge Centre

At RadiatorsforHeatPumps, we specialise in radiators designed for modern, energy-efficient heating systems. Unlike most radiator retailers, our website displays heat output at ΔT30 (Delta 30) rather than the traditional ΔT50 (Delta 50).

This is because we focus on low-temperature heating systems, such as air source and ground source heat pumps, which operate at lower flow temperatures than conventional boilers.

Why ΔT30 Instead of ΔT50?

• ΔT50 (Delta 50):

  • The industry standard for many years.

  • Based on a system flow temperature of around 75°C with a return of 65°C, giving an average water temperature of 70°C and a room temperature of 20°C.

  • Suitable for older, high-temperature boiler systems.

• ΔT30 (Delta 30):

  • Reflects the performance of radiators on low-temperature systems, where flow temperatures are typically between 40–50°C.

  • More accurate for heat pump setups, which are becoming increasingly popular in modern, sustainable homes.

  • Helps you choose radiators that truly match the output of your system, ensuring comfort without oversizing.

What This Means for You

• When browsing our store, you’ll see radiator outputs calculated at ΔT30.

• This ensures the radiator you choose is correctly sized for your heat pump or low-temperature heating system.

• If you are used to shopping with ΔT50 outputs, you may notice lower numbers — but this is simply because we’re showing the realistic heat output for your setup, not the traditional figures.

Need Help Sizing?

If you’re unsure about radiator sizing or converting from ΔT50 to ΔT30, our expert team is here to help. Get in touch for advice on selecting the right radiators for your home and heating system.

The terms ΔT50 (Delta 50) and ΔT30 (Delta 30) describe the temperature difference between the radiator’s average surface temperature and the room temperature. For example, a ΔT50 radiator will operate at a higher temperature than a ΔT30 radiator. A lower water temperature means you will need a larger radiator to emit the same amount of heat. 

Most radiators manufacturers & suppliers will quote ΔT50 heat output of their radiators as this has historically been the most common type of heating system. As more and more households move to heat pumps, ΔT30 radiators will become more common.

A valve on a household radiator is a control device that regulates the flow of hot water into the radiator. By adjusting the amount of heat entering the radiator, the valve controls how much heat the radiator gives off into the room.

Why a valve is needed

• Temperature control: The valve allows you to adjust or stop the heat output from the radiator. This means you can make individual rooms warmer or cooler as needed.

• Energy efficiency: By closing or reducing the flow to radiators in rooms you don’t use often, you save energy and reduce heating bills.

• System balance: Valves help ensure that hot water is distributed evenly throughout the heating system. Without valves, some radiators might get too hot while others stay cold.

• Maintenance & isolation: A valve lets you shut off an individual radiator for repair or removal without draining the entire heating system.

Types of radiator valves

1. Manual Valve

• How it works:
  Works like a tap — you turn it by hand to increase or decrease water flow into the radiator. The setting stays the same until you adjust it again.

• Advantages:

  • Simple and inexpensive

  • Reliable (fewer moving parts)

• Disadvantages:

  • No automatic temperature regulation — the room can become too warm or too cool if not manually adjusted

  • Less energy-efficient than thermostatic valves

📝 Typical use: Good for spaces where temperature doesn’t need to change frequently (e.g., hallways, guest rooms).

2. Thermostatic Radiator Valve (TRV)

• How it works:
  A TRV automatically adjusts the flow of hot water depending on the room temperature. It contains a temperature-sensitive element (often wax or liquid) that expands or contracts as the air warms or cools, opening or closing the valve accordingly.

• Advantages:

  • Maintains a more consistent room temperature

  • Saves energy by reducing heat output when the room reaches the desired temperature

  • Allows different rooms to be set at different comfort levels

• Disadvantages:

  • Slightly more expensive

  • Can be less effective if covered by curtains or furniture, which block airflow around the sensor

📝 Typical use: Ideal for living rooms, bedrooms, and other spaces where maintaining a steady, comfortable temperature is important.

RadiatorsforHeatPumps supply three types of valves; straight, angled and corner. Depending on where your pipework comes into the room will influence the type of valve you choose.

Straight Valve

A straight valve connects the pipework directly into the radiator without any bend. The water flows straight through the valve and into the radiator inlet.