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How it works: Hydronic heating


Hot water radiators: The basics

Hydronic heat is one of the most effective ways to warm a building. It is highly controllable, silent and maintains a much steadier ambient temperature than central air systems.

Components of a hydronic radiator. Control Valve: This connects to the flow, or inlet side of the radiator, allowing hot water to enter the radiator. It might be manual or thermostatic. We usually recommend thermostatic valves because they add comfort and control, and can dramatically reduce energy use. Bleed Valve: Used to purge air, ensuring the radiator is completely full of water. Our hydronic radiators come with bleed valves included as standard. Lockshield: Lockshield The return valve is used to control the flow through the radiator. It’s set by the plumber during installation and shouldn’t be adjusted during normal operation.

Hot water (hydronic) radiator components

Hot water enters the radiator through a control valve and exits through a lockshield. On initial fill, air is vented through the bleed valve to ensure the radiator is completely full of water. Bleeding the radiator shouldn’t be a frequent necessity (the need to frequently bleed a water radiator is a sign of a problem in the system).

The control valve may be manual or thermostatic. A thermostatic radiator valve adds comfort and control. The modern energy efficiency of TRVs can give a dramatic saving on fuel bills.

The lockshield is used to balance the system, ensuring the radiator furthest from the boiler reaches the same temperature as the one closest to it.

All our hydronic radiators are supplied with a bleed valve included as standard. We also stock bleed valves for use in restoration projects.

Read about one-pipe steam and two-pipe steam radiators.