Valves and Connections for Steel Panel Radiators: What to Specify at Order Time

When a buyer specifies steel panel radiators for a project, the conversation usually centers on heat output, dimensions and finish — and then the valve and connection details get left to the installer. That works on a small residential job, but on a project order it is a false economy: the connection configuration determines how the radiator can be plumbed in, which valves fit, and whether the units a buyer receives actually match the pipework already roughed into the walls. This guide covers the connection positions, valve types and tapping dimensions that belong on the order sheet, not on a snag list after delivery.

Side connection vs. bottom connection: two different radiators Steel panel radiators are built in two broad connection families, and they are not interchangeable after manufacture. A **side-connection** radiator has four threaded tappings — two at the top and two at the bottom, one pair at each end — usually G1/2 (half-inch) internal thread. The installer chooses which tappings to use and plugs the rest: flow into the top tapping at one end and return out of the bottom tapping at the opposite end (TBOE, top-bottom-opposite-ends) is the classic layout, while bottom-bottom-opposite-ends (BBOE) suits pipework rising from the floor. A **bottom-connection** radiator (also called center- or integral-valve) has its tappings grouped at the bottom center, typically on a 50 mm pitch, and is designed to pair with an integrated or bottom-mounted valve set so the pipes rise straight out of the floor or wall below the unit. A buyer cannot convert one into the other on site; the tapping pattern is set when the radiator is fabricated. So the first line on any valve-and-connection spec is simply: side connection or bottom connection?

Which valve goes where: TRV, lockshield and manual A correctly valved radiator has a control valve on one connection and a balancing valve on the other. The **control valve** is either a thermostatic radiator valve (TRV), which modulates flow to hold a room temperature set on its head, or a simple manual valve where room-by-room thermostatic control is not required. The **lockshield valve** sits on the opposite connection and is set once during commissioning to balance flow across the system — it is not adjusted by the occupant. On a side-connection radiator these are angled or straight valves chosen to match whether the pipe comes from the wall or the floor; on a bottom-connection radiator the control and balancing functions are combined into a single bottom valve set matched to the 50 mm tapping pitch. The practical point for a buyer: decide early whether thermostatic control is required on every unit, because it changes the valve package and, on bottom-connection radiators, sometimes the radiator model itself.

The numbers that belong on the order Three dimensions turn a vague 'with valves' note into something a factory and an installer can both work to. First, the **thread size** of the tappings — G1/2 is standard for steel panel radiators, but it should be stated rather than assumed, because the valve tails must match. Second, for bottom-connection units, the **tapping pitch** (the center-to-center distance between flow and return, commonly 50 mm) — this must line up with the valve set and the pipe spacing. Third, the **connection layout** in plain words — for example 'side connection, TBOE' or 'bottom connection, center, 50 mm' — so there is no ambiguity between what the drawing shows and what ships. These details sit naturally alongside the heat-output and dimension figures already covered in [choosing steel panel radiator types](/en/blog/steel-panel-radiator-types-how-to-choose) and in [calculating output per room](/en/blog/calculate-radiator-output-per-room).

Why this belongs in the order, not the snag list On a project — a residential development, a retrofit, a tender-specified job — the pipework is often roughed in before or in parallel with the radiators arriving. If the radiators turn up with the wrong connection family, the choice on site is to re-run pipework or to source adaptor fittings, both of which cost time and money that a few lines on the order would have saved. This is the same logic that applies to sizing a retrofit before the radiators are made, covered in [sizing radiators for a renovation](/en/blog/retrofit-steel-panel-radiators-renovation-projects), and to writing a complete specification in [an engineering tender](/en/blog/specifying-steel-panel-radiators-engineering-tenders). The connection and valve spec is cheap to get right on paper and expensive to fix after a container has shipped. A good factory will confirm the tapping pattern, thread size and — where valves are part of the order — the valve configuration back to the buyer before production, rather than leaving it to be discovered on unpacking.

JD Radiator (Tianjin Jiuding Yangguang HVAC Co., Ltd.) is a family-run manufacturer since 2002, supplying steel panel radiators to project buyers across Europe, Russia and Central Asia. Our panels are available in side- and bottom-connection configurations with G1/2 tappings, comply with EN 442 with Declarations of Performance available for specification, and GOST compliance is covered for orders bound for the Russian and EAEU markets. We can confirm connection layout, tapping pitch and valve requirements with buyers before production, and supply the documentation pack — packing list, certificate of origin, technical data sheets — that supports customs clearance. For a quotation or to discuss connection and valve details for your project, contact lunan@jdradiator.com / kevin@jdradiator.com or call +86-22-69189950; full product range at /en/products and certification details at /en/credentials.