To connect a valve-integrated panel radiator at the bottom, you need an H-block valve, angled for pipes from the wall or straight for pipes from the floor, plus two compression fittings matching the pipe and a thermostatic head; we include the valve insert with our radiators. A trade installer should mount and connect the radiator, as stated in our radiators' safety instructions.
From pipe to thermostat: the parts in order
The heating water passes through a chain of parts before the radiator warms up. For a bottom connection, it looks like this:
- Pipe: The heating flow and return come from the wall or floor.
- Compression fitting: It clamps the pipe to the H-block valve to form a watertight seal. There are two per radiator, one each for flow and return.
- H-block valve: It connects both pipes to the radiator. On the pipe side it has a ¾″ male thread with Eurocone, and on the radiator side a ½″ male thread with 50 mm spacing. Flow and return can be isolated individually.
- Valve insert: It sits in the radiator and controls the flow. It is included with our valve-integrated panel radiators and fitted during installation.
- Thermostatic head: It fits onto the valve. A sensor in the head responds to room temperature and throttles or opens the valve accordingly.
Parts list: what do you need for your installation?
The table shows which parts go together for each valve-integrated panel radiator with a bottom connection. A thermostatic head is also needed in every case; ours has the common M30 × 1.5 connection thread.
| Installation situation | H-block valve | Compression fittings (1 pair = 2 pieces) |
|---|---|---|
| Pipes from the wall, 15 × 1 mm copper pipe | 1 × angled | 2 × 15 mm |
| Pipes from the wall, 16 mm composite pipe | 1 × angled | 2 × 16 mm |
| Pipes from the floor, 15 × 1 mm copper pipe | 1 × straight | 2 × 15 mm |
| Pipes from the floor, 16 mm composite pipe | 1 × straight | 2 × 16 mm |
| Pipes centred beneath the radiator | does not fit without modifying the pipes, see below | |
Angled or straight: where do the pipes come from?
The H-block valve design depends solely on the direction of the pipes. Pipes from the wall need the angled version; pipes rising vertically from the floor need the straight version. Connection dimensions, material and isolation are the same for both: nickel-plated brass, ¾″ towards the pipe and ½″ towards the radiator.
Our H-block valves are designed for two-pipe heating systems. If your radiator is on a one-pipe system, the installer determines which valve assembly is suitable. They can also tell you whether your system is two-pipe or one-pipe.
Measuring the pipe: which compression fitting is needed?
The pipe's outside diameter determines which compression fitting fits. Measure it directly on the pipe with a vernier calliper.
- 15 mm fits 15 × 1 mm copper pipe; stainless steel pipe of the same dimensions is also suitable. The fitting is nickel-plated brass.
- 16 mm for plastic and composite pipe.
Both have the ¾″ Eurocone that fits our H-block valves. You generally need two of the same size for one radiator; we stock them as a pair.
Thermostatic head: M30 × 1.5 thread and settings 1 to 5
The thermostatic head in our accessories range screws on with an M30 × 1.5 thread; this is the common standard for valve inserts. If you only want to replace the head on an existing valve, first check whether the valve has this thread; older valves sometimes have a different connection.
Settings 1 to 5 represent the room temperature the head should maintain: the higher the setting, the warmer the room. The exact temperature for each setting is determined by the respective manufacturer. Our head measures Ø 48 × 79 mm, weighs around 132 g and comes in white or grey, supplied without a valve insert.
Bottom or side connection?
Each of our valve-integrated panel radiators has six connection openings, two each on the left, right and bottom, all with ½ inch female threads. Connection is at the bottom left, bottom right or at the side, as with a compact panel radiator. Unused openings are closed with the supplied blanking and air vent plugs.
Our radiators do not have a central bottom connection. If your pipes arrive centrally beneath the radiator, they must be modified. For side connection, we stock presettable thermostatic valves and ½″ radiator unions as order items. The installer determines which parts your radiator needs.
What the installer's connection work includes
The installer assembles the parts and checks everything for leaks at the end. Connection generally includes:
- hanging the radiator on the included wall bracket, supplied with plugs and screws,
- fitting the valve insert and closing unused connections with the blanking and air vent plugs,
- fitting the H-block valve and compression fittings to the radiator and pipe,
- opening the flow and return, filling and venting the radiator,
- checking the connections for leaks and fitting the thermostatic head.
The installer also checks the limits: according to the technical data, our valve-integrated panel radiators withstand up to 10 bar operating pressure and up to 120 °C operating temperature, and the heating system must not exceed either.
Frequently asked questions
Is the valve insert already fitted in the radiator?
No. It is supplied loose with each of our valve-integrated panel radiators and fitted during installation. Also in the box are the wall bracket with plugs and screws, and the plugs for the open connections.
Can the radiator be removed later without draining the system?
Yes, with our two-pipe H-block valves. Flow and return can be shut off individually. If you later want to paint the wall behind it or replace the radiator, it can be removed while the water stays in the system.
Does the same H-block valve fit both copper and composite pipe?
Yes. The H-block valve always has a ¾″ Eurocone on the pipe side. Only the compression fitting determines whether it fits copper or composite pipe: 15 mm for copper, 16 mm for composite pipe.
Does every radiator need its own thermostatic head?
Yes. Each radiator has its own valve, and each valve takes a head. This allows each room to be controlled individually.
How is the H-block valve fitted?
The H-block valve's ½-inch male thread connects to the radiator's two bottom connections, which are 50 mm apart on our valve-integrated panel radiators. On the pipe side, the two flow and return compression fittings sit on its ¾-inch Eurocone. The installer then opens both lines, fills and vents the radiator and checks all connections for leaks. First establish whether the pipes come from the wall or floor; this determines whether the angled or straight version fits.
Does the H-block valve fit every radiator with a bottom connection?
It fits valve-integrated panel radiators with bottom connections and 50 mm pipe centres. This is the standard for valve-integrated panel radiators with bottom connections and the dimension of our Type 22 and Type 33. On another radiator, measure the distance between the two bottom connections centre to centre.
Enquiring about an H-block valve: what must be established before fitting?
Send a photo of the bottom radiator connections and pipes, together with the radiator model, connection spacing and pipe dimensions. State whether the pipes come from the wall or floor and whether the system is one-pipe or two-pipe. The installer checks flow, return and the permitted combination of H-block valve and fittings before installation. This avoids having a matching thread diameter but an unsuitable installation arrangement. Establish the correct radiator size using the replacement measuring guide.
Suitable products and collection in Hagen
The H-block valves are available as an angled two-pipe H-block valve and a straight two-pipe H-block valve. You can find compression fittings, the thermostatic head and side connection parts under Accessories. Enquire about the parts together with the radiator so we can put together a matching set.
Collection is from our warehouse – Im Mühlenwert 22, 58135 Hagen (rear entrance), Mon–Fri 8:30–17:30 and Sat 10–14, by appointment. Radiator unions and thermostatic valves are order items: they will be ready for you after the goods arrive, and we will give you the collection date in our reply. Advice is available in our shop – Eilper Straße 29, 58091 Hagen. Delivery by arrangement; details under Collection and enquiries.