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Radiator parts & Accessories. What should I look for???
In addition to choosing the right thermostatic valves, it is essential to have the other components of your heating system in order. In this category you will find radiator valves , base blocks or foot valves , connection couplings , inserts , bypasses , servo motors and various appendages . All these components contribute to a well-functioning and efficient heating system. Below you can read what each component does, what you should pay attention to and which brands (Heimeier, Herz, Danfoss, Comap, Kemper) we offer.
Radiator valves
What is it?
A radiator valve controls the water flow to your radiator. This can be done with a manual valve (open/closed) or a thermostatic valve, which measures the temperature in the room and automatically adjusts the radiator output.
What to look out for?
- Connection : Check the thread (e.g. M30 x 1.5, M28 x 1.5 or Danfoss RA).
- Brand compatibility : Some taps are specifically designed for Heimeier, Herz or Danfoss valves.
- Left or right : Pay attention to the supply side (left or right connection).
Supply side
The supply side is the side where the hot water from the central heating boiler or heat pump flows into the radiator. It is important to connect the radiator and any taps to the correct supply side for optimum flow and heat output
Which brands?
- Heimeier : Known for their M30 x 1.5 connection and reliable thermostatic taps.
- Herz : Often M28 x 1.5, with various versions for specific applications.
- Danfoss : Uses RA, RAV, or RAVL systems, so check valve type.
- Comap & Kemper : Offer universal and brand-specific taps with high-quality materials.
Bottom blocks / Foot valves
What is it?
A bottom block or foot valve is located at the bottom of the radiator and provides the supply and return of water. This allows you to easily shut off the radiator for maintenance, without having to drain the entire system.
What to look out for?
- Connection distance between supply and return (e.g. 50 mm for certain radiators).
- Connection size of your radiator and your central heating pipe (e.g. 3/8", 1/2", 3/4").
- Thermostatic or manual : some base blocks can be directly combined with a thermostatic head.
Which brands?
- Heimeier, Herz, Danfoss, Comap, Kemper : Each brand has its own models that often fit perfectly with their other radiator parts. However, always check whether the thread and centre distance match.
Connection couplings
What is it?
Connection couplings connect the radiator (or lower block) to the central heating pipe. They come in all sorts of designs: compression couplings, press couplings, screw couplings, etc.
What to look out for?
- Pipe material (e.g. plastic, copper pipe, multilayer pipe).
- Diameter and thread size of the coupling.
- Gasket / O-ring : Make sure you have the correct seal, for example axial or radial.
Which brands?
- Heimeier & Herz : Often make their own couplings that connect to their taps and bottom blocks.
- Danfoss, Comap, Kemper : Universal and brand-specific couplings in various sizes.
Inserts (screw-in parts) and Appendages
What is it?
An insert, also called a screw-in part, goes into the radiator or into the tap to regulate the flow. Fittings can be all kinds of extra accessories, such as air vents, drains, reduction pieces or other internal parts of the tap.
What to look out for?
- Insert type : Each radiator manufacturer can have its own type of insert.
- Kv-value : This determines how much water can flow through per unit of time. Important for example for pre-adjustable valves.
- Thread : As with taps and knobs, these inserts can be M30 x 1.5, M28 x 1.5 or another size.
Which brands?
- Heimeier : Offers specific inserts for their valves, often with pre-adjustment option.
- Herz : Has special Herz inserts (e.g. for M28 x 1.5).
- Danfoss, Comap, Kemper : Here too you will find inserts that fit their own or universal valves.
Bypass
What is it?
A bypass is used to ensure a minimum water flow in the heating system, even when all radiators are closed. This allows the boiler or pump to continue circulating and the system does not become “locked up”.
What to look out for?
- Adjustable : Some bypasses can be set to a specific flow rate.
- Compatibility with your pipe diameter and pump capacity.
- System type (open or closed central heating system).
Which brands?
- Heimeier, Herz, Danfoss, Comap, Kemper : Supply bypass solutions that can often be combined with their other accessories and valves.
Servo motors (e.g. from Herz)
What is it?
A servo motor (also called an actuator) is an electrically powered motor that opens or closes your radiator valve, often based on an external thermostat or home automation system.
What to look out for?
- Voltage / power supply : 24V or 230V, depending on the control system.
- Control type : 2-point (on/off) or modulating (0-10V).
- Connection to the valve : Does the engine physically fit the brand and type of valve?
Which brands?
- Herz : Offers servo motors for their own valves.
- Heimeier, Danfoss, Comap, Kemper : May also have actuators, but always check the datasheet.
What should you pay attention to when purchasing?
-
Thread and dimensions
The most common connection is M30 x 1.5 (Heimeier, Comap, Kemper), but at Herz you will often find M28 x 1.5, and Danfoss works with RA, RAV or RAVL type connections. -
Kv value or preset
Some valves and inserts are pre-adjustable, which is useful for tuning your installation. Check if your system needs balancing valves or not. -
Complete set or individual parts
Sometimes it is cheaper to buy a set (e.g. tap + bottom block + couplings) than to look for everything separately. Make sure that all parts fit together (brand/dimensions). -
Brand preference
Do you already have Heimeier valves? Then it usually makes more sense to also use Heimeier parts for the best fit and warranty. The same goes for Herz, Danfoss, Comap and Kemper.
Need advice? We're happy to help
We understand that all these technical details can be overwhelming. Our product descriptions give you a clear overview of the specifications , dimensions and compatibility . If you still can't figure it out or are unsure which parts you need, please feel free to contact us. We will help you step by step to make the right choice for a perfectly functioning heating system.
At viawww.nl you will find everything in one place: high-quality radiator parts, expert advice and the best prices. This way you can be sure that your heating will not only stay warm, but also durable and reliable!