A pump group manifold is an element of a heating installation that plays a very important role – it enables the connection of several independent heating circuits to a single heat source, e.g., a gas boiler, heat pump, or solid fuel boiler. Thanks to it, it is possible to simultaneously supply different parts of the installation, such as underfloor heating, wall radiators, or a domestic hot water storage tank. But the question is - is it always necessary, when can you do without it?
A boiler manifold acts as a kind of distribution center in the heating system - but let's say one that is at least minimally developed, to the extent that it contains at least 2 pump assemblies. As we know, this is not always the case in very small systems.
The pump assemblies connected to the manifold direct heat to selected circuits – each pump serves a different part of the installation, working independently of the others. This makes it possible, for example, to simultaneously maintain a low temperature in the underfloor heating and a higher one in the radiators. Could this be done without a manifold? Yes, probably by using some other distributors - however, the pump group manifold is intended to be a ready-made solution. It's faster to install (and therefore cheaper, because a specialist's work is expensive) - and easy to operate, ensuring that the whole setup takes up less space in the boiler room, which is also important.
A boiler manifold can also be supplemented with an additional device known as a Boiler Guard, which provides extra hydraulic separation for the system.
It probably is worth it - generally, the trend of using ready-made components instead of improvised (and yet time-consuming solutions) is visible everywhere. A pump assembly itself could also be replaced by a separately purchased three-way mixing valve and a pump - and the reason for installing it is similar. The same applies to hydraulic separators on mounting plates, etc.
✅ A pump group manifold naturally comes at a cost. So what does it offer?
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Pump group manifolds or just boiler manifolds are used in both single-family homes and larger buildings where several circuits requiring different operating parameters are present. This solution is particularly useful in modern installations with heat pumps or condensing boilers. Very often also in mixed systems - e.g., part of the building with underfloor heating - and part with radiators; in multi-story systems, it allows, for example, the use of a separate circuit with a separate pump group for each floor, etc.
Of course, since there are manifolds of very different sizes, it would be difficult to provide a universal flow diagram. However, it is generally a device of simple construction that is connected alternately - otherwise, it wouldn't be functional. Below, as an example, we present a flow diagram for a boiler manifold that can handle up to 7 pump groups (4 on top and 3 on the bottom), which will help understand how the flow works in this type of device:
Flow diagram with connection directions in a Nordic Tec 4-8 boiler manifold. This is a multi-section manifold, allowing for the connection of a larger number of groups. The extreme bottom connections (i.e., the last connection on the right and the last on the left) are used to connect the supply and return from the heat source. To maintain the most accessible and clear boiler room layout - the upper connections are used first. The lower ones are used only if a greater number of circuits is needed. Unused circuits are blanked off with special blanking plugs; it's worth checking if they are included in the set before potentially purchasing similar equipment.
Practically all sorts, basically a wide choice. The most readily available on the market seem to be boiler manifolds for a maximum of 2-4 pump assemblies, as there is the highest market demand for these. They simply correspond to the size of classic heating installations. However, larger ones, even for several dozen pump groups, whose length is measured in almost meters, are also available in more specialized stores.
There are several things to pay attention to when purchasing this equipment.
The first issue is whether the boiler manifold has insulation. This is standard today for this product; if it's missing, the manifold will act like a radiator in the boiler room. Heat isn't free, and we probably don't want to pay for a radiator in the boiler room.
The second thing - very important - is the center-to-center distance for the groups. If the pump groups are from a different brand than the manifold, you must ensure they have the same connection center-to-center distance.
✅ Many professionals consider 125mm to be the classic center-to-center distance for connections, and indeed this is very often the case. However, if our pump group has a different center-to-center distance than the manifold, there might be a problem with connection, as they might be incompatible. It's best to choose manifolds with the classic center-to-center distance - i.e., 125mm; this way we gain almost certainty that most pump assemblies on the market will be compatible. Similarly, if you already have a manifold and are buying an assembly for it, this is a point that needs to be checked.
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