Correctly position the manifolds of the floor system

Even before starting the installation of a radiant floor system, one of the indispensable operations is the installation of the so-called "distribution manifold".

What are we talking about?

It is a section of piping with a larger diameter, from which all the pipes with a smaller diameter that will form the various circuits embedded in the floor of our house will start:

From the image above it is clear that the distribution manifolds are an important element of the system and their correct positioning can really make the difference!

The basic rules for deciding the position of the manifold box are as follows:

1. Choose a barycentric position with respect to the house plan, in order to optimize the lengths of the circuits and consequently the flow rates and the balancing of the system.
2. Avoid heavily involving the rooms to be heated/cooled (those to which we want to dedicate real circuits) with the passage pipes relating to the circuits of the other rooms.
3. Use the passage pipes (i.e. the sections of piping that go from the collector to the room in which the actual circuit will be built) to fill the rooms to which you do not want to dedicate a real circuit (corridors, closets, etc...).

It is not always easy to respect all 3 rules at the same time: it goes without saying that the best choice corresponds to a fair compromise between the three.

They seem trivial rules... but I assure you that a few visits to the construction site are enough to realize that radiant systems are often made in the most complete forgetfulness of these simple indications.

Let's take an example

In this house the distribution manifold (C-1 with 11 circuits) is positioned in room 5: a sort of hallway for the arrival/departure of the stairs. As you can see, there are two details that catch the eye:

• The position of the manifold is not exactly the symmetrical center with respect to the house plan. There are circuits very close to the manifold, such as those in rooms 4 and 6, and other circuits very far apart, such as those in rooms 1 and 2. This means that the balancing operations of the system (regulation of the water flow rate in each circuit by means of special micrometric valves supplied with the manifold) will certainly require much more time and greater care. Not to mention that these operations, once the system is completed, are often "forgotten"... with easily imaginable operational consequences (example: rooms 1 and 2 where the floor does not heat enough)!
• Room 5 is entirely covered only by the passage pipes. It does not have a dedicated circuit, but since it is a corridor the choice does not seem to be particularly serious.

Let's see, in the following image, how the system could have been optimized:

By moving the distribution manifold a few meters and placing it inside room 7, the right compromise is obtained between the fundamental rules for installation, with the following results:

• The manifold is located in a more central position. The passage pipes that feed the furthest circuits (rooms 1, 2, 4 and 6) also have a path of acceptable length and the balancing operations of the system are certainly easier.
• While maintaining the same number of circuits (in total 11, as in room 7 it is possible to create 3 circuits instead of 4 due to the proximity of the manifold), it is possible to dedicate an independent circuit also to room 5 (previously covered only by the passage of the pipes). In this way, if we wanted to install a temperature regulation thermostat in every room, including room 5 (which could be used, for example, as a "study" or "PC work area" or other), we would have no impediment because each thermostat would command the opening or closing of the relative circuits. Conversely, in the previous situation, we could not independently control the temperature of room 5.

 As you can see, the choice of the position of the manifold can have an important impact on the correct operation of the system, in terms of balancing the water flow rates, and on the possibility of making the most of it, in terms of individual room temperature control.

The mistakes that are most often encountered on construction site are the following:

• Positioning of the manifold linked to the position of the boiler (under the boiler or in the installation room itself): a choice that cannot have any technical reasons.
• Positioning of the manifold in non-compliance with one or more of the three identified rules: a choice that denotes a lack of attention to the real potential of this system.

In conclusion

The accurate design of a radiant floor system does not only concern the choice of materials and the sizing of the circuits. Remember to pay the right attention also to the positioning of the distribution manifolds.

Let's start off on the right foot ... to guarantee a perfectly functioning system and optimal comfort!

Please note. Source of some images: web