Manifold for underfloor heating. The choice of material

Over the past decade, the system of water underfloor heating has become very popular. During this time, the quality of design and installation has increased. In addition, the "commodity" direction is developing. If before, many laid the hinges of multilayer pipes, now in the trend PERT pipes. "Shift by materials" occurred in the category of manifolds. Today we will talk about this.

Pict.1 Example of placing a manifold unit for underfloor heating

Brass was a unique leading material for the manufacture of heating products in Europe for a long time. Therefore, it is not surprising that manifolds for the underfloor heating also began to be produce from it. To do this, produce a special workpiece - a brass hollow rod. It is cutting to the desired length. Drill holes for installing flowmeters or valves and cut the connection threads. The market also have options with the stamped body.

Pict.2 The manifold on the left made of finished rod, to the right - stamped

Considering the fact that the price of brass is constantly growing (+ 60% to the cost of brass in Europe over the last 2 years), manufacturers started looking towards cheaper materials. The search led to two new types of manifolds - stainless steel and polymer materials (plastic). It would seem that there should be no difference in the final product. But it's not true. Let's consider in more detail.

Pict.3 Products from different materials (from left to right) - brass, stainless steel, technopolymer

Material

Brass has practically no flaws. Hypothetical washing out of zinc and corrosion are eliminate by applying nickel or chromium.

Manifolds made of stainless steel have an internal weld seam. Which in time can lead to corrosion. However, in many respects it depends on the type of steel. Such European manufacturers as Itap, Kermi, Capricorn, etc. use AISI 304 (1.4301). It has excellent corrosion resistance.

In addition, this material is stronger than brass. On this basis, the wall thickness of the collector is smaller. Accordingly, the cost too.

Nevertheless, buying a stainless steel manifold "unverified" manufacturer you can "run into" the "rusty steel"))). Therefore, I do not recommend much saving.

Polymer manifolds are the least common in Ukraine. By the way, to use the word "plastic" is not entirely appropriate. Since a technopolymer is used to make reservoirs. Often this is polyamide PA66. To increase the strength, 30% of the glass fiber is add to it.

However, the main advantage of products made of polymers is their cost. Although at the moment, the difference between metal manifolds and polymer is not very large.

Specifications

Analyzing the technical parameters, we see that brass manifolds are better. Nevertheless, considering that the system "underfloor heating" is low-temperature, this advantage is relative.

The only parameter to pay attention to is the expense. Due to the small thickness of the wall, stainless manifolds have a larger internal section. Through which more water can flow. Polymer reservoirs, on the contrary, have a "narrowed" cross section in comparison with brass competitors.

Physical parameters

One of the shortcomings of polymer products is oxygen permeability. To avoid this, the technopolymer is reinforce with glass fiber. However, diffusion of oxygen is still present.

But on the other hand, polymeric manifolds have resistance to virtually all corrosive media and to electrochemical corrosion. This is their advantage over metal counterparts.

Another advantage of this material is its low thermal conductivity. That is, such a manifold loses less heat than a stainless steel and especially a brass one.

Design Features

Weak strength of plastic thread - the main factor that prevents the spread of such reservoirs. To securely connect this thread, the manufacturer recommends using a torque wrench. European installers, not to mention ours, rarely do this. The first acquaintance of the plastic thread with local installers was sad. In addition, this negative experience is hard to eliminate. Therefore, manufacturers had to resort to changes in the design. Now threads on polymer manifolds are brass. And they "collapse" much harder.

Pict.4 Polymer manifolds

Summing up, I think that in the near future the share of brass manifolds will decrease. Manifolds made of stainless steel will become more popular. As for the "plastic" manifolds, there will be a little heavier here. When it will be possible to "break" stereotypes, then they will conquer the market. So to with the increase in sales, the price for them will decrease. The main question, when will this happen - in 1, 3 or 5 years? That the future behind plastic - to doubt it is not necessary.