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.
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| 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.
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| 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.
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| 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.
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| 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.
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