Wavin - Control Units

1. Energy saving, temperature control

units, legislation

In recent years, energy efficiency and saving questions have

aroused ever more interest, on the part of all the players in-

volved in this sector. The importance these matters have ac-

quired is due, first of all, to the intent to reduce the consumption

of fossil fuels and, secondly, the desire to lower emissions of

CO2 and other pollutants into the atmosphere.

In this context, efficient building and system design can provide

fundamental leverage for acting in this regard.

Therefore, one can certainly state that temperature control of

a radiant air conditioning system falls within the area of energy

efficiency and saving of a building. In fact, it is necessary to see

to it that a system only provides the heat needed, when and

where it is needed, thereby limiting energy and economic waste.

As regards, radiant systems, the reference standards are the

following:

•

UNI/TS 11300 The reference technical standard on energy

saving and energy certification of buildings. It is broken

down into four parts, the first three of which are currently

being revised.

•

UNI EN 1264-4 Water radiant heating and cooling systems

that are built into the structures.

Part 4 - Installation

This lays down the need for radiant system distribution

manifolds to be fitted with instruments that regulate the

flow rate.

•

Technical Regulation UNI/TR 11619:2016 Low tempera-

ture radiant systems - Energy classification The aim of

which is to assist the designer when it comes to choos-

ing and designing a radiant system that is also complete

with adequate auxiliaries and suitable control. All of this is

aimed at designing and building radiant air-conditioning

systems that are as environment-friendly as possible.

We wish to deal specifically with the technical regulation (vol-

untary standard) in which the concept is introduced of “Energy

efficiency index for the radiant system RS

“. This represents

the overall efficiency of a radiant system made up of piping on

the ceiling, walls, or in the floor, connections, manifold, and con-

trol system.

RS

η

× η

bal

× η

circ

The four aspects go together to make up the RS

index, are:

•

Losses due to radiant system emissions

η

•

Losses caused by the control system

η

•

More or less correct hydraulic balancing of the system

η

bal

•

Efficiency of the circulator,

η

circ

Energy performance is taken to be the ratio between the quanti-

ty of energy required for an ideal heating system (which makes it

possible to have a uniform temperature, equal on all the spaces),

and the energy required under real conditions. According to

UNI/TS 11300-2:2014 the energy performance of radiant pan-

els, according to their position, is as follows:

Manifolds and Temperature Control Units - Product Guide

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•

Ceiling

•

Wall

•

Floor

η

= 0.97

η

= 0.97

η

= 0.99

NOTE. Classification of radiant systems with a low tempera-

ture difference, covers floor, ceiling, and wall systems used in

heating systems, without introducing distinctions in relation to

the various types, such as dry, wet, or thin systems. Radiant

systems therefore have to conform to UNI EN 1264 in terms of

characteristics, types of materials, and components.

The generation performance is represented by the ratio be-

tween the heat required to heat the spaces, with theoretical tem-

perature control, and the heat required to heat the same spaces,

with real temperature control.

NOTE. A theoretical temperature control compensates for fluc-

tuations in the thermal load, in real-time.

To calculate the

RS

index, only the "panels built into the struc-

tures and detached thermally" are taken into consideration, as,

according to UNI EN 1264-4, radiant systems must be equipped

with an insulating layer that limits the outward flow of heat, in a giv-

en direction. The generation performance levels are indicated in

UNI/TS 11300-2.

The balancing performance may have two values:

• η

= 0.97 for unbalanced systems.

• η

= 1 for balanced systems.

A system is balanced when there are suitable instruments in

place to regulate the flow rate. Therefore, the distribution mani-

fold must be fitted with micrometric regulation flow rate valves,

for the individual circuits, as called for by UNI EN 1264.

When more than one manifold is used, there must also be con-

trol valves on the supply line.

The system is not balanced when it does not have any flow rate

control instruments.

The circulation performance

η

circ

is obtained by comparing the

electrical consumption of a circulation pump with a fixed num-

ber of rpm, with a circulation pump that is efficient for a variable

regime for a given building.

According to the energy efficiency requirements, from 1 Janu-

ary 2015 the energy efficiency index for IEE circulators cannot

exceed 0.23 according to the CE 641 2009 Regulation.

The lower the IEE value, the higher the efficiency of the circula-

tor, and therefore of the system.

Circulators can be divided into two categories:

•

With performance

η

circ

= 1 and IEE≤0.23

•

With performance

η

circ

= 0.98 and IEE≤0.23