Technical data
Glossary
Installation and maintenance instructions ecoTEC plus 0020116700_06  81
18
18 Glossary
Air/flue gas duct  
An air/flue gas duct is a line system with two separate flow 
channels. The flue gas is routed into separate chambers at 
the same time as the required combustion air is pumped to 
the boiler. The air/flue gas duct can be designed as a con-
centric or adjacent double flue gas line (the exhaust gas 
channel is sealed from the air channel). Floor standing boil-
ers and gas fired wall hung boilers can be operated inde-
pendent of room air through the air/flue gas duct. As a 
result, boilers can be installed in new buildings that do not 
offer sufficient combustion air for open-flued heat genera-
tors due to their airtight construction.
 Burner anti-cycling time
The burner is electronically locked for a specific time after 
each time it is switched off ("restart interlock") to avoid fre-
quent switching on and off of the burner (energy losses) 
and to extend the working life of the boiler.
The burner anti-cycling time is only activated for the heat-
ing mode. 
Hot water handling is not affected if burner anti-cycling 
time is running.
Calorific value 
Unlike the heating value, the calorific value of a fuel 
describes the total useable heat during combustion, based 
on the quantity of fuel used, including the condensation 
heat in the steam.
The energy contained in steam can also be used if the 
steam liquefies on cooling. 
Compact thermal module 
The compact thermal module is an assembly of Vaillant 
condensing units that consists of the following five main 
components in the ecoTEC plus: speed-regulated fan, gas 
valve including support plate, venturi including gas supply 
pipe, burner door and premix burner.
Condensing technology 
Technology which maximises the use of the calorific value 
of the fuel. The flue gas is cooled until the water vapour 
that it contains condenses. The condensation heat that this 
releases can also be used. 
In particular, the flue gas losses are greatly reduced. The 
losses from conduction of heat and radiation are also 
reduced by the lower system temperatures. The entire heat-
ing installation should therefore be designed for low system 
temperatures (flow/return temperature) for the effective 
use of the calorific value. The level of efficiency attainable 
for boilers is always given based on the heating value of the 
gas. Due to the additional condensation heat used, the cal-
culated values can exceed 100%. 
Digital information and Analysis system (DIA) 
The Vaillant ecoTEC plus boiler is fitted with a digital infor-
mation and analysis system (DIA). If additional settings are 
required, which have not been configured using the installa-
tion assistant, then you can view and modify these using 
the DIA.
eBUS 
eBUS is an abbreviation for energyBUS. The eBUS is a spe-
cial bus used in heating technology, which assists the com-
munication between intelligent components in the heating 
technology. In a Vaillant system, up to eight different heat 
generators can be connected via the eBUS.
The eBUS communications protocol simplifies the control-
related linking of different system components within a 
heating installation. It provides particular flexibility for ret-
rofitting and expanding the system. This simplifies the 
installation of boiler cascades or the subsequent addition of 
components such as solar hot water generation.
The eBUS provides extended facilities for connecting con-
trollers.
Multi-functional module 
The multi-functional module is an accessory that controls 
additional functions or components in combination with 
Vaillant boilers with eBUS electronics. It also allows you to 
select and control 2 in 7, e. g. circulation pump, external 
heating pump, external solenoid valve or response from the 
flue non-return flap.










