Unical NOVAIREX 35, Installation And Maintenance Instructions Manual

23

Tec

hnical f

eatures and dimensions

3.9 -  CONNECTION TO THE 
 FLUE

To connect the flue gas exhaust pipe, local and national stand-
ards must be observed. 

The chimney is essential to good boiler operation: accordingly, 

the chimney needs to be water-proof and well-insulated.

Old or new chimneys, built without respecting the specific 

requirements, can be recovered by “piping” the chimney itself.

It will be necessary to introduce a metallic pipe inside the existing 

chimney and insulate the space between the metallic pipe and 

the chimney.

Chimneys made of prefabricated blocks must have perfectly 

sealed joints to avoid that flue condensate smudging the walls 

due to permeation.

The entrance to the chimney should be at a 45° angle.

At the base of the chimney a flue inspection opening has to be 

made. 
It is recommended to insulate the pipe connecting to the chimney 
to reduce heat loss and noise.
The dimensions of the chimney must guarantee the draught 
required to properly operate the boiler. 
An insufficient draught, besides causing smoke leakage from 
the generator, it considerably reduces the heat output. On the 
contrary, an excessive draught causes an abnormal heat output 
increase, a higher flue gas temperature in the chimney and too 
much fuel consumption.

Use only exhaust pipes suitable for the type 
of fuel used. 
The supplier will have no contractual or ex-
tra-contractual liability for damage caused due 
to incorrect installation and use and anyway 
failure to comply with the instructions provided 

by the manufacturer. 

It is forbidden to exhaust NOVAIREX combus-
tion products in shared flues.

The flue must comply with the standards in 
force.
The flue gas chimney must be made properly 
to favour the normal flow of flue gas from the 
combustion chamber towards the outside in 
the case of a power outage.
Remember that the elimination of excess 
heat is managed optimally by the electronic 
control unit.

The following are the main features of the 
flue gas exhaust pipe according to that es-

tablished by standards UNI 7129 and UNI 10683:

-  The flue gas exhaust pipe must have airtight inspection ports;
-  The minimum height of the pipe connected directly to the 

flue gas exhaust is between 2-3 m;

-  If a horizontal section is inevitable, it is recommended that it 

be no longer than 1.5 m at most and at a gradient of 3-5% 
to favour the escape of the flue gas;

- 

A weatherproof terminal must be used

 to avoid altering 

the slight state of overpressure found in the flue (do not fit a 
horizontal section at the end of the pipe);

-  The exhaust ducts must be made with material resistant to 

combustion products and condensation (the inspection valve 

can drain any condensation which may be formed);

-  Pipes must be built in such a way to guarantee maximum 

smoke tightness (UNI 10683);

-  It is recommended to insulate the piping, especially the 

outside part exposed to foul weather.

Do not make sections fully horizontal.

There must be no flue gas exhaust hoods installed or already 
existing in the room where the heat generator is installed to 
avoid creating a vacuum in the environment.

It is prohibited to close the air vents.

Have the flue cleaned at least once a year; we therefore 
recommend having both the chimney and the flue gas fitting 
thoroughly cleaned.

Should the flue or piping catch fire, immedi-
ately switch the boiler off and disconnect it 
from the household electrical mains.

Draught limiter/

adjuster

Soot container with 

condensate drain