4- General Precautions; 5- External Factors That Influence A Chimney's Operation; 6- Summary Of Standards - hergom CRAFTSBURY Installer Manual

1.2.4- GENERAL PRECAUTIONS

• Only use special prefabricated metal chimneys for high temperatures.
• Do not connect a heating appliance to any air distribution duct or system.
• Do not connect to chimneys that have other services, as it will affect the safety of the
appliance's operating and of the other applications.
• The premises where the heating appliance is going to be installed must have sufficient air
inlet to the premises to supply the appliance's air requirements. Excessively insulated houses
may cause the chimney operating badly and in fact cause inverse draughts that may take the
smoke into the inside of the room, when for example the kitchen air extractor is working. In
this case it is necessary to make a special air inlet from outdoors into the room to supply to
the appliance.
1.2.5- EXTERNAL FACTOR THAT INFLUENCE A CHIMNEY'S OPERATION:
• Houses with good indoor insulation, without air draughts; as not enough air enters the
heater, it causes a poor draught. This may be corrected by supplying air from outside to the
heater.
• Trees and/or tall buildings close to the house.
• The wind speed. Generally, persistent strong winds increase the draught, although stormy
winds may decrease the draught.
• The indoor/outdoor temperature difference. The colder it is outdoors, the better the draught.
• Barometric pressure. On rainy, humid or stormy days, the draught is generally weak.
• Liveliness of the fire. The hotter the fire, the stronger the draught.
• Cracks in the chimney, badly sealed or a dirty appliance door, air inlets through the tube
joints, another appliance connected to the chimney, etc. may produce unsuitable draughts.

1.2.6- SUMMARY OF STANDARDS

Next we indicate a summary of general standards that must be respected when building
a chimney:
e) Use resistant and non-combustible materials. Do not fit in cement fibre tubes.
f) Choose a run as vertical as possible. Do not connect several appliances to the
same chimney.
Excessively
flat deviation
Ash
accumulation
Incorrect
Correct
Fig.-6
Correct
deviation