3.4 Multiple fans on steel chimney
y
If two or more chimney fans are required to create sufficient draft, installation
procedures are the same as for single fan installation on a steel chimney. The
only difference is that the fans are sitting next to each other on the top of the
chimney. A special adapter plate is required.
y
When installing multiple fans, it is extremely important that the fans are of
the same model and size, and they must be controlled in tandem by one (1)
motor speed control.
3.5 Multiple fans on a brick chimney – Oversized flue
y
If two or more fans are required to create sufficient draft, a special adapter
plate is required. The adapter plate should be made of stainless steel (14 GA
or thicker), depending on the size and the fan models used.
y
The two holes in the plate should match the throat diameter of the fan
model used and the distance from center to center should be at least equal
to the fan width (dimension
B
in 2.1. Dimensional Data).
y
The adapter should be sealed with silicone and bolted onto the top. When
installing multiple fans, it is extremely important that the fans are of the
same model and size, and they must be controlled in tandem by one (1)
motor speed control.
y
A similar approach should be taken if the flue size exceeds the fan base
dimensions. The adapter plate should be sized so it covers the flue and
secured. A hole should be cut in the center of the plate and the fan mounted
centered over the hole.
3.6 Installation for high temperatures
y
if the fan is used for applications where the flue gas temperatures exceed
400 °F at the flue exit, and does not exceed 650 °F, dilution bolts must be
used.
y
Dilution bolts will cause cool air to dilute the warm flue gas, by lifting the fan
and leaving space so the cool air can get in under the fan base.
y
The dilution bolts should be installed in the outer holes in the fan base.
y
The dilution bolts are adjustable and should be adjusted so the flue gas
temperature does not exceed 400 °F when discharged through the fan. When
using dilution bolts the fan’s actual capacity is reduced and a stronger model
may be required. The fiber mat is not required when using dilution bolts
.
8
3000270 RS gas and oil 20210818 - international
