Model VIP+
14
Owner's Manual
Rigid Structural Brace Specifications
When necessary a Support Assembly must be secured to the building with a rigid structural framework. Satisfactory performance and service life of
VIP+ Chimney Systems requires the product be rigidly braced and supported. Every installation presents unique support and bracing requirements
and the following guidelines will provide minimum acceptable sizes for the mechanical hardware supplied by others.
Figure 17
Figure 18
Elbows and Offsets
•
Elbows are used for changes in direction in horizontal or vertical portions of a chimney system.
•
Elbows are used in combination to make up different angles in horizontal and vertical breechings of the chimney.
•
Special care should be exercised in designing the bracing for elbows because elbows can only take limited forces due to any bending
moments
•
Except where absolutely necessary, sloped or horizontal offsets in the vertical portion of a chimney above the breeching should be
avoided.
•
Sloped offsets require more expansion joints and secure bracing above and below elbows.
•
Structural parts such as posts or beams may also be needed to hold chimney supports in position.
•
There is no limit on the angle or slope of an offset for gas or liquid fuel burning appliances
•
Chimneys for combination fuel heating appliances that are capable of burning solid fuel or are convertible to solid fuel are limited to 30º
slope even if the current choice of fuel is gas or oil.
•
The maximum length of offset, if one is necessary, is determined by strength considerations. The maximum dimension between supports
(Base Supports or Wall Supports), given as the “
MHS
” dimension in the
Support Methods and System Design Limits (Table 7)
section
of these instructions, is applicable to all horizontal and sloped orientations. (See
Figure 20
)
•
To assure proper guidance of expansion joints and to prevent unnecessary joint bending, use an adequate number of supports at closer
intervals.
•
With generator set or turbine exhaust use Bellows Expansion Joint below each support in offset runs. For boiler exhaust use an Expansion
Length.
•
The ends of any sloped or horizontal offset must be anchored to prevent overstressing elbows and to assure proper operation of expansion
joints.
•
With frequent re-support, there is no structural or operational limit to the length of horizontal or sloped portions of a VIP+ Chimney,
providing the system meets the capacity, pressure drop or available draft requirements of the appliance or equipment.
•
The carrying capacity of the VIP+ supports and their structure attachments must consider the weight of the offset plus whatever vertical
pipe is carried by that support. See
Table 6
for height limit of VIP+ supports (
MCH
).
