Installation guide

Whetheryouarecombiningtwoappliancesor
more,youwillfollowthesamemethodof
totalingindividualfluesizestodetermineyour
mainflueormanifold.
Common Systems
Figures 35 and 36 show the most common types
of multiple appliance venting systems the
tapered manifold system and the constant sized
manifold system.
When determining the sizing for the tapered
manifold system (Figure 35), size each section
according to the combined input of the appli-
ances that vent through that section. The section
furthest from the chimney vents only one
appliance. The middle section vents two appli-
ances. The section closest to the chimney vents
three appliances.
Damper Locations
Finally, you should also be familiar with proper
barometric damper locations. Figure 37 provides
this information.
ALTERNATIVE VENTING SYSTEMS
In some cases, existing chimneys may be
inadequate----or there may be no chimney at all
(e.g., electric-to-oil conversions). Constructing a
new chimney may be difficult. In these cases,
alternative venting methods may be called for.
Power Chimney Venting
Sometimes an otherwise inadequate chimney can
do the job with the help of a power draft inducer.
(See Figure 38.)
This consists of a vent fan placed in the flue pipe,
or at the top of the chimney, to create an "artifi-
cial" draft. If the fan is located in the flue pipe,
the portion of the pipe between the fan and the
chimney is under a positive pressure--which
requires that portion of the pipe to be tightly
sealed to prevent escape of flue combustion gases
into the home.
A metal chimney liner and condensate drain may
be required to prevent damage to the chimney.
Side-Wall Venting
If no chimney exists--or the existing chimney
cannot be used, even with a liner---_.heonly
solution may be to vent through the wall
(Figure41).
Side-wall venting systems eliminate the need for
a chimney. One way to side-wall vent, power
venting, utilizes an induced draft fan, which
provides the draft required to exhaust the
combustion products through a side wall. This
system normally requires an air-flow proving
switch to confirm that the required draft is
present before combustion begins. Another way
is direct venting, without an induced draft fan.
With both types of systems, discharge fittings are
designed to pass through combustible walls and
minimize the effects of wind on the venting of
the combustion products. Burner, appliance, vent
system and controls must be considered as a
system, not just independent parts pieced together.
Flue Diameter Equiv.Sq.In, Area
3" 7.06
4" 12.56
5" 19.63
6" 28.27
7" 38.48
8" 50.27
9" 63.62
10" 78,54
Flue Diameter Equiv.Sq. In. Area
11" 95.03
12" 113,10
13" 132,73
14" 153.94
15" , 176.71
16" 201.06
17" 226.98
18" 254.471
FIGURE 34 Square inch area of flue collars
J
- " 7" 6"
U.II1 "U.,'_2-- _"tjn_l 3"
....ola j
i i l_ PRE-FAa CHIMNEY
_l _" co...cTio.
ii
Ea,ctt _on sL__:_ to h;/ilcJle It_mt Ot ¢omb_nalJon of
,a_p_l,_',c6'.sattac_e_
FIGURE35 Tapered manifold vent system
:1
1
1
1
i
i
i©
I 7" 7" 6"
i
Unll 1 Unit 2 Unit 3
Mlnlfold
PRE-FAB CHIMNEY
CONNECTION
E_t6re m_tfold suff_tty tal"ga for a_l
a_'_,:Fsan_ _et as _mtr_ vent
FIGURE36Constantsizedmanifoldventsystem
25