17
111079-01 - 12/20
FR
Installation & Service Manual
Figure 5-1: Recommended Smoke Pipe Arrangement and Chimney Requirements
A. GENERAL GUIDELINES
1. Vent system installation must be in accordance
with these instructions and applicable
provisions of local building codes. Contact
local building or fire officials about restrictions
and installation inspection in your area.
2. The FR™ Series is designed to be vented
into a fireclay tile-lined masonry chimney or
chimney constructed from type-L vent or a
factory built chimney that complies with the
type HT requirements of UL103. The chimney
or vent pipe shall have a sufficient draft at
all times, to assure safe proper operation of
the boiler. See Figure 5-1 for recommended
installation.
a. Install a draft regulator (supplied by
installer) following the instructions furnished
with the regulator. See Figure 5-2 for
alternate regulator locations.
b. With any new or replacement installation the
chimney has to be considered. Chimneys
that have a high heat loss become less
suitable as the heat loss of the home
goes down and the efficiency of the boiler
goes up. Most homes have a chimney
appropriate for the fuel and the era in which
the home was built. That may have been
a coal fired or an inefficient oil fired boiler
built into a home without insulation or storm
windows. With increasing fuel prices that
home probably has been insulated and
fitted with storm windows so that the heat
loss of the home has been reduced. This
requires less fuel to be burned and sends
5
Venting
less heat up the chimney.
A new boiler probably has a higher
efficiency than the boiler being replaced.
That probably means that the stack
temperature from the new boiler will be
lower than that from the old boiler and with
less room air being drawn up the chimney
to dilute the stack gases. The combination
of a large uninsulated chimney, reduced
firing rate, reduced firing time, lower stack
temperature and less dilution air can, in
some cases, contribute to the condensing
of small amounts of water vapor in the
chimney. Such condensation, when it
occurs, can cause chimney deterioration.
In extreme cases, the chimney may have to
be lined to insulate the chimney and thus
prevent the condensation. The addition of
dilution air into the chimney may assist in
drying the chimney interior surfaces.
A massive chimney on a cold, or exposed
outside wall may have produced adequate
draft when it was fired with a higher input
and greater volumes of heated gases.
With reduced input and volume, the draft
may be severely affected. In one instance
our research showed a new chimney of
adequate sizing produced only -.035” W.C.
after 30 minutes of continuous firing at
13.0% CO
2
. Outside wall chimneys take
longer to heat up and can have .00” W.C.
draft at burner start-up. You may have to
consider a special alloy chimney flue liner
with insulation around it and stabilizing draft
cap or even a draft inducing fan in severe
cases.