George R. Carey, Jr.
Vice President,
Fluid Industrial Associates
gcarey@fiainc.com
twitter: @Ask_GCarey
Boiler Facts
Venting Condensing Appliances
with Polypropylene Pipe: Part 2
Why Polypropylene?
Polypropylene is environmentally
friendly, designed
for sustained flue gases up to 230°F
(110°C) and provides performance
properties better suited to handle flue
gases than polyvinyl chloride (PVC) or
chlorinated PVC (CPVC) technology.
The polypropylene flue gas vent system
is specifically engineered for the
intended application.
Polypropylene has a
vicat softening temperature
that exceeds
300°F (meaning the
temperature at which
the thermal plastic
deforms under the
load). The polypropylene
vent pipe has
higher temperature
ratings and enhanced
corrosion resistance
to the acidic properties
of the condensate
associated with highefficiency
appliances.
Unlike other polymeric
or metal systems,
polypropylene is
resistant to aromatic
hydrocarbons, sulfuric
acid and hydrochloric
acid, which allows it to be used with
oil-, propane- and natural gas-fired
high-efficiency appliances. It is only
limited by the flue gas temperature,
making it an ideal choice for condensing
Photo: Energy Kinetics. Venting shown also applies to Energy Kinetics Resolute™ & Ascent™
Plus Combi non-condensing oilheat/B20 boilers with stack temperatures below 230°F.
heating appliances.
Editors note: Polypropylene venting
is also an ideal choice for oilheat
non-condensing dilution air boilers,
which run with appropriately low
vent temperatures and are approved
for use with polypropylene venting.
Several systems have gained market
acceptance in the United States for
over a decade, and are also now rated
for use with B20 fuel blends.
Polypropylene vent systems are
manufactured specifically to perform
as a vent system. All the various and
necessary components, such as test
ports, siphons and condensate drains,
are available to install the proper vent
system. There is no need to modify the
vent system to analyze the combustion
numbers or drain excessive condensate
from the vent system. The manufacturers
offer single-wall pipe, flexible
pipe, as well as concentric pipe, so
regardless of the structure type, the
flue gases from the condensing appliances
can be safely vented out of the
building to the atmosphere.
The polypropylene venting systems
do not use glues and primers to join
the lengths of pipes and fittings together.
Instead they use a gasketed
system to seal each connection point.
The gasket technology allows the vent
system to be installed rapidly; there
is no need to rough-in the fittings
as the components can be rotated in
place, as well as disassembled. Once
the venting system is completed, the
high-efficiency appliance can be fired
off immediately because, unlike glued
systems, there is no 24-hour
curing period required.
These polypropylene gas
vent systems are designed to
be used on condensing heating
appliances that can produce
one gallon of condensate per
hour per hundred thousand
British thermal units (BTUs).
It is important that the vent
system has proper pitch back
towards the appliance, while
the flue gases flow in the opposite
direction towards the
vent termination.
The pitch ensures that
condensate is not allowed to
build up in the vent system,
which can cause back pressure
leading to a forced shut
down of the furnace or boiler.
Also, build up of condensate
gathering around a gasket
can become a leak path, so good pitch
allows the condensate to slide past
each connection joint all the way back
to the condensate trap.
A little history
Polypropylene gas vent systems have
been around since 1994 for the European
high-efficiency boiler market. The
system is listed to the CE EN 14471
Safety Standard; the technology has
proven to be safe and reliable. It is
the dominating technology in Europe
26 ICM/November/December 2022