P-K MACH
®
Gas Fired Boiler
Technical Service 1.877.728.5351
Revised: January 3, 2020
Released: January 3, 2020
Patterson-Kelley 2020
All Rights Reserved.
1004905981 P-K MACH C1500H-C4000 Installation and
Owners Manual (Rev F Jan-2020).docx
Page 33
The image to the left represents a simplified vent
installation. A condensate trap loop (minimum 4” height)
must
be installed in the flue vent system prior to the
boiler’s
flue connection.
3.5.3 Venting for Multiple Boilers
While the vent design parameters outlined in
still apply, achieving those same parameters
in a combined vent system adds a significant degree of complexity. Therefore, venting systems for
multiple appliances shall be designed by experienced and knowledgeable venting professionals. The
venting system shall be designed to prevent backflow of exhaust gas through idle appliances. For
combined breeching installations, please follow recommendations of a qualified venting
engineer/manufacturer.
Patterson-Kelley recommends that common venting systems be designed for a maximum continuous
exhaust pressure of
-
0.04” W.C.
when measured in the common vent. Locking inline dampers are
recommended on the exhaust connection of each individual appliance in order to control the exhaust
back pressure within the appliance and upstream of this damper. The -0.04
” W.C. in the common flue
will also help make sure the exhaust gases from an online appliance does not backflow through offline
appliance(s). In addition, Patterson-Kelley also recommends the use of motorized combustion air
dampers in the combustion air intake ductwork of each individual appliance. When an appliance is
offline, its combustion air damper will remain closed which will also help prevent the backflow of flue
gases from online appliances. Please refer to Section
for more information.
If the common venting system uses a draft inducer fan or damper
device, this
MUST
be interlocked with the appliances. In the event this
draft inducer device fails, the interlock circuits to the appliances must be
opened in order to prevent operation. Failure to do so could result in
appliance operation under excessive back pressure conditions which
could result in damage to the appliance and lead to serious injury or
death.
The design of any common venting system
MUST
prevent backflow of
combustion gases through offline boilers or water heaters. Failure to do
so could result in damage to the appliance and lead to serious injury or
death
.
4” Tall Condensate Trap
