Installation & Operation Manual
18
2 General venting
Common venting
Crest boilers may be common vented; however, the following
criteria MUST BE followed:
1. Only Crest boilers may be connected to the common
vent. DO NOT mix other manufacturer’s appliances or
other Lochinvar models.
2. Crest boilers connected to the common vent must all be
of the same size.
3. Each Crest boiler must have a Lochinvar supplied flue
damper installed (see Table 2D).
4. Only vertical direct vent, positive pressure, Category
IV or vertical/chimney vent, negative pressure, Category
II may be used when common venting Crest boilers.
Sidewall venting is not allowed.
5. Crest boilers in a common vent must be connected and
controlled with the integral Crest SMART TOUCH
Cascade.
a. The Leader may be controlled through the Crest
SMART TOUCH control through BMS (external
0 - 10V signal), ModBus or its own internally
calculated set point.
b. The Cascade (Members) must be controlled by the
Crest Leader boiler using the Lead/Lag Cascade
option.
For approved common vent sizing, contact the factory.
WARNING
When Crest boilers are common vented,
the criteria above MUST BE followed.
Failure to follow all these requirements
will result in severe personal injury, death,
or substantial property damage.
Table 2D Flue Damper Kits
Flue Damper Kits
Model Damper Size Kit Number
FB0751 6" DRH30007
FB1001 6" DRH30007
FB1251 8" DRH30001
NOTICE
When Crest boilers are common vented,
hot water generators must be piped to the
primary heating loop and tank thermostats
must not be connected to the Crest.
Installing vent and air piping
Use only cleaners, primers, and solvents
that are approved for the materials which
are joined together.
NOTICE
PVC/CPVC
All PVC vent pipes must be glued, properly
supported, and the exhaust must be
pitched a minimum of a 1/4 inch per foot
back to the boiler (to allow drainage of
condensate).
NOTICE
WARNING
The vent connection to the appliance must
be made with the starter CPVC pipe section
provided with the appliance if PVC/CPVC
vent is to be used. The field provided
vent fittings must be cemented to the
CPVC pipe section using an “All Purpose
Cement” suitable for PVC and CPVC pipe.
Use only the vent materials, primer, and
cement specified in Table 2E to make
the vent connections. Failure to follow
this warning could result in fire, personal
injury, or death.
WARNING
Insulation should not be used on PVC
or CPVC venting materials. The use of
insulation will cause increased vent wall
temperatures, which could result in vent
pipe failure.
This product has been approved for use with the PVC/CPVC
vent materials listed in Table 2E on page 19.
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