IBC VFC 15-150 Installation And Operating Instructions Manual page 30

NOTE
This piping drawings in this
manual are simple schematic
guides to a successful
installation. There are many
necessary components not
shown, and details such as
thermal traps are left out so
the drawings have greater
clarity. We require that
our boilers be installed by
licensed and experienced
trades people who are familiar
with the applicable local
and national codes. System
design is to be completed
by an experienced hydronic
designer or Engineer. It is
necessary to carefully read
and follow these installation
instructions along with the
application drawing that fits
your system.
NOTE
VFC boilers are equipped
with a factory installed
pressure sensor-type Low
Water Cut Off system. The
minimum operating system
pressure allowable with this
is 4 psig. Check local codes
if a Low Water Cutoff Device
is required. If so, determine
if this device meets the local
codes.
1-24
VFC 15-150, VFC 45-225 MODULATING GAS BOILERS
1.6.2 Installation Rules
NOTE: The Boiler Trim element – common to each of the following systems
- includes the pressure relief, fill, expansion tank and air bleed elements. The
primary pump can be located on either the Supply or Return piping sections.
Figure 28: Basic Primary/Secondary, 3 load piping concept
Features of the preferred Primary / Secondary piping system:
1. Good circulating water flow through the boiler irrespective of load or radiation
system head
Allows flexible ΔT° control in secondary loops
2.
Adds to the system's thermal buffering, to assist in handling small loads and
3.
temperature transition.
This piping configuration requires an extra pump. The VFC modulating series
boilers' controller hosts wiring terminals and integral relays to simplify installation
and operation of this preferred layout, offsetting such costs.
For optimal performance, place pumps on the supply side of secondary loops
to facilitate air evacuation. Use pumps with internal check valves to avoid ghost
flows and thermal siphoning.
The primary loop temperature may need to transition from a 180°F domestic water
heating load to a 100°F radiant floor requirement. The secondary pumps will swap
off/on simultaneously, provided the pre-set maximum allowable temperature of the
new load is not exceeded. In the case of the typical maximum limit for a radiant
floor (most would enter 140°F); the floor pump would remain off, the boiler shut
down, leaving primary circulation on until the primary loop temperature drops into
the acceptable range for the floor. Temperature sensing is done using thermistors
at the boiler supply and return – no further sensors need to be installed.
INSTALLATION AND OPERATION INSTRUCTIONS