IBC Technologies Inc.
18
VFC 15-150 and VFC 45-225
edge). Neither pump shall be wired to
the normal Primary pump connection
point on the controller’s upper right-
hand backside. The pump signal leads
are to be wired in series to the variable
speed pump connector, located within
the control wiring box.
Check valves or thermal traps should be
used to isolate both the supply and return
piping for each load - to avoid thermal
siphoning.
To ensure adequate water flow through
the boiler under high-head / single zone
space heating conditions, a pressure
activated bypass may be necessary on
that load.
This approach often suffers from high
and unequal head in the opposing loads.
For a given installation, it normally
requires a higher-head pump, at a higher
cost. An imbalance in the head between
the loads may call for a balancing valve
on the low head side.
Zone valves should be wired to the
Pump/Zone Valve Terminal Block. Run
24 V to this terminal block from an
external transformer. No extra relays are
needed. Use check valves or thermal
traps on return pipes to avoid thermal
siphoning.
For further information, consult our
Application Notes
– which provide detail on a
modularized load by load basis (e.g. DHW, low temp. radiant, air handler), with
comments for each on “
Piping”, “Wiring”
and
“Settings”
. The Notes also deal with
multiple boiler installations, using multiple/networked VFC modulating boilers or mixed
pairings of either VFC boilers leading one to four units in IBC’s Fixed-Fire boiler series
or other 3
rd
party condensing units. 3-way motorized mixing valves control options are
similarly covered.
Figure 9 – Single Pump Parallel Zones ( OK in places)