IBC Technologies Inc.
14
VFC 15-150 and VFC 45-225
1.5 Water
Piping
1.5.1 General Piping Issues
The VFC modulating series boilers are
designed for use within a closed loop,
forced circulation, low pressure system.
A 30 psi pressure relief valve (¾” NPT)
is supplied for field installation in the
flow supply line – see below. Relief
valve discharge piping must terminate 6”
(15cm) or less above a drain using plain
un-threaded end, or per local Code.
System piping is connected to the boiler
using the 1¼” NPT-M threaded fittings.
Unions and gate or ball valves at the
boilers supply and return water
connections are recommended to simplify
servicing. Any un-insulated hot water
pipes must be installed with a minimum
1” clearance from combustible materials.
Figure 6 – Boiler Trim
Do not place any water connections
overhead the boiler;
leaks can damage
the fan & controls. If needed, create a
shield over the louvered top of the cover,
but allow clearance for airflow and
service access.
For best results, use a
Primary:
Secondary
piping system, with a pumped
boiler loop using 1¼” piping. Heat
exchanger head is approx. 7’ w.c. at 14
gpm, so for the 15-150 model, an
inexpensive Grundfos
15-58
or Taco
008
sized pump is normally adequate. Use a
larger pump (e.g. 26-64) with the 45-225
model.
P:S
piping ensures adequate flow
and de-couples
∆
°T issues (boiler vs.
distribution). Aim for a 20° to 30° F
∆
°T
across the heat exchanger at high fire
(there is a boiler protection throttle fence
limiting the
∆
°T to 35°F).
The VFC modulating series boilers are
designed to supply three different heating
loads with temperatures within the range
60°F to 180°F - to meet three separately
piped loads. Use closely spaced tees to
connect each pumped “load” (e.g. DHW,
baseboards or radiant floor) to the
primary loop
Always ensure that loads sensitive to high
temperatures are protected using means
such as an aquastat (wired to the boiler's
auxiliary interlocks) or mixing valve set
for maximum limit (say 140°F) to protect
radiant floors.
Table 4 – Pressure Vessel Head
Flow rate (gpm)
4 8 12 16 20
Head
@ flow (ft wc)
0.7 2.5 5.0 8.3 12.3
Ensure the pump is rated for the design
circulating water temperatures; some
pumps have a minimum water
temperature rating above the low
temperature potential of the boiler.
Following installation, confirm actual
performance by measuring
∆
°T (under
high and low flow conditions) after
establishing the correct firing rate (see
Section 3.2 – Check Boiler Input
).
We require water flow after burner
shutdown to utilize legacy heat – this is
significant due to the mass of the heat
exchanger (41 Kg) plus its 9L internal
water volume. Default software values
will run the boiler’s primary pump for 5
minutes (300 seconds) after burner
shutdown. This can be adjusted down as