IBC Technologies VFC 160 Installation And Operating Instructions Manual - page 12
IBC Technologies Inc.
- 12 -
VFC 160
The VFC boiler is designed for supply
water temperatures within the range
80°F to 180°F, with a 20°F rise. Water
flow rates and pressure drop (head in ft.
w.c.) associated with a 20°F maximum
rise (
∆°T) for the respective VFC
models are as follows:
Table 4 - Flow Rate
Model
Flow
(Usgpm)
Approx.
Head (ft. wc)
VFC 160
16.0
12
Water flow rates must not be allowed to
fall below 8 gpm in any possible
operating condition (eg. Single zone in
use).
To achieve system flow rates and
temperatures within such limits, care
must be taken to select the appropriate
pump. Evaluate pressure drop across the
system, including the above head values
for the boiler itself. Ensure 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 2.2 – Check
Boiler Input).
VFC-series boilers are supplied with a
integral low-water flow switch, which
allows installation of the boiler above
radiation level. The flow switch is
calibrated to close with at 4.5 US gpm
and open at 4.0 US gpm.
When installed in a low mass heating
system such as an in-floor radiant
application, the VFC-series boilers may
benefit through use of a buffer tank to
ensure a controlled supply temperature,
and to prevent short cycling. It is highly
recommended that a buffer tank be
included in any heating system in which
any single zone has radiative loading
lower than 1/3
rd
of the minimum input of
the boiler (i.e. at 160 000 BTU/hr, the
boiler should be buffered if any single
zone attached is below 55 000 Btu/hr).
Propylene glycol solution is commonly
used in a water heating loop where
freeze protection is required. Its density
is lower than that of water, resulting in
lower thermal performance at a given
flow and pressure. As a rule of thumb, a
50%:50% solution of propylene glycol
and water will require an increased
system circulation rate (gpm up 10%),
and system head (up 20%) to provide
performance equivalent to straight water.
Whether required by local Codes or
otherwise, it is recommended that piping
systems include a suitable check valve,
gate valve and feedwater regulator set at
12 psig. In the make-up water link with
the city main. Use of unions and gate or
ball valves at the boilers supply and
return water connections is
recommended to simplify servicing.
1.6 Gas Piping
The boiler requires an inlet gas pressure
of at least 3.5” w.c. and no greater than
14.0” w.c. Confirm this pressure range
is available with your local gas utility.
The inlet gas connection of the boiler’s
gas valve is 1/2” NPT (female).
Adequate gas supply piping shall be
provided with no smaller than 1/2” Iron
Pipe Size (IPS), in accordance with the
following chart: