Other Operating Features - IBC VFC 15-150 Manual

WARNING
This boiler is equipped with
an automatic blocked vent
shutoff system. In the case
of an "Insufficient Airflow
Error" event, a licensed and
qualified service technician
shall follow the steps set out
at Section 5.3.1 Airflow.
2-6
VFC 15-150 - VFC 45-225 MODULATING GAS BOILERS
temperature load (e.g. DHW at 180°F) to a cool target (e.g. radiant floor on
outdoor reset, at perhaps 90°F). in the case in which the temperature is outside
the applicable differentials, the burner will shut off while the pump remains
on until water temperature is 11°F below the new load (radiant floor) target
temperature. thermal shock avoidance routine is employed to avoid undesirable
effects of large temperature swings: the hot load pump remains on until the
boiler's return water sensor detects temperature stability - to sink excess heat.
For example, upon satisfaction of a dHW call the dHW zone pump will remain
running until the boiler return water temperature falls to the dHW tank target
temperature. this deposits legacy heat from the primary loop into the water tank
before activation of a radiant floor load pump.
always ensure that loads sensitive to high temperatures are protected using
appropriate means - e.g. a three way mixing valve set to restrict entering water
temperature to 130°F, or at minimum, an aquastat (set to130°F, for example) to
be wired to the boiler's auxiliary interlocks to protect a radiant floor.
2.5.6 - Error Mode
the controller continually checks sensors to see that they are operating within
normal parameters. if sensors indicate the boiler is operating outside it limits, it
will declare an error condition.
two types of error conditions can occur:
•
Soft Errors: result when an abnormal condition exists which does not present
an immediate safety hazard. the boiler enters an extended purge, followed
by the error cycle of 5 minutes for all conditions other than Maximum ignition
Trials (a modified Hard Error which locks out for 1 hour after 3 unsuccessful
ignition attempts). Following the purge, the fan and pump are stopped until
the end of the error cycle. normal operation then resumes.
•
Hard Errors: result when a condition exists that may be a safety hazard.
the boiler enters an extended purge then the fan and pump are stopped.
the boiler is in a lockout, and must be checked and restarted by a service
technician.
With software versions 3.10.0 and higher, the boiler offers an error status signal
feature. Please see IBC Technical Note: Boiler Status – Analog Output.
see Section 5.3.1 Control Panel for a list of hard and soft errors and their
likely causes. note that other problems such as disconnected wires or defective
sensors may be the cause of the error. Always check connections and wiring first.
2.6

otHer oPerating Features

2.6.1 Prioritization
the control module hosts a scheduling routine to manage the boiler's operation
when more than one load has been defined. Typically, loads declared as DHW
receive significant - but not absolute - priority. A time vs. differential system will
allocate heat amongst each of up to 3 loads over time.
Multiple heating loads - with varying temperature targets - are run sequentially
as opposed to simultaneously (with a mixing valve). the objective is to serve
each load at the minimum possible temperature, as opposed to running hot
then mixing down – with hardware, saving the related hardware and fuel cost.
INSTALLATION AND OPERATION INSTRUCTIONS