AERCO KC1000 Boiler July 2011 - Manual (Page 20)

INSTALLATION
2-10
2.7.9.2 DELAYED INTERLOCK IN
The delayed interlock circuit (DELAYED INTL’K
IN) is typically used in conjunction with the
auxiliary relay described in paragraph 2.8. This
interlock circuit is located in the purge section of
the start string. It can be connected to the
proving device (end switch, flow switch etc.) of
an auxiliary piece of equipment started by the
boiler’s auxiliary relay. The delayed interlock
must be closed for the boiler to fire. If the
delayed interlock is connected to a proving
device that requires time to close (make), a time
delay (Aux Start On Dly) that holds the start
sequence of the boiler long enough for for a
proving switch to make can be programmed.
Should the proving switch not prove within the
programmed time frame, the boiler will shut
down. The Aux Start On Dly can be
programmed from 0 to 120 seconds. This option
is locate in the Configuration Menu (Section 3).
2.7.10 FAULT RELAY
The fault relay is a single pole double throw
(SPDT) relay having a normally open and
normally close set of relay contacts that are
rated for 5 amps at 120 VAC and 5 amps at 30
VDC. The relay energizes when any fault
condition occurs and remains energized until the
fault is cleared and the CLEAR button is
depressed. The fault relay connections are
shown in Figure 2.11.
2.8 AUXILIARY RELAY CONTACTS
Each Boiler is equipped with a single pole
double throw (SPDT) relay that is energized
when there is a demand for heat and de-
energized after the demand for heat is satisfied.
The relay is provided for the control of auxiliary
equipment, such as pumps and louvers, or can
be used as a Boiler status indictor (firing or not
firing). Its contacts are rated for 120 VAC @ 5
amps. Refer to Figure 2.11 to locate the AUX
RELAY terminals for wiring connections.
2.9 FLUE GAS VENT INSTALLATION
The AERCO Venting and Combustion Air Guide,
GF-1050, must be consulted before any flue or
inlet air venting is designed or installed.
Suitable, U/L approved, positive pressure,
water-tight vent materials as specified in
AERCO’s GF-1050, must be used for safety and
UL certification. Because the unit is capable of
discharging low temperature exhaust gases, the
flue must be pitched back to the unit a minimum
of 1/4" per foot to avoid any condensate pooling
and to allow for proper drainage.
While there is a positive flue pressure during
operation, the combined pressure drop of vent
and combustion air systems must not exceed
140 equivalent feet of 0.81” W.C.. Fittings as
well as pipe lengths must be calculated as part
of the equivalent length. For a natural draft
installation the draft must not exceed - 0.25”
W.C..These factors must be planned into the
vent installation. If the maximum allowable
equivalent lengths of piping are exceeded, the
unit will not operate properly or reliably.
2.10 COMBUSTION AIR
The AERCO Venting and Combustion Air Guide,
GF-1050, MUST be consulted before any flue or
combustion supply air venting is designed or
started. Combustion air supply is a direct
requirement of ANSI 223.1, NFPA-54, CSA
B149.1 and local codes. These codes should be
consulted before a permanent design is
determined.
The combustion air must be free of chlorine,
halogenated hydrocarbons, or other chemicals
that can become hazardous when used in gas-
fired equipment. Common sources of these
compounds are swimming pools, degreasing
compounds, plastic processing and refrigerants.
Whenever the environment contains these types
of chemicals, combustion air must be supplied
from a clean area outdoors for the protection
and longevity of the equipment.
The more common methods of combustion air
supply venting are outlined below. For
combustion air supply from ducting, consult the
AERCO GF-1050, Venting and Combustion Air
Guide.
2.10.1 COMBUSTION AIR FROM
OUTSIDE THE BUILDING
Air supplied from outside the building must be
provided through two permanent openings. For
each unit these two openings must have a free
area of not less than one square inch for each
4000 BTUs input of the equipment or 250
square inches of free area. The free area must
take into account restrictions such as louvers
and bird screens. For Canada installations, refer
to the requirements specified in CSA B149.1.10,
8.4.1 and 8.4.3.
2.10.2 COMBUSTION AIR FROM INSIDE
THE BUILDING
When combustion air is provided from within the
building, it must be supplied through two
permanent openings in an interior wall. Each
opening must have a free area of not less than
one square inch per 1000 BTUH of total input or