2.2 I
NSTALLATION TYPES
Always use insulated ducting of a minimum R-4 insulation factor.
2.2.1 S
A
TAND
LONE
The installer shall ensure that, if necessary, an in-line heater sized according to the required airflow and
outside design heating temperature from Manual J or ASHRAE table is installed to avoid condensation on
uninsulated duct distribution systems within the house or surfaces near the distribution register. The in-line
heater shall have an integrated airflow sensor and an over temperature sensor to prevent heating in no-flow
or low-flow conditions.
When deciding if a preheater is required and
whether it should be installed BEFORE or
AFTER the supply fan, consider the following:
•
This supply fan's minimum operating
temperature is 14 °F.
•
The minimum distance between
the preheater and the supply fan is
12 inches.
•
The temperature distributed in the
dwelling should not be below 55 °F.
2.2.2 I
NSTALLATION WITH AN
The installer shall ensure that, if necessary, an in-line heater sized according to the required airflow and
outside design heating temperature from Manual J or ASHRAE table is installed to ensure that the air
delivered to the AHU is never below the minimum temperature allowed by the manufacturer (generally
55 °F). The in-line heater shall have an integrated airflow sensor and an over temperature sensor to prevent
heating in no-flow or low-flow conditions.
When deciding if a preheater is required and whether it should be installed BEFORE or AFTER the supply
fan, consider the following:
•
This supply fan's minimum operating temperature is 14 °F.
•
The minimum distance between the preheater and
the supply fan is 12 inches.
•
The temperature distributed in the ducting
should not be below 55°F, unless the AHU
blower is continuously running.
I
NSTALLATION
AHU
CAUTION
VJ0150
4 4
Follow AHU
manufacturer's
guidelines for
minimum distance.
VJ0149