Manual D

pressure drop

A ________ is the pressure loss that occurs between any two points in a duct system.

every branch-take off

A reducing trunk system is similar to an extended plenum design EXCEPT the sectional area of the trunk is reduced after _______

Dampers

Air volume is controlled by ________

Dedicated return air duct/transfer duct/opening fitted with two return air grilled

An engineered low resistance path should be provided for every room or space the receives air. This can be established by using ______

OEMs blower table

Available static pressure is the pressure that is available for the straight duct runs and fittings after it is subtracted from the eternal static pressure available value from the ____________ .

0.03

Default pressure drop value for: air supply grilles, registers/diffuses. return air and manual balancing dampers is _______ IWC [hint: it's small]

available

Duct sizing is not based on the amount of pressure the that blower produces. It is based on the net pressure that is ________ to move the air through the circulation path that produces the most resistance to airflow.

insulated

Ducts installed in an open crawl space must be tightly pealed and _______.

larger

Friction rate duct sizing is not the only to design a duct system. Velocity noise should also be considered. In most cases duct sizing that satisfied the friction rate procedure are too small to satisfy the velocity limit. Therefore, two sizes are created. The final design always uses the ______ of these two sizes.

100

Friction rates are measured in inches of water column per _____ ft of duct

4%

Helix duct friction chatrs or duct slide rule equivalents do NOT apply to flexible duct that has more than _____% compression

if the air velocity just up stream from a branch duct slows to about 50% of the initial velocity.

In a reduced plenum system, the size of the air way can be reduced __________________ ?

0.12/0.24

Manual J default for an average sealing effort is _____cfm/sq ft of duct surface on the supply side and _____ cfm/sq ft on the return side.

0.35/0.70

Manual J default for an average unsealed duct is _____cfm/sq ft of duct surface on the supply side and _____ cfm/sq ft on the return side.

Line the first 5ft of supply duct/Line first 10ft of return duct/design the return so it has two 90 degree turns

Noise in a duct system can be reduced by using sound traps. Effective attenuating components used to decouple a system is __________

multiplying/dividing

Once the design value for the blower cfm is know, the air flow required for each room can be estimated by ______the blower cfm by the room load, then ______the result by the Manual J design load

roughly compatible with

One part of Manual D is used to see if blower performance is ___________the airflow and pressure requirement of the proposed air distribution system.

not endorsed

Panned joints and stud spaces are ________ by ACCA

200

Plastic coated steel ducts cannot be used when temps exceed ________ degrees.

pressure drop

Resistance created when air is forced through equipment or a device installed in the air stream translated to a ______across the component

Flexible Duct

The LEAST efficient type of duct material per ACCA Manual D is ___

Extended plenum

The MOST common duct system per ACCA Manual D is ___

adding

The Total Effective Length (TEL) is obtained by ______the straight run length and the fitting equivalent length.

room air

The airflow rate that is required for a conditioned space depends on either the sensible cooling load or heating load AND on the temperature difference between the air supply and the _________

match

The airflow resistance [produced by the duct system in terms of static pressure drop] should ____________ the External Static Pressure produced by the blower package when the blower delivers the desired cfm.

installing and adjusting balancing dampers

The excessive path cfm problems are resolved by ____ in appropriate locations.

blower

The goal of Manual D is to design a duct system that will work with the _____ that is supplied with the HVAC equipment.

largest

The procedure for sizing a duct system with multiple supply and return air outlets creating multiple effective lengths is to size based on the _______________ effective length value

0.09 cfm

The recommended minimum dealing requirement for panned airways is ______ per 100 sq ft at 0.10" w.c.

straight/fitting

The total pressure drop for a duct run equals the pressure loss for all ________ sections PLUS the pressure loss produced by each and every _________ in the duct run

Blower cfm

To achieve the heating cooling factors, the design loads are divided into the ___________

Total Effective Length

When adding a ducted return air to the system, some pressure is used to move air through the return air duct, so less pressure is available for the supply side of the system. The only change in the format to convert the system pressure drop value to a friction rate value will be the _______

900, 700

When considering air velocity for noise control, the maximum velocity for the supply side trunk is ___________ fpm and ___________ fpm for the return air trunk using rigid duct.

exterior walls

When looking at supply duct geometry, a perimeter supply duct system blankets the ________ with supply air.

up and to the right

When speed INCREASES on a blower, what direction does the line move on the duct curve?

friction rate

______________ is the pressure loss that occurs between two points in a duct system that has separated by a specific distance.