Common Causes

Common Causes of Unsatisfactory Operation of Heat
Pumps on the Heating Cycle
A. Dirty Filters or inadequate air volume through indoor coil.
When the heat pump is on the heating cycle, the indoor
coil is functioning as a condenser; therefore, the filters
must always be clean, and sufficient air volume must
pass through the indoor coil to prevent excessive
discharge pressure and high-pressure cutout.
B. Outside Air into Return Duct: Cold outside air should not
be introduced in the return duct of a heat pump installation
on the heating cycle close enough to the indoor coil to
reduce temperature of the air entering the coil below 65°F.
Air below this temperature will cause low discharge
pressure, thus low suction pressure and excessive defrost
cycling with resultant low heating output. It may also cause
false defrosting.
C. Undercharge: Undercharge on the heating cycle will
cause low discharge pressure resulting in low suction
pressure and frost accumulation on the lower part of the
outdoor coil.
D. Poor "Terminating" Defrost Thermostat contact. Defrost
thermostat must make good thermal contact on return bend,
otherwise it may not terminate the defrost cycle quickly
enough to prevent unit from cutting out on high discharge
pressure during the defrost cycle.

Funneling

Funneling AND DUCTWORK ACOUSTICAL LAGGING

Clamor transmitting from funneling and ventilation work can be a genuine issue in current

building development. Turbulent stream funneling commotion can be created by water or other

fluids passing through elbows, valves or other move pieces. Channel commotion is

brought about via air streaming past hindrances or limbs which brings about the vibration of

the metal ventilation work. This vibration then transmits commotion into the building

Kinetics Noise Control

Kinetics Noise Control has developed a unique and specific combination
absorber/barrier material which is well suited for pipe and duct wrapping applications.
KNM-100ALQ combines a 1.0 lb./sq. ft. barrier material with an aluminum foil facing
on one surface and a 1” or 2” (25 or 50 mm) thick quilted fiber glass decoupler layer
on the opposite surface. This product thus combines the decoupler and the barrier
into a single product which significantly minimizes the cost, time and labor required to
use both a separate barrier and a separate decoupler layer. The reinforced barrier
aluminum outer layer provides a clean surface that is easily adhered with tape. This
aluminum covering also increases the mechanical strength, wearability and fire
retardancy of the barrier. The barrier used in this product features an STC of 28,
which is more than sufficient for most normal HVAC plumbing and duct applications.
In the event that higher acoustical performance should be required to suite an
unusual application, a second layer of KNM-100ALQ can be overlaid on top of the
first layer, with care taken to stagger and overlap the joints.

The easiest

The easiest and best treatment technique for the control of funnel and conduit

breakout clamor is to wrap the channeling and ventilation work with acoustical cladding. This

acoustical material comprises of three (3) segments:

1. Vibration damping material (for sheet metal)

2. Light thickness decoupling material

3. Acoustical boundary overwrap

Relevant local building

Relevant local building and fire codes should always be referenced for the suitability
of all materials used within an occupied space within a building.
All piping and ductwork should be supported from the deck above via vibration
isolation hangers in lieu of rigid rods. Vibration isolation hangers suppress any
vibration which might be present within the piping from traveling up the rod into the
building structure. Further, at through-wall passage points the piping or ductwork
must be prevented from making any rigid connection with the building via the use of
conventional insulation sleeves between the piping and the wall.

Acoustical barrier

Acoustical barrier wrap improves the transmission loss of the pipe or duct and
therefore minimizes breakout noise. This barrier needs to be a heavy material
which is sufficiently flexible so as to permit wrapping around small diameter
piping. In the past lead sheeting was utilized for this purpose but recent concerns
over lead exposure and legal restrictions concerning its use have rendered this
material obsolete. Current barrium sulfate loaded vinyls are best suited for this
application as this material presents no known health hazards. It is important that
there be no barrier gaps or open areas over the region of the installation as these
represent significant acoustical “leaks” that greatly reduce effectiveness. Barrier
weights of 0.5 lb./sq. ft. to 1.0 lb./sq. ft. (2.5 to 5.0 kg/sq. meter) are commonly
specified as these materials are thin enough to permit good workmanship by the
installing contractor. Should additional acoustical performance beyond the
capabilities of a single barrier layer be required for a particularly sensitive project,
it is recommended that a second layer be applied over the first. For optimum
results, this second layer should be separated from the first barrier layer with a
decoupler as discussed in paragraph 2 above. This “double layer” of acoustical
cladding provides superior acoustical performance compared to the use of a
single, heavier layer.

Acoustical cladding

Acoustical cladding material should be used around all piping and ductwork which
passes through noise-sensitive areas within buildings. While it is recommended
that, for most applications, the wrapping should be continuous over the length of
the pipe or duct, it is appreciated that there are some instances where this
represents a large amount of material. Partial wrapping may be acceptable for
some non-critical applications. It is recommended that cladding be used a
minimum of 10 pipe diameters upstream and 20 diameters downstream of all
transitions, tees, valves, branch takeoffs or similar to ensure laminar flow beyond
the cladding.