MrCool GeoCool : Install Manual : Page 14

Important Note: If ductwork i s i nstalled i n an attic area, the ductwork needs to be built “low

profile” and l aid directly on the ceiling j oist (code permitting). After being i nstalled and wrapped

in i nsulation, i t i s recommended the ductwork be covered with six to eight i nches of cellulose. If

the attic ductwork i s not covered with cellulose i t can l ose a significant amount of i ts heating and

cooling capacity i nto the attic area!! Ductwork that i s i nadequately insulated will cause poor system

performance and customer dissatisfaction.

In the USA, ductwork sizing methods should follow ACCA “Manual D” recommendations. Install

ductwork within the conditioned space of the building to minimize duct heat l oss or gain,

wherever possible.

To minimize air velocity noise transferring to the air supply grills, a flex duct should be i nstalled

from the supply grill six feet back.

Ductwork should be designed to handle the CFM delivery for the unit while running i n High

Speed. Supply duct should be based on .08 i nches of pressure drop per 100 feet. Return duct

should be based on .05 i nches of pressure drop per 100 feet.

Note: Always check register CFM requirements against register manufacturer’s data for register

performance. It i s extremely i mportant to ensure that duct system for return airflow i s NOT

undersized. Undersized return air ductwork can cause poor system performance and i n some

cases can cause the blower to “pulse”. Furthermore, i t i s also i mportant to provide adequate sized

supply air plenums and ductwork. Make all turns as smooth as possible avoiding any restrictions.

For residential design the target static pressure should not be greater than 0.3 inches.

Caution: Observe the location where your ductwork is being attached to the unit. Ensure

that drilling and screws do not penetrate and damage the air coil.

A quality i nstallation should be one where noise i s not a complaint. A number of i nexpensive

features can be added to reduce noise and also aid i n i nstallation and maintenance. Flexible

hose kits to the hot water l oop will make for an easy connection to the heat pump and the hot

water tank and also reduce any noise being transmitted from the heat pump to the i ndoor

plumbing. Next the heat pump and all associated water pumps should be i nstalled on a shock-

absorbing pad to i solate the heat pump from a hard surface floor. This pad will help stop the

possibility of the cabinet being rusted out by trapped moisture under the unit. Flexible duct

connections help to eliminate noise from the heat pump being transmitted through the metal

ductwork. This collar also makes the connection of the heat pump to the ductwork a much simpler

task.