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Index:
Economics of Duct Tightening in Manufactured Housing (see
Appendix C)
Costs for implementing tight duct recommendations were recently
reported by Bert Kessler, VP Engineering, Palm Harbor Homes;
Craig Young, Engineering Manager, Palm Harbor Homes, Florida
Division; and Michael Wade, Director of Quality Assurance
& Code Conformance, Southern Energy Homes.
Correspondence
from Bert Kessler, VP Engineering, Palm Harbor Homes (Kessler,’03.)
(Included in Appendix C.)
Mr. Kessler wrote to BAIHP, “Based on research with
BAIHP, Palm Harbor Homes implemented duct system testing and
increased return air pathways from bedrooms to 50in2 per 100cfm
supply air company-wide. Since this implementation started,
PHH has manufactured 35,000 homes and has had no incidents
of moisture related issues in homes installed in hot-humid
climates. Additionally, air flow issues have been all but
eliminated.”
Kessler
comments that, “The benefits of testing and return air
requirements far exceed the cost, both to the consumer and
the manufacturing facility.” The target leakage level
is Qntotal<=3% and return air requirements adopted by the
manufacturer based on 50in2 for every 100cfm of supply air
delivered to the space. Excluding the 1 time cost for duct
blaster equipment, Kessler estimates average mastic materials
cost at $2.90 and labor cost for the duct sealing and testing
at $12.42, totaling $15.32 for a 28 X 76, 2026 ft2, 3 bedroom,
double wide home. Per floor cost equaling half that or $7.66
Kessler
estimates total cost for materials and labor = $7.66 per
floor
Kessler
notes that all duct systems manufactured by Palm Harbor Homes
are pressure tested and that costs for implementing the tight
duct procedure vary significantly from plant to plant based
on when during the production process the duct testing takes
place. The system layout as well as previous production standards,
impact the incremental implementation cost. This is illustrated
in the following information from Craig Young of Palm Harbor’s
Florida Division who reports lower labor costs but higher
material costs that Mr. Kessler reports for the company at
large.
Correspondence
from Craig Young, Engineering Manager, Palm Harbor Homes,
Florida Division (Young, 03.)
Mr. Young reported production department supervisor estimates
to BAIHP, finding that the labor cost of applying the mastic
to the duct system is $3.47 per floor and the labor cost of
testing the duct system including setting up the equipment
(Minneapolis Duct Blaster) is also $3.47 per floor. The incremental
material cost compared to tape for mastic is estimated at
$1 per floor.
Young
estimates total cost for materials and labor is approximately
$8 per floor.
Correspondence from Michael Wade, Director of Quality
Assurance & Code Conformance, Southern Energy Homes (Wade,
03.) (Included in Appendix C.)
Mr. Wade reported that Southern Energy Homes is projected
to produce 8,000 homes in 2003. They test their duct systems
to evaluate if their goal of Qntotal <= 3% has been achieved.
Mr. Wade says, “The test procedure is so quick that
we don’t take testing labor cost into consideration.”
Mr. Wade is of the opinion that there is no additional installation
cost compared to tape. Material costs were stated to be $6
per floor compared to $2 per floor for tape, an incremental
cost of $4 per floor.
Wade
estimates total cost for materials and labor is $4 per floor.
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