Meet Fred

Fred Weldin, P.E. (DE #5431, MD #25003) is President of Weldin Engineering
Co. His experience includes:
• “Working with the Tools” as a Plumber-Pipefitter with the family business,
beginning by digging a ditch (and it was one of the crookedest known to man)
more than 5
3 years ago.
• Operating a Mechanical Contracting business doing “Plan and Spec”,
“Design-Build”, HVAC Troubleshooting and HVAC Service and Repair from
1973 to 1996 (finally realizing he'd live longer focusing on engineering).   
• Troubleshooting mechanical systems to reduce energy consumption,
improve comfort levels, remedy maintenance and repair problems and/or
improve personnel safety.
• Balancing air and water flows.
• Designing and commissioning mechanical systems for buildings, including
construction oversight.
• Certification as a Mechanical Code Construction Inspector (ICC #5143701-
M2); he's the only one
living in Sussex County, DE.

Fred graduated from the University of Delaware with a Bachelor of Mechanical
Engineering degree in 1965. He passed the Delaware Engineer in Training
exam in 1964 and the Delaware Principles and Practice of Engineering exam
in 1978. He was registered in Delaware on July 11, 1978; in Maryland on April
19, 2000.

Much of his knowledge and experience was gained in the early 90's
troubleshooting problems in a development in the Wilmington, DE suburbs;
Fred personally inspected more than 110 duct systems, developed scopes of
work to correct them, and then balanced them once the corrections were

Fred has lived in three homes in the last 4
3 years, and each has presented a
learning experience gained by "tinkering" with the
HVAC systems:
1. Hot Water Heating is as good as it gets, and it can be inexpensive to
2. You don't need a return in every room; central returns are a valid way to
reduce installed cost.
3. You don't need high returns if you have low supplies.
4. While Heat Pumps are the cheapest form of heating-cooling (to buy) known
to man, they won't provide good heating comfort in heating climates
very cold weather
; you do get what you pay for.
5. Fixing a deficient duct system can be DIY, even for an old guy who rarely
works with tools these days.

Fred’s professional memberships include ASHRAE (
Life Member and past
President, Delaware Chapter), NSPE (past President, New Castle County
Chapter) and ICC (formerly SBCCI). Fred is past Chairman of the Wilmington
Mechanical Trades Examining Board, and past President of PHCC of
Delaware. Fred spent some time on an NFPA Code committee, gaining
valuable insight into the Code development process.

The Wilmington Development

The problems we saw during the three years it took to straighten out the 60-
odd homes illustrate just about everything that can go wrong in homes:

Main Ducts
· Holes in tops (apparently the installers intended to connect branch ducts at
those locations, changed their minds, and forgot to patch the holes).
· Gaps at “panning” (that’s sheet metal that closes a joist space used as an
air return).
· “Slip(s)” or “Drive(s)” omitted (they join sections of rectangular metal ducts –
“slips” go on the tops and bottoms, “drives” go on the sides, are “hammered
over” ends of “slips” to secure the joint and align the sections).
· Joints not sealed.
· One missing “end cap” (that’s what’s used to close the end of a main duct).

Branch Ducts
· Undersized branch ducts.
· One missing branch duct: A “collar” (that’s the connection at the main duct), a
“boot” (that’s the duct fitting below a floor outlet), a floor outlet, but no airflow at
the outlet because there was no branch duct; all this above a drywall ceiling
with no access.
· Branch ducts separated from “boots”.
· Metal branch ducts assembled without required screws
· Metal branch ducts that’d been “smooshed” by plumbers, to make room for
· Metal branch ducts with broken elbows.
· Excess lengths of flex ducts (using more flex than necessary to get from
“collar” to “boot”), and in one home, runs that were 20+ feet longer than
· Flex duct installed in inaccessible locations (this is a “Common Sense” item
– the things come apart, so you need to be able to reinspect when problems
· Crimped flex duct - bends made with too short an inside radius, ducts run
through spaces narrower than the ducts themselves (through trusses,
between structural members, between pipes, between pipes and structural
members, etc.), ducts that’d been walked on, etc. ad nauseam (some of it
really was disgusting!).

· Dampers at least one size smaller than the ducts in which they’d been
installed, and dampers that’d been bent in half before installation (hard to
balance with these!).
· Dampers installed above basement ceilings in many homes, with no way to
access them
· Dampers omitted at inaccessible AND ACCESSIBLE locations in other
· Damper handles covered by duct insulation, or “banding material” (straps
used to secure flex ducts to “collars”), or secured with screws.
· Larger than necessary holes (in ducts) for damper shafts (nothing for
damper locknuts to seat against).

· Under- and over- sized outlets.
· Floor outlets roughed in by duct installers, but covered over by flooring
installers (one home had FOUR outlets covered over!).
· Wall outlets roughed in by duct installers, but - you guessed it – covered over
by drywall installers.
· Large master bathrooms with ceiling outlets near inside walls.

Indoor Air Quality (“IAQ” – a hot topic in today’s environmentally-conscious
· Undersized air filters.
· Construction debris in the “boots” at floor outlets, and in concealed spaces
used for air returns.
· Failure to keep the filters clean when systems were used for temporary
heating/cooling during construction.

· A “two zone” home (that’s one with two HVAC systems, typically one for each
floor of a two story home) with the smaller furnace connected to the zone with
the larger heat loss, and vice versa.
· A 2½ ton “condensing unit” (that’s the outdoor component of an air
conditioning system) connected to a 2 ton cooling coil.
· Homes in which the homeowners had requested larger cooling systems,
and the installers had installed larger units, WITHOUT ENLARGING THE
DUCT SYSTEMS (young readers say “DUH”).
· Failure to check/adjust furnace gas pressures.

Think about
Weldin Engineering Co. if your heating and air conditioning’s not
up to par
, and you're not happy with what the contractors are telling you.
About Us
Fred doing one of
the toughest jobs
known to man (you
gotta respect
people who can do
this day in and day
out): Applying
fiberglass duct
wrap; and he's
doing it the

Note the use of
staples to
secure the seams
before sealing with
tape. AND note how
"baggy" the wrap is:
Yes, it's an
Fred taking some
time off.
Fred plays a little

He's just gotten the
break of a lifetime:
A carom off the red
car back onto the
course; he then
gets up and down
to make par at the
18th of The Old
Course at
St. Andrews.

Fred doing what he
loves best:

Above Fred's hand
is a joist bay used
to convey return
air. Beyond Fred's
hand is the return
main. The
connection between
the two was not
sealed as required
by Code, meaning
the system was
drawing air from the
crawl space, an
proposition in the
winter, and certainly
an air quality issue
anytime the system