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What You Need to Know
About Home Comfort Systems
By
HANK RUTKOWSKI
There
are three major issues when a contractor installs a new HVACR
system in your home. The major issues are design, installation
and commissioning. A failure to do any of these tasks correctly
will have an adverse effect on one or more aspect of the overall
performance of your system.
Design
work consists of:
1)
Selecting the type of system and equipment (plus operating and
safety controls) that are compatible with the architecture of
your home (you may need zoning in your home), fuel availability,
fuel costs, the space available for equipment and duct runs, appearance
issues and project cost. You should also compare the marginal
cost of an increased increment of efficiency with the potential
savings and the return on this investment. At some point, the
payback on more efficiency becomes unattractive.
2)
Having a Manual J load calculation completed for each room and
for the load on each (if more than one) central unit.
3)
Use of Manual S procedures and manufacturer's application data
to select equipment.
4)
Use of Manual T procedures and manufacturer's data to locate,
select and size the supply outlets and the returns.
5)
Use of manufacturer's blower data, Manual J loads and Manual D
procedures to design the duct system.
HVACR
installation work consists of:
1)
Installing the indoor and outdoor equipment, (a split system is
preferred because it offers more installation options and because
small tubes penetrate the building envelope).
2) Installing the refrigerant lines.
3)
Installing supply air outlets and returns.
4)
Installing duct runs (must be sealed and insulated to R-6 or R-8
if in unconditioned space).
5)
Installing control system.
6)
Installing furnace gas piping and vent (if applicable).
7)
Charging the refrigerant system.
The
commissioning work consists of:
1)Checking
all control cycles.
2)
Checking refrigerant charge.
3)
Checking all power supplies, connections, fuel trains and vents.
4)
Measuring and adjusting air flow at the unit and at the rooms
(balancing work).
5)
Educating the homeowner about the system and equipment (provide
all instructions and manufacturer's documents).
Make
certain contractors you hire have all of the appropriate licenses
for installing HVACR equipment in your state and local area, are
members of ACCA. Ask if the contractor employs NATE-certified
technicians.
Be
aware that some contractors, as a matter of policy, do the things
listed above and some do not do these things. It takes more time
and effort to do the job correctly. Ask them if they do these
things. Expect to pay more for comprehensive service.
With
regard to placement of the unit, one must consider operating cost
as well as installation cost. The hot environment near the roof
makes the cooling unit less efficient. However, if the ducts are
in the attic, it may be less expensive to install the system with
a roof location. The bottom line is that you need to find a contractor
who follows the procedures that are recommended by the ACCA manuals,
the manufacturer's installation instructions, the local and state
codes and the local utility regulations. (ACCA procedures are
required by code or regulation in many locations. Many utilities
endorse ACCA procedures.)
Choosing a Quality HVACR
Contractor
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