Carrier ZONE-MIZER 50ME - Manual (Page 34)

Application data
(cont)
heating coil. One connection is required for supply and
return hot water/glycol. Connect external piping to the unit
in accordance with existing codes. Include proper relief
for water flow (the maximum allowable hot water/glycol
system working pressure is 30 psi) or a modulating control
to compensate for decrease in water flow rate to zone coils
under partial load conditions when some coils are cycled
closed. System heater coils operate with a water/glycol
solution of 20% minimum glycol for proper freeze-up
protection. Select and rate hot water/glycol using Hot
Water/Glycol Heating Capacities graphs.
Do not install hot water/glycol on a steam system. Where
steam is the only heating medium available, use a steam-to-
water converter or a steam-to-water interchanger.
Field-fabricated ductwork
To simplify supply air connection, field fabricate and install
a zone duct plenum. Duct plenum may be installed prior
to unit positioning if desired. Zone supply air duct openings
on base unit are fitted with a tab slot connection similar to
those on plenum except for end partitions which are
hemmed. This hem is positioned so that the 1-in. flange at
the entering end of the field-fabricated plenum will force-fit
between it and adjacent unit frame member.
Use standard flexible duct connections between duct
plenum and duct system. Follow applicable codes.
Insulate supply air ducts passing thru unconditioned
spaces and cover with vapor barrier. Separate parallel
duct runs of longer than 5 ft by insulation to prevent heat
transfer between zone ducts.
Return air duct connection consists of 4 sheet metal
flanges.
Balancing dampers — Provide suitable balancing
dampers in each zone duct run. Normally, a 2-bladed
damper is preferred to a single blade. Adjust the balancing
dampers to give the desired airflow and static pressures in
each module. Ready access to balancing dampers is neces­
sary in a multizone system.
Low cfm, long run zones — If possible, avoid small
zones with long runs. As the cfm decreases at a given duct
HOT WATER/GLYCOL HEATING CAPACITIES
(Hot Water with 20% Ethylene Glycol Solution)
90
4.
5.
Determine zone module air quantity as described in the
Selection Procedure (1000 cfm)
Enter curve at determined zone module air quantity Project left
to intersect with entering air temperature curve (70 F)
From this intersection, project up to intersect with entering
water temperature (180 F)
From this intersection,project right to intersect with Water Flow
Rate (4 gpm).
From this intersection, project down to read Zone Module
Heating Capacity (49,500 Btuh)
6 When using solution mixtures above 20% glycol concentration,
reduce the capacity using the correction factor
i e If 30% glycol concentration applies to the example.
Corrected Zone Module Heating Capacity
= Zone Module Heating Capacity x Correction Factor
= 49,500
X 0 985
= 48,750 Btuh
7 See Module Pressure Drop graph. The Ap at 4 gpm is 8.2 psig.
34