Carrier 48N Instrukcja Użytkownika Pobierz pdf (Strona 5)

• VAV units provide multiple stage,

cooling capacity control for

improved part load operation and

greater efficiency

• optional digital compressors provide

a nearly infinite number of steps of

capacity for unmatched load match-

ing and part load performance

• Humidi-MiZer adaptive dehumidifi-

cation system

• refrigeration system designed to

operate with outdoor temperatures

down to 32 F, optionally to –20 F.

• modulating power exhaust or return

fan options for precise building

pressure control

Filtration

The filter options include mixed air and

final filter choices. The MERV ratings

range from a MERV 8 to a MERV 17

HEPA type. The filters are snug fitting

in a rigid track with seals that limit air

leakage around the filters.

Installation and serviceability

Access panels — All full-size access

panels are hinged for easy access to

serviceable components. No fasteners

need to be removed to open the

hinged panels. This reduces service

time and prevents roof leaks caused by

discarded screws puncturing the roof.

Electrical connections — Single

point electrical connections are stan-

dard on all units. Electrical service ac-

cess can be made through roof curb or

side of unit. All 48N units provide a

single point gas connection.

Run testing — To ensure a successful

start-up, every rooftop unit is factory

run tested.

Unit design — Unit design is ETL

and ETL, Canada, listed according to

UL (Underwriters Laboratories) Stan-

dard 1995.

Navigator™ display module —

When using the standard Navigator

user interface, serviceability becomes

even easier, including:

• local or remote alarm and alert

monitoring

• self-diagnostic run testing to confirm

control and component operation

• expedited troubleshooting and unit

repair through self-diagnostic dis-

play of unit troubleshooting alert

and alarm codes with expanded text

descriptions to immediately identify

reason for unit outage

• filter maintenance alarm

• monitoring of supply-air fan run

time, permitting easy service sched-

ule planning

Tranducers — Serviceability is further

facilitated with suction and discharge

pressure transducers. These allow suc-

tion pressure and discharge pressure to

be monitored remotely with alarm ca-

pability. These transducers also control

condenser head pressure to maintain

the minimum differential pressure re-

quired across the electronic expansion

valve (EXV) for proper operation, re-

ducing energy consumption.

Non-fused disconnect — A factory

installed non-fused disconnect (NFD)

option is available to simplify unit in-

stallation and improve unit serviceabili-

ty. The location of the NFD in the

main control box simplifies field power

supply routing into the unit. The NFD

incorporates an access panel interlock

feature, ensuring that all power to the

unit will be disconnected before a ser-

vice person opens the control box.

Gas heat units (48N units)

The 48N units are gas heating units,

using natural gas combustion, with up

to 4 heat sizes available for every unit.

The unit heating systems employ multi-

ple heat exchanger sections, with each

section equipped with a 2-stage redun-

dant gas valve and independent igni-

tion control, with all sections operating

in parallel.

Units with gas modulating heating

are equipped with an additional modu-

lating gas valve installed downstream

of the 2-stage redundant gas valve.

Gas heat system — The induced

draft fan system draws hot combustion

gas through the heat exchanger tubes

at the optimum rate for the most effec-

tive heat transfer and combustion pro-

cess. The heat exchanger operates un-

der a negative pressure, preventing

flue gas leakage into the indoor supply

air.

Flue outlet hoods with wind baffles

are located on the side of the unit, to

minimize the effects of wind on heat-

ing operations. Standard units use 2-

stage control, for unoccupied, morning

warm-up and occupied space heating.

Modulating control option is available

by specifying the modulating gas con-

trol option.

A single hinged panel gains access to

the complete heat exchanger assembly

and controls, for improved serviceabili-

ty. A single point gas connection pro-

vides for easy installation.

Heat exchanger — The tubular steel

heat exchanger design optimizes heat

transfer for improved efficiency. The

tubular design permits multiple passes

across the supply air path. Each tube

has an individual in-shot burner, ensur-

ing uniform combustion in each tube

of the heat exchangers. Tubes are dim-

pled to create a turbulent gas flow to

maximize heat efficiency and to ensure

uniform surface temperatures for re-

duced corrosion effects, improved du-

rability and long-life service. Heat ex-

changer material is aluminized steel or

optionally, stainless steel for improved

corrosion resistance and reliability.

Integrated gas unit controller —

The IGC (integrated gas unit controller)

ignition and safety control system is

used on each heat exchanger section.

The IGC, unique to Carrier rooftop

units, simplifies system evaluation and

troubleshooting by providing system

status and visual fault notification via

an on-board LED (light-emitting diode).

Ignition is initiated by a direct spark

ignition system; flame status is deter-

mined by flame rectification process.

Combustion fan operation is proven by

a Hall Effect speed sensor circuit for

units equipped with 2-stage or staged

gas heat. For units equipped with mod-

ulating gas heat, combustion fan oper-

ation is proven with a pressure switch.

Safeties include flame rollout and limit

switch. Auto reset with manual lockout

is also provided for repeated limit

switch trips. The IGC also prevents

short-cycling due to thermostat jiggle

by ensuring a full minute heating cycle

operation on each call for heat.

Optional modulating gas heat —

The modulating gas heat option moni-

tors unit supply-air temperature and

controls the unit heat exchanger to

provide first-stage demand heating

control, with modulation to maintain

user-configured heating supply air tem-

perature set point. The option also

provides full-fire demand heating on

heating control command and temper-

ing heat control, based on user-config-

ured ventilation supply air tempera-

ture set point, to eliminate cold draft

conditions with low mixed-air tempera-

tures. The modulating gas control op-

tion consists of a modulating controller

capable of ensuring the proper fuel air

mixture at operating firing rates, sup-

ply air temperature thermistors with

duct-mounting base, a limit switch tem-

perature thermistor, and stainless steel

heat exchanger tubes.

1 2 3 4 5 6 7 8 9 10 ... 91 92

Komentarze do niniejszej Instrukcji

Brak uwag

Carrier 48N Instrukcja Użytkownika Strona 5

Komentarze do niniejszej Instrukcji

Powiązane produkty i podręczniki dla Klimatyzatory typu split Carrier 48N