Carrier 42C,V Manual de instalación descargar pdf (Pagina 81)

and other literature for detailed information regarding each in-

dividual unit and its controls. Since controls and features may

vary from one unit to another, care should be taken to identify

the controls used on each unit and their proper control

sequence. Information provided by component manufacturers

regarding installation, operation, and maintenance of their indi-

vidual controls is available upon request.

When changing from one mode to another (cooling to heat-

ing or heating to cooling), it may take some time to actually no-

tice a change in the leaving air temperature. In addition, some

units may be designed for a very low air temperature rise in

heating. Before declaring a unit inoperative or a component

defective, it may be necessary to verify operation by more than

one method.

SERVICE

Excessive Condensation on Unit —

Running chilled

water through a fan coil unit with the unit fan off can cause

excessive condensation. If fan cycling is used, a water flow

control valve should be installed to shut off the water when the

fan stops.

Other methods of control that avoid condensation problems

are as follows:

1. Continuous fan operation with motorized chilled water

valve controlled by a thermostat.

2. Continuous fan operation with thermostat control to

switch fan from high to low speed (instead of off).

To Clean Coil

1. Be sure electrical service switch is open, locked, and

tagged while working on unit.

2. Remove return-air grille access panel and brush between

coil fins with stiff wire brush. Care should be taken to not

damage coil fins. Follow-up by cleaning with vacuum

cleaner. If coil is cleaned with air hose and nozzle, take

care not to drive dirt and dust into other components.

Blow air through the coil fins from the leaving air face.

This should again be followed by vacuuming. Units pro-

vided with the proper type of air filters, replaced regular-

ly, will require less frequent coil cleaning.

3. Install clean filter. Refer to Clean or Replace Air Filters

section.

Check Drain — Lock open and tag unit electrical service

switch.

Check drain pan, drain line and trap before initial start-up

and at start of each cooling season. A standard type pipe clean-

er for

-in. ID pipe can be used to ensure that pipe is clear of

obstruction so that condensate is carried away. Check the drain

line at filter cleaning time during the cooling season. Be sure

that debris has not fallen into unit through supply-air grille.

Should the growth of algae and/or bacteria be a concern, con-

sult an air conditioning and refrigeration supply organization

familiar with local conditions for chemicals or other solutions

available to control these agents.

Fan Motor Bearings — Lock open and tag unit electri-

cal service switch.

Standard motors are permanently sealed and lubricated. No

lubrication is required unless special motors have been

supplied or unusual operating conditions exist.

Clean Fan Wheel — Lock open and tag unit electrical

service switch.

For access to fan assembly, remove front or bottom panel.

Fan assembly may be removed from its tracks if unit has a long

conduit lead. Dirt and debris should not be allowed to accumu-

late on the blower wheel or housing. This can result in an un-

balanced blower wheel condition which can damage a blower

wheel or motor. The wheel and housing may be cleaned peri-

odically using a vacuum cleaner and a brush, taking care not to

dislodge the factory balancing weights on the blower wheel

blades.

Clean Electric Heater — Lock open and tag unit elec-

trical service switch.

1. Remove dust, dirt, or foreign material before start-up. Do

not block normal airflow to and from units; blockage may

damage electric heaters.

2. Clean heater elements with soft brush or vacuum cleaner

as necessary.

3. To replace blown fusible links (nichrome heaters only):

a. Remove fan deck (horizontal units only) for

access to heater.

b. Remove nut securing link at each end; install new

link; reinstall nuts.

c. Reinstall fan deck (if removed).

Electric resistance heaters typically require no normal peri-

odic maintenance when unit air filters are changed properly.

The operation and service life may be affected by other condi-

tions and equipment in the system. The two most important op-

erating conditions for an electric heater are proper airflow and

proper supply voltage. High supply voltage and/or poorly dis-

tributed or insufficient airflow over the element will result in

element overheating and possible limit switch opening. This

condition may result in the heater cycling on the high-limit

thermal cutout. Sheath heaters have automatic reset switches

only. Open strip heaters have an automatic reset switch with a

backup, high-limit thermal switch. Automatic reset switch re-

sets automatically after the heater has cooled down. High limit

thermal switch must be replaced once the circuit has been bro-

ken. The high-limit thermal cutout device is a safety device

only and is not intended for continuous operation. With proper

unit application and operation, the high-limit thermal cutout

will not operate. This device only operates when a problem ex-

ists, and ANY condition that causes high-limit cutout MUST

be corrected immediately. High supply voltage also causes ex-

cessive amperage draw and may trip the circuit breaker or blow

the fuses on the incoming power supply.

After proper airflow and supply power are assured, regular

filter maintenance is important to provide clean air over the

heater. Dirt that is allowed to deposit on the heating element

will cause hot spots and eventual element burn through. These

hot spots will normally not be enough to trip the high-limit

thermal cutout device and may not be evident until actual heat-

er element failure.

Clean or Replace Air Filters — Lock open and tag

unit electrical service switch.

At the start of each cooling season and after each month of

operation (more or less depending on operating conditions) re-

place throwaway filter or clean permanent filter.

THROWAWAY FILTER — The type of throwaway filter

most commonly used on fan coil units should be replaced on a

regular basis. The time interval between each replacement

should be established based on regular inspection of the filter

and should be recorded in the log for each unit. Replace filter

with a good quality filter of the size shown in Tables 1-4. Do

not attempt to clean and reuse disposable filters. If the replace-

ment filters are not purchased from the factory, the filters used

should be the same type and size as those furnished from or

recommended by the factory. Consult the factory for applica-

tions using filter types other than the factory standard or

optional product. Filters with high arc pressure drops are gen-

erally not compatible with the fan coil units in this manual.

PERMANENT FILTER — A maintenance schedule for per-

manent filters should be developed in the same manner as

throwaway filters. Unlike throwaway filters, permanent filters

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