Continental Electronics 816R - Page 22

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Deflectors

at

the

fan

can

be

used

to

direct

air

into

areas

that

might

not

otherwise

have

moving

air.

3.

All

fans

aid

each

other.

The

fan

that

is

forcing

air

into

a

room

is

aiding

the

transmitter

fans

in

cooling

the

transmitter.

All

the

fans,

the

room

fan,

the

transmitter

cabinet

fan,

and

the

power

amplifier

cavity

blower

are

moving

the

air

in

the

same

direction

through

the

transmitter.

4.

Like

the

exhaust

system,

the

pressure

system

will

also

ventilate

the

room.

The

transmitter

will

exhaust

about

500

cu-ft/min.

of

air

to

the

outside.

If

the

room

fan

is

capable

of

moving

three

or

four

thousand

cu-ft/min.

of

air

into

the

room,

another

opening

in

the

room

must

be

provided

for

room

ventilation.

An

example

of

positive

room

ventilation

will

be

described

here.

This

is

intended

only

as

an

example

and

can

be

modified

to

meet

your

particular

requirements.

Locate

the

left

end

or

the

rear

of

the

transmitter

near

an

outside

wall

in

order

to

keep

the

exhaust

ductwork

as

short

as

possible.

Position

the

transmitter

so

that

the

exhaust

duct

will

not

interfere

with

the

coaxial

RF

output

line.

If

the

total

duct

run

is

eight

feet

or

less

and

there

are

no

more

than

two

elbows,

16

inch

round

or

the

equivalent

square

duct

can

be

connected

directly

over

the

transmitter

exhaust

output

using

sheet

metal

screws.

(Use

care

when

drilling

holes

for

sheet

metal

screws

so

as

to

avoid

metal

shavings

falling

into

the

transmitter.)

The

duct

will

have

to

be

turned

down

at

the

outside

to

prevent

rain

and

snow

from

getting

into

it.

A

bell

type

transition

should

be

used

at

the

end

of

the

duct

to

reduce

turbulence.

The

duct

above

the

transmitter

will

have

two

dampers

and

an

opening

to

the

room.

The

dampers

will

be

motor

controlled

and

mechanically

linked

together

so

that

the

opening

to

the

room

will

be

closed

off

at

the

same

time

that

the

air

from

the

transmitter

will

be

directed

to

the

outside.

With

the

dampers

in

the

second

position,

the

air

from

the

transmitter

will

be

directed

to

the

room

instead

of

outside.

The

mechanical

linkage

is

necessary

to

prevent

the

possibility

of

both

dampers

being

closed

at

the

same

time.

This

arrangement

will

allow

the

transmitter

to

exhaust

to

the

outside

in

the

summer

and

recirculate

to

the

inside

in

the

winter.

A

fan

that

has

enough

capacity

to

change

the

room

air

at

least

once

each

minute

is

installed

in

the

wall.

This

fan

pulls

filtered

air

into

the

room

through

motor

controlled

louvers.

A

3000

cfm

fan

will

change

the

air

once

a

minute

in

a

15X20

foot

room

having

a

10

foot

ceiling.

An

opening

with

motor

controlled

louvers

is

provided

in

the

same

wall

where

the

fan

is

mounted.

The

reason

for

intake

fan

and

room

air

outlet

being

on

the

same

wall

is

to

minimize

the

effects

of

wind

on

the

ventilation

system.

If

both

inlet

and

outlet

are

on

the

same

wall,

the

effects

of

wind,

regardless

of

direction,

is

neutralized

since

the

wind

pressure

is

the

same

on

both.

The

transmitter

air

exhaust

should

be

on

this

wall

also.

The

transmitter

exhaust

should

not

be

positioned

so

that

there

is

a

risk

of

recirculation.

With

motor

control

on

inlet

and

outlet

louvers

and

transmitter

duct

dampers,

it

is

possible

to

control

the

operation

of

louvers,

dampers,

and

the

ventilation

fan

with

thermostats.

Set

the

thermostats,

based

on

environmental

conditions,

to

maintain

the

required

equipment

operating

temperature

at

all

times.

Three

conditions

are

described

below

that

will

give

different

results:

1.

A

condition

of

maximum

ventilation

and

cooling

will

result

during

the

hottest

periods.

The

transmitter

will

be

ducted

to

the

outside

and

the

intake

fan

will

be

running.

The

outlet

wall

louvers

will

also

be

opened

to

permit

room

ventilation.

2.

A

condition

of

minimum

ventilation

will

exist

at

times

when

it

is

not

necessary

to

run

the

room

intake

fan,

but

the

transmitter

should

be

vented

to

the

outside.

Under

these

conditions

the

transmitter

exhaust

dampers

will

direct

the

transmitter

exhaust

to

the

outside,

the

outlet

wall

louvers

will

be

closed,

the

fan

will

be

off,

and

the

inlet

fan

louvers

will

be

open

to

allow

fresh

filtered

air

into

the

room

and

transmitter.

3.

A

condition

of

recirculation

for

heating

will

exist

during

cold

periods.

The

transmitter

exhaust

dampers

will

be

positioned

to

allow

18