Bryant 378 User Manual

378

Installation Instructions

ALL WEATHER HEATING & COOL!!^iG

GENERAL

The Model 378 is approved by the American &
Association for:

1. Use with natural, mixed, and propane gases.

2. Outdoor installation

a. On a roof

b. At ground level

3. Indoor installation (when equipped with Bryant
draft hood assembly. Part No, 36154C8 and special
front door in place of door furnished.)

a. Attic
b. Basement, utility room, etc.

4. Use with 36W, 54W, 90W, and 108W water coils.

5. Use with 48R, 60R, 90R, and 120R direct expan
sion coils.

Series B

bpi|ont

39378 D9
5/10/65

INSPECTION

Be sure available gas supply is the same as shown
on American Gas Association rating plate.

Check electric supply - voltage, phase, and fre
quency - to be sure that it is the same as required

on the rating plate. Check to be sure that adequate
power is available to handle the increased electri
cal load when the unit is used for cooling.

Installation of the all-weather heating and cooling
unit consists of the following:

1. Locating the Unit

2. Gas Piping

3. Venting

4. Electric Connections

5. Start-up and Adjustment

6. Connection with Electric Air Conditioner (when

used)

7. Connection with Gas Air Conditioner (when
used)

LOCATING THE UNIT

When installing in conjunction with a cooling sys
tem refer to the applicable section of this instruc
tion for additional information.

Before locating the unit, refer to local codes.

OUTDOOR INSTALLATION

Mounting

The unit design permits use of four corner posts,
rails, or any other method of support sufficiently
strong to accommodate the weight; however, consult

local codes - particularly for roof installation.
Units must be level.

Clearances

1. Provide a minimum 1 inch clearance on bottom

for water drainage (rain, sleet, and snow).

m

3;

co

00

378 ALL WEATHER INDOOR/OUTDOOR UNIT

48R-378 60R-378

Heating input Btuh 150-100,000
Bonnet capacity

Btuh 112-75,000

DX Coil rating Btuh 48,000

Water Coil rating

Btuh

— —

Air flow CFM 1600

External static

Blower motor

In. water 0.20
H.P.
Volts
Phase

150-100,000

112-75,000 112-75,000

60,000

2000

0.20 0.15

1/2 3/4

230 230

1 1 1
Cycle 60
FLA

4
Suction line In. o.d. 1-1/8 7/8
Liquid line
Inlet water line
Outlet water line NPT
Condensate drain In. o.d. 7/8
Refrigerant R 500
Filters (disposable) In.
Approx, shipping wt. Lbs.

In. o.d.
NPT

1/2

3/8

- -

- ­7/8

500

(2)25x20x1 (2)25x20x1

580

600

36W-378 54W-378

150-100,000

- -

36,000

1200 1800 3000 ' 4000

1/2

230

60

60

5 4

- - 1-1/8

­1-1/4

JTTpri

7/8

- -

(2) 25x20x1

595 605 975 985

90R-378 120R-378 90W-378

150-100,000

300-200,000

300-200,000

112-75,000 225-150,000 225-150,000

54,000

0.20

90,000

—

0.25 0.30 0.25

110,000

■ — 90,000

3/4 1 Ir 1/2

230 230 230

1 1 1

60

60

5 7

1-3/8

­1-1/4

1-1/4 ■■

7/8

5/8 5/8

-

—

7/8

-

­7/8

22 500

(2) 25x20x1

(4) 25x20x1

(4)25x20x1 (4) 25x20x1

■ 300-200,000
225-150,000 225-150,000

: 3000

1 1- 1/2

: ; (230

1

60 60

9 7

- - - —

­1-1/4

1-1/4

7/8

—

710

108W-378

300-200,000

__

108.000
3600

0.30

230

1

60

9

' -

1-1/4
1-1/4

7/8

(4)25x20x1

995

Outdoor Installation - Clearances (cont’d)

2. Provide adequate clearance for outlet and return
duct connections.

3. Clearance from combustibles:
From casing, all sides and top 6"

* From base ...............................

0”

When the furnace is installed in a building of un
usually tight construction, air for combustion and
ventilation should be obtained from outdoors or from
spaces freely communicating with the outdoors. Two
openings should be provided, each having a free
area of one square inch for each 2000 Btu per hour ­one located above the draft diverter relief opening
and the other near the floor.

*This permits use of combustible material as sup

port.

Caution: When using rails, etc. as support, do not

enclose unit so as to interfere with drainage.

4. Service clearance:
Front - 24"

Side - Provide adequate side clearance for fil

ter removal. Clearance on left side for blower
service; side clearance for coil service.

Provide adequate clearance when air conditioner is
located adjacent to unit.

INDOOR INSTALLATION

Mounting

Unit may be set flush with floor or mounted on sup
ports. There is no need to provide clearance under
the base. Shim as required to make unit level.

Clearances

1. From combustible materials:
a. 0 " clearance on bottom.

b. 6" clearance from casing surface; line con
tact allowed.

c. 6" vent and draft hood.

2. Service access: Same as for outdoor installa
tion.

COMBUSTION AND VENTILATION AIR

When the furnace is installed in a confined space,
but in a building otherwise having adequate infiltra
tion from the outside, air for combustion and venti
lation may be taken from the building. Two openings
should be provided, each having a free area of one
square inch for each 1000 Btu per hour- one located
above the draft diverter relief opening and the other
near the floor.

For further information on this subject, refer to

ASA Z21.30-1959, or later editions of this standard,

“Installation of Gas Appliances and Gas Piping.”

GAS PIPING

The gas supply line should be a separate line direct
from the meter to the furnace.

Check local utility for recommendations concerning

existing lines. Choose a supply pipe size large
enough to keep the pressure loss as low as practi
cal.

Never use pipe smaller than the gas connection to
the furnace. Observe local codes for all gas pipe

installation.

The following are pertinent recommendations:

1. Avoid low spots in long runs of pipe, it is best
to grade all pipe 1/4 inch in 15 feet to prevent
traps. All horizontal runs should grade to risers.
Risers should be used to connect to the furnace and
to the meter.

2. Install a drip leg in the riser leading to the
furnace. This drip leg will serve as a trap for dirt

and condensate.

The drip leg can be installed by connecting a tee to

the riser leading to the furnace so that the straight­through section of the tee is vertical. Then, connect
a capped nipple to the tee. The capped nipple
should extend below the level of the gas controls
a minimum of 6 inches.

3. A manual shut-off valve should be installed in
the gas line within sight of and convenient to the
furnace. This shut-off valve is furnished.

4. Support all piping with appropriate hangers, etc.
Properly support gas piping at furnace to prevent
damage to weather tight seal.

5. After all connections are made, check for leak
age using soap and water solution, or in accordance

with local utility regulations. Never use a match or

other open flame.

- 3

EH 378

VENTING

INDOOR INSTALLATION

Consult local codes. Unless the local codes direct
otherwise, the unit may be vented to a permanent
chimney, or to a listed Type B or Type C gas vent.

The Model 378 furnace is approved for indoor instal
lation only when used with draft hood, Bryant Part
No. 36154C8.

To install indoor draft hood:
a. Remove upper front access panel to gain en

trance to flue collector.

8. If more than oiie appliance is vented into the
same chimney, the cross-sectional area of the chim
ney must be as large as the largest flue pipe being
connected, plus 50 per cent of the cross-sectional

areas of the additional flue pipes being connected.

9. If more than one appliance is manifolded into the
same flue connecting pipe, the cross-sectional area

of this manifold pipe must be as large as the sum of

the cross-sectional areas of the pipes connecting

into it.

10. Flue pipe must be at least 6 inches from any

combustible materials.

b. Insert draft hood inside furnace casing collar
and push it down over the flue collector collar to
form snug connection.

c. Fasten draft hood to flue collector collar with
sheet metal screws.

The following recommendations are made:

1. Select flue connection material that is satis
factory for the installation and that meets the
requirements of the local codes.

2. The flue connection pipe must be the same size
as the outlet collar on the furnace. No reduction in
this size is permissible in the pipe run.

3. Run pipe as directly as possible with a minimum
number of turns.

4. Maintain a minimum of 1/4 inch per linear foot
upward slope on all horizontal runs.

5. Rigidly support the flue pipe with hangers and

straps to insure that there will be no movement after
installation.

6. Extend the flue connection pipe through the
chimney wall, flush with the inner face of the chim
ney liner. Never connect into a chimney serving an
open fireplace unless the fireplace opening is
sealed off.

Do not use dampers or other adjustable restrictions
in flue.

Any part of the vent which is outdoors must be ade
quately insulated to assure proper chimney action
and prevent condensation.

OUTDOOR INSTALLATION

The Model 378 all-weather unit is shipped with out

door vent as standard equipment and must be instal
led in accordance with the following instructions
and without alterations.

Installing Outdoor Vent

1. Remove upper front access panel to gain en

trance to flue collector.

2. Insert cap and pipe assembly through furnace
casing.

Important: Be sure the outer wall of the double

walled pipe extends over the furnace casing con

nector collar to assure weather tight connection and
that the inner wall connects to the flue collector
collar.

3. Fasten the flue pipe assembly to the flue col
lector collar with sheet metal screws. Note: Addi
tional venting is not required on outdoor units.

7. The chimney or gas vent should extend high
enough above the roof or neighboring obstruction
so that wind from any direction will not create a
positive pressure in the vicinity of the outlet of the

chimney or gas vent. The installer is referred to
Part V of American Standard “Installation of Gas
Appliances and Gas Piping”, ASA Z21.30, 1959 for
detailed information on chimney and gas vent use.
In general, the chimney or gas vent should extend
3 feet higher than the point of emergence through
the roof, and at least 2 feet higher than any object
within a radius of 15 feet.

EH 378

ELECTRIC CONNECTIONS

1. All electrical connections are to be made in
accordance with National Electrical Codes and

local codes governing such wiring.
Field connections are to be made in accordance

with wiring label attached to unit. See Figures 1 and

2.

2. Weather tight connections must be made at elec
trical entrance to the unit on all outdoor installa
tions.

4 -

3. Thermostat connections for heating only are to
be made at terminals 4 and W. See Figure 3 for low
voltage connections when cooling equipment is

used.

unit. The limit will shut off the main gas if the
temperature goes too high. The limit may be checked
by removing the fan belt and firing the unit. The
burners should shut in a few minutes.

4. A separate, fused, electrical line should be run
for this installation.

START-UP AND ADJUSTMENT

1. Before Starting the Unit:

a. Check to see that electric and piping con

nections have been made.

b. Make sure gas piping is purged and free of

air; do not purge into the combustion chamber
of the furnace. All gas piping connections
should be leak tested. Do not use an open
flame. Use a soap and water solution.

2. Start-Up:

'Follow lighting instructions attached to the unit.

Sequence of control operation is as follows:

a. When pilot gas cock is opened, gas flows to

the pilot and to the pilot pressure switch.

b. Pilot pressure switch then closes to com

plete the 24 volt circuit. The pilot then
lights automatically.

3. Adjust Gas Input:

Air Shutter Adjustment - To adjust the air shutter,
pull the shutter closed until there is a slight yellow
tip at the top of each flame. Then open the shutter
until the yellow tip disappears.

Gas input should agree with that shown on the rating
plate of the unit. The burners are equipped with
orifices sized to give the correct input with a mani
fold pressure of 3 inches w.c. ± 0.3 for natural and
mixed gases, and II inches w.c. for propane gas.

The furnaces are approved for minimum firing rates
(shown on rating plate) as follows:

Size 150 - May be fired at 100,000 BTUH input.
Size 300 - May be fired at 200,000 BTUH input

Note: The size 150 furnace (natural gas only) is
also approved for modulated input down to 50,000
BTUH when equipped with an approved modulating
valve. The size 300 furnace (natural gas only) is

approved for modulated input down to 100,000 BTUH.

c. Subsequent switch action completes circuit

through Y and W to energize the electric gas
valve.

When the thermostat calls for heat, circuit is closed
between W and 4. This allows current to flow through
combustion air fan relay which energizes the com
bustion air blower and builds up pressure in the
combustion air switch. When combustion air pres
sure switch is closed, low voltage is completed.

The conditioning air blower is not actuated by a fan
switch, but by a delay fan relay.

If the lower limit opens, the automatic gas valve is
de-energized.

If the upper limit opens, the automatic gas valve is
de-energized, and the combustion air pressure switch
is by-passed so that the conditioning air blower will
continue to run.

The automatic pilot turns the main gas off, should

pilot flame be put out. This can be checked by turn
ing the main burners and pilot oh, then shutting the
pilot gas off. The main burners should shut off.

See next page for

Gas Input Measurement

The limit controls the temperature reached in the

5 -

EH 378

Determine gas input as follows:

a. Determine the number of seconds required for

the gas meter test dial to complete one revo
lution.

b. Divide 3600 by the nuniber of seconds in

Item (a) above.

c. Multiply result of Item (b) by the number of

cubic feet shown for one revolution of the
test dial. This gives you cubic feet per hour
of gas flow.

d. Multiply result of Item (c) by the heating

value of the gas in BTU (consult local util

ity for value). This gives you the total meas
ured input in BTUH. Compare this value with

that on your rating plate.

TABLE

Model No.
36W, 54W, 48R,

60R,&l50-378
90W, 108W, 90R

120R, 8s300-378

Input Btu

per hr.
150,000 45 ° F to 75 ° F

100,000
300,000 45 ° F to 75 ° F

200,000

Temperature Rise Air

through Furnace

20 ° F to 75 ° F

20 ° F to 75 ° F

The pulley setting has been made at the factory to
give an air flow compatible with the intended use of
the equipment; i. e., the setting varies with the
type of cooling coil to be used. Table II gives the
pulley setting as the furnace leaves the factory,
and shows also how the pulley can be adjusted to
give the desired air flow if the duct resistance is
higher than normal.

Example: Suppose that the size of the test dial is

1/2 (.5) cu. ft.; it takes 20 seconds for the dial to
complete one revolution; heating value of gas is
1050 BTU/cu. ft. Proceed as follows:

a. 20 seconds to complete one revolution.

b. 3600 divided by 20 equals 180.

c. 180 X 0.5 equals 90 cu. ft. per hour of gas

flow.

d. 90 X 1050 equals 94,500 BTUH input.

Only minor changes should have to be made at the
pressure regulator. If the manifold pressure must be
changed more than ±.3 w.c. to obtain rated input,
the orifices should be changed accordingly.

4. Air Flow and Temperature Rise

The furnace is approved for operation under the

temperature rise conditions shown in Table I.

Model Normal Static (ARI)
No.

Static

in. w.c. Pulley Turns Open in. w.c.

Factory Setting of

36W - 378 0.15 31/2
54W - 378 0.20 4
48R - 378 0.20
60R - 378 0.20
150 - 378 0.20

The static pressure against which the furnace is
operating is the difference in pressures in the
return air duct and the discharge duct hear the

furnace. If this differential pressure, determined
when the filters are clean and the pulley is opened
the number of turns shown for normal static, is more
than shown for normal static in Table II, the blower
speed should be increased by changing the pulley
setting to that shown in the column for higher than
normal static pressures.

The temperature rise is the difference between the
temperature of the air in the return duct and in the
discharge duct near the furnace. This temperature

rise, measured after equilibrium has been attained,
should be within the range shown in Table I. The
pulley setting shown in Table II should give an air
rise within the approved range.

TABLE II

High

er Static *

Static Pulley Setting

Turns Open

IV2

3V2

21/2

0.50

0.50

0.40

0.50

0.50

1V2

2
0

IV2

V2

90W - 378

108W - 378

0.25

0.30
90R - 378 0.25
120R - 378

0.30 1
300 - 378 0.25

* The furnaces are approved for operation up to 0.50 in. w.c.

EH 378 . 6 -

11/2

21/2

ya

V2

0.45 0

0.50

0.35 0

0.40 0

0.35 0

1

CONNECTING CONDENSING UNIT

TO R TYPE MODEL 378

The evaporator coil is supplied as an integral part
of the “R” Type 378 unit.

The condensing unit may be installed remotely or
adjacent to the “R” Type 378 unit.

Consult Condensing Unit Installation Instructions
for minimum clearances and connection of refrigerant
tubing.

All openings in refrigerant lines from evaporator
coil and condensing unit are plugged or capped to
keep moisture out of the system. These plugs or
caps should not be removed until each connection
is made. Each connection should be made in the
shortest time possible to avoid contamination from
surrounding air.

Note: The 90R and 120R 378 units have a factory

installed expansion valve. Items 1 through 5 will,

therefore, not apply for these sizes in the following
instructions. The expansion valves for the 48R and
60R 378 units are supplied as a loose part with the
condensing unit.

5. Uncoil capillary line of Expansion valve and
attach sensing bulb to top of horizontal suction
line inside of unit casing. Wrap bulb with prestite
tape (shipped with unit as a loose part).

6. Connect coil to condensing unit per instructions
packaged with the condensing unit.

7. Follow procedures outlined in Condensing Unit
Installation Instruction for leak testing and evacua
tion.

8. Replace panels on unit and connect condensate
(located on opposite side of unit) to a suitable
drain site.

9. All electrical connections should be made in
accordance with National Electric Code and any
local codes that might apply. Make electrical con

nections as shown in wiring diagram in condensing
unit instruction and the low voltage diagram in this

instruction.

To install the expansion valve, proceed as follows:

1. Remove panels from right-hand side of the 378

unit.

2. Remove plug from flare nut connector on dis
tributor and insert expansion valve.

3. Remove plug from external equalizer line flare
fitting and connect equalizer to expansion valve.

4. Shipped as loose parts on 48 & 60 sizes are

2 large metal seals, a neoprene gasket, and nuts and
nuts and bolts to seal the liquid line opening. In
stall air seals as shown.

CONNECTING GAS AIR CONDITIONER

TO W TYPE 378

AH Weather Indoor—Outdoor Unit

Water Coil Connections

For installation of chilled water lines from the gas
air conditioner to the water coil in the Model 378,
refer to installation instructions furnished with the

gas air conditioner.

For piping and wiring recommendations on multiple
gas air conditioner installations as required for the
Models 90W 378 and 108W, contact your Bryant
distributor.

Winter Shut-Down Protection

It will be necessary to add anti-freeze to the chilled
water system for winter protection whether the
Model 378 is installed indoors or outdoors. The ad
dition of the anti-freeze will furnish freeze protec
tion for the coil and piping. It will also provide for
expansion of water in the coil if the coil is located
in the heated air stream.

- 7 -

EH 378

Winter Shut-Down Protection (continued)

MAINTENANCE

Winter shut-down protection can be provided as
follows:

1. With the pump circulating water with additive
(borax), add one gallon of methanol (uninhibited
methyl alcohol) for each 20 gallons of water or
fraction thereof, and circulate for ten minutes.

2. It is not necessary to drain the system,

3. Tag the unit to show methanol has been added.

4. Determine the correct amount of methanol re
quired as follows:

a. Estimate the system water capacity in gal

lons from table below. Multiply the length of
pipe in feet by the gallons in one foot; then
add the gallons of water in chiller, or chil
lers, and coil.

b. Water Capacity Table:

Water Capacity Gallons

36-450 Chiller

54-450 Chiller .....

36W-378 or 54W-378 Coil
90W-378 or 108W-378 Coü

1 ft. of 3/4 inch pipe

1 ft. of 1 inch pipe . . .

1 ft. of 1 -1/4 inch pipe.

1 ft. of 1 -1/2 inch pipe.

c. With the pump operating, adjust the water

.....................

______

5

8

1.5

3.0
.03
.05
.08

.12

operating level in the chiller.

Summer Operation

In general, it is recommended that the methanol be
flushed from the chilled water system for summer
operation. The presence of methanol in the chilled
water will reduce the capacity with a corresponding
increase in operating cost. However, the reduction
in capacity resulting from the 5% solution of meth
anol is small (less than 1%) and the methanol may be
left in the system.

If the system is drained, flushed, and refilled with
water, be sure to add one box of chilled water ad
ditive (borax) for each 20 gallons of water or frac
tion thereof in the system.

Note: The above explanation covers only the normal

winter shut-down protection. If, for any reason, the
gas air conditioner must operate when the outdoor
temperatures are below freezing, it will be neces
sary to prepare the chilled water system for the
minimum temperature. Consult your Bryant distri
butor for special procedures to follow.

LUBRICATION

Blower Motor - if equipped with oil cups, oil motor

bearings with SAE10-20 non-detergent oil each
heating and cooling season. Use approximately six
drops for each bearing. Some motors are equipped
with bearings of a permanently lubricated type and,
therefore, need no further oiling.

Blower Bearings -are of the permanently lubricated

type and, therefore, need no further oiling.

Combustion Air Blower Motor — (located in control

compartment). Oil motor bearings with SAE 10-20

non-detergent oil each heating season. Use approxi
mately three drops for each bearing.

Air Filter

Periodically inspect air filters. Replace when dirty
with filters of the same size (see marking on fil

ters), making sure that arrows on edge of filter

point in direction of air flow (toward blower).
Excessively dirty filters reduce furnace efficiency.

Cleaning the Unit

1. Be sure main line disconnect switch is in the

“off”^ position. Tag with suitable warning label.

2. Turn manual gas and pilot valve to “off” posi

tion.

3. Remove upper and lower front access panels.

4. Disconnect pilot and escapement tubing.

5. Remove burners.

6. Remove screws holding horizontal dividing panel
and flue collector in place,

7. Tip dividing panel and flue collector up and
back to give access to flue outlets.

8. Remove flue baffles.

9. Clean flue passages with suitable brush.

10. Re-assemble furnace by reversing the above
procedure, making sure all seals are properly re
placed.

See following pages for Wiring Diagrams.

EH 378

- 8 -

IF ANY OF THE ORIGINAL WIRE AS SUPPLIED WITH THIS APPLIANCE MUST BE
REPLACED, IT MUST BE REPLACED WITH SAME OR EQUIVALENT WIRE:

LOW VOLTAGE WIRES—18 A.W.G. 4/64THK. 600V. I05“C. INSULATION
LINE VOLTAGE WIRES—14 A.W.G. 5/64 THK, 600V. I05®C. INSULATION
S.P.D.T. LIMIT SWITCH WIRES--» A.W.G. 2/64 THICK 600V. I50**C. INFLATION

IF THIS APPLIANCE IS CONVERTED TO PROPANE GAS THE INSTALLATION WILL NOT
BE COMPLETE UNLESS THIS WIRING LABEL IS REPLACED WITH THE WIRING
LABEL SUPPLIED WITH CONVERSION KIT.

57389CI

Figure 1 - Wiring for City Gases

- 9 -

EH 378

208/230 VOLTS
60 CYCLE
SINGLE PHASE
CURRENT DRAW LESS

THAN 12 AMPERES

--------

FACTORY LOW VOLTAGE

--------

FIELD LOW VOLTAGE

—— FACTORY LINE VOLTAGE

-—FIELD LINE VOLTAGE

LIMIT SWITCH

S. P. D. T.

COMBUSTION

AIR BLOWER

MOTOR

EH 378

ONE PILOT RELAY

IF ANY OF THE ORIGINAL WIRE AS SUPPLIED WITH THIS APPLIANCE MUST BE
REPLACED, IT MUST BE REPLACED WITH SAME OR EQUIVALENT WIRE-*

LOW VOLTAGE WIRE I8A.W.6. 4/64 THICK 600V. I05»C. INSULATION.
LINE VOLTAGE WIRE

S.P. D.T. LIMIT SWITCH WIRES

THIS APPLIANCE IS CONVERTED TO PROPANE GAS THE INSTALLATION WILL NOT
BE COMPLETE UNLESS THIS WIRING LABEL REPLACES THE WIRING LABEL

SUPPLIED ON UNIT.

-------------

I4A.W.G. 5/64 THICK 600 V. 105® C. INSULATION .

----------------

18 A.W.6. 2/64 THICK 600V. 150“C. INSULATION.

TWO PILOT RELAYS

57814 CI

Figure 2 - Wiring for Propane Gas

- 10 -

LOW VOLTAGE

TERMINAL STRIP

ON CONDENSING UNIT

LOW VOLTAGE

TERMINAL STRIP

ON 378 UNIT

Figure 3 - Low Voltage Wiring

- 11 -

EH 378