SYSTEM OPERATION
9
GAS PIPING CHECKS
Before placing unit in operation or after servicing, leak test
gas connections.
WARNING
T
O A
V
O
I
D TH
E
PO
SSI
BL
I
TY OF
EX
PLO
SI
ON O
R
F
IRE
, N
EVER
USE
A
M
ATCH
O
R
OP
E
N FLA
ME
TO T
ES
T FO
R
L
E
A
KS
.
Check for leaks using an approved chloride-free soap and
water solution, an electronic combustible gas detector, or
other approved testing methods.
NOTE:
Never exceed specified pressures for testing. Higher
pressure may damage the gas valve and cause subsequent
overfiring, resulting in heat exchanger failure. Disconnect
this unit and shutoff valve from the gas supply piping system
before pressure testing the supply piping system with
pressures in excess of 1/2 psig (3.48 kPa). Isolate this unit
from the gas supply piping system by closing its external
manual gas shutoff valve before pressure testing supply
piping system with test pressures equal to or less than 1/2
psig (3.48 kPa).
WARNING
I
F TH
E
I
NFO
RM
AT
I
ON
I
N TH
ESE
I
N
S
T
RU
CT
I
ON
S
IS
NOT FOLLO
WE
D
EX
ACTLY, A
F
IRE
O
R
EX
PLO
SI
ON
M
AY
RESU
LT CA
USI
NG P
R
OP
ER
TY DA
M
AG
E
, P
ERS
ONAL
I
N
JUR
Y O
R
LO
SS
OF L
I
F
E
.
–
D
O NOT STORE OR USE GASOLINE OR OTHER FLAMMABLE VAPORS AND
LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER APPLIANCE.
–
W
HAT
TO
DO
I
F
YO
U
SME
LL
GA
S
:
•
D
O NOT TRY TO LIGHT ANY APPLIANCE.
•
D
O NOT TOUCH ANY ELECTRICAL SWITCH; DO NOT USE ANY
PHONE IN YOUR BUILDING.
•
I
MMEDIATELY CALL YOUR GAS SUPPLIER FROM A NEIGHBOR’S
PHONE.
F
OLLOW THE GAS SUPPLIER’S INSTRUCTIONS.
•
I
F YOU CANNOT REACH YOUR GAS SUPPLIER, CALL THE FIRE
DEPARTMENT.
–
I
NSTALLATION AND SERVICE MUST BE PERFORMED BY A QUALIFIED INSTALLER,
SERVICE AGENCY OR THE GAS SUPPLIER.
HIGH ALTITUDE DERATE
The furnace, as shipped, requires no change to run between
0-4500 feet. At all altitudes the air temperature rise must
be within the range listed on the the Specification Sheet
applicable to your model for the fuel used. Manifold pressure
adjustments and combustion analysis are required for all
installations above 4500 ft. Refer to “Gas Supply Pressure
Measurement” section for instruction on how to properly
measure and adjust manifold “outlet” pressure. The furnace
should operate for a minimum of 15 minutes before taking
a combustion sample. Combustion samples should be
taken from beyond the furnace exhaust and must be within
provided CO2% range. See table below for recommended
manifold pressure adjustments and proper CO2% range. Gas
heating values can vary; further pressure adjustment may
be necessary to ensure furnace operates within acceptable
CO2 range.
MODEL
Manifold
Pressure
at 5000 ft
Manifold
Pressure
at 7500 ft
CO
2
%
Natural
Gas
Max Allowable
Venting (3 in
only)
*MES960403BU
100 ft
*MES960603BU
100 ft
*MES960805CU
80 ft
2.5" w.c.
2.4" w.c. 6.5 - 8.5
ELECTRICAL CONNECTIONS
WARNING
T
O A
V
O
I
D TH
E
RISK
OF
E
L
E
CT
RI
CAL
S
HOC
K
,
WIRI
NG TO TH
E
U
N
I
T
MUS
T B
E
P
R
OP
ER
LY POLA
RI
Z
E
D AND G
R
O
U
ND
E
D.
WARNING
H
I
GH
V
OLTAG
E
D
IS
CONN
E
CT
ALL
PO
WER
B
E
FO
RE
SERVI
C
I
NG O
R
I
N
S
TALL
I
NG TH
IS
U
N
I
T.
M
U
LT
I
PL
E
PO
WER
S
O
UR
C
ES
M
AY
B
E
P
RESE
NT.
F
A
I
L
URE
TO DO
S
O
M
AY CA
USE
P
R
OP
ER
TY
DA
M
AG
E
, P
ERS
ONAL
I
N
JUR
Y O
R
D
E
ATH.
CAUTION
L
AB
E
L ALL
WIRES
P
RI
O
R
TO D
IS
CONN
E
CT
I
ON
W
H
E
N
SERVI
C
I
NG CONT
R
OL
S
.
W
IRI
NG
ERR
O
RS
CAN CO
USE
IM
P
R
OP
ER
AND DANG
ER
O
US
OP
ER
AT
I
ON.
V
ERI
FY P
R
OP
ER
OP
ER
AT
I
ON AFT
ER
SERVI
C
I
NG.
WARNING
T
O A
V
O
I
D TH
E
RISK
OF
E
L
E
CT
RI
CAL
S
HOC
K
,
I
N
JUR
Y, O
R
D
E
ATH, TH
E
F
UR
NAC
E
MUS
T B
E
E
L
E
CT
RI
CALLY G
R
O
U
ND
E
D
I
N ACCO
R
DANC
E
WI
TH LOCAL
COD
ES
O
R
,
I
N TH
EIR
AB
SE
NC
E
,
WI
TH TH
E
LAT
ES
T
E
D
I
T
I
ON OF TH
E
N
AT
I
ONAL
E
L
E
CT
RI
C
C
OD
E
.
WARNING
H
I
GH
V
OLTAG
E
D
IS
CONN
E
CT
ALL
PO
WER
B
E
FO
RE
SERVI
C
I
NG O
R
CHANG
I
NG ANY
E
L
E
CT
RI
CAL
WIRI
NG.
M
U
LT
I
PL
E
PO
WER
S
O
UR
C
ES
M
AY B
E
P
RESE
NT.
F
A
I
L
URE
TO DO
S
O
M
AY CA
USE
P
R
OP
ER
TY DA
M
AG
E
, P
ERS
ONAL
I
N
JUR
Y O
R
D
E
ATH.
