CTHN-S
ERIES
I
NSTALLATION
, O
PERATION
AND
S
ERVICE
M
ANUAL
74 of 91
9. After lock-o
u
t, the control m
u
st be reset by
t
u
rning do
w
n the thermostat for five seconds,
then raising it again to the desired temperat
u
re,
or by disconnecting and re-connecting po
w
er to
the control.
17.3.4 To Shut Off Heater - Multiburner
17.3.5 To Start Heater - Multiburner
17.3.6 Setting the Vacuum - Multiburner
1. Set thermostats above room temperat
u
re. See
that all b
u
rners are operating properly.
2. Allo
w
at least one-half ho
u
r operation for
temperat
u
re to normalize before checking
system vac
uu
m balance. Vac
uu
m differential
can be meas
u
red by connecting a manometer
across the “tee” tappings inside the control
ho
u
sing (after meas
u
rement, the caps m
u
st be
installed on the “tees” to prevent leakage). See
for manometer connection to b
u
rner
control ho
u
sing.
3. Approximately 1.0'' of vac
uu
m differential is
req
u
ired at the b
u
rner
w
hen the system is cold.
Normal operating (hot) differential of the b
u
rners
sho
u
ld be adj
u
sted to .75"
w
c.
Vac
uu
m adj
u
stments are made by means of the
p
u
mp inlet damper and the adj
u
stable damper
co
u
pling(s). Check the vac
uu
m differential at all
b
u
rners, then adj
u
st the damper co
u
pling to obtain
eq
u
al vac
uu
m differential readings. Adj
u
st the p
u
mp
inlet damper
u
ntil vac
uu
m differentials at the b
u
rners
are as given above. With systems designed to
capacity, it may not be possible to obtain vac
uu
m
differential readings at slightly above 1"
w
c (
w
hen
cold). If so, adj
u
st damper co
u
plings to maxim
u
m b
u
t
approximately eq
u
al vac
uu
m readings. Be s
u
re to
lock all dampers sec
u
rely after adj
u
stment.
4. Reset thermostats to desired room temperat
u
re.
5. If heat is not req
u
ired, t
u
rn off main s
w
itch and
close main gas valve.
FIGURE 35: Vacuum Differential Reading
0
1
2
1
2
Remo
v
e Cap
Attach Manometer Hose
Remo
v
e Cap
Attach Manometer Hose
Manometer
Burner
.75"
w
.c.
Remove cap,
attach manometer hose.
Remove cap,
attach manometer hose.
Manometer
B
u
rner
