Weil-McLain CGi Series 3 Installation And Maintenance Manual page 48

CG i
GAS-FIRED wATER BOILER- sERIEs a -
Boiler Manual
lOb
48
Service & maintenance - annual start-up
<cont.)
0
Check/test
• • •
Gas piping
1. Sniff near floor and around boiler area for any in-
dication of a gas leak.
2. Test gas piping using bubble test, per Section 5
of this manual, if there is any indication of a leak.
Cold
fill
and operating pressures
1.
While the syste m
is
cold, note the pressure reading
on the boiler pressure/temperature gauge. Verify that
cold till pressure is correct
2. Watc h the pressure as the boiler and system heat
up to ensure pressure rise is normal. Too high a rise
would indicate a waterlogged or undersized expan -
sion tank.
Air vents and air elimination
1.
Inspect automatic air vents ( if used). Also inspect
air separators to ensure they are operational.
2. The cap must
be
unscrewed on e turn to allow air to
escape.
3. See Figure 34.1f the air vent is leaking, remove cap
A and briefly push valve B and then release to
clean
the valve seat.
4.
Replace cap
A
by tw isting all the way o nto valve B
and then unscrewing one turn.
Figure 34
Limit controls and cutoffs
1.
Inspect and test the boiler limit control Verify op-
eration by turning control set point below boiler
temperature. Boiler should cyde off. Return dial to
original setting.
2. Inspect and test additional limit controls or low
wate r cutoffS installed o n syste m.
Expansion tank
1.
Expansion tanks provide space for water to move in
an out as the heating syste m water expands d ue to
temperature increase or contracts as the water cools.
Tanks may be open, dosed or diaphragm o r bladder
type. SeeSection4 of this manual for suggested best
location of expansion tanks and air elimmators.
Open-type - located above highest radiator or
baseboard mlit, usually in the attic or closet. Has a
gauge glass and overflow pipe to a drain.
Closed-type - welded gas tight and located above
boiler. Tank is partially tilled with water, leaving an
air cushion for expansion.
Make sure tllis type of tank is fitted with a tank
IHtlng, such as the B & G
Tank-Trot
or Taco
Taco-TroL
This fitting reduces gravity circula-
tio n of air-saturated tank water back to the
system and p revents the air fro m bubbling up
thro ugh the water as it returns from the syste m.
Do not use automatic air vents In systems
with closed-type tanks. The air will escape
fro m the syste m instead of returning to the tank.
Eventually, the tank will wate rlog and no longer
control p ressurization. The boiler relief valve
will weep freq uently.
Diaphragm- or bladder-type - welded gas tight
w ith a rubber membrane to separate the tank pres-
surizing air an d the water. May be located at an y
point in the system, b ut most often found near the
boiler.
Systems with this type of expan sion tank require
at least o ne automatic air vent, preferab ly lo-
cated on top of an air eliminator, as shown in
exan1ples in manual Section 4.
2.
If relief valve has tended to weep freq uently, the ex-
pansion tank may be wate rlogged o r u ndersized.
Closed-type tank - tank is most likely water-
logged. Install a tank fitting
if
n ot already installed.
Then check fill level per fitting manufacture r's
instructions. If till level is correct, check tank size
against manufacturers instructions. Replace with
a larger tank if necessary.
Diaphragm- or bladder-type - first, check tank
size to be sure it is large enough for the syste m. If
size is too small, add additio nal tan k(s) as neces-
sary to
provide sufficient expansion . If tank size is
large enough, remove tank from system and check
charge pressure (usually 12 psig for residential ap-
plicatio ns). l f tank won' t hold pressure, membrane
has been damaged. Replace tank.
Part
Number 550-142-780/0712