Weil-McLain 550 MBH Nstallation And Operation Manual page 93

®
SlimFit Series 3
Annual startup
Check expansion tank
1. Expansion tanks provide space for water to move in and
out as the heating system water expands due to temperature
increase or contracts as the water cools. Tanks may be open,
closed or diaphragm or bladder type. See pages 14-19, of this
manual for suggested best location of expansion tanks and
air eliminators.
Open-type — located above highest radiator or baseboard
unit, 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 filled with water, leaving an air cushion
for expansion.
Make sure this type of tank is fitted with a tank fitting,
such as the B & G Tank-Trol or Taco Taco-Trol. This
fitting reduces gravity circulation of air-saturated
tank water back to the system and prevents the air
from bubbling up through the water as it returns
from the system.
Do not use automatic air vents in systems with closed-
type tanks. The air will escape from the system instead
of returning to the tank. Eventually, the tank will
waterlog and no longer control pressurization. The
boiler relief valve will weep frequently.
Diaphragm- or bladder-type
a rubber membrane to separate the tank pressurizing air
and the water. May be located at any point in the system,
but most often found near the boiler.
Systems with this type of expansion tank require at
least one automatic air vent, preferably located on
top of an air eliminator, as shown in examples in
this manual.
2. If relief valve has tended to weep frequently, the expansion
tank may be waterlogged or undersized.
— tank is most likely waterlogged.
Closed-type tank
Install a tank fitting if not already installed. Then check
fill level per fitting manufacturer's instructions. If fill
level is correct, check tank size against manufacturer's
instructions. Replace with a larger tank if necessary.
Diaphragm- or bladder-type
be sure it is large enough for the system. If size is too small,
add additional tank (or tanks) as necessary to provide
sufficient expansion. If tank size is large enough, remove
tank from system and check charge pressure (usually 12
psig for residential applications). If tank won't hold pres-
sure, membrane has been damaged. Replace tank.
Inspect ignition electrode
1. Remove the ignition electrode from the boiler heat exchanger.
2. Remove any white oxides accumulated on the ignition elec-
trode using steel wool. If the ignition electrode cannot be
cleaned satisfactorily, replace ignitor with a new one.
3. Reinstall ignition electrode, making sure gasket is in good
condition and correctly positioned.
4. Replace gasket if necessary.
5. Make sure the ignition electrode ground wire is under the
top screw that secures the ignitor to the casting.
Part number 550-100-168/0516
COMMERCIAL CONDENSING GAS
(continued)
— welded gas tight with
— first, check tank size to
—
-
FIRED WATER BOILER
Check ignition wiring
1. Check ignition cable electrical resistance. A good cable will
have resistance between 900 and 1000 ohms. Replace if not
acceptable.
2. Inspect boiler ground wire from ignition electrode to ground
terminal strip.
3. Verify all wiring is in good condition and securely attached.
4. Check ground continuity of wiring using continuity meter.
5. Replace ground wires if results are not satisfactory.
Check all boiler wiring
1. Inspect all boiler wiring, making sure wires are in good condi-
tion and securely attached.
Check control settings
1. Use the Control display to navigate through all settings. Adjust
settings if necessary.
2. Check settings of external limit controls (if any) and adjust
if necessary.
Perform startup and checks
1. Start boiler and perform checks and tests specified in this
manual.
2. Verify cold fill pressure is correct and that operating pressure
does not go too high.
3. Complete the check-out procedure on page 89.
Boiler Manual
93