Part number 550-100-168/0516
83
Antifreeze
1. Use only antifreeze listed by Weil-McLain as suitable for
use with SlimFit Gas Boilers. A list of approved antifreeze
products is available at www.Weil-McLain.com.
2. See Replacement parts at the end of this manual for Weil-
McLain part numbers to obtain antifreeze through a Weil-
McLain distributor.
Use the correct amount of antifreeze
1. Determine the freezing temperature needed (to protect
against lowest likely temperature the system water will
encounter).
2. Find the antifreeze concentration by volume needed for this
temperature from the antifreeze manufacturer’s data on the
antifreeze container.
$/./4
exceed 50% by volume con-
centration of antifreeze.
3. Add up the volume (gallons) of all system piping and com-
ponents, including the expansion tank and boiler.
a. Boiler water content is listed on page 121.
b. Remember to include expansion tank water content.
4. Multiply this volume by the (percent) antifreeze needed to
find the number of gallons of antifreeze to add.
Fill and test water system
1. Fill system only after ensuring the water meets the require-
ments of this manual.
2. Close manual and automatic air vents and boiler drain valve.
3. Fill to correct system pressure. Correct pressure will vary
with each application.
a. Pressure will rise when boiler is turned on and system
water temperature increases. Operating pressure must
never exceed 80 psig.
4. At initial fill and during boiler startup and testing, check
system thoroughly for any leaks. Repair all leaks before
proceeding further.
Eliminate all system leaks. Continual fresh make-up
water will reduce boiler life. Minerals can build up
in sections, reducing heat transfer, overheating heat
exchanger, and causing heat exchanger failure.
Purge air from water system
1. Connect a hose to the purge valve (see purge/drain valves,
item 11, in piping diagrams beginning on page 14. Route hose
to an area where water can drain and be seen.
2. Close the boiler or system isolation valve between the purge
valve and fill connection to the system.
3. Close zone isolation valves.
4. Open quick-fill valve on cold water make-up line.
5. Open purge valve.
6. One zone at a time, open the isolation valves. Allow water
to run through the zone, pushing out the air. Run until no
noticeable air flow is present. Close the zone isolation valves
and proceed with the next zone. Follow this procedure until
all zones are purged.
Clean system to remove sediment
1. You must thoroughly flush the system (without boiler
connected) to remove sediment. The high-efficiency heat
exchanger can be damaged by buildup or corrosion due to
sediment.
2. If necessary, use an approved chemical cleaning agent, fol-
lowing the manufacturer’s guidelines for procedures. A list of
approved cleaning products is available at www.Weil-McLain.
com. See Replacement parts at the end of this manual for
Weil-McLain part numbers to obtain cleaning agents through
a Weil-McLain distributor.
3. For zoned systems, flush each zone separately through a purge
valve. (If purge valves and isolation valves are not already
installed, install them to properly clean the system.)
4. Flush system until water runs clean and you are sure piping
is free of sediment.
Do not use petroleum-based cleaning or sealing
compounds in boiler system. Damage to elas-
tomer seals and gaskets in system could occur,
resulting in substantial property damage.
Before filling the boiler and system with water,
verify the following.
$/./4lLLWITHSOFTENED
WATER
Boiler corrosion can occur.
Failure to comply could result in boiler failure
or unreliable operation.
Water chemistry
Water pH between 7.0 and 8.5
1. Maintain boiler water pH between 7.0 and 8.5. Check with
litmus paper or have chemically analyzed by water treatment
company.
2. If pH differs from above, consult local water treatment com-
pany for treatment needed.
3. Softened water maybe used to fill boiler providing Sentinel
X100 is added to the system at the proper dosage and properly
maintained. Without Sentinel X100, softened water
must not
be used or boiler corrosion may occur.
Hardness must be less than 7 grains
1. Consult local water treatment companies for unusually hard
water areas (above 7 grains hardness).
Chlorine concentration must be
LESS THAN 200 ppm
1. Filling with chlorinated fresh water should be acceptable since
drinking water chlorine levels are typically less than 5 ppm.
2. Do not use the boiler to directly heat swimming pool or
spa water.
3. Do not fill boiler or operate with water containing chlorine
in excess of 200 ppm.
SlimFit
®
Series 3
COMMERCIAL
CONDENSING
GAS
-
FIRED
WATER
BOILER
—
Boiler Manual
Startup — fill the system
