
Part Number 550-142-900/0519 5
CGa Series 2 Gas-Fired Water Boiler — Boiler Manual
 Failure to adhere totheguidelinesbelow can result in severe personalinjury,deathorsubstantial property damage.
When servicing boiler —
• To avoid electric shock, disconnect all 
electrical supplies to the boiler before 
performing maintenance.
• To avoid severe burns, allow boiler to 
cool before performing maintenance.
• This boiler contains ceramic fiber 
and fiberglass materials. Refer to 
the WARNING and instructions on 
page 66.
Boiler operation —
• Do not block flow of combustion or 
ventilation air to boiler.
• Should overheating occur or gas sup-
ply fail to shut off, do not turn off or 
disconnect electrical supply to pump. 
Instead, shut off the gas supply at a 
location external to the appliance.
Combustion air —
• DO NOT install combustion air in-
take where there is a risk of combus-
tion air contamination. 
Boiler water —
• Do not use petroleum-based cleaning 
or sealing compounds in boiler sys-
tem. Gaskets and seals in the system 
may be damaged. This can result in 
substantial property damage.
• Do not use “homemade cures” or 
“boiler patent medicines”. Serious 
damage to boiler, personnel and/or 
property may result.
• Continual fresh makeup water will 
reduce boiler life. Mineral buildup in 
sections reduces heat transfer, over-
heats cast iron, and causes section 
failure. Addition of oxygen and other 
gases can cause internal corrosion. 
Leaks in boiler or piping must be 
repaired at once to prevent makeup 
water. 
• Do not add cold water to a hot boiler. 
Thermal shock can cause heat ex-
changer to crack.
Freeze protection fluids —
• NEVER use automotive or standard 
glycol antifreeze. Use only freeze-
protection fluids made for hydronic 
systems. Follow all guidelines given 
by the antifreeze manufacturer. 
Thoroughly clean and flush any re-
placement boiler system that has used 
glycol before installing the new boiler
 Frozen Water Damage 
Hazard
Residences or buildings that are unat-
tended in severely cold weather, boiler 
system components failures, power out-
ages, or other electrical system failures 
could result in frozen plumbing and water 
damage in a matter of hours. For your 
protection, take preventative actions such 
as having a security system installed that 
operates during power outages,senses low 
temperature, and initiates an effective ac-
tion. Consult with your boiler contractor 
or a home security agency.
 If any part of a boiler, burner or its controls has 
been sprayed with or submerged under water, 
either partially or fully, DO NOT attempt to op-
erate the boiler until the boiler has been either 
replaced orcompletely repaired, inspected,and 
you are sure that the boiler and all components 
are in good condition and fully reliable.
 Otherwise, by operating this boiler, you will cause 
a fire or explosion hazard, and an electrical shock 
hazard,leading to serious injury,death,or substan-
tial property damage. See the instructions at right.
Saltwater Damage — The exposure of boiler components to 
saltwater can have both immediate and long-term effects.While the 
immediate effects of saltwater damage are similar to those of fresh-
water (shorting out of electrical components,washing out of critical 
lubricants,etc.),the salt and other contaminants left behind can lead 
to longer term issues after the water is gone due to the conductive 
and corrosive nature of the salt residue. Therefore, Weil-McLain 
equipment contaminated with saltwater or polluted water will no 
longer be covered under warranty and should be replaced.
Electrical Damage — If any electrical component or wiring 
came into contact with water, or was suspected to have come into 
contact with water, replace the boiler with a new Weil-McLain boiler.
 Installer— Read all instructions, including this 
manual and all other information shipped with the 
boiler, before installing. Perform steps in the order 
give no prevent personal injury or death.
 User — This manual is for use only by a qualified 
heating installer/service technician. Refer to User’s 
Information Manual for your reference.
 User — Have this boiler serviced/inspected by a 
qualified service technician, at least annually.
 Failure to comply with the above could result in severe 
personal injury, death or substantial property damage.
 Write in the CP number in the space provided on 
the Installation certificate on page 33 if not already 
shown.
 When calling or writing about the boiler— Please 
have the boiler model number from the boiler rating 
label and the CP number from the boiler jacket.
 Consider piping and installation when determining 
boiler location.
 Any claims for damage or shortage in shipment 
must be filed immediately against the transportation 
company by the consignee.
Please read before proceeding