How to Make Up the Water Losses for Steam Boilers

Examine your boiler and check the manual to determine whether it is a cast-iron design. Most boilers require water treatment to prevent minerals in the water from forming a scale inside the boiler and impeding its function. Water additives wear out the seals in cast-iron boilers, however, and should be avoided in that type of boiler.

Request that your water be tested by a professional boiler technician. This testing is difficult for you to perform, but it is important for the overall health of your boiler. The technician determines the mineral content currently in your water and provides water treatments to the system to dissipate those minerals so scale is avoided. Replacement water also requires this treatment, or it will contribute to boiler corrosion.

Add the water treatment chemicals to the replacement water before adding it to the boiler. Follow all instructions provided by the boiler technician at the time of water testing to ensure you don't over-treat or under-treat the new water supply. Sodium sulfite and hydrazine are two commonly used water treatments used to remove oxygen from the replacement water before it is added.

Pour the treated water into the manual fill valve of your boiler until the amount in the system registers above the fill line on the gauge.