How to Fill a Hot Water Boiler

According to the International Mechanical Code, a boiler is by definition a closed heating appliance intended to supply hot water or steam for space heating, processing or power purposes. The typical boiler installed in a residential environment operates with water as its main heating medium. Normally, these boilers have an automatic fill device to maintain an adequate water volume to prevent boiler failure and to ensure heating capacities. Fortunately, it is very easy to fill most boilers when the occasion rises.

Things You'll Need

• Radiator bleed key

Instructions

1. Confirm the minimum operating pressure of the boiler relief valve.

2. Close all bleed valves and boiler drains.

3. Turn on water supply to boiler and activate the manual override for the automatic fill valve.

4. Shut the manual override when the boiler reaches within 5 to 10 psi of the minimum operating pressure of the boiler pressure relief valve.

5. Bleed the radiators starting with the farthest and highest point first.

6. Check the boiler system for leaks.

7. Proceed with a live heating cycle to confirm the proper operation of the system.

Tips & Warnings

• Be patient in the bleed process, it can take a couple of trips to the same radiator due to individual piping characteristics.

• Never leave the boiler unattended throughout the process, because of risk of flooding and/or damage to the system.

References

• Weil-Mclain: Boiler Manuals
• Triangle Tube: Installation Instructions