Gas piping, Expansion tank | Weil-McLain 550-110-710/0107 instruction

GOLD CGi Gas-Fired Water Boiler — Boiler Manual

10b Service & maintenance – annual start-up (cont.)

❏Check/test . . .

Gas piping

1.Sniff near floor and around boiler area for any in- dication of a gas leak.

2.Test gas piping using bubble test, per Section 5 of this manual, if there is any indication of a leak.

Cold fill and operating pressures

1.While the system is cold, note the pressure reading on the boiler pressure/temperature gauge.Verify that cold fill pressure is correct.

2.Watch the pressure as the boiler and system heat up to ensure pressure rise is normal. Too high a rise would indicate a waterlogged or undersized expan- sion tank.

Air vents and air elimination

1.Inspect automatic air vents (if used). Also inspect air separators to ensure they are operational.

2.The cap must be unscrewed one turn to allow air to escape.

3.See Figure 34. If the air vent is leaking, remove cap A and briefly push valve B and then release to clean the valve seat.

an 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 Section 4 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-Trolor Taco Taco-Trol. This fitting reduces gravity circula- tion of air-saturated tank water back to the system and prevents the air from bubbling up through the water as it returns from the sys- tem.

•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.

4.Replace cap A by twisting all the way onto valve B and then unscrewing one turn.

Figure 34 Automatic air vent, typical

Limit controls and cutoffs

1.Inspect and test the boiler limit control. Verify op- eration by turning control set point below boiler temperature. Boiler should cycle off. Return dial to original setting.

2.Inspect and test additional limit controls or low water cutoffs installed on system.

Expansion tank

1. Expansion tanks provide space for water to move in

Diaphragm- or bladder-type — welded gas tight with a rubber membrane to separate the tank pres- surizing 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 lo- cated on top of an air eliminator, as shown in examples in manual Section 4.

2.If relief valve has tended to weep frequently, the ex- pansion tank may be waterlogged or undersized.

Closed-type tank — tank is most likely water- logged. 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 — first, check tank size to be sure it is large enough for the system. If size is too small, add additional tank(s) as neces- sary to provide sufficient expansion. If tank size is large enough, remove tank from system and check charge pressure (usually 12 psig for residential ap- plications). If tank won’t hold pressure, membrane has been damaged. Replace tank.

46	Part Number 550-110-710/0107