How the boiler works | Weil-McLain 3 Series manual

GOLD GV Ser. 3 — User’s information manual

How the boiler works . . .

①Control module

The GCM control module responds to signals from the room thermostat, air pressure switch, inlet water sensor and boiler limit circuit to operate the circulators, gas valve, igniter and blower. When a room thermostat calls for heat, the GCM starts the system circulator and blower.

The GCM runs the blower long enough to purge the boiler flue passages, then turns on the igniter and lets it warm up.

After a 15-second warmup, the GCM opens the gas valve, turns the igniter off, and checks for flame. The flame must come on within 4 seconds or the GCM will shut down and try the full cycle again.

When the room thermostat is satisfied, the GCM turns off the boiler components and waits for the next heat call.

The GCM indicator lights show normal sequence when the lights are on steady. When a problem occurs, the GCM flashes combinations of lights which indicate the most likely reason for the problem.

②

③

Transformer

The control transformer reduces line voltage to 24 volts for the gas valve and limit circuit.

Blower

The blower pulls in air and mixes it with gas from the gas valve. The blower forces this mixture into the burner for combustion inside the boiler chamber.

④Air pressure switch

The air pressure switch signals the control module, telling the control module whether air is moving through the blower.

⑤Water temperature limit switch

The water temperature limit switch turns off the gas valve if the temperature in the boiler goes above its setting. (The circulators will continue to run as long as there is a call for heat.)

⑥System circulator

The system circulator circulates water through the external (system) piping. The flow rate of the circulator is controlled by the GCM, depending on the temperature of the water entering the boiler sections.

⑦Bypass circulator

The GCM operates the bypass circulator to mix hot water from the boiler outlet with colder return water from the system when needed to prevent condensation of flue gases in the boiler.

When the water returning to the boiler is below 140 °F, the GCM regulates the bypass circulator and system circulator flow rates to raise the water temperature up to 140 °F before it enters the boiler sections. By balancing these flow rates, the GCM can protect against condensation even if return water is as low as 60 °F.

⑧Water temperature sensor

The water temperature sensor monitors the temperature of the water entering the boiler sections. The sensor sends this information to the GCM, telling the GCM how much to adjust the circulator flow rates to provide at least 140 °F entering water.

10	Part number 550-141-812/0699

3 Series specifications

The Weil-McLain 3 Series is a highly regarded line of cast iron boilers known for their reliability, efficiency, and ease of installation. Designed to provide optimal heating solutions for residential and light commercial applications, the 3 Series is built to meet the demands of any heating challenge while ensuring long-lasting performance.

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Another significant aspect of the Weil-McLain 3 Series is its user-friendly interface. The series features intuitive controls that simplify the operation of the boiler. This ease of use extends to maintenance and serviceability, with accessible components that make it straightforward for technicians to perform regular upkeep and repairs.

The 3 Series is also equipped with innovative technology that enhances its performance. This includes the option for modulating burners, which allow the boiler to adjust its output based on the current heating needs of the space. This means less energy is wasted, leading to further cost savings for the user.

In terms of size and installation, the Weil-McLain 3 Series caters to a variety of configurations. It comes in multiple sizes and has a compact design that allows it to fit seamlessly into different environments. Whether you are upgrading an existing system or installing a new one, the 3 Series provides versatility that meets diverse heating requirements.

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