Bryan Boilers 250, & 300, 200 Boiler Commissioning, Modulation, Test Setup, PRE Checks and Setup

2.3BOILER COMMISSIONING

NOTE:

All of the installation instructions found in section 1 must be completed before commissioning the boiler.

WARNING:

The following procedures must be followed carefully before putting the boiler in operation. Failure to do so will present severe hazards to equipment, operating personnel and building occupants.

2.3.1MODULATION

Date: 8-4-2010

Revision: 0

Form: 2396

The regulating gas valve is a 1:1 differential pressure air / gas ratio controller. This means that the control adjusts the same pressure difference on the gas side as it senses on the airside. The airside pressure is the difference between the pressure in the burner housing and the pressure downstream of the furnace section. The gas side pressure is the difference between the pressure upstream and downstream of the gas limiting orifice valve. For the locations of the +/- gas and air connections see (Figure 39). Air to gas ratios are adjusted with the gas limiting orifice valve (Figure 7 item 26).

During the burner pre-purge period, when the gas valve is closed, only the air pressure difference acts on the regulator causing the air diaphragm to move to the left and closes the regulating hydraulic bypass valve. When the actuator is powered, the gas valve begins to open. The downstream gas pressure difference immediately begins to increase until the gas pressure difference is in balance with the air pressure difference.

Figure 39 Air / Gas Ratio Tappings

Modulation on the Triple-flex boiler is accomplished with air / gas ratio control. The system consists of two major components, a blower (Figure 10 item 6) and a regulating gas valve (Figure 7 item 3). The blower is variable speed and provides combustion air to the burner. The blower rpm is controlled by a PWM (pulse width modulation) signal. The PWM signal increases or decreases as the load increases or decreases in the hydronic system.

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2.3.2TEST SETUP

Connect a u-tube manometer to the gas manifold pressure tapping (Figure 7 item 12).

Connect a 0 – 5 psi gauge in the port provided in the low gas pressure switch connection (Figure 7 item 28).

Connect a u-tube manometer to the pilot gas pressure port provided (Figure 7 item 14).

A suitable combustion analyzer shall be used for measuring O2, CO, and Nox levels. The analyzer probe should be inserted in the stack above the boiler outlet and before any draft controls. Calibration is required for the Nox and CO cells at the time of commissioning.

2.3.3PRE CHECKS AND SETUP

Close the manual gas cock (Figure 7 item 4).