Raypak 133-4001 Mode H2 - Motorized Modulation, Mode H3 - 2-StageFiring, Mode H4 - On/Off Firing

MODULATING VALVES

W/ BUILT-IN REGULATOR

Fig. 28: Mechanical Modulating Valve Location

Fig. 29: Mechanical Modulating Valve

Mode H2 - Motorized Modulation

The design uses a motorized valve which varies posi- tion based upon an external controller that communicates with the gas valve actuator, through a 3-wire 0-135 ohm wiper circuit. Minimum fire is 20% of rate. The actuator runs on 120V power, and takes 26 seconds to go from fully closed to fully open. Raypak offers a single-boiler digital controller which drives the actuator; see controller options B-40 and B-41 (includes outdoor reset). For systems with mul- tiple boilers, see controller options B-45 through B-47. For a field-supplied controller with a 4-20 mA signal, see option B-35.

Mode H3 - 2-Stage Firing

The boiler will fire at low fire when there is closure across the stage 1 contacts. Thereafter, it will fire at high fire when there is closure across the stage 2 contacts. Numerous staged controllers are available.

Mode H4 - On/Off Firing

The boiler will fire at full fire when there is closure across the TH contacts. Numerous mechanical staged controllers are available (see Fig. 37), as well as digital controllers offering additional features. A typical wiring diagram for a mid-size H4 unit is shown on page 35; this basic layout applies to most other firing modes as well.

Mode H9 - 4-Stage Firing

The boiler will fire at lowest setting when there is clo- sure across the stage 1 contacts. Thereafter, it will fire at increasing rates when there is closure across the contacts for additional stages. Loss of closure across stage 1 will shut down the entire boiler imme- diately. Numerous digital controllers are available.

WH Modes

Connections for Tankstats in WH modes are shown in Figs. 30 and 31.

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Fig. 30: Single Stage Tankstat

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