Lochinvar 495, 065, 000 - 2 service manual Primary/Secondary Boiler Piping

Hydronic Heating Boilers and Domestic Water Heaters

INSTALLATION

Continued

Circulator Pump Requirements

This is a low mass, high efficiency hot water boiler which must have adequate flow for quiet, efficient operation. Pump selection is critical to achieve proper operation. A pump should be selected to achieve proper system design water temperature rise. Two heat exchanger head-loss charts (Figure 25A & 25B) are provided to assist in proper pump selection. Also provided is a System Temperature Rise Chart (TABLE-K). This table provides GPM and boiler head-loss at various temperature rises for each boiler based on Btu/hr input. Temperature rise is the difference in boiler inlet temperature and boiler outlet temperature while the boiler is firing.

Example: The boiler inlet temperature is 160°F (71°C) and the boiler outlet temperature is 180°F (82°C), this means that there is a 20°F (11°C) temperature rise across the boiler.

Heat Exchanger Pressure Drop Chart

Figure 25A - Pressure Drop Chart_Models 495,000 - 745,000 Btu/hr

Figure 25B - Pressure Drop Chart_Models 985,000 - 2,065,000 Btu/hr

Circulator Pump Specifications

1.Maximum operating pressure for pump must exceed system operating pressure.

2.Maximum water temperature should not exceed nameplate rating.

3.Cast iron circulators may be used for closed loop systems.

4.A properly sized expansion tank must be installed near the boiler and on the suction side of the pump.

Circulator Pump Operation

(Heating Boilers Only)

The boiler pump should run continuously unless the boiler is provided with the optional pump delay control system. This optional pump control system is available as a factory-installed option. External wire leads are furnished with this option to allow the power supply for the pump to be switched across the normally open contacts of the relay, allowing the control relay to cycle the pump on each call for heat. The field installed boiler pump (using the optional factory supplied pump control system) must not exceed 10 AMPS at 120VAC. As shipped from the factory, the optional control system is set to cycle the boiler pump on at each call for heat before the burners fire and run the pump for a 30 second period after the thermostat is satisfied. This will remove any residual heat from the combustion chamber before turning the pump off. See Wiring Diagrams, page 47.

Pump Installation and Maintenance

For installation and maintenance information on the circulator pump, refer to pump manufacturers instructions included in the instruction package.

Primary/Secondary Boiler Piping

Boiler installations with a primary/secondary piping system as shown in Figure 26 are recommended. This type of system uses a dedicated pump to supply flow to the boiler only. This secondary pump is sized based on desired boiler flow rate, boiler head loss and head loss in the secondary system piping only. A properly-sized system pump provides adequate flow to carry the heated boiler water to radiation, air over coils, etc. The points of connection to the primary system should be a maximum of 12" (or 4 pipe diameters) apart to ensure connection at a point of zero pressure drop in the primary system. Multiple boilers may also be installed with a primary/secondary manifold system as shown in Figure 27. The multiple boilers are connected to the manifold in reverse return to assist in balancing flow to multiple boilers.

￿CAUTION: DO NOT allow the flow in the primary loop to drop lower than the flow in the secondary loop at any time during boiler operation. Improper operation of the boiler(s) and possible tripping of the high limits and relief valves may occur.

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