Honeywell EN2H-0221GE51 R0808 service manual Primary pump, Boiler circuit pump

Hydraulic Components SDC / DHC

7.2.15Primary pump

NOTE Function only active if the PRIMARY PUMP function was assigned to one of the outputs variable output 1 or variable output 2 in the "Hydraulics" menu.

Function The primary pump is the functional equivalent of a loading pump. It is only active when heating demand to the heat generator is present. Hot-water requests are not considered.

Bus system A primary pump connected to the central device under address 10 will start up as soon as any request is present on the data bus (including all heating and hot-water circuits within the control network).

A primary pump connected to an extension controller (address 20, 30 ... 50) runs only upon a demand from the heating circuits associated with the respective control device.

Primary pump To avoid a high-temperature safety switch-off of the heat extended running time generator, the primary pump is switched off according to the set

time delay when a request to the heat generator is withdrawn.

7.2.16Boiler circuit pump

NOTE This function is only active if the BOILER CIRCUIT PUMP 1 function was assigned to one of the outputs, i.e. direct heating circuit pump, variable output 1 or variable output 2, in the "Hydraulics" menu.

Function This function is mainly used with multi-boiler systems with thermohydraulic distributors and is used for water-side cut-off of a heat generator not in use. The variable output controls a boiler circuit pump with a non-return valve with a faulty spring or a motorised shut-off device. The function becomes active immediately upon demand for the heat exchanger. The heat exchanger is not enabled until the set pre-running time expires. Once the heat generator switches off, the variable output remains active for the duration of the set extended running time.

Boiler circuit pump 2 For systems with two individual boilers or a double boiler, two boiler circuit pumps can be connected. The second output then controls the boiler circuit pump of the downstream boiler.

158 EN2H-0221GE51 R0808