Honeywell EN2H-0221GE51 R0808 service manual Sdc / Dhc

Hydraulic Components SDC / DHC

By means of district heating return temperature limitation the required temperature difference is assured. The maximum limit can either be a fixed value limitation or a flexible limitation according to the outside temperature. A fixed value limit of e.g. 50°C means that the district heating return temperature will not exceed this value over the entire outside temperature range.

In case of higher outside temperatures it is desirable that the maximum limit can be reduced, i.e. flexible district heating return temperature limitation is to be adopted. Through the assignment to the respective outside temperature, the lowest possible district heating return temperature and thus good heat exploitation are obtained.

The values for the maximum limitation of the district heating return temperature (code 08) and the starting point of the flexible district heating return temperature limitation (code 09) can be set for the operation with heating circuits. The flexible return temperature limitation can be switched off by selecting 10°C as the starting point.

+40°C is set as the bottom return setpoint for the flexible return temperature limit.

If the maximum limit is exceeded, a second Pl controller intervenes with the same parameters as in the secondary control (heating temperature control).

Return temperature limit	Starting point of the flexible
	return temperature limitation
Example 1: 90°C	10°C	Factory setting
Example 2: 50°C	10°C	Fixed value limit
Example 3: 80°C	5°C
Example 4: 50°C	–10°C

148 EN2H-0221GE51 R0808