How to reduce the costs for domestic hot water with controller PROMATIC® WDC

Due to the quality of construction and energy renovation of buildings we have drastically reduced the costs of heating in our houses. Here we have made big step forward in the past few years. But there are quite a few possibilities and options, to save money also in preparation of domestic hot water.

domestic hot water heatingWHERE DO LOSSES OCCUR, WHEN WE PREPARE THE DOMESTIC HOT WATER?

If we focus only on losses from the withdrawal of the domestic hot water (further on: d. h. water) from the hot water heater, the biggest heat losses occur in pipelines and distribution of d. h. water to the user or sanitary fittings. Therefore, it makes sense to pay particular attention to the quality of the pipe insulation and reduce losses, caused by the circulation of d. h. water.

 

WHERE DO LOSSES OCCUR, IF THE IMPLEMENTATION OF DOMESTIC HOT WATER CIRCULATION IS POORLY DONE?

Uncontrolled operation of the d. h. water circulation cause, that circulation pump constantly forwards the hot water to the sanitary fittings, regardless of whether the user needs it or not. This will increase the heat losses in the pipes and at the same time it will cause unnecessarily consumption of the electricity, to power the pumps. In this way we constantly mix diverse warmed water in the hot water heater – in this case we have to heat up the water regularly, although the user doesn’t use it.

Since the installed insulation of the pipe system can't be later on significantly improved, it is the only way, to maintain comfort and economical operation, that we optimize the functioning of circulation pump.

 

ADVICES FOR IMPLEMENTATION AND SETTINGS FOR ECONOMICAL OPERATION OF THE D. H. WATER CIRCULATION: 

Heating controllers PROMATIC® WDC have in addition to numerous functions for space heating and heating system protection also a sophisticated system for economical d. h. water circulation.


  1. The operation of hot water circulating is in the first place defined and limited by time program P1 or P2 for the d. h. water. Within the time program the circulation pump is operating in intervals. By adjustment of the parameter P4.8 we determine the operating time of the pump, with the parameter P4.9, we set the idle time of pump (time when the pump is on hold/standby). The duration of the operating time must be chosen wisely – we must ensure that the hot water can make one whole circulation cycle over the pipe installation and then returns to the return or circulation connection. Standby time (pause) should be as long as possible or such, that the water doesn't cool down to the temperature below the lower limit for use. In this way we ensure that the user has immediate access to hot water and circulation works only as much as is absolutely necessary. It is factory default adjusted, that the time program for the circulation operation is the same as the time program for d. h. water heating, but we may choose that the circulation operates after separate circulation time program. This setting can be changed via parameter P4.7.

  2. In the case that we regularly use the d. h. water outside the time programs, we can help us with additional temperature sensor or a flow switch. This way we can activate (anytime) the »One time d. h. water pump circulation« outside the set time zone.

  3. When we use the temperature sensor, we connect it on the free input T1 or T8. Afterwards we make parameter adjustments - S1.4=6 (temperature sensor connected to input T1) or S1.5=7 (temperature sensor connected to input T8). Sensor must be installed on the outlet pipe of the hot water heater. Operation of the circulation is activated by short opening of the sanitary fitting for the hot water. This causes a rapid rise in temperature at the outlet pipe, which the controller detects and then activates the circulation pump. The operating time of the pump is determined by the parameter P4.8.

  4. If we use the flow switch, we also connect it on the free input T1 or T8. In this case we have to make adjustments of the parameter S1.4=7 (flow switch connected to input T1) or S1.5=8 (flow switch connected to input T8). Flow switch we install in the outlet pipe of the hot water heater. Similarly as in the previous case, functioning of the circulation is activated by short opening of the sanitary fitting for the hot water. The operating time of the pump is determined by the parameter P4.8.

NOTE: If the idle time of the circulation pump (after its operation) doesn't expires (parameter P4.9), the pump can’t be re-activated with a flow switch or temperature sensor. Also, triggering with a sensor or flow switch isn’t possible within the time schedule (time program), for the circulation of d. h. water.

 

EXAMPLE: how to implement the circulation of d. h. water by hot water heaters with the connector for circulation – hydraulic scheme # 409.

hydraulic scheme # 409

EXAMPLE: how to implement the circulation of d. h. water by hot water heaters with the connector for circulation – hydraulic scheme # 416.

(If the heater for the d. h. water doesn't have the connector for the circulation, we also use the same principle).

 

Milan Kren
Thursday, September 3, 2015