Individual hot water supply (DHW) today is easily organized thanks to heating and hot water equipment. Units are produced in ergonomic designs with modern control and management systems, so owners of country houses do not have any particular difficulties with the private use of such equipment. At the same time, a lot depends on the water supply scheme and configuration of equipment connection, including energy costs. In this context, the most developed and advantageous system is a hot water supply system with recirculation of the coolant.
Principle of operation of a conventional DHW structure
The traditional hot water system is implemented according to the scheme of simple wiring of cold water circuits with bottling, which rests against dead-end risers. The elevator assembly can include two taps for filling: on the return and feed lines. In accordance with the heating schedule, the DHW recirculation direction changes by switching between circuits. The active flow is shifted from return to feed and vice versa (depending on season and temperature).
What are the disadvantages of ordinary dhw?
The advantages of such schemes include simple maintenance and low implementation costs. But in practice, applications are found and quite significant shortcomings. So, why, instead of the usual wiring, many use DHW recycling? Lack of effective and timely water intake leads to cooling of water in underwater channels and risers. This means that each turn on of hot water after a certain break will require a few minutes of waiting. At this time, cold water simply drains. As a result, in the long run, costs are accumulated for unused resources, not to mention the time spent waiting for hot water treatment.
What is the difference with a recirculation system?
If the usual DHW scheme involves the withdrawal of water with an improper temperature regime into the sewer, then recirculation ensures a constant flow of liquid along the bottling between risers and inlets. In this case, only the water used for its intended purpose is discharged. Also, the DHW recirculation system has the following advantages:
- Hot water flows without delays at the tapping point, regardless of the removal of the circuit. The difference in delivery time can depend only on the quality of the piping and the efficiency of the pump, which maintains the pressure in the system, but recirculation as such, in principle, eliminates the slightest hiccups when delivering the coolant.
- In apartment buildings, heated towel rails are transferred to the riser from the in-house hot water supply. Continuous circulation in such a circuit makes the flows hot constantly. In private houses, the same thing happens, but instead of a riser, a separate bottling appears.
- The temperature in the circuits is stabilized. Thermal management depends on the settings in the thermostat (if there is an appropriate control unit), and not on cyclic cooling and heating.
Are there any flaws in recycling? Of course, this system requires the use of additional functional elements, but practice shows that the savings in the operation of hot water supply justify organizational investment.
Recirculation system equipment
A typical recycled water supply infrastructure includes the following components:
- The source of thermal energy is a boiler (necessarily double-circuit). Gas and electric models can be used depending on specific supply options. In the case of the same country house, there is not always a gas main, but it can be replaced with a gas tank or, at worst, with cylinders. The downside of electricity is the large financial costs, but this solution is safer and more reliable in any case.
- Boiler. An accumulative installation with a volume of 30-40 liters will be required if we are talking about a family of 3 people living in a private house with several hot water consumption points. Also, the boiler in the DHW with recirculation must have its own temperature control sensor, which will automate the process of regulating the coolant through the thermostat.
- Circulation pump. Actually, the main component that distinguishes the recirculation system and, in principle, makes possible the rational use of water supply circuits.
How to choose a pump for recirculation in domestic hot water?
The choice should be based on the technical and operational characteristics of the device, including power, performance and parameters of the connection pipe. The optimum power potential is 20 watts. Such a model can serve a house with an area of more than 200 m 2 , releasing about 30 l / min through a pump. Productivity up to 50 l / min and more is provided by industrial units of 30 W or more, originally designed to work with large volumes of liquids, including technical ones. For domestic use, 15 watts may be enough.
As for equipment manufacturers, Grundfos, AL-KO, Grinda and Elitech products should be considered optimal solutions. For example, the Grundfos DHW recirculation pump, made by ALPHA3 25-40, is considered one of the best in the class for homes with an area of 200 m 2 . Its stainless steel construction can be used in servicing media with temperatures up to 2-110 ° C. As for the technical parameters, the nozzle size is 25 mm, and the pressure reaches 40 m, as can be seen from the marking. According to experts, this model reduces fuel costs by up to 20%, and pays for itself in 2 years of use in an average operating mode.
Recycling in apartment buildings
The main task in ensuring recycling in the contours of apartment buildings is reduced to the formation of a ring with the continuous movement of the coolant. This is done in the following ways:
- Two hot water spills were initially brought to the building. Connection to risers is carried out in turn. As an option, you can offer a divided connection of bottling - one only to the risers, and the second - to heated towel rails.
- The bonders are bonded (if necessary, with heated towel rails) using jumpers on the upper technical room. In one group you can combine up to 4 risers. A Mayevsky crane (air vent) is installed in the jumper node, due to which excess air will be bleed from the circuit.
In order for the described DHW recirculation circuit to work, a pump is needed. It is cut between bottling and risers (heated towel rails). If necessary, several circulation pumps are used. To switch operating modes when changing the heating seasons, a collector with an elevator and inset on the pipe entry flanges is installed.
The implementation of the system in a private house
It is possible to loop over the DHW line by forwarding a distant bottling to a water supply point. The optimal recirculation scheme assumes the presence of three pipes - a standard system with an indirect heating boiler . DHW recycling in a private house will also work from a circulation pump, but with the obligatory connection of a thermostatic mixer. The fact is that the circuit with the coolant in this scheme is more susceptible to temperature differences, therefore, the presence of a regulatory node of the three-way system will not be superfluous.
Recycling Efficiency Tips
Since this is a highly responsible communication infrastructure with high equipment loads, experts advise a comprehensive approach to accident prevention measures. At least in the electrotechnical basis of the boiler and boiler, a safety block must be provided, as well as a voltage stabilizer, if we are talking about an electric boiler. In the case of gas equipment, it is recommended to use only flexible hoses when connecting. In a room with such units, effective ventilation should be organized. It will not be superfluous to have an alarm system about malfunctions or depressurization. For example, Grundfos pumping units for domestic hot water recirculation provide an indication of the operating mode characteristics, current parameters of the coolant movement and energy consumption. Periodically it is recommended to check the circuits for the quality of the connections. At the slightest deviations in pressure, crimping of the branches should be carried out - both in individual sections and in the complex.