The simplest way to organize the flow of hot water for washing is to put a flowing electric water heater in the bathroom for a shower. A household appliance is noticeably cheaper than a storage boiler and takes up less space. When choosing and installing a heating apparatus, it is necessary to take into account a number of points - the available power consumption, the number of draw points, the state of wiring, and so on. Let's look at how to independently select and install a flowing water heater in a suburban country house or apartment.
3 types of water heating devices for a shower
Electric instantaneous water heaters that can be used for the bathroom come in 3 types:
- pressureless devices with a flexible hose and shower head;
- water heater tap with pressureless shower;
- pressure water heaters.
First, we will understand how non-pressure models differ from pressure ones. The former can serve 1 consumer, for example, a kitchen sink or shower head. When the tap is closed, water does not enter the device, after opening it is freely drained, therefore there is no excess pressure.
Flowing water heaters of pressure type crash into the water supply network of a private house (like a boiler). Accordingly, the device is constantly under pressure and is capable of servicing several points of sampling, provided that the electric heater has enough power.
Reference. The device and the principle of operation of these water heaters are approximately the same. After the tap is opened, the flow sensor is activated, the heater is turned on, the consumer receives almost instantly hot water. The heating element is protected by a second sensor, which turns off the power in case of overheating.
Features of each type of domestic hot water boilers:
- The non-pressurized instantaneous water heater with shower is a flat plastic box attached to the bathroom wall. Inside is a tubular or spiral heating element and a control unit - relay (mechanical) or electronic. Power consumption - 3 ... 6 kW, productivity - 1.6 ... 3.5 liters per minute when heated by 25 degrees.
- The water faucet with a shower head in structure resembles a conventional water mixer, only larger. A “gander” of the crane is installed on the cylindrical body and a hose with a shower is attached. Inside there is a spiral heater with a power of 3 kW, managing to heat up to 2 l / min. Some models are equipped with a digital temperature indicator.
- The pressure electric water heater is also made as compact as possible - a flat body with 2 nozzles for connecting water pipes (fittings with an external thread, diameter ½ or ¾ inch). Power of devices - from 6 to 25 kW, productivity - 3.3 ... 10 l / min.
The device, the pros and cons of different instantaneous water heaters, we examined in detail in another article. Judging by the above characteristics, the best option is a pressure "water heater" of sufficient performance. But here another problem arises - we need a decent electric power at the entrance to the house, which is often not there. How to provide hot water in various situations, read on.
Choosing an Electric Water Heater
To instantly heat running cold water, you need to spend a large amount of energy. Example: the minimum water flow for a comfortable wash in the shower should be 5.5 l / min, the required power of the electric heater is 10 kW (in summer). If you add a kitchen sink here, you need all 15 kW.
An important point. Normal temperature of shower water lies in the range of 40 ... 45 ° C.In summer, the temperature in the water supply reaches 15 ... 20 ° C, that is, the water needs to be warmed up by 20–25 degrees. In winter, it can drop to +5 ° C, much more energy will be required. This means that with a constant heater power, water consumption will decrease significantly.
To choose a flowing water heater for a shower by capacity, we suggest using the table where the performance of the appliance is indicated depending on energy consumption, initial and final water temperature.
So, the level of comfort when washing depends on the power of the water heater. But in ordinary apartments, the supply of electricity can be limited by a limit of 3 ... 3.5 kW, cottages and small private houses - 5 kW. For the shower, 10 kW is required, and this is a three-phase connection with a supply voltage of 380 volts. We’ll give a number of tips on how to get out of the situation and choose the right “water heater” correctly:
- If the limit of electricity consumption is 3 kW, the instantaneous water heater is definitely not suitable, you will have to buy a boiler, at least with a small tank of 30 liters. A 3 kilowatt filling device will provide a flow of no more than 2 l / min, this is enough only for washing dishes.
- You should not buy an electric water heater tap for a shower, whose power does not exceed the above 3 kW. According to homeowners, such a plumbing fixture allows you to slightly rinse with warm water, the flow rate is too small.
- In a country house or apartment with a limit of 5 kW, you can take a non-pressure water heater for 4 ... 4.5 kW with a flow rate of 3 l / min and above. You won’t get much comfort, but you can wash yourself in the shower. Using 2 taps at the same time will not work.
- The best option for a flow-through electric heater is a pressure model for 10 ... 12 kW. Available in private homes with a 3-phase cable line and a corresponding limit.
Recommendation. As you can see, the requirements for power supply greatly limit the choice of a water heater. Better not try experimenting by buying a low-power device up to 3 kW. Below we present an eloquent video where the user tries to show his faucet-water heater in the best light, but the result is not impressive.
Regarding the choice of the manufacturer, there are no particular preferences. If you want the water heater to look good in the interior of the bathroom, pay attention to the expensive models from the firms Termex, Stiebel Eltron or Electrolux. The appearance of pressure vessels does not matter, because they are placed in a separate room or hidden in cabinets.
In homes with autonomous heating from the boiler, do not discard the option with an indirect heating boiler. Such a storage tank will always provide you with hot water, regardless of electricity, although it will cost more.
Installation and connection of a water heater
Installation of a water heater is carried out in 3 stages:
- Laying a power cable power line, installing a residual current device (RCD or differential circuit breaker).
- Mounting the water heater itself.
- Connection to a water supply and electric network.
Powerful appliances consuming more than 3 kW can not be plugged into a conventional outlet. A separate power line should be drawn, protected by a differential circuit breaker. The minimum leakage current for the machine to operate is 30 mA.
As a conductor, we use a copper 3-wire cable (220 volt connection to the network). When the water heater requires three-phase power, we take a 5-wire cable. The working section of the cores depends on the power consumption of the device and is taken according to the table:
We lay the cable from the electric meter in the grooves of the walls or in an open way, necessarily - inside a plastic corrugated sleeve. We install the differential machine in a common cabinet with the rest of the switches. The rating of the device is selected according to the instructions of the electric heater.
How to install and connect a flow-through water heater correctly:
- The device must be mounted strictly according to the passport.If you rotate the housing 90 °, part of the heater can protrude from the water, overheat and burn. The water heater tap with shower head is screwed to the sink in an upright position.
- The room where it is planned to place the pressure model must be heated. Otherwise, the water will freeze, the ice will split the tube, this is obvious.
- It is forbidden to install additional taps at the outlet of hot water from the pressureless heater, since the internal elements of the device are not designed for water supply pressure.
- We make the piping of the water heater from polypropylene or metal-plastic pipes, we use American women for connection. Pressure versions of the devices are best connected through shut-off valves, as shown in the diagram above.
Important. A flowing electric water heater for a shower must necessarily be grounded by a separate residential cable. It connects to the corresponding terminal of the device according to the instruction manual. If your private home does not have a ground loop, we advise you to read the next section of our material.
Protective ground loop device
The most common version of this circuit is a triangle of metal ground electrodes connected by a steel strip. The same strip is displayed on the wall of the building, then connected to the body of the electrical panel with a copper bus.
How to make grounding in the form of a triangle:
- Get 3 earthing switches - smooth or corrugated reinforcement rods Ø16 mm, each 2 meters long. To connect, you need a strip of 40 x 5 mm.
- At a distance of 3 m from the base of the house, dig a foundation pit in the form of a triangle with a side of 2 m. Depth - 0.5 m.
- Sharpen the ends of the reinforcement, drive it into the ground to the full depth. Clog points are the tops of the triangular pit.
- Weld a steel strip to the ends of the rods, as done in the photo. Bring the end of the strip through the trench to the outer surface of the wall. Attach the tire to the base, weld a bolt at the end.
- From the shield, lay out the copper bus bar, screw it to the strip. The ground loop is ready.
Conclusion
The main problem when choosing an electric instantaneous water heater for a shower is to find a balance between comfort and the limit of allocated power. If a 3-phase 380 V line is drawn into the cottage, the issue is very easily resolved in favor of comfort. When the supply of electricity is limited to 4–5 kilowatts, you have to buy a low-power device, which produces barely warm water in winter. With a limit of 3–3.5 kW, only a boiler can provide a normal shower.