In contrast to the storage boiler, the instantaneous water heater turns on simultaneously with the opening of the mixer tap, after the cessation of water withdrawal, the heating instantly turns off. The algorithm is more economical - only the used volume of water is heated. Home appliances are divided into 2 groups - electric and gas water heaters. Our goal is to consider the types of water heaters, find out their pros and cons and suggest how to choose the right flow heater for an apartment, a private house, a summer residence.
Which water heater is better - gas or electric
Despite the different operating principles and energy consumption, the devices differ little in terms of operation. Columns regularly heat water, rarely break, maintenance - about once every 1-2 years.
Comment. It is understood that a flowing electric water heater is equal in power to a gas one, otherwise the comparison is incorrect.
Heating devices differ significantly in the complexity of installation. To install a geyser, the following conditions must be met:
- it is necessary to carry gas into the house - main or liquefied from cylinders (gas tank);
- obtain permission to install new gas-using equipment, order development or change of design documentation;
- organize the supply and exhaust ventilation in the room where the device is planned to be installed; in the kitchen, the existing hood and ventilation through the window are enough;
- build a chimney or provide a place for the output of the coaxial pipe through the wall;
- to connect the heater to the gas pipeline, you need to contact a specialized company, unauthorized insertion is not allowed.
How much the listed events will cost is not easy to calculate, the cost depends on the specific conditions - the region of residence, the type and degree of preparedness of the housing. To install a flowing electric heater, only one factor is important - the presence of the required electric power at the entrance to the apartment / country cottage. Connection permission is not required.
Compare both types of heaters according to other criteria:
- Electric heaters are more compact than columns, are put in any room. Gas "water heater" should not be placed in the bathroom.
- Automatic ignition in atmospheric speaker models often runs on batteries - they discharge at the wrong time.
- Inexpensive gas units with an open combustion chamber operate without electricity. This is a plus for areas where the lights are often turned off.
- Natural gas water heaters are more powerful. The range of devices from different manufacturers begins with models of 8 ... 10 kW, and electrical appliances - from 3 kilowatts.
- In Russia, natural gas is much cheaper than electricity. Accordingly, a gas-powered heater will win at an operational cost.
- On the other hand, connecting to the main gas pipeline costs fabulous money if the house is not previously gasified.
Reference. The situation with the price of energy varies depending on the country of residence. In the Baltic states and Ukraine, using electricity is cheaper than burning blue fuel.
Conclusion. The choice of instantaneous water heater depends, first of all, on the supply of the desired energy source. When there is gas, and the input power is limited to 3–3.5 kilowatts, put a column. In the absence of gas fuel, you can pick up a low-capacity mini-water heater that consumes up to 3 kW of electricity.
How to choose a heater power
Before choosing a water heater, you need to find out how much hot water is needed.The volume of water consumption is determined as follows:
- kitchen sink - up to 3 liters per minute;
- shower head - 5.5 l / min (water saving);
- take a normal shower - up to 8 l / min;
- at the same time use hot water supply (DHW) at 2-3 points, take a bath - 10 ... 15 l / min.
The technical characteristics always indicate the productivity of the device (l / min) when heated at Δt = 25 ° C, since the initial temperature of the water can be different. In summer, it reaches 15 degrees, in winter it often drops to +5 ° C.
We suggest choosing the power of the electric heater according to the table, where the calculated performance indicators are presented depending on the initial temperature:
An important point. The efficiency of flowing gas water heaters is slightly lower - 84 ... 90% versus 99% for electrical counterparts. When selecting a column, you cannot use this table, a specific model is selected by performance (the characteristic is indicated in the instruction manual).
Choose a gas column
The principle of operation of the heater is similar to the operation of a gas boiler - when it is necessary to raise the temperature of the water in the heat exchanger, the burner automatically turns on. Only the start command is given not by the temperature sensor, but by the hydraulic membrane module or the flow sensor (in turbocharged versions).
Features and varieties of hot water columns:
- There are 2 types of units - with an open and closed combustion chamber, otherwise - atmospheric and supercharged (turbo). The first take combustion air directly from the room, in a turbocharged stream it is pumped from the street by a fan.
- Atmospheric models are non-volatile, the main burner is ignited by a pilot or spark electrodes that are powered by batteries. Turbo versions must be connected to the mains.
- Columns with an open chamber work due to natural draft, therefore they need a traditional chimney. Supercharged water heaters emit gases and suck in air through a coaxial double-walled pipe brought out through the shortest route.
- The combustion rate is controlled manually or automatically - the modulation burner is controlled by an electronic unit (controller).
Tip. If you want to get more information about gas flow units, we recommend reading the article on the designs of such devices, the piping scheme and DIY installation.
How to choose a gas instantaneous water heater:
- Determine column performance based on the number of draw points. Multiply this figure by 2 - get the approximate thermal power of the unit.
- It will not be possible to install an atmospheric model into an apartment where there is no special smoke channel - the exhaust gases can not be drawn into the exhaust ventilation shaft. Need a turbo station with a coaxial chimney.
- For a private house, any "water heater" of sufficient power is suitable.
- If you have a chimney, it is better to purchase a water heater with an open chamber - it is cheaper and easier to use.
- Choose the type of ignition at your discretion - a burning ignitor or electrodes that create a spark discharge using batteries or a hydrogenerator.
Types of instantaneous electric heaters
In online stores and construction supermarkets 2 types of such devices are sold:
- Pressure apparatuses are designed for installation in a water supply system and heat water for various household needs - for a shower, a kitchen sink, a dishwasher.
- Non-pressure models are installed at the end points of the system. The most common options are a faucet nozzle for a sink or a heater with a shower head.
An important nuance. There is a fundamental difference between pressure and non-pressure electric heaters. The first are always under pressure equal to the pressure in the water supply. The second one has a valve at the inlet - it regulates the flow of water flowing through the open outlet. There is no overpressure.
Now we will deal with the design and principle of operation of various electric “grooves”.
Features of pressure units
The device of a water heating apparatus cannot be called complex:
- A copper tank with a heating element (TEN) inside is placed in a decorative plastic case.
- Tubes of cold supply and heated water outlet are connected to the tank. A strainer and a flow sensor are installed on the supply line.
- An overheating sensor, which is responsible for safety, is attached to the DHW output tube.
- The electrical part of the apparatus includes an executive relay, controls, a heating indicator lamp and terminal blocks. More "advanced" versions are equipped with an LCD display, an electronic board for automatic adjustment, a thermostat.
Reference. The heating element is a tubular heating element (1-3 pcs.) Or nickel - a chrome spiral. In the first case, the tank is made in the form of a pipe with end caps; in the second, the element takes the form of a coil, as shown in the photo.
The algorithm of work looks like this: when any hot water tap opens in the apartment, the pressure in the line drops. The flow sensor works, sends a signal to the relay, which closes the contacts and turns on the heating elements. After the cessation of water consumption, heating is turned off. If the water temperature reaches a critical threshold of 60 ... 65 ° C, the overheating sensor will break the power supply circuit and deenergize the heating elements.
In cheap devices, mechanical control of heating is involved. The hydraulic flow sensor is a common membrane, which, under the influence of water pressure, presses the rod onto the microswitch plate. The relay power circuit closes, the heater turns on. More expensive models of electric water heaters are electronically controlled.
Briefly list the features of pressure type devices:
- water heater power - from 6 to 25 kW, productivity - 3.3 l / min or more;
- supply voltage 220 or 380 volts depending on power,
- connection - single-phase or three-phase, with a separate cable from a common electrical panel;
- the device is built into the water supply system, mounted permanently;
- simple models with mechanical control “can” only heat water, in expensive versions a set of additional functions is implemented - temperature maintenance, programming of modes, several levels of protection.
For a better understanding, we offer to see an overview of a flow-type water heater from the German brand Stibel Eltron:
Differences of non-pressure apparatus
How open type heaters differ from pressure ones:
- the device serves 1 draw-off point;
- a valve is installed on the supply line to adjust the amount of heated water;
- the tank and tubes of the water heater are often made of plastic, because they do not experience the effect of high pressure;
- the power of the flow apparatus lies within 3 ... 6 kW, the volume of water is up to 3 l / min;
- the hydraulic module turns on heating when the pressure in the circuit rises, turns off after a pressure drop;
- the water heating device is easily mounted and transferred to a new place;
- devices of small power 3 ... 3.5 kW are powered from a standard 220 volt outlet.
Note. The device can be used as a regular plumbing fixture of cold water - turn off the hot water element and simply open the valve.
The rest of the design of open and closed devices are very similar. Heating elements or a spiral is placed inside a small container, an overheating sensor is provided, turning on / off is in charge of a mechanical or electronic pressure switch.
The water heater is made in 3 executions:
- faucet with a water and heating regulator mounted on the sink;
- flow module with a flexible hose and shower head at the end;
- autonomous mini-boiler for 5-10 liters with electric heating.
Installation instructions for the electric heater
You can install any instantaneous heater yourself, observing the following rules:
- The device is attached to the wall or to the sink only in the position specified in the operating instructions. Otherwise, you risk burning TEN.
- The water heater is located in a heated room, since there is always water in the tank.
- Pressure type models are best installed during the installation of the water supply network. Embedding the device in existing highways is inconvenient.
- Pipeline valves are not allowed to be installed on the “hot” line of the non-pressure device (above is a diagram of the strapping of pressure modules). From accidental shutoff of the tap, the plastic heating bulb will undergo water supply pressure and burst.
- All devices sold without a plug are connected to the mains via a circuit breaker, or better, a differential one, with a tripping current of 30 mA. The rating (amperage) is selected according to the passport of the heater, depending on the power.
- Grounding is a must!
It is better to connect a stationary electric heater to the water supply network with pipes - polypropylene or metal-plastic according to the presented scheme. Shower models and faucet water heaters, used as portable, can be connected with flexible hoses.
The power supply line of the device should be laid with a copper cable of type VVG for 3 or 5 cores. The wire section is selected according to the power consumption of the device, the parameters for the 220 and 380 V network are presented in the table.
Selection recommendations
Making a choice is much easier when you are well aware of the design and operational features of household appliances. We also found out the power. Now we will give some recommendations on how to choose an instantaneous water heater that runs on electricity:
- If the device is purchased during the installation of a water supply system, without hesitation, take the pressure version of sufficient capacity. The device will provide water to several consumers at the same time.
- A non-pressure model will fit for a summer house, summer kitchen or apartment with a ready repair. If the room is not heated, the water heater will have to be removed for the winter.
- Remember the difference in water temperatures in summer and winter. For year-round use, pick up more powerful appliances.
- Sellers often focus on an electronic duct sensor, they say, such an element is more reliable. In fact, the reliability of all heater parts depends on the quality of the product as a whole. Proof: the well-known German company Stibel Eltron equips its apparatus with hydraulic non-electronic pressure switches.
- Before buying, get acquainted with the set of functions of an electric water heater. There is no need to overpay for options that you do not plan to use.
- Do not get carried away too cheap Chinese products - they can fail at the most inopportune moment.
Reference. Some shower modules of European brands are equipped with the “contrast shower” function. It is possible to adjust the temperature and the time interval between the supply of heated water.
Finally, we present a small rating of the best manufacturers whose hot water appliances are sold in the countries of the former USSR:
- Stibel Eltron;
- Electrolux;
- AEG;
- Kospel;
- Atmor;
- Termex.
User reviews about electric water heaters
Usually, people leave feedback when they are unhappy with purchased appliances. Real positive feedback is rare. Here are a few suggestions regarding flowing electrical appliances, we hope this helps to understand which heater is better.
Hope, Samara.
We have been using the Atmor Basic electric shower for 2 years. Installed by ourselves, because the device is very easy to install, fasteners were included. In addition, we have a three-phase socket for a washing machine in our apartment. There was only one minus of the water heater - a plastic shower head cracked from an accidental blow to the bathtub. Otherwise, there are no complaints - there is enough hot water for washing.
Milena, the city of Railway.
Due to lack of space and old wiring in the apartment, they decided to purchase a flowing electric water heater Electrolux Smartfix 3.5 kW. Unfortunately, a miracle did not happen - at 2 kilowatts the water runs barely warm, at the maximum the wiring starts to warm up. The device, of course, has nothing to do with it, it’s such inappropriate conditions for us. There’s nowhere to hang the boiler, you’ll have to make something smart with the power supply.
Valentine, Nikolaev.
Atmor Platinum 5 kW 220 V shower module is lying and dusting at home. I was tempted by the attractive price, compactness and appearance, only then I realized that the instantaneous water heater consumes a lot of current. That is, you need to conduct a separate cable with a cross-section of 6 mm², home wiring is not suitable. Paving is not a problem, but where to connect? The limit is only 3 kW, I see, it can’t do without a boiler.
Ivan, Odessa.
Electric shower water heater does not do its job well. Running water heats normally, but gives out too little, do not wash in the shower. At a price of $ 80, you can buy something more decent, for example, a boiler. I do not recommend to anyone.
If we study a larger number of reviews, we can draw the following conclusion: instantaneous electric water heaters are quite suitable for home use. Incoming complaints are often groundless - users buy a low-power device and have high expectations. A comparison with a gas water heater is appropriate here: to take a comfortable shower, you need a power of 8 kW or more.