First of all, deal with the source of energy for the water heater. Some of them run on electricity, others use gas. If you have a gas stove in the kitchen there is all necessary flue systems, you might want to pay attention to the gas unit, the more that costs much cheaper.
The second caveat is your decision regarding the use of water. You can purchase a tankless heater or storage. In the first case, the cold water passes through the tubes of the heater and the output hot water. In the second case the tank is filled with water, and then heated. Accordingly, the hot water, if not used, is still in the tank in a heated condition.
When considering a purchase, you should take into account the dimensions of the room where it will be your heater. Flow devices are much smaller in size. They usually hang on the wall. Accumulative waterheaters take up much more space. In some cases, they even appropriate to allocate a separate room. They are both vertical (i.e. hung on the wall) and horizontal. Some models of horizontal machines can be equipped under the sink. But remember that in this case it needs to be with bottom connection.
Gas water heaters (instantaneous waterheaters) of power are divided into three groups: small (17-19 kW), medium (22-24 kW) and high (28-30 kW) of power. If you use hot water a lot and in different places, it makes sense to take the column more powerful. Pay attention to the way the ignition column: piezosurgery or electronic. More convenient for electronic, as in this case, you open the water – column-and-play. Sparkle is formed with the help of batteries or ministertaro.
Electric flowing water heater consumes a lot of power, because its task is to instantly heat the water. Making a choice in his favor, decide for what purpose you will need. Dishwashing and showering will fit the unit with power up to 8 kW. For hot tubs you better buy a more powerful device (13 kW). But to install such a water heater must be three-phase supply voltage 380 V, which in conventional homes is not provided, and therefore, this issue you have to solve with the experts.
Cumulative electro -heaters of water economical. For their operation requires a regular socket, not three-phase network. Hot water through the insulation lasts a long time, and so if you have a reduced rate for using electricity at night, then you can heat the water. Selection of size of tank depends on your needs. For a large family and a regular bath, its volume must be at least 120-150 liters.
When buying a boiler (gas and electric), pay special attention to its protective coating. Porcelain and enamel are cheaper and not subject to corrosion. But enamel is sensitive to temperature changes. Water heaters with tanks in stainless steel and with titanium coating is more expensive but more durable.
It is important to choose the device from the point of view of thermal insulation. The thicker insulating layer in the boiler, the better. Ask also and easy replacement of the magnesium anode (prevents corrosion inside the tank). What it is, the less frequently it will need to be replaced.
Well, if your boiler will be installed, in addition to the main, an additional thermostat. This increases the safety of the unit. Whatever you buy, don't be afraid to ask more about the properties of a device from the sellers and consult with experts. Only in this case you make a purchase that will not disappoint you.