Saving water heater - this is, simply speaking, the expansion tank, which is installed heater and protective anode for the prevention of scale. Average power storage water heater of about 1.2 - 3.0 kW, and it is perfectly suited to the requirements of our power. As for the cost, it is determined by the volume of container and the name of the manufacturer. Average price - Italian Termex and Isea (from 70 to 500 ye). More expensive water heater will cost you from REDRING (England), Stiebel Eltron, and Takagi (Japan). Their value of 200 y.e and above. The principal difference between expensive and cheap is not just in English and German heaters plenty of space is insulated (due to its water loses only 5 degrees per day), and they are covered with expensive titanium enamel.
The more expensive model, the more it needed technical functions. For example, quick radiant heating (when the water cools to 0.5 degrees, turn on automatic radiant heating).
Before you buy a water heater, you should determine for what purpose you will use it. If you only want to wash the dishes, then you have enough water heater to 10 -15 liters. To take a shower - no less than 30. For the needs of a large family of at least 100 liters. Note also that the majority of storage heaters work under pressure, they are called artesian. There is also the so-called liquid - water, they poured directly into the tank, and they are designed for one faucet (sink).