Tankless Water Heaters
 Tankless water heaters have been around since the early 1900s. Early tankless water heaters were essentially a coil of copper pipe with a gas fire below it. Early models performed well but were not very efficient and were troubled with safety problems due to the lack of safety controls. In the United States tank style became popular for residential use because they were cheap, relativity safe and did not require large gas lines. In the rest of the world the tankless water heaters were refined and improved and became the water heater of choice
 Today’s tankless water heater has a stainless steel heat exchanger with a variable gas burner that is computer controlled to adjusts the flame to get every bit of heat into the water. Some of the advantages of tankless water heaters are that they can produce unlimited amounts of hot water, what this means is you could take a shower for eternity if you could afford the gas and water.
Tankless water heaters come is sizes based on the amount of hot water the will produced based on flow and temperature rise of the water. A typical tankless heater will produce 8.5 gallons of hot water at a 40 degree temperature rise. in other word if the incoming water temperature is 50 degrees you could get 90 degree hot water at a rate of 8.5 gallons per minute. If you wanted hotter water the gallons per minute would drop. The average shower head uses 2,5 gallons of water per minute. When the tankless heater is not n use there is no gas used.
There are a few drawbacks with tankless heaters one of which is called the" cold water sandwich" this is when the water is run turned off then turned on again a small amount of cold water passes thru the heater on startup which gets sandwiched between the hot water making the water go from hot to cold then hot again. Another drawback is they are not recirculation friendly meaning that in large homes were you pump the water from the last hot water fixture back into the hot water heater to provide instant hot water normally voids or shortens the warranty. The ideal location for a tankless heater is about five feet from the fixtures it will supply. The final drawback is they require a large gas line which sometimes makes the installation unfeasible. |
Hybrid water heaters are a cross between a tankless and a tank type water heater. Due to the problems experianced with tankless water heaters especially in large homesand resurants the Hybrid was developed. the hybrid used a small tank to mix the water before leaving the water heater virtually stopping the cold water sanwich effect. Hybrid heaters also are recirculation friendly and great for large homes or resturants. 
gas available. Most tankless electric units are used in under sink type installations such as bathrooms or small hospitality sinks were it is not practical to extend the existing hot water piping or there is no hot water in the building. A typical electric hot water heater is 99% efficient.