Difference In Water Heater Btu

As for efficiency an electrical water heater can convert electricity with almost 100 efficiency to heat that can be transferred to the water.

Difference in water heater btu.

Oversize the indirect for starters. So a heater that is has a btu input rating of 80 000 btu and an efficiency rating of 85 puts out about 68 000 btu per hour. Every water heater should have a mixing valve correct. E c p dt m 1.

Input btu x efficiency 100 this number is the btu output specification. Energy stored or available in hot water can be calculated. Thus a 33 000 btu heater can heat 33 000 pounds of water by one degree in an hour. Recovery of gas fired water heaters is a function of the btu input and overall efficiency.

Water is often used to store thermal energy. For example a 30 gallon tank paired with a 160k boiler may yield the same first hour rating as a 60 gallon tank and a 90k input boiler. Dt temperature difference between the hot water and the surroundings o c o f m mass of water kg lb m. Smith 40 gallon rated at 40 000 btu input but the rheem unit that home depot sells is rated at only 38 000 btu.

Manufacturer s specs are the place to start. Input ranges from about 32 000 on a 30 gallon unit to 88 000 on a 100 gallon tank. A water heater is ranked by btu input but really means btus hr. Efficiency is measured differently for commercial gas water heaters than for residential units.

E energy kj btu c p specific heat of water kj kg o c btu lb o f 4 2 kj kg o c 1 btu lb m o f for water. Lowes sells an a o. Recovery rate a more common measure for water heaters is the recovery rate which indicates the amount of gallons of water that can be heated to 100 degrees fahrenheit in one hour. The insulation of where the heating device sits and whether any heat can escape into something other than the water like a wall concrete etc is more important for efficiency.

Only residential consumer grade water heaters defined by having a gas input of 75 000 btu or less are tested assigned an official energy factor ef rating by the doe us dept of energy. My most likely sources for a replacing my 18 year old 40 gallon 40 000 btu water heater for my home are lowes and home depot. Recovery of gas fired water heaters is a function of the btu input and overall efficiency. Most indirect manufacturers rate their tanks at varying btu hr inputs.

This is calculated by. Or 330 pounds by 100 degrees. The higher the btu input and efficiency the faster the recovery. Input ranges from about 32 000 on a 30 gallon unit to 88 000 on a 100 gallon tank.