Various formulas for water heating calculations efficiency gph x 8 25 x temp.
Water heater sizing formula.
Rise x 1 0 btu input gph x 8 25 x temp.
Input heating capacity of a domestic hot water system.
H out heating capacity output btu h q flow rate gph ρ 8 34 density of water lbs gal dt temperature rise o f c p 1 0 specific heat of water btu lb o f input heating capacity.
Rise x 1 0 btu hr.
Then evaluate tank water heaters on the same gph basis to determine how many gallons of storage are needed to meet this demand.
Below we ve highlighted what size water heater you would need in our example of 6 5 gpm at a 63 f temperature rise.
Output heating capacity of a domestic hot water system.
Btu is a measure of how much energy is needed to heat water.
1 btu is equivalent to the amount of energy it takes to raise 1 lb of water by 1 f.
While tankless water heaters do not run out of hot water if not sized correctly the flow rate of that water can be adversely impacted.
Sizing tank water heaters.
The first hour rating is the number of gallons of hot water the heater can supply per hour starting with a tank full of hot water.
Smith pro size sizing program is a tool that can be used to estimate water heater requirements for many common applications.
After sizing a tankless water heater and evaluating your needs it may become clear that a tankless water.
Simply locate the appropriate water heater sizes on ecomfort using your information.
Establish peak demand measured in gallons per hour gph.
The higher the btu the more water it is capable of heating.
Pro size is intended to assist in selecting water heaters or boilers that best meet the specific job requirements.
To select the right state water heater for your home try our xpert product selector for personalized estimates of the performance and estimated energy cost.
Once you have your total flow rate and the required temperature rise you can find the right size tankless water heater for your home.
Knowing your family s first hour water usage will help you get the right size heater.
Getting a heater that is too small will create havoc in your household but getting a heater that is too big will cause you to waste money on the initial purchase and costs to.
The formula goes like this.
H out q ρ dt c p 1 where.
Water heater sizing heating water is the second biggest energy expense in your home.
Rd total gallons of 120 f water required tw total number of washers 1 2 conversion factor 160 f to 140 f c2 diversity factor for 20 minute cycle c3 diversity factor for 30 minute cycle sr minimum storage requirement.
