Choosing a water heater size
Use the tables below to determine the recommended
sizes of standard and small element water heaters

Owners Notebook hot water heaters
Alter Eagle
Alter Eagle Construction Logo
Serving Sonoma County, based in sebastopol California
Alter Eagle Construction
A design / build residential and light commercial construction company.
CL # 769640 General B / HIC
(707) 823-5145
Example: Your home uses the most hot water during a one hour period
in the morning.
3 showers x 20 gal. = 60 gal.
1 shave x 2 gal.= 2 gal.
1 shampoo x 4 gal. = 4 gal.
Dishwashing by hand x 4 gal. = 4 gal.
Peak-Hour Demand 70 gal.
Recommended FHR: 68-72

The Owners Notebook - Hot Water Tanks
How to estimate the size of hot water tank for your home
Hot water heaters page
Maintenance
Open the drain valve at the bottom about
every 6 months, letting the water run into a
bucket until it looks clear (usually about 5
gallons). This will prevent sediment
accumulation.
Annually test the temperature-pressure relief
pressure buildup by lifting or depressing its
handle and draining water from the overflow pipe.
If water doesn't drain out, shut off water to the
heater, open a hot water faucet somewhere in
the house, and replace the valve.
Remove and inspect anode rod(s). Replace if 6
inches or more of the rods core wire is exposed.
On a gas or oil-fired unit, check combustion
chamber and flue vent for rust, corrosion,
andobstructions.
On an electric heater remove and check the
heating elements (first shut off power & drain
tank)
Water Heater Safety Tip
If steam or boiling water ever comes out of the
valve or the hot water faucets, shut the heater off
at once. If you ever hear a rumbling sound,
assume the heater is overheating and turn it off.
Water Temperature
Keep the water temperature between 120° to
130°. Check it with a thermometer held under
the tap. Higher temperatures speed corrosion.
Draining and Flushing the Tank
Turn off the gas or electricity.
Close the cold water valve.
Attach a hose to the drain valve, to route water
into a floor drain or outdoors.
Open the drain valve and open one hot
water faucet somewhere in the house to let in
air.
When all water has drained, turn the cold
water valve on and off until the water from the
drain looks clear.
Close the drain valve and the hot water faucet,
open the cold water valve and restore power.
Water Heaters are easy to ignore- until they stop working. The average one lasts about 8 to 12 years and accounts for
roughly 15 to 20% of your utility bill. So if your heater getting along in years, or if you're adding or upgrading a bathroom,
remember 3 cardinal rules of shoppiung for a standard storage water heater:
Don't rush. Size matters. Energy efficiency matters more.
Water Heater Worksheet
Use the water-consumption numbers in the chart to estimate how
many gallons of hot water you use at the busiest hour. Then add up
the "gal. used in one hour" to determine the peak demand.
A water heater's "first-hour rating" (FHR) should be within 2 gals. of
this total to meet your homes hot water needs


Use

Average Gal. / use

multiplied by Times used in One Hour

equals Gal. Used in One Hour

Shower

20

   

Bath

20

   

Shaving

2

   

Washing Hands and Face

4

   

Shampooing Hair

4

   

Dishwashing by Hand

4

   

Dishwasher

14

   

Food Preperation

5

   

Washing Clothes by Hand

26

   

Clothes Washer

32

   

(Peak-Hour Demand) TOTAL

 














Standard Water Heater Sizing

Number of Bathrooms

1 to 1.5

2 to 2.5

3 to 3.5

Number of Bedrooms

1

2

3

2

3

4

5

3

4

5

6

Nominal Tank Size

20

30

40

50

50

50

66

50

66

66

80


Small-Element Water Heater Sizing

Number of Bathrooms

1 to 1.5

2 to 2.5

Number of Bedrooms

1

2

3

1

2

3

4

Nominal Tank Size

40

52

52

52

52

66

66