Home
Search waterheatertimer.org / all results
Search waterheatertimer.org / all results
Search using 
Approximately: (tank capacity) x .70 + (recovery) = first hour delivery
|
Home
Search waterheatertimer.org / all results Search using
|
Calculate
first hour delivery of water heater Approximately: (tank capacity) x .70 + (recovery) = first hour delivery |
 Electric water heater thermostats Thermostats stick melt and come out of calibration... replace thermostat Symptoms: Cold water, uneven temperatures, reset tripping, TP releasing water Buy: Water heater thermostats at Amazon Resources: How to replace electric water heater thermostat Add another thermostat to water heater How to wire thermostats Marathon water heater thermostats Two water heaters Troubleshoot electric water heater |
  Gas water heater thermostats If tank is overheating or not heating correctly, replace thermostat Symptoms: Cold water, uneven temperatures, TP releasing water Buy: Gas water heater thermostats at Amazon Resources: How to replace gas water heater thermostat Add another thermostat to water heater Troubleshoot gas water heater |
| What
is first hour delivery? First hour delivery is amount of hot water a fully heated water heater can deliver in the first hour period. Start with a water heater that is fully heated (has recovered to its thermostat setting) and someone begins to use hot water such as a shower or bath. It does not mean the hot water will last for one full hour. First Hour Rating is "the calculated amount of hot water a fully heated water heater can deliver in the first hour period. Resources: Average temperature shallow groundwater How to calculate cost of running gas water heater First hour is based on 2 factors: (tank capacity) x .70 + (recovery) = first hour delivery 1) Initial storage tank capacity (gallonage of tank) 2) Recovery or the ability to heat water as it is being drawn (how fast the heater can heat the water). So a gas water heater rated for 40,000 BTU will heat water faster than 30,000 BTU, so the 40,000 BTU tank will have higher recovery, and thus higher first hour delivery. |
|
 |
ENERGYGUIDE label
sometimes shows first hour rating. The number is approximation. |
 Part I: Tank
capacity x .70"Residential water heater can deliver 70% of tank capacity at the thermostat setting minus 20 degrees. What does this mean? If the thermostat is set on 120 degrees, the unit should deliver 70% of tank volume at a temperature between 100 degrees and 120 degrees." What does 70% of tank capacity mean? It means 70% of the gallon capacity listed on the rating plate. For example 30 gallon x .7 = 21 gallons as seen on chart. |
|
| Why 70% of the tank
capacity? As hot water is being used, cold water enters bottom of heater. The cold water mixes with hot water in the tank, causing the water inside tank to cool, just like adding cold water to a hot cup of tea. As hot water is used, the dip tube, attached to the cold water inlet on water heater, delivers cold to the bottom of the tank. The pressure of incoming cold water pushes hot water out of the tank. Once cold water has mixed with the hot water, the water turns warm, then tepid, then cold. Once cold reaches 30% of tank capacity, the available hot is 70% and the water will quickly become cold. Check your heater with Draw-down test: Is the tank producing enough hot water to match size of tank? "Residential water heater can deliver 70% of tank capacity at the thermostat setting minus 20 degrees. What does this mean? If the thermostat is set on 120 degrees, the unit should deliver 70% of tank volume at a temperature between 100 degrees and 120 degrees." Steps: Turn off heater. Connect hose to drain. Run hose into 5 gallon bucket. With a 50 gallon tank. Expect minimum 70% or 35 gallons of hot water before it starts to cool. Run water fast before it cools. If result shows correct amount of hot, then tank is functioning. |
|
| Part II: Recovery Offsetting loss of heat, the water heater thermostat responds to cold water and turns on the burner or element. The tank is heating the water even while hot water is being used. This means the tank is recovering. Water heater recovery must be factored with the 70% rule to determine first hour delivery. To determine the 'ballpark' first hour delivery use the following formula: (tank capacity) x .70 + (recovery) = first hour delivery Resource:: How to calculate recovery |
| Part III: Calculate
first hour: (tank capacity) x .70 + (recovery) = first hour delivery Use chart on left for recovery. Check the rating plate of your water heater for the input in watts (electrical) or BTUs (gas). Resource:: How to calculate recovery Example first hour calculations: Summertime: Assume 60° incoming temperature and thermostat set at 120° resulting in 60° rise in temperature. 40 gallon, 30,000 BTU gas water heater (40 x .7) + 61 = 89 gallons first hour delivery Winter: Assume 40° incoming temperature and thermostat set at 120° resulting in 80° rise in temperature. 40 gallon, 30,000 BTU gas water heater (40 x .7) + 46 = 74 gallons first hour delivery |
| More first hour calculations | |
| 40 gallon
electric
water heater with 4500 watt elements: Summertime: Assume 60° incoming temperature and thermostat set at 120° resulting in 60° rise in temperature. (40 gallon x .7) + 31 gallon recovery = 59 gallons 40 gallon electric water heater with 5500 watt elements: (40 gallon x .7) + 38 gallon recovery = 66 gallons |
40 gallon
electric
water heater with 4500 watt elements: Winter: Assume 40° incoming temperature and thermostat set at 120° resulting in 80° rise in temperature (40 gallon x .7) + 23 gallon recovery = 51 gallons 40 gallon electric water heater with 5500 watt elements: (40 gallon x .7) + 28 recovery = 56 gallons |
 |
Support
the economy: Buy water heaters from my associate links: 50 gallon Gas water heaters at Amazon 40 gallon gas water heaters at Amazon 50 gallon Electric water heaters at Amazon 40 gallon electric water heaters at Amazon Hybrid / heat pump/ water heaters at Amazon Resources: How to install gas water heater How to install electric water heater Troubleshoot gas water heater Troubleshoot electric water heater Point of use water heaters |
|
|
|
||||||
 Contactors/ relays |
|
|
||||||
|
|
|
 |
Buy Electronic parts Industrial supplies Tools and home improvement Home and garden Hayward pool Pentair pool Southwire electric |
 |
Buy
Tools DEWALT Black and Decker Stanley SKIL Makita Porter-Cable Bosch Irwin Hand tools Klein hand tools Fluke electrical testing Dremel hobby tools Campbell Hausfeld air powered Tekton automotive Powerbuilt automotive Saws and saw blades |
 |
Resource: Compare box timers DPDT timers Intermatic Control water heater w/ Z-wave |
 |
Resource: Intermatic control centers: and parts Digital control centers and parts Tork control centers and parts Subpanels All control centers and parts Enclosures |
 |
Resource: Programmable timers Countdown timers Off delay timers On delay timers Timer modules Din rail Twin & one-shot Woods Intermatic Tork |
 |
Recirculation systems |
 |
Buy
from my affiliate links every time/ thanks: Amazon As an Amazon Associate I earn from qualifying purchases Enter Amazon from any link on my site, fill cart with any item ... purchases pay small commission E-mail: geno03245w@gmail.com My response might end up in spam folder, check email folders Waterheatertimer on Twitter Message thru facebook |
