RV Water Heater Recovery Calculator
Estimate RV hot-water recovery rate, time to heat the tank, mixed shower minutes, and useful BTU or kWh heat demand for propane, electric, or combined operation.
🚿RV Water Heater Presets
⚙Tank, Heat Source, Temperature, and Shower Inputs
The calculator treats water as 8.34 lb per gallon, converts electric watts with 3.412 BTU/hr per watt, derates the propane burner by altitude, and reports useful heat delivered to the tank.
🧮Recovery Formula Cards
Useful heat need
Gallons times 8.34 times temperature rise gives the useful BTU needed in the water.
Mode heat rate
Propane BTU/hr plus electric watts times 3.412 gives rated input before efficiency.
Gallons/hour
Useful BTU/hr divided by 8.34 and target temperature rise gives recovery gallons/hour.
Shower capacity
Hot fraction equals mixed minus inlet divided by tank target minus inlet, then flow sets minutes.
🔥Heater Mode and Spec Grid
📊Recovery and Shower Reference Tables
| Tank | Mode | Input | Typical Recovery |
|---|---|---|---|
| 6 gal | Propane | 10,000 BTU/hr | 8-11 gph |
| 6 gal | Electric | 1,400 W | 5-7 gph |
| 6 gal | Both | Gas + 1,400 W | 13-17 gph |
| 10 gal | Both | 12,000 + W | 15-20 gph |
| Temperature Rise | 6 Gal Heat | 10 Gal Heat | Use Case |
|---|---|---|---|
| 50 F | 2,502 BTU | 4,170 BTU | Mild inlet |
| 60 F | 3,002 BTU | 5,004 BTU | Typical camp |
| 70 F | 3,503 BTU | 5,838 BTU | Cool inlet |
| 80 F | 4,003 BTU | 6,672 BTU | Winter water |
| Hot Tank | Cold Inlet | Mixed Shower | Hot Share |
|---|---|---|---|
| 120 F | 60 F | 100 F | 67% |
| 125 F | 60 F | 103 F | 66% |
| 130 F | 55 F | 104 F | 65% |
| 140 F | 50 F | 105 F | 61% |
| Altitude Derate | 10k Burner | 12k Burner | Effect |
|---|---|---|---|
| 0% | 10,000 | 12,000 | Sea level |
| 10% | 9,000 | 10,800 | Some loss |
| 20% | 8,000 | 9,600 | Slower gas |
| 30% | 7,000 | 8,400 | High camp |
💡RV Hot Water Recovery Tips
An RV recovery calculator allow you to calculate the amount of hot water you has in your RV and how quickly the water heater can refill the water tank in your RV. You can use an RV recovery calculator to plan your water use before you reach the campground. By using an RV recovery calculator, you can ensure that you dont run out of hot water during your trip.
The first variable to enter into the RV recovery calculator is the size of the water tank. Smaller tanks hold six gallon of water. This is often enough for two people to take short showers.
How to Use an RV Hot Water Calculator
Larger tanks hold ten gallons of water. This is enough hot water for a larger group of individual. The second variable that you enter into the RV recovery calculator is the starting water temperature.
This affect the amount of heat that the water heater will need to supply to reach the desired temperature. If the water in the campground is very cold, then the water heater will have to work more hard to heat the water. This will result in a longer time for the water heater to refill the water tank.
The third variable to enter into the RV recovery calculator is the altitude. The altitude affect the propane burners of the RV. The propane burners will not have the same output at high altitudes as they will at low altitudes.
If you are camping at a high altitude, you will have to account for the reduced output of the propane burners. The next variable is the mode for the water heater. You can choose the mode of propane only, electric only or combined mode.
Propane only heat the water using propane fuel. Electric only heats the water with electricity but is only used if you have shore power to conserve propane. Combined mode use both propane and electric to heat the water to optimize the temperature.
The RV recovery calculator can calculate the number of gallons of water that the heater will deliver in an hour. This will show you the recovery rate for the water heater. The recovery rate of the water heater will tell you how much hot water can be used within one hour.
Your habit while taking showers will affect the amount of water that is used from the water heater. You will have to adjust the mixed shower temperature in the RV recovery calculator. This will determine the amount of hot water that will be needed for mixing with the cold water from the RV.
If you reduce the temperature of the water in your shower head, less hot water will be used. This will allow the water tank to last longer. The flow rate can also be adjusted.
Using a low flow rate will reduce the amount of water used per minute. This will allow you to take longer showers with the hot water that is in the RVs water tank. Another variable is the drawdown allowance.
Drawdown is the amount of water that can be used before the temperature of the water begins to drop. The drawdown allowance is usualy set at 90% but it can be adjusted. The recovery rate will allow you to calculate the time that you will have to wait between using the hot water from your RV.
The rate of 6 gallon of water per hour, for example, will calculate the number of minutes that you will have to wait once you have used 4 gallons in your shower for it to be filled again. The heat demand output of the RV recovery calculator will allow you to determine the total amount of heat that will be demanded from either the propane or the electrical heater in your RV. The heat demand output will tell you the total amount of propane that will be used or the amount of electricity that will be used by your RV.
External factor can impact the performance of the water heater. If it is cold outside, for example, the wind may cool the outside of the water heater. This will impact its recovery rate of the water heater.
If there is sediment buildup within the water tank of your RV, this can also reduce the amount of water that can be held. Another problem may be a clogged shower head which will reduce the flow rate of the water from the shower head. Cold weather may also dramaticly affect the water heater as it may remove heat from the plumbing of the RV.
The reference table can help you to understand your result. The reference tables will help you to determine the performance of different sized tanks using different mode of heaters. The reference tables also display the impact of altering the temperature rise.
The temperature rise is the difference between the initial temperature of the water and the desired temperature. If the temperature rise is large, then the recovery rate will be slower. If the temperature rise is small, then the recovery rate will be faster.
Altitude derate affect the propane burner. At high altitudes, the propane burner will have less power than at low altitudes. The altitude derate feature in the RV recovery calculator will allow for this adjustment.
Electric elements will have the same power at high altitudes as at low altitudes. You can use this RV recovery calculator to study the pattern of your RV water heater. With the RV recovery calculator, you can determine that a six-gallon tank with propane is often enough for two people.
A ten-gallon tank with combined heat settings is often enough for a family. If you used the calculations of an RV recovery calculator, you may change your habit to use a low-flow rate shower head or change the way that you take your showers. Using this calculator will help you to plan your trip to ensure that your RV has enough hot water for the number of people that will be using it.
You should of checked the tank size first. It is more important than teh flow rate. It is actualy quite simple.
Youll find it is much more comfortabley once you know the math. It isnt as hard as it looks. The furnitures in the RV might be heavy but the math isnt.
If your looking for accuracy, use this tool. You can see the results real quick. The water heater is a modernt piece of equipment.
