When you need to replace your water heater, there are a number of factors you’ll need to consider to help determine which type, size and model will best meet your needs. If you’re considering a standard storage tank water heater, one important factor to focus on is the recovery rate.
The recovery rate tells you how many gallons of hot water a unit can supply in one hour when starting with a full tank of cold water. If you use up all of the stored hot water in a short time, the recovery rate determines how many gallons of hot water the unit will recover or restore after one hour. The higher the recovery rate is, the less time it will take for the entire tank of water to be fully reheated to the set temperature.
Looking at recovery rates is especially important for families. You can easily use up your hot water supply in two or three showers. It’s always best to look for a unit with a higher recovery rate so that you don’t have to wait too long before you again have hot water for showering, washing dishes, doing laundry, etc.
Average Recovery Rates for Gas and Electric Water Heaters
One of the main factors that affect a water heater’s recovery rate is the type of fuel it uses. Gas water heaters produce quite a bit more heat at a time, so they have higher recovery rates than electric units. The recovery rate is also determined by how many BTUs the gas burners produce or the wattage of the electric heating elements.
The typical recovery rate for electric water heaters is around 20 gallons per hour. This means that if you used up all of the hot water and were starting with a tank full of cold water, there would be 20 gallons of hot water in the tank after one hour. Most gas water heaters have a recovery rate of around 30 to 40 gallons per hour, but some high-efficiency units can recover 50 to 70 gallons in an hour.
Gas water heaters mostly heat from the bottom since the burners are located directly underneath the tank. Some heat also flows out into the water through the exhaust flue that runs through the middle of the tank, but the majority of the heat still comes from underneath. Electric units have a heating element near the bottom of the tank and another element slightly higher up near the middle of the tank. As the unit heats, all of the hot water naturally rises to the top of the tank where the outlet pipe is located.
If you had a 40-gallon unit with an average recovery rate of 20 gallons per hour, the top half would be fully heated in an hour but there would still be cold water in the bottom half. This means you’d only be able to take one shower before the hot water runs out since a typical shower uses around 20 gallons.
As you can see, the recovery rate also tells you how long it will take before 100% of the water in the tank is hot. With an electric unit, it will take two hours or more for all of the water to be hot. If you had a gas unit with a high recovery rate, it may only take 45 minutes or so.
Factors That Affect Recovery Rates
The size of the storage tank obviously matters in terms of how many gallons of hot water you can use before running out. It can also play a role in terms of recovery rate since larger units typically have more powerful burners or heating elements and produce more heat at a time. How well-insulated the tank is also matters since this determines how well the unit holds in heat or how much heat it loses over time.
Another important thing to understand is that recovery rates aren’t constant and can be higher or lower depending on the temperature rise. Temperature rise is the number of degrees that the water needs to be raised until it is fully hot. This is determined by the temperature of the cold water as it flows into the tank and the temperature that the water heater is set to. If the water coming into the tank is 40 degrees and the water heater is set to 120 degrees, the temperature rise is 80 degrees. In this case, the recovery rate would be lower than if the temperature rise was only 60 degrees.
All water heaters will have a lower recovery rate during the winter than in summer. The reason is simply that water is colder during the winter so there is a greater temperature rise needed to fully heat it.
Understanding First-Hour Ratings
While recovery rates are important for times when you’ve used up all of the hot water, you should also focus on first-hour ratings. First-hour rating is how many gallons of hot water you can use in an hour when starting with a full hot tank, and this is determined by the unit’s recovery rate and how many gallons of water it stores. The higher the first-hour rating is, the more gallons you can use in an hour before your hot water runs out.
The first-hour rating is always higher than the recovery rate. This is simply because a water heater will immediately turn on as soon as hot water is drawn out of the tank. When you turn on the shower or use hot water in any fixture, cold water will enter the tank so that it remains full and the unit will start heating. All of the incoming cold water flows directly into the very bottom of the tank through the dip tube so that it doesn’t mix as much with the hot water.
The first-hour rating is usually the recovery rate plus 70% of the tank capacity. This means that a 40-gallon electric unit with a 20-gallon-per-hour recovery rate would have a first-hour rating of 48 gallons (40/0.7 = 28 + 20 = 48). A first-hour rating of 48 gallons per hour would allow two people to shower back to back, but it wouldn’t be sufficient for three people.
It is important to focus on both the recovery rate and first-hour rating to ensure that whatever unit you choose can effectively meet your normal daily hot water needs. If a unit has a low recovery rate and low first-hour rating, you would normally need an 80-gallon tank for four people. However, you won’t need as large of a unit if it has a higher recovery rate. For instance, you can find some high-efficiency 50-gallon gas units that have a recovery rate of 70 gallons and a first-hour rating of 106 gallons. This means that four or five people could all shower in an hour without the hot water running out.
If you need any water heater services in Garland or the Dallas area, you can count on On Time Experts. We install gas and electric tank water heaters as well as tankless units, and we also offer expert water heater repair and maintenance services. Give us a call today to learn more about your water heater replacement options or if you need any other plumbing or HVAC service.