What Size Water Heater Do I Need For A Jacuzzi Tub? (Find Out Now!)

You’re getting ready to enjoy your new jacuzzi tub. You’ve poured yourself a glass of wine, lit some candles, have some Epsom salts and your favorite bath bomb on hand, and begun filling the tub with hot water. However, your bathtub only gets about halfway full before you’re fresh out of hot water. This is a common occurrence when your water heater isn’t big enough to accommodate your jacuzzi tub.

So, at this point, you may find yourself asking: “What size water heater do I need for a jacuzzi tub?” In order to ensure that your water heater is large enough to supply your tub, the water heater tank should be approximately 2/3 the size of the jacuzzi tub. For instance, if you have a 50-gallon water heater, it is just large enough for a 75-gallon tub.

With that said, let’s take a deeper look at how to properly size a water heater according to your needs and the size of your jacuzzi tub.

Storage tank water heaters are the most common type found in residential homes. As the name suggests, these water heaters heat water and then store it in an insulated tank until it’s needed. A pipe comes out of the top of the tank to deliver the hot water to the desired destination, whether it’s the bathroom, kitchen, or another location in the home.

As a homeowner, you’ve likely experienced the despair of running out of hot water or having to wait for the water to heat up before you can hop in the shower. These situations occur because tank-style water heaters have what’s known as a ‘recovery rate,’ which refers to the amount of hot water the water heater can provide in a given period of time. The more you depend on hot water in your home, the higher the recovery rate you’ll need.

Pros of Storage Tank Water Heaters

Although tankless water heaters are known for being pretty expensive upfront, they provide hot water pretty much on-demand – which makes sense considering they are also called ‘on-demand water heaters.’ These water heaters are outfitted with high-powered burners that heat water quickly as it runs through a heat exchanger and directly to your faucets and fixtures. As the name suggests, tankless water heaters do not utilize a tank for storage.

Tankless water heaters are between 24 and 34 percent more energy efficient than traditional storage tank water heaters. This means that they can save you quite a bit on your utility bills, and if you have a gas-fired model you can expect over $100 in annual savings. Though, the drawback to these water heaters is that they provide a limited amount of hot water per minute but the newest models can deliver up to 9.8 gallons of water per minute simultaneously!

Pros of Tankless Water Heaters

A water heater’s first hour rating (FHR) refers to how much hot water the tank can create in a single hour when fully heated. So, if a water heater has an FHR of 90 gallons, this means that it can provide up to 90 gallons of hot water in a single hour.

Ideally, you want a water heater with an FHR that either meets or exceeds the number of gallons of hot water needed for all the activities that will take place simultaneously at the busiest time during the day. Consider the numbers in the following table to help you figure out peak hour usage and your ideal FHR:

Ultimately, the size water heater that you need will depend on the specific size of your jacuzzi tub. Soaking tubs and freestanding tubs usually hold around 60 to 80 gallons of water. Whereas, corner or spa tubs can hold between 70 to 120 gallons of water. With this in mind, your water heater tank must be at least 2/3 the size of your jacuzzi tub.

So, if you jacuzzi tub holds 120 gallons, you need at least an 80-gallon water heater. If you plan on using more appliances, faucets, and fixtures at the same time, you’ll need a water heater tank that’s even bigger.

If you choose to opt for a tankless water heater instead – whether it’s for the improved energy efficiency, smaller size, or on-demand hot water – your shopping experience will be slightly different. Since tankless water heaters do not have a tank for storing water, you don’t need to concern yourself with capacity size. Instead, you must consider two key factors: flow rate and temperature rise.

Flow rate is measured in gallons per minute (GPM). To find out the size tankless water heater you need, determine the maximum number of appliances you want to run at the same time and their flow rate, then add up these rates. For temperature rise, you must subtract the incoming water temperature from the preferred output temperature.

Unless you know the incoming water temperature, you can assume that it’s 50 degrees Fahrenheit. Though, if you live in a warmer climate, it’ll be much higher. In most cases, you want the output water temperature to be between 105 and 115 degrees. This means that you’ll need a tankless water heater that produces a temperature rise of 55 degrees.

So, with these two factors in mind, the following table provides a good reference point for figuring out your home’s total simultaneous water needs: