Your tankless water heater’s size is important. It is, in fact, the most crucial aspect of selecting a new unit for your house.
And if you want to replace your old 50 gallons with a new tankless water heater, then this article is for you. So know what size tankless water heater to replace a 50 gallon that you need.
What Size Tankless Water Heater Do I Need To Replace A 50 Gallon?
You would, approximately, need a 10 GPM gas tankless water heater to replace a 50-gallon. The last resort would be 11 GPM units if you needed more hot water for things like bathtubs, jacuzzis, laundry, and large bathrooms.

Here is a list of the sizes of tankless water heaters to replace a 50-gallon.
Space | Family Members | Size of Tankless Water Heater |
---|---|---|
1 bathroom | 2-3 | 4.5 GPM |
2 bathrooms | 3-4 | 6.5 GPM |
3 bathrooms | More than 4 | 8.5 GPM |
Additional Things | – | 10-11 GPM |
How To Select The Best Size Tankless Water Heater To Replace A 50 Gallon?
Unlike conventional tank-style water heaters, which are large and bulky, tankless water heaters can be mounted on a small piece of the wall.
Here are some considerations to keep in mind if you’re trying to install tankless models and aren’t sure which size to buy.
House Size
Tankless water heaters can completely steam your home’s water supply. Choosing smaller models can be ineffective.
You must ensure that the size you choose won’t produce less warm water than is necessary to fill all of your bathrooms with today’s fixtures and fittings.
Flow Rate Of The Water In Your Home

Unlike traditional tank heaters, tankless water heaters steam the water as it enters your home. This implies that the flow rate produced by your heater controls the rate at which water emerges from your taps.
Summing up two showers’ flow rates, one may determine the necessary tankless water heater flow rate.
Rise Of Temperature
Calculating how hard your heater will have to work depends on your state’s groundwater temperature.
According to estimates, certain states can experience highs of up to 75 degrees and lows of up to 35 degrees.
Size Of Households

A tankless water heater should be able to handle sporadic hot water use coming from different faucets.
A decent starting point for selecting a tank is an estimate of around 13.6 gallons per minute, which may be higher than the typical usage.
Identify The Highest Hot Water Demand
The maximum amount of hot water that your house might need is called the peak hot water demand.
It’s not meant to be a practical estimate; rather, it’s there to make sure your water heater can handle a maximum demand scenario.
Do I Need A Gas Tankless Water Heater Or A Electric Tankless Water Heater To Replace A 50 Gallon?
Gas tankless water heaters have a one-minute heat-up time of up to 5 gallons of water at 70 degrees Fahrenheit.
The power of tankless gas water heaters exceeds that of their electric counterparts. Before making a purchase, always check the product specs for GPM and temperature increase ratings.
What is the best tankless water heater size to replace 40 gallon?
How To Install The Right Size Tankless Water Heater To Replace A 50 Gallon?
The procedures for replacing a tankless water heater to replace a 50-gallon is identical.
Tools And Materials
The equipment and supplies you’ll need include a 4-in-1 screwdriver, a flexible wrench, electronic tape, a pipe wrench, Tape for plumbers, security lenses, a soldering iron, Measurement tape, Voltage tester for a tube cutter, wire cutter/stripper, Release pipe, Fitting’s compound for pipe thread, valve for pressure relief, Solder, connections and venting pipe, Gas and water piping.
Installation
You need to replace your water heater as soon as it starts to leak. In less than a day, we’ll demonstrate how to install a tankless water heater on your own.
In general, water heaters endure seven to fifteen years. If you know how to use some simple equipment and have some soldering experience, replacing a water heater is not difficult.
For installation you need to swapping out a water heater powered by natural gas. The procedure for replacing a propane water heater is the same as for replacing an electric water heater.
Which Size Tankless Water Heater Lasts Longer To Replace A 50 Gallon?
Tankless water heater durability is more influenced by type than by size. Compared to electric water heaters, gas tankless heaters often have longer lifespans.
The lifespan depends on the model and the manufacturer of the product, but generally speaking, gas-fired tankless heaters have a lifespan of over twenty years whereas electric water heaters have a lifespan of seven to ten years.
Can I Install A Tankless Water Heater To Replace A 50 Gallon Of A Certain Size By Myself?
No, as you require the skills of a certified installer, this is not a do-it-yourself project. The installation procedure is rather challenging.
It involves propane tanks, electrical circuits, gas hookups, and other things. Sometimes the store will always suggest an IT expert.
Which Tankless Water Heater Size Is Simpler To Care For Than Replacing 50 Gallons?
It stands to reason that smaller model sizes would be simpler to maintain than larger models.
Nevertheless, you will want a professional to do some checks on your tankless water heater at regular intervals. This entails leak detection, air vent inspection, burner cleaning, etc.
Consider using vinegar to flush your tankless water heater every year if you reside in a hard water location.
Final Thoughts
The highest temperature rise that may be achieved at a specific flow rate is used to rate tankless water heaters.
So, in order to size a tankless water heater when replacing it for your home, you must identify the flow rate and temperature rise you want.
It’s crucial to remember that under-sizing your tankless water heater is never a good way to save money.
So know what size tankless water heater to replace a 50-gallon and make your home hassle-free.