Why Does My New Water Heater Run Out of Hot Water?

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Written By Mary Samantha Katherine

Does your water heater run out of hot water within a short time? This post will give a complete idea about this issue and how to fix it.

A new water heater may go out of hot water quickly if there is an excessive demand for hot water, a small water heater, incorrect temperature setting, reduced water pressure, damaged dip tube, or sediment build-up.

Here is the list of various water heaters and their maximum temperature, pressure range, and capacity range that will help you to operate the machine effortlessly.

Type Of Water HeaterMaximum TemperaturePressure RangeCapacity Range
Conventional Tank Water HeaterMore than 120° Fahrenheit40 to 100 psi20 to 80 gallons on average
Tankless Water HeaterAs high as 140° Fahrenheit15 to 150 psi2 to 5 gallons per minute
Heat Pump Water HeaterAs high as 80° Fahrenheit12 to 150 psi40 to 80 gallons on average
Instant Gas Water HeaterAs high as 120° Fahrenheit15 to 100 psi10 to 30 liters per minute
Solar-Powered Water HeaterAs high as 80° Fahrenheit20 to 150 psi100 to 300 liters on average
Condensing Water HeaterAs high as 140° Fahrenheit15 to 80 psi34 to 75 gallons on average
Various water heaters and their maximum temperature, pressure range, and capacity range

Why Your New Water Heater Runs Out Of Hot Water Quickly And How To Solve It?

It is crucial to figure out the main culprit. Here are the most common causes that trigger a new water heater to go out of hot water swiftly.

Inadequate Water Heater Size

How many family members do you have?

Choosing a larger tank is essential if you have a large family.

You are more likely to run out of water faster if all family members actively use water daily.


If you have chosen a too-small water tank for your large family, replace it with a new one.

Here is an ideal water tank size depending on your family size.

Family SizeNumber of people in the familyIdeal Storage size
Small Family2 to 3 people50- to 60 gallons of water
Medium Family3 to 4 people70- to 80 gallons of water
Large Family4 to 6 people50- to 60 gallons of water
Water tank sizes on your family’s sizes

Excessive Demand

Do all your family members bathe or use hot water during the peak hours at a time?

This will cause a quick ending of hot water storage.

The water storage can’t cope with the excessive demand.


01. Install a new water tank with a larger water capacity.

02. Or, make a schedule for when to use the water. Avoid using it during peak hours.

03. Alternatively, increase the psi of your main water line to refill the tank rapidly.

Decreased Water Pressure

Didn’t you install a compatible water pressure regulator to ensure the optimal water pressure level?

Extremely slow or rapid changes in water pressure level can lead to a quick shortage of hot water.


01. Grab all handy tools to increase the water pressure.

02. Keep the psi level at least 40 for a smooth water flow.

03. Follow the manufacturer’s recommendation to know the ideal psi

Sediment Build-Up

Does your tap water have an extreme water hardness or too much contaminant?

Water with 120 to 170 mg/L hardness level is more likely to cause a faster sediment build-up

Cross-check the base of the water heater tank to learn its current condition.  


01. Drain ad flush all water from the water heater tank.

02. Add one gallon of cider vinegar and keep the entire tank soaked for 6 hours.

03. Finally, wash the tank properly with normal water and refill the water.

Improper Installation

Another common issue could be improper installation.

Some household owners prefer to install them of their own to save a few bucks.

But it could lead to long-term issues.


01. Hire a professional plumber if you don’t have advanced plumbing skills.

02. Go through all plumbing fittings and parts to ensure everything is installed correctly.

03. If any parts are leaked or damaged, repair or replace them immediately.

Final Words

Regardless of the reason for the quick hot water shortage in a water heater, it is crucial to address them immediately to avoid further issues in the future.


01. Vermont Department of Health, Health & The Environment, 2022. HARDNESS IN DRINKING WATER, DRINKING WATER

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