How long does it take for a tankless water heater to heat up in 2022 – Complete Guide

There are many kinds of water heaters available today, each having a somewhat different duration required to heat the water.  Among these, the tank and tankless water heaters are the most common to be compared. Tank water heater stores water and heat it as a whole and can take 30-40 min for a gas tank water heater, while an electric tank water heater can take 60- 80 min.

On the other hand, a tankless water heater takes only a few seconds to bring the water to your desired temperature. Usually, it can take 5-15 seconds to bring the hot water to your desired temperature depending upon the tankless temperature setting.

Now that you know the answer how long does it take for a tankless water heater to heat up? Let us go over the reason why your unit is taking longer than it should.

Why is my tankless water heater taking so long to heat up

There could be various reasons why your water heater is taking so long to heat water. We have compiled some of the common reasons why your tankless water heater could be taking longer to heat the water.

Hindrance factor

  • Distance between unit and outlet
  • Lower water supply
  • Scalp or sediment deposit
  • Age of unit

How is the distance between unit and outlet a hindrance to getting hot water?

Before we answer your question, let us explain what it means that tankless water heaters work on-demand. The work on-demand feature means that the water heater only works when you open your faucet.  But it doesn’t mean that upon opening the tap, you will get hot water immediately unless a water recirculation system is installed in your house.

 In case it is not. It will take the same amount of time for the water to reach your faucet from the tankless unit. But this is not a drawback as around the same amount of time will be taken regardless of you have a tank or a tankless water unit. So, you will first get the cold water stuck in pipes; after that cold water has been drained will the hot water come out.

But, draining the cold water isn’t the best thing to do. As in some places like Massachusetts, there is a sewer tax imposed on people based on the water they drain in the sewer line. So the best option available is to install a water recirculation pump.

What does a water recirculation pump do?

A water recirculation pump circulates the water around your house. It comes in handy as it creates a loop using your pipelines. It distributes the hot water in your pipelines through this loop and brings cold water in the pipes back to the water heater to heat it.

This way, you get instant hot water whenever you open the tap without any delay.

Installing a water recirculation pump reduces water wastage and can save you from a sewer tax if applicable in your locality.

How does low water supply act as a hindrance to your hot water?

Every tankless water heater has a flow sensor near the point where the cold water enters the tankless water heater unit. As you open the faucet, water is pushed out of the tap, and new water from the waterline replenishes at its place, or in other words, hot water from the unit moves toward the tap. Simultaneously, freshwater is sent to the tankless water heater unit. As it enters the unit, the flow sensor sense this movement and starts the tankless water heater to heat the freshwater.

Because the tankless water heater is energy efficient and the unit’s safety has a function installed in it. What this function does is that it turns off the tankless water heater if the water drawn is less than a certain limit, like when all you need to do is water hands. This function enables the tankless to save energy and prevent the heat exchanger from overheating when the water is heated too small.

How does Scalp or Sediment act as a hindrance to your hot water?

Scalp or sediment can be a big problem, making it difficult for the tankless unit to heat the water properly. Minerals like calcium, magnesium and etc present in the water are the reason for scalp or sediment formation. If the ratio of these minerals in water is high, we call it hard water. So, if the region you live in has hard water, then your tankless unit is more likely to build up sediment, which gets deposited on the heating element. The reason being that upon heating, these minerals get separated from water under great heat and get deposited on the heating element. With time, the sediment gets deposit so much that it forms a layer which makes it harder for the heat exchanger to heat the water. Hence your water heater takes much longer to heat the water. That’s why it is recommended that you do maintenance of tankless water heater once a year or more based on the hardness of the water in your region.

How does the age of the unit act as a hindrance to your hot water?

Every appliance is susceptible to wear and tear with age because the appliance can’t keep on working at 100% efficiency. This results in the water heater heating the water and delivering it to you taking longer. It is susceptible to all the above factors but will face a greater impact if the age of the unit is nearing the end of its lifespan.

Frequently Asked Questions

Why does my tankless water heater take so long to heat up?

Two possible explanations are as follows:
1. you are exceeding the tankless water supply or
2. The distance from your water heater and outlet is far to reach quickly.

For the exceeding water supply, you need to know each tankless water heater has a maximum supply of hot water that it can provide at a time. If you exceed it, it means that tankless doesn’t get sufficient time to bring the water to the desired temperature. As a result, the water heating process will be prolonged.
While for the second problem, you need to install a recirculation pump, bringing the cold water in pipes back to the water heater and circulating the hot water into the pipes. Hence, you get hot water the instant you open the tap.

Why am I not getting hot water from my tankless water heater?

Check whether other faucets are open simultaneously to make sure that you do not exceed the maximum capacity of the tankless water heater. In this case, tankless capacity can’t keep up with your demand. If this is not the issue, it could be a precursor of a bigger problem like scalp in tank or sediment on the heating element, making it harder for the hot water to reach you. This issue may be resolved by flushing your tankless water heater.

Is 140 too hot for a water heater?

Most tankless water heaters come with a temperature setting of a maximum temperature of 120. Although you can further increase the temperature to 140, it is not recommended that the water temperature above 120 Fahrenheit is too hot and can lead to scalding and burns.

How do I make my tankless water heater heat faster?

You can make your tankless water heater heat water faster in but following ways:
By installing a recirculation pump.
Keeping up with the maintenance plan.
By Controlling the water outlets open at a time.

Conclusion

Among the various factors which cause a delay in you getting hot water, it can be seen that all of these can be solved by taking proper care of your unit and by being mindful of things that cause it. So, next time be sure to find the root cause before you decide that you should replace your unit with a new one.


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