Tankless Water Heater Low Flow Problem

Consumers often face tankless water heater low flow problems. A water heater has got some issues like other electronic items. But we can fix troubles and use them efficiently. One of the most common complications is the slow flow of water. It may happen for various reasons.

Tankless Water Heater Low Flow Problem – 3 Common Problems

It wastes time. You may need more time doing work and, for example, taking a shower or cleaning dishes. The slow flow of water causes a delay in daily work. You may get frustrated. But you don’t need to get hyper. Just follow some easy and simple tricks. If nothing works, then you should consider a plumber. The water flow rate measures the flow of water.

Measuring The Flow Rate Of Water Heater

A clear concept of the water heater’s flow rate is a must to know. Its rate is based on the bathrooms at your house. The flowing rate also helps in sizing a tankless water heater.

There are simple ways to measure flow rate—necessary items and instructions for measuring.

A 1-gallon tank is acceptable for measurement. If you have a tank of another size, then you need to do a conversion later.

To record water flowing timing, you may need a timer device like a stopwatch, smartwatch, smartphone, etc.

Turn on the tap for water.

Calculate the time until water fills the container using a timer device.

For example, you can divide 60 by the number of seconds it took to fill up a bucket. For instance, if it took 20 seconds to fill up, then 60/20= 3 gallons per minute.

Gallons per minute is the water flow measurement.

By following the above instructions, you can easily measure your water heater’s flow rate.

Water Flowing Restriction In Tankless Water Heaters

There is no need for storage in a tankless water heater. After turning on the tap, cold water comes through a pipe. Heating elements heat the water and give consumers hot water. It’s an instant hot water supply. Its output limits the flow rate. Usually, its flow rate is 2-5 GPM.

Flow Rate Of Water Heater

The gas water heater’s flow rate is higher than the electric one’s. But it cannot provide hot water instantly. The same thing happens with electric water heaters. For example, taking a shower and washing dishes at the same time may cause trouble with flowing water.

Problems and Solutions Of  Water Flowing In Water Heaters

Don’t get angry after seeing the slow flow rate of a water heater. Having a problem is normal & there is always a solution. Below I am going to describe the tankless water heater low flow problem and solution.

Should check the flow sensor regularly. If it gets damaged, it could slow the flow. Replace it with a new one if necessary.

Minimum pressure is needed for flow switch opening. The burner will not ignite on too slow a flow. It is the most frequent problem you may face.

The inlet filter gets dirty. Please keep it clean for a good flow of water.

You should install cold water and hot water lines in a sequence. If it’s installed in reverse, then there will be a problem regarding the flow of water. Installation should be done correctly.

Consumers should clean aerators in faucets regularly. Sediment builds up in faucets and slows down the flowing speed. You need to check and maintain the faucet.

Washer failing problem in a single faucet.

Faults in the valve. Repair it or replace it to get a good flow.

Install more than one water heater. You can install them near your home appliances. You should select home appliances that use the most water for work. For example, clothes washers or dishwashers.


  • Can a tankless water heater restrict the normal flow of water?

Ans. Yes, a tankless water heater can restrict the normal flow of water. Restrictions continue until water reaches the preset temperature. You can increase it by lowering the temperature. However, if the water flow problem continues, then because your heater is too small.

  • Does a tankless water heater responsible for creating low water pressure?

Ans. Yes, hard water is the main reason behind low water pressure. The Tankless system’s outlets become clogged. It happens because of the deposits in the heat exchanger.

  • What are the common problems regarding tankless water heaters?

Ans. You may face some problems using a water heater. That’s normal as tankless heaters do not heat water all the time, so they usually rust. But they do corrode sometimes. For sample gas burner, blockage, heat exchanger corrode and overheats, etc.

  • Does a tankless water heater require regular maintenance?

Ans. Of course, maintenance is a must. At least maintenance in a year is a must. Electric tankless water heater needs proper maintenance every six months. Having hard water or heater is set to a high temperature may cause problems and needs maintenance.


We can say there are various solutions regarding the tankless water heater low flow problem. All you need is to care for and maintain regularly. Careless use of anything can not run for a long time. Consumers can not tolerate slow flow rates because they need hot water fast for various work.

Tankless water heaters were invented recently with the latest technology. It brings many advantages to us. Just after seeing the slow flow problem, don’t replace it. Follow the manual book or get a plumber. A tankless heater can give you a long life service. Troubleshooting is necessary to keep an item valid.

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