Why Is My Tankless Water Heater Cycling Between Hot And Cold Temperatures?

If you have a tankless water heater, you are aware that it may occasionally run hot and cold. This is due to the fact that tankless heaters are designed to heat water quickly. It's pretty unusual for tankless heaters to be on high one second and then turn off the next. The concern is that this might potentially reduce the efficiency of your tankless water heater, causing your energy bill to rise! Let's take a look at why your tankless water heater runs hot and cold, what causes these oscillations, and how to solve them.

Cold Water, Hot Water

Although it is uncommon, you may encounter a tankless water heater problem known as a cold water sandwich. Your water heater will first supply hot water before a deluge of cold water followed by plenty of warm water. It appears like your tankless water heater briefly shuts down before heating water; however, this is not the case. This can happen if one fixture is switched on quickly after another is shut off. Before the gas burner can fully heat the heat exchanger, you'll get some hot water stored by the faucet, followed by cold water from the tankless water heater.

A cold water sandwich is probably not a huge concern if you're washing your hands. However, it is inconvenient to be forced to take a cold shower when you desire hot water. Here's how to get rid of this vexing water temperature variation.

How to Fix

Installing a recirculating system to your tankless unit will avoid the heat exchanger delay if you don't need a huge supply of hot water at once.

Installing a recirculating system or adding a small tank water heater are the two choices for repairing a cold water sandwich. In fact, some manufacturers now incorporate a buffer tank.

Wrong Gas Line Size

For enough gas supply, most tankless water heaters require you to lengthen(size) your gas line. If you've previously done this, and it's still running hot and cold, your line is the wrong size. To guarantee that your water heater receives adequate fuel, you may need to upgrade your gas metre.

How to Fix It

The diameter of the line for a tankless water heater should be between 1/2" and 3/4". If yours is too tiny, please contact us.

Inadequate Plumbing System Crossover

Tankless water heaters require direct access to both the supply and return lines. If the pressure balancing shower valve is not functioning, cold water can enter the hot water line, causing the hot water to become tepid. You'll experience hot and cold water bursts until the line warms up from frequent use. Without the assistance of a skilled plumber, determining the nature of the problem might be difficult.

How to Fix It

When it comes to repairing a faulty plumbing system crossover, you have two alternatives. You have two options: increase the temperature on your tankless water heater or add a pressure balancing valve. If you opt to raise the thermostat, you'll have to use hot water at every tap all the time. This gradually raises the temperature of your hot water supply, enabling it to warm up in your return line.

Flow Sensor Broken

A faulty flow sensor might cause your tankless water heater to cycle between hot and cold. The flow sensor monitors the amount of water entering your system and sends that data to the control board of your unit. When a burst of cold enters the system, the controller modulates the flame. This guarantees that you have adequate hot water around your home right away.

How to Fix

You must determine the source of the harm. Check for problems with your system's gas pressure, thermostat, or water heater component.

Corroded Lines

Corroded water lines are a typical case of hot and cold water bursts. Discoloured water or rusty-brown particles in the water are two symptoms of this condition. Internal corrosion might develop caught in your tankless heater's filter when water passes through your home's plumbing system.

How to Fix

Call an Expert

Mineral Deposition

Mineral buildup from hard water, such a filthy water filter, can cause issues with how tankless water heaters supply hot water. In fact, this type of accumulation is the leading source of temperature concerns.

How to Fix

Call an expert. You may need to descale your tankless system or install a water softener, depending on the severity of the concern.

One of the most aggravating aspects of a tankless system that runs hot and cold is the difficulty in determining why your water heater is doing so. For water heater issues in Edmonton, call Soul Mechanical for advice, as we will explain the situation and the next move.