A tankless water heater is a great idea if you want to cut down on the space your water heater takes up in your home. However, if yours isn't working right, it can cause more issues than just taking up space. If you've noticed that your tankless water heater isn't heating water appropriately or consistently enough, there are a few different things you can try to figure out what's wrong. Here is how you can troubleshoot a tankless water heater that's not heating water the way it should:

Check the thermostat

The first thing you should check is the thermostat. Many tankless water heaters have a digital thermostat, and if this is faulty, it will not turn the burner on when it's supposed to. You can also try adjusting the thermostat up or down a few degrees to see if that fixes the problem.

Check the burner

If the thermostat is working fine and your water isn't getting hot, the burner itself could be faulty. The burner is what heats the water, so if it isn't working properly, your water won't get hot. To check it, turn off the water coming into the tankless water heater, and then remove the burner from the top of the tankless water heater. If there are any leaks or signs of rust around the burner, it's time to replace it. If there aren't any leaks, try spraying some water into the burner. If it turns the burner on, the water is leaking out of the tankless water heater somewhere else. If it doesn't turn the burner on, the burner itself is faulty and needs to be replaced.

Check the burner pilot light

If the burner is working properly and the burner isn't turning on, the pilot light could be faulty. The pilot light is what heats up the burner, but it runs on propane. If the pilot light is faulty, you'll need to replace it. To check the pilot light, turn off the flow of gas to your tankless water heater, and then remove the burner from the top of the tankless water heater. If the pilot light turns the burner on, it's working properly. If it doesn't, you'll need to replace it.

Check your supply line and pressure regulator

If the burner isn't turning on, you might need to replace the supply line and pressure regulator. The pressure regulator reduces the pressure of the gas coming into the tankless water heater, and the supply line connects the regulator to the burner. If the regulator is faulty, you'll need to replace it. To check the regulator, turn off the flow of gas to your tankless water heater, and then remove the burner from the top of the tankless water heater. If the regulator is faulty, the pressure of the gas will be too high, and the gas will not flow into the burner. You'll need to replace it.

Check your gas valve

If the regulator and supply line are working properly and the burner isn't turning on, you might have a faulty gas valve. The gas valve controls the flow of gas from the main line to the tankless water heater. If the gas valve is faulty and won't turn the gas on, you'll need to replace it. To check the gas valve, turn off the flow of gas to your tankless water heater, and then remove the burner from the top of the tankless water heater. If the gas valve is faulty, the flow of gas won't be able to reach the burner and the tankless water heater won't be able to heat water.

Replacements you can try before replacing the whole unit

If none of the above fixes the problem, you can try replacing the burner, pilot light, and regulator. These are the most common things that go wrong with tankless water heaters, and replacing them should fix the problem. If you're replacing these, make sure to follow the instructions carefully and wear the correct safety gear, as burning gas is dangerous. If the problem still isn't fixed, you can replace the whole unit. If you need to replace the whole unit, make sure to contact a plumber. If you do it yourself, you could risk serious injury or death from a faulty water heater.