There are several reasons your tankless water heater isn't getting your water hot. Some have to do with the way you use water, and other reasons are related to mechanical failure. The first thing you should do is check the water and power supply because both have to be operational for the tankless heater to work. If the water is flowing through the unit and it has gas or electricity, then call a plumber for help. These are some things that can go wrong with a tankless heater.
Mineral Buildup Clogging The Heater
If your home has hard water, you'll probably need to flush out your water heater fairly often or scale will build up and clog the insides of the heater. A more permanent solution is to talk to your plumber about installing a filter or water softener to keep minerals out of the heater. Once the heater is clogged up, it has to be descaled. Your plumber can perform this task, or you can do it yourself if there are directions in your owner's manual.
Once the water is flowing freely and the unit is heating well again, you might need to prevent this problem by flushing out the heater once or twice a year if your home has very hard water.
Ignition Problems Due To Bad Parts
Your heater may display error codes that let the plumber know exactly what part is malfunctioning. If there's a problem with the heater igniting or the flame staying lit, your plumber may need to replace bad parts in the ignition system. The gas lines may also need to be checked and serviced. A blocked exhaust vent can affect airflow and lead to problems with the heater, so the plumber may need to check the vent to make sure it isn't clogged with a bird's nest or other debris.
Using Too Much Hot Water At Once
While you don't have to worry about hot water running out since there is no reservoir to empty, you do have to worry about using too much hot water at the same time. If you have multiple bathrooms and multiple people shower at the same time in the morning, it's possible there won't be enough hot water to go around. This happens when the size of the hot water heater isn't large enough for your household. You can talk to your plumber about adding a second tankless water heater, or you can just take turns with showers and never worry about running out of hot water.
For more help, reach out to tankless water heater repair services.