In the hemispheres where temperatures get too adventurous and dip below zero, winter is never kind to the plumbing and could impact your tankless water heater by freezing it. The best way to start the process of ensuring that you can prevent the tankless water heater from freezing is to purchase a tankless water heater that can withstand stress like this before you apply the remedies.

The thing that poses the biggest danger to a tankless water heater is standing water that sits in the unit and gets exposed to these frigid temperatures. The water will expand in the unit and end up killing the fragile inner parts completely. It is more common with outdoor installations but sometimes, even indoor models placed on an exterior wall can get hit. 

These methods work for basically all tankless water heaters, provided that they are not already faulty in some other way. 

1. Install The Heater in Warm Places

No, don’t move to the tropics. Just find a place in the house that doesn’t get exposed to the cold and start with that.  It is the most common way that most people use when they are protecting their tankless water heaters. Locate the heaters away from prevailing winds and try using the vent terminations as a location. By keeping the heater in a warm place, even water that gets accidentally left in there, will not pose a danger. 

2. Drain The Heater

Winter cannot freeze the water heater itself. If you have standing water in the heater, it doesn’t matter how little, it will freeze and block the unit. The ice will most likely wreak havoc on the internal components made of plastic. To prevent this, drain the water heater when you are going to be away from the house for a long time. Isolate the water that leads into the heater by using valves that are usually on the cold and hot water lines.

3. Have a Reliable Power Source

If you were wise during the purchase, you will get a tankless water heater that has a freeze protection system, which has become pretty standard nowadays. Maintaining power will keep this system working all the time to make sure that freezing does not occur. If power is not reliable, have a backup like a battery or drain down solenoids. These can be good stand-ins for when the power goes out.

4. Recirculation System

These are added to the main water heater system to keep hot water nearby so that it can be used on demand, immediately. The warm water can keep the system from freezing by being the heat source that prevents solidification. It is an easy way to keep the water from freezing even though there needs to be power to keep the water warm and that may not be very efficient but it is better than replacing a frozen and damaged heater. Plus, you can only reserve use for winters only. 

5. Insulate

This is the standard and go-to method that is used when we are protecting our plumbing systems. Insulate everything and not just the water heater. Insulate the pipes to ensure that they do not freeze over because they could be too cold to be protected by whatever system you have, protecting the heater. This is the cardinal rule of protecting the plumbing in winter. If you follow it, you will most likely enjoy your winter. 

6. Trickling

This is a hack where you run water through the system in a trickle. If it is moving, it is harder to freeze. Run a trickle that measures anywhere between 0.1 and 0.2 gallons of water per minute. Do this through the hot side on the furthest fixture while the gas is turned off to the heater. This keeps the water running in the system and the chances of freezing become drastically lowered.

Tips and tricks are good only when you remember to use them. Do not forget that standing water in the heater is very bad. Forget everything but don’t forget this one rule.