Protecting Your Tankless Heater This Winter: Important Information You Should Know

Modern homes all over the PNW are equipped with tankless water heaters—they’re efficient, compact, and provide endless hot water. However, when the temperature drops below freezing, these high-tech systems are surprisingly vulnerable. Unlike traditional tanks that hold a large volume of heated water, tankless units rely on small, intricate copper pipes that can freeze and burst in a matter of hours.

If you want to avoid a mid-winter cold shower, here is how to winterize your tankless unit.

1. The Power of "Freeze Protection"

Most modern indoor and outdoor units come with built-in freeze protection. This system uses electric heaters to keep the internal components just above freezing.

• Crucial Step: Never unplug your unit in the winter. If the power goes out, the freeze protection goes out with it.
• Pro Tip: If you live in an area prone to power outages, consider a Battery Backup (UPS) specifically for your water heater to keep those internal heaters running.

2. The "Slow Drip" Method

If a hard freeze is coming and you’re worried about the pipes leading to the unit, use the oldest trick in the book: the slow drip.

• Find the faucet furthest from the water heater.
• Turn on the hot water tap just enough to get a thin, steady stream (about 1/8 of an inch wide).
• Why it works: Moving water is much harder to freeze than standing water. This also relieves pressure if ice does begin to form.

3. Insulate Your External Pipes

The unit itself might be protected, but the pipes carrying water in and out are often exposed. Use high-quality foam pipe insulation to wrap every inch of exposed copper or PEX piping.

For extreme climates, you might even consider heat tape—an electric cable that wraps around the pipe and generates heat when temperatures dip.

4. Guard Against Backdraft

This is the "silent killer" of indoor tankless units. When it’s freezing outside, cold air can travel down the vent pipe and reach the heat exchanger inside the unit.

• Ensure your vent terminations have flappers or cowls that prevent wind from blowing directly into the system.
• If your unit is in a garage or basement, make sure the room itself stays above freezing.

5. What to do During a Power Outage

If the power fails and the temperature is sub-zero, your internal freeze protection is gone. In this emergency scenario, you must drain the unit:

1. Turn off the gas and power.
2. Close the cold water inlet and hot water outlet valves.
3. Open the pressure relief valve and the drain ports (usually found on the service valves) to let all the water out of the machine.

As always, you can count on Maxwell Plumbing for

any tankless water heater maintenance, repairs, or replacement.

Call 360-209-4048 or book your FREE ESTIMATE on our website www.maxwellplumbingPNW.com