Do NOT turn the water off unless there's an actual leak. The correct thing to do is to run the water 24/7 until temperatures rise.
You can stop the unit from freezing by preventing heat from escaping in the first place. Primarily, you want to apply fiberglass or polyethylene insulation to the pipes connected to the tankless water heater. Heat tape is another option that can prevent freezing, but it only works when there is power.
Water heaters almost always have water flowing through them, so they rarely freeze. However, if your water heater is off when the temperature outside drops below 32 degrees Fahrenheit, it may freeze within a couple of hours.
Any water heater can freeze if water is left inside it
Tank water heaters usually hold between 40 and 55 gallons and can require electricity. So when the power goes out in freezing temperatures, the water eventually can freeze, expand and burst the storage tank.
With colder water coming into the home and many water heaters located in parts of the house that tend to be exposed to colder temperatures (be it a garage or an unfinished basement), adding insulation to the water heater can help protect the appliance and help it perform better.
There are a few situations where draining your water heater is a good precaution to ensure the unit can't freeze, such as if your power ever goes out during the winter when the outside temperature is below freezing. Draining your water heater is also a good idea if you're going on vacation.
Q. During winter, why do hot-water pipes freeze and burst more frequently than cold-water pipes? A. Foster Lyons, an engineer and building-science consultant, responds: The short answer is because hot-water pipes aren't attached to toilets, which help reduce the number of burst cold-water pipes.
Open a Hot Water Valve
By opening faucets, water will have a path to flow as the pipe unfreezes. Steam will also need a place to go as heat is applied. As the pipe thaws, running water will accelerate the defrosting process. Therefore, it's beneficial to have faucets running until the pipe is completely thawed.
Prevent Frozen Pipes
Moving water keeps pipes from freezing. Find shut off valves for emergencies. Insulate pipes in unheated areas. Open cupboards and vanities to warm pipes.
In most instances, pouring hot water down the drain will unfreeze drain pipes. However, it's essential to take your time with this method to increase its effectiveness and ensure your safety. Follow these simple steps: Fill a pot with a half-gallon of water and bring it to a boil on the stove.
Frozen pipes can cut off your home's water supply and cause damaging leaks. In many cases, the help of a plumber is needed to resolve the problem. To prevent further damage, it is generally recommended that you turn off your main water supply valve and your water heater until repairs have been made.
Likely places for frozen pipes include against exterior walls or where your water service enters your home through the foundation.
Wrap pipes with heat tape or thermostatically controlled heat cables. Be sure to follow all manufacturers' installation and operation instructions. Seal leaks that allow cold air inside, near where pipes are located (i.e. around electrical wiring, dryer vents, other pipes), with caulk or insulation.
Drain the water heater. Disconnect the power and gas supply. Shut off the cold water supply.
Turn off the gas, power, and cold water, and connect a hose to your tank. Open the drain valve and let all the hot water drain out to a safe location. We recommend draining your water heater when you plan to be gone for longer than two weeks. To be extra safe, you could drain your entire plumbing system of water.
Well, water heaters are designed to heat water, and when there's no water, the system works harder to do its job. If left on, it'll try to heat an empty tank. That leads to “dry firing,” where the heating element burns out, or worse, damages the tank itself.
We repeat: keep your faucets open and your water turned off while pipes thaw! Keeping the faucets open will also expedite the thawing process and allow the thawing ice to run through the pipes.
For hidden pipes: Use an infrared lamp to target frozen areas. You may need to make an opening in your wall to access the pipe. For exposed pipes: Use a hair dryer, infrared lamp, portable heater, heating pad, heat tape, or steamed towels to apply heat (never use an open flame).
If your pipes have been frozen for more than two days, shut down your home's water supply. Locate the frozen length using touch, sight and sound. Make sure the pipe hasn't burst, and open indoor faucets. Unfreeze the pipe using a hair dryer, heat tape, space heater or heating pad.
On gas water heaters, insulation should be kept at least 6 inches from the flue. If pipes are within 8 inches of the flue, your safest choice is to use fiberglass pipe-wrap (at least 1-inch thick) without a facing. You can use either wire or aluminum foil tape to secure it to the pipe.
According to the Department of Energy, wrapping your water heater with an insulation blanket can cut standby heat losses as much as 45%. This equates to savings of up to 16% annually on your hot water bill. Quick Tip: Before you go out and purchase a water heater blanket, make sure your water heater actually needs one.
Water Heaters Outside Or In The Garage
Because the garage typically isn't climate controlled, any exposed plumbing to the water heater should be insulated to protect it from freezing. As long as the unit is running and supplied with gas/electricity, the water heater produces enough heat to protect itself from freezing.