Keep Outdoor Tankless Water Heaters From Freezing
How to keep an exterior tankless water heater from freezing?
Outdoor tankless water heaters are built for the elements, but the water inside the unit and connected pipes can still freeze when temperatures drop—especially during windy nights, long power outages, or periods of no hot-water use. The goal is simple: keep water moving, keep the unit supplied with power (if it uses electric freeze protection), and reduce exposure to cold air.
1) Use the unit’s built-in freeze protection correctly
Many exterior tankless models include freeze-protection heaters, but they only work when the heater has power (and in some cases, when gas supply and proper ventilation are maintained). Make sure the unit stays plugged in and the circuit won’t be shut off overnight. If you’re using an outdoor propane tankless setup, confirm the installation meets the manufacturer’s clearance and venting requirements so internal protection can do its job.
2) Add pipe insulation and protect the valves
Insulate all exposed hot and cold water lines with weather-rated foam sleeves and seal gaps at fittings. Pay special attention to isolation valves, pressure relief components, and any short runs of pipe near exterior walls—these are common freeze points. Insulation won’t “heat” pipes, but it slows heat loss and buys time during sudden cold snaps.
3) Keep water from sitting still in extreme cold
When a hard freeze is expected, run a small trickle of hot water from a nearby faucet to keep flow through the heater and lines. If your area is prone to sub-freezing nights, consider installing a recirculation option (where compatible) or a thermostatically controlled pipe-heating cable on the most vulnerable sections (installed per code).
4) Plan for outages: drain it when you can’t protect it
If power may be lost or the heater will be unused in freezing weather, draining is the safest approach. Shut off water, open a hot-water faucet to relieve pressure, then drain the unit and lines using the service valves per the manufacturer’s procedure. For a deeper look at outdoor propane tankless operation and setup considerations, see the guide here: https://splendena.com/guide-120000-btu-outdoor-propane-tankless-5-1-gpm-guide/.
FAQ
Should I drain my tankless water heater if I’m leaving town in winter?
Yes, if temperatures may drop below freezing and you can’t guarantee power and safe freeze protection. Draining the unit and exposed lines prevents trapped water from freezing and cracking internal components.
Leave a comment