[Peony58]

Just looking for a bit of advice. With temps in the mid/high 20's on Sat night through Sunday, should we be worried about our outdoor tankless water heater freezing up? The internals have a heating element to keep it warm but Inlet and outlet pipes are exposed. Thanks!

[GpaVader]

I have one but I suspect it won't be cold enough long enough to matter. If you are concerned, you can also turn a faucet on low to keep the water flowing.... I have a gas one and I'm not as concerned for those as I am for those with electric units.

[Kenswing]

Ours is a recirculating model so I'm not concerned. But for a couple of bucks it certainly wouldn't hurt to put a stick of pipe insulation on the exposed plumbing.

[retiredguy123]

I agree with adding pipe insulation, but the chance that the pipe will freeze is very slim. I would use the black foam insulation. You can also buy insulation covers for the hose bibbs, which are commonly used in colder climates. I have seen pipes freeze, but it is usually when the temperature stays below freezing for an extended period or there's a strong wind blowing against the pipe.

[TravelswithD&K]

When It's Cold Outside, Will My Outdoor Tankless Hot Water Heater Still Work? - McLay Services, Inc.

Your water heater isn’t the only thing water runs through. Your pipes are also at risk of freezing, and they don’t have the freeze prevention mechanisms that most tankless water heaters have.

If you’re unfamiliar with pipe insulation, here are a few materials you can use to protect your pipes from freeze damage effectively:

Heat tape insulation
Polyethylene insulation
Fiberglass insulation

[vintageogauge]

During January or early February of 2018 it was in the low to mid 20's and nothing froze on us, 5 or 6 hours below 32 just isn't going to freeze anything, not even your hose. I'm going to put a bucket of water outside when I get home if I don't forget just to see what it does overnight.

[JerryP]

Originally Posted by GpaVader

I have one but I suspect it won't be cold enough long enough to matter. If you are concerned, you can also turn a faucet on low to keep the water flowing.... I have a gas one and I'm not as concerned for those as I am for those with electric units.

Why would you be worried about electric water heaters they are enclosed in garages or utility rooms in garages?

[Altavia]

Originally Posted by JerryP

Why would you be worried about electric water heaters they are enclosed in garages or utility rooms in garages?

OP indicated tankless hot water heater, they are mounted on an exterior wall for homes south of 44.

[vintageogauge]

I placed a plastic cup with a couple inches of water out from 6PM until 6AM, no ice. It was 26 degrees at our home at 6AM.

[dewilson58]

Originally Posted by vintageogauge

I placed a plastic cup with a couple inches of water out from 6PM until 6AM, no ice. It was 26 degrees at our home at 6AM.

Good to know.

I was chicken, got up at 3am and ran water thru heater.

[JerryP]

Originally Posted by Robbie0723

OP indicated tankless hot water heater, they are mounted on an exterior wall for homes south of 44.

Yes you are correct, I was questioning post #2 from GpaVader.