Another tankless water heater question

1,485 Views | 7 Replies | Last: 3 yr ago by InMyOpinion
75AG
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We have no water right now. Are there any concerns about our tankless water heater? Should we turn it off? I don't know nuthin' about this thing.
mosesrab90
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Assuming you're without water for a while (24 hrs) turn off the breaker to the water heater(s).
scd88
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Thanks. Dumb question - why not just turn it off at the inside control panel?
birdman
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It likely has a inlet valve for water. I would cut off the water. Same thing with gas if that is heat source. Unplug or flip breaker. Probably a way to drain the little bit of water also. That is strongly recommended.

If you haven't had hot water for the last few days, there is good chance your water control valve cracked from ice.
75AG
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Water went off around 5PM today.
scd88
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Update for those who asked about their tankless.

I lost water yesterday and turned my tankless off via the switch in our master closet. I did not turn the gas off nor did I flip the breaker.

This afternoon, our water has come back. I punched the button and it came on without a hitch. I have hot water again.

Rheem external gas unit.
InMyOpinion
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Just curious why you would need to do anything to a tankless?

Asking because I have 2 of them and I was without water/very low water pressure (not enough to trigger the unit to come on) for a little over 24.

Water was back to normal last night and everything works just fine
Chase
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InMyOpinion said:

Just curious why you would need to do anything to a tankless?

Asking because I have 2 of them and I was without water/very low water pressure (not enough to trigger the unit to come on) for a little over 24.

Water was back to normal last night and everything works just fine
Well, a tankless water heater is still comprised of pipes that can freeze. If it's indoor, it might be kept warm enough to not matter but most people have them installed on the exterior surface of the house.

If you know that you are going to have potential for really low temps and aren't looking to keep the water heater running via streams of water in the house, I'd cut off the inlet supply, drain the lines via the flush and turn it off so it doesn't have any potential for issues. A lot of folks don't run enough of a stream when they drip faucets to actually engage the water heater so they can definitely be at some risk in bad conditions.

We put a polyfill body pillow around our exposed pipes on the exterior unit and wrap them up for freezing temps but we also do streams of hot water if temps are going to be below freezing for any significant amount of time.

For those talking about using a breaker, I highly recommend a tankless install have an indoor cutoff valve for the water inlet, an indoor switch for power and, if gas, an indoor cutoff valve for the gas all placed close to the panel for adjusting temp. It really improves ease of use/maintenance, IMO.
InMyOpinion
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Chase said:

InMyOpinion said:

Just curious why you would need to do anything to a tankless?

Asking because I have 2 of them and I was without water/very low water pressure (not enough to trigger the unit to come on) for a little over 24.

Water was back to normal last night and everything works just fine
Well, a tankless water heater is still comprised of pipes that can freeze. If it's indoor, it might be kept warm enough to not matter but most people have them installed on the exterior surface of the house.

If you know that you are going to have potential for really low temps and aren't looking to keep the water heater running via streams of water in the house, I'd cut off the inlet supply, drain the lines via the flush and turn it off so it doesn't have any potential for issues. A lot of folks don't run enough of a stream when they drip faucets to actually engage the water heater so they can definitely be at some risk in bad conditions.

We put a polyfill body pillow around our exposed pipes on the exterior unit and wrap them up for freezing temps but we also do streams of hot water if temps are going to be below freezing for any significant amount of time.

For those talking about using a breaker, I highly recommend a tankless install have an indoor cutoff valve for the water inlet, an indoor switch for power and, if gas, an indoor cutoff valve for the gas all placed close to the panel for adjusting temp. It really improves ease of use/maintenance, IMO.
Gotcha

When mine were installed (external new construction) it was explained that they have internal freeze protection that would protect the internal components down to -30 (confirmed in owners manual). The plumber insulated the pex tubing visible in the box. My thoughts were that even without water or low water pressure that would not trigger the unit to kick on you would be fine, and you would not want to unplug it because that would turn off the internal freeze protection. I guess if I lost power and water for an extended period then I would be more concerned.

Obviously if I was not gonna use it at all, then drain and unplug would be the way to go.
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