If you completely lose water to your house, should you turn off your gas water heater, or is it OK to keep it on the lowest setting?

Looking forward to any replies

I shut ours off, even turned off the gas in the feed line

Now, curiously, I can't get the pilot to relight. Unfortunately the viewing port/glass is so hazed up on this ~7 year old Rheem I can't tell if the igniter is sparking or not

Seems somewhat coincidental the heater died at this point and won't relight

(Multiple edits 'cuz I didn't proof read my post....)

From previous post here the past week.....

Seems to be mixed opinions. I turned my water off but didn't mess with the water heater. Everything turned out fine. Couple plumbers have said it isn't dangerous because the water stays in the heater.

Tanked water heaters require positive inlet pressure to work. Ports are on top leaving the tank full even with water shut off. Unless you drain it of course.

I heard from someone else that it's ok if there's water in the tank to just leave it on pilot mode.

XXXVII said:

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If you completely lose water to your house, should you turn off your gas water heater, or is it OK to keep it on the lowest setting?

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As mentioned, as long as the tank is full, you'll be fine. It doesn't hurt to turn it off if you're worried about it, but if there's any chance of the heater being exposed to freezing temps, you'd be better off leaving it on but turning the thermostat temp (red dial on the gas valve) all the way down.

Water heaters have an inlet tube on the cold water side that direct cold water to the bottom of the heater. That tube should also have a small hole near the top of the tube that prevent siphoning, but they can sometimes siphon. If you notice hot water trickling out of the cold side with the faucet open, the heater is siphoning (emptying the tank). Something to watch for and much more likely with heaters in attics. This will only happen if the cold water side is off or frozen/blocked.

RC_57 said:

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Looking forward to any replies

I shut ours off, even turned off the gas in the feed line

Now, curiously, I can't get the pilot to relight. Unfortunately the viewing port/glass is so hazed up on this ~7 year old Rheem I can't tell if the igniter is sparking or not

Seems somewhat coincidental the heater died at this point and won't relight

(Multiple edits 'cuz I didn't proof read my post....)

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If there is an electronic ignition, there may not be a pilot, or do you know there is a pilot? Most pilots require you to hold down the red button, light the pilot, then wait long enough for the pilot flame to heat up the thermocouple (1 full minute or so). If you know there is a pilot, but the spark doesn't work, can you get a long click lighter in there? Don't mess with it if your not comfortable! I've blown my eyebrows off with propane heaters before....

If you've done all this and this pilot won't stay lit, the thermocouple may be out.

magnumtmp, thanks for replying.

Well, I got a better view of the site window, and with a better set of glasses (yea, I'm an old) and a bright beam from my headlamp, I could see into the site window.

Would appear the spark igniter is not working. I hit it a few times and never saw a spark.

Look like a trip to the plumbing supply shop Monday. Which should be fun...

RC_57 said:

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magnumtmp, thanks for replying.

Well, I got a better view of the site window, and with a better set of glasses (yea, I'm an old) and a bright beam from my headlamp, I could see into the site window.

Would appear the spark igniter is not working. I hit it a few times and never saw a spark.

Look like a trip to the plumbing supply shop Monday. Which should be fun...

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Are you holding down the pilot as you hit the spark igniter? Not trying to insult anyone's intelligence, but you have to turn the top valve to 'pilot', hold down the red button, then hit the spark igniter to get the pilot flame lit (you may have to click it several times). There should be a scallop in the valve handle that only lets you push down the pilot bypass with the valve in the pilot position. Continue to hold down the red button for about a minute once the pilot lights, only let off if the pilot goes out again. When you let off after the minute, pilot should stay lit if the thermocouple works. If you make it this far, then turn the valve from 'pilot' to 'on.' Your heater should then kick the gas on and the pilot will light the main burner.

I'll see if I can find a video.

Video with lighting instructions. He explains it pretty well.

Follow up question. I opened the pressure relief valve after putting my water heater in pilot mode. After that I just heard some gargling in my pipes, but no water came out at the drain outside. Does this indicate a problem, or would this be expected since I do not have any cold water pressure?

XXXVII said:

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Follow up question. I opened the pressure relief valve after putting my water heater in pilot mode. After that I just heard some gargling in my pipes, but no water came out at the drain outside. Does this indicate a problem, or would this be expected since I do not have any cold water pressure?

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Very normal with no pressure. You basically let a little air in, and I'd guess you have a hose bib or faucet partially open. The water you expected to come out of the T&P probably came out at that open faucet from siphon.

Ah ok. I did have a toilet with an empty bowl that was trying to fill. My concern is that maybe this whole time with no water pressure that I've been siphoning water out of my water heater through the cold water intake pipe while using faucets and toilets in my house. Is this possible?

EDIT: If I just tap on my water heater what should it sound like if it is empty vs full?

XXXVII said:

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Ah ok. I did have a toilet with an empty bowl that was trying to fill. My concern is that maybe this whole time with no water pressure that I've been siphoning water out of my water heater through the cold water intake pipe while using faucets and toilets in my house. Is this possible?

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. Yes, it is possible, but not likely at all. The fact that it gurgled when you tripped the T&P means it had a slight suction. If you had already siphoned water out, no gurgling would have happened.

I mentioned in a previous post that there should be a small hole at the top of the cold water dip tube. It's there to prevent siphon. When you opened the T&P, you let some air in at the top, which let water drain down into the toilet tank. Now that there is air at the very top of your heater, further siphoning is highly unlikely unless that hole is plugged or not there at all.

Hope this makes sense. I don't feel I'm explaining it very well.

Reply to edit: there is insulation between the steel skin and the tank itself. The sound won't tell you much. You'd be better off rocking the unit to get a feel for weight.

If you don't have water pressure, and your heater is off (gas is off), I would just let it sit and not re-light it. The really cold is passed, so freezing isn't as big an issue.

Thanks, I went ahead and just turned it off completely and also turned off the gas supply. My worry was that once it went off I wouldn't be able to re-light it since the unit is pretty old. I guess I'll find out when the water comes back.

magnumtmp said:

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RC_57 said:

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magnumtmp, thanks for replying.

Well, I got a better view of the site window, and with a better set of glasses (yea, I'm an old) and a bright beam from my headlamp, I could see into the site window.

Would appear the spark igniter is not working. I hit it a few times and never saw a spark.

Look like a trip to the plumbing supply shop Monday. Which should be fun...

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Are you holding down the pilot as you hit the spark igniter? Not trying to insult anyone's intelligence, but you have to turn the top valve to 'pilot', hold down the red button, then hit the spark igniter to get the pilot flame lit (you may have to click it several times). There should be a scallop in the valve handle that only lets you push down the pilot bypass with the valve in the pilot position. Continue to hold down the red button for about a minute once the pilot lights, only let off if the pilot goes out again. When you let off after the minute, pilot should stay lit if the thermocouple works. If you make it this far, then turn the valve from 'pilot' to 'on.' Your heater should then kick the gas on and the pilot will light the main burner.

I'll see if I can find a video.

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"Not trying to insult anyone's intelligence" Quite all right. You never know when the obvious has been missed.

But yes, I was holding it down. No go.

Next plan is, I can't get the required parts by Tuesday, I'm probably going to go ahead an remove the cover plate, breaking the seal/gasket, and light the pilot with a fireplace match.

Also, thanks for that video. I had already found it, and another one that I thought was excellent in detailing how the whole gas valve gate, thermocoupler, pilot, burner, etc work. And how to troubleshoot it all.
Here it is for any one's interest

You're on the right track. My next suggestion was going to be a long click lighter. The electronic light feature being out is a minor inconvenience, you should still be able to light the unit manually.

No telling how long the igniter has been out

Just haven't had to use it since ....well, that long ago.

Thanks again

magnumtmp said:

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XXXVII said:

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If you completely lose water to your house, should you turn off your gas water heater, or is it OK to keep it on the lowest setting?

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As mentioned, as long as the tank is full, you'll be fine. It doesn't hurt to turn it off if you're worried about it, but if there's any chance of the heater being exposed to freezing temps, you'd be better off leaving it on but turning the thermostat temp (red dial on the gas valve) all the way down.

Water heaters have an inlet tube on the cold water side that direct cold water to the bottom of the heater. That tube should also have a small hole near the top of the tube that prevent siphoning, but they can sometimes siphon. If you notice hot water trickling out of the cold side with the faucet open, the heater is siphoning (emptying the tank). Something to watch for and much more likely with heaters in attics. This will only happen if the cold water side is off or frozen/blocked.

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Mr Magnum ... During the cold snap, Thursday afternoon to be exact, i had a rupture and cut off the supply to rupture which includes the hot water heaters. Could not get a plumber out that afternoon so water stayed off to half the house until a plumber showed up the next morning. I opened up all the faucets that were shut off to drain as we were going to get a hard freeze again Thursday night. Also continued to trickle cold on the working side overnight. On the shut off side, as i recall, only a few had any flow and most were cold or tepid. One had a trickle that was crazy hot ... probably the siphoning you mentioned? I turned that one off. Turned off any that had no flow and turned the two water heaters to pilot. We used cold water in sinks and toilets in half the house the rest of the night and the next morning until the plumber showed up. Rupture was up stairs. Heaters in garage at ground level.

Can you esplain what was going on with the heater during this time? Was i doing it right?

Mr. Frodo said:

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magnumtmp said:

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XXXVII said:

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If you completely lose water to your house, should you turn off your gas water heater, or is it OK to keep it on the lowest setting?

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As mentioned, as long as the tank is full, you'll be fine. It doesn't hurt to turn it off if you're worried about it, but if there's any chance of the heater being exposed to freezing temps, you'd be better off leaving it on but turning the thermostat temp (red dial on the gas valve) all the way down.

Water heaters have an inlet tube on the cold water side that direct cold water to the bottom of the heater. That tube should also have a small hole near the top of the tube that prevent siphoning, but they can sometimes siphon. If you notice hot water trickling out of the cold side with the faucet open, the heater is siphoning (emptying the tank). Something to watch for and much more likely with heaters in attics. This will only happen if the cold water side is off or frozen/blocked.

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Mr Magnum ... During the cold snap, Thursday afternoon to be exact, i had a rupture and cut off the supply to rupture which includes the hot water heaters. Could not get a plumber out that afternoon so water stayed off to half the house until a plumber showed up the next morning. I opened up all the faucets that were shut off to drain as we were going to get a hard freeze again Thursday night. Also continued to trickle cold on the working side overnight. On the shut off side, as i recall, only a few had any flow and most were cold or tepid. One had a trickle that was crazy hot ... probably the siphoning you mentioned? I turned that one off. Turned off any that had no flow and turned the two water heaters to pilot. We used cold water in sinks and toilets in half the house the rest of the night and the next morning until the plumber showed up. Rupture was up stairs. Heaters in garage at ground level.

Can you esplain what was going on with the heater during this time? Was i doing it right?

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Sounds like you did everything right. Cutting the water off, and turning the water heater to pilot because you turned the water off is the right move. I have a couple questions before trying to guess at what you were seeing. When you opened the faucets, specifically the one that had really hot water trickle, did the hot water come out of the cold water side of the valve? Maybe you opened up the valve to both hot and cold (if this is the case, it'll be hard to know for sure)? Was the hottest faucet also the closest to the water heater? Was the rupture upstairs on the cold side of your system or hot side? Did the trickle continue for a long time, and did you leave the valves open all night?

Since you said the rupture was second story, it could just be gravity draining the water in piping. I've mentioned in this thread about a little hole in the cold water dip tube....that small hole will stop the water heater from emptying itself, but not until there is enough air at the top of the tank to break the siphon. If it was indeed siphoning, the really hot water would be coming from the cold water side of the faucet you mentioned, which would also require air to be allowed in to the hot water side, either through the rupture itself or an open valve on the hot side. That siphoning should be fairly temporary if all worked as designed....like maybe 5 gallons siphoned out.

One last question....do you have a hot water circulating system on this particular water heater?

BCStalk said:

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Tanked water heaters require positive inlet pressure to work. Ports are on top leaving the tank full even with water shut off. Unless you drain it of course.

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This post could have saved countless hours for people who turned their water heaters off because of the facebook post about a friends dad who was a firefighter. Next time use Facebook and add a story like a cousin's dad who was a firefighter used the full tank from a house with no running water to put out a fire.

magnumtmp said:

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Mr. Frodo said:

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magnumtmp said:

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XXXVII said:

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If you completely lose water to your house, should you turn off your gas water heater, or is it OK to keep it on the lowest setting?

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As mentioned, as long as the tank is full, you'll be fine. It doesn't hurt to turn it off if you're worried about it, but if there's any chance of the heater being exposed to freezing temps, you'd be better off leaving it on but turning the thermostat temp (red dial on the gas valve) all the way down.

Water heaters have an inlet tube on the cold water side that direct cold water to the bottom of the heater. That tube should also have a small hole near the top of the tube that prevent siphoning, but they can sometimes siphon. If you notice hot water trickling out of the cold side with the faucet open, the heater is siphoning (emptying the tank). Something to watch for and much more likely with heaters in attics. This will only happen if the cold water side is off or frozen/blocked.

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Mr Magnum ... During the cold snap, Thursday afternoon to be exact, i had a rupture and cut off the supply to rupture which includes the hot water heaters. Could not get a plumber out that afternoon so water stayed off to half the house until a plumber showed up the next morning. I opened up all the faucets that were shut off to drain as we were going to get a hard freeze again Thursday night. Also continued to trickle cold on the working side overnight. On the shut off side, as i recall, only a few had any flow and most were cold or tepid. One had a trickle that was crazy hot ... probably the siphoning you mentioned? I turned that one off. Turned off any that had no flow and turned the two water heaters to pilot. We used cold water in sinks and toilets in half the house the rest of the night and the next morning until the plumber showed up. Rupture was up stairs. Heaters in garage at ground level.

Can you esplain what was going on with the heater during this time? Was i doing it right?

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Sounds like you did everything right. Cutting the water off, and turning the water heater to pilot because you turned the water off is the right move. I have a couple questions before trying to guess at what you were seeing. When you opened the faucets, specifically the one that had really hot water trickle, did the hot water come out of the cold water side of the valve? Maybe you opened up the valve to both hot and cold (if this is the case, it'll be hard to know for sure)? Was the hottest faucet also the closest to the water heater? Was the rupture upstairs on the cold side of your system or hot side? Did the trickle continue for a long time, and did you leave the valves open all night?

Since you said the rupture was second story, it could just be gravity draining the water in piping. I've mentioned in this thread about a little hole in the cold water dip tube....that small hole will stop the water heater from emptying itself, but not until there is enough air at the top of the tank to break the siphon. If it was indeed siphoning, the really hot water would be coming from the cold water side of the faucet you mentioned, which would also require air to be allowed in to the hot water side, either through the rupture itself or an open valve on the hot side. That siphoning should be fairly temporary if all worked as designed....like maybe 5 gallons siphoned out.

One last question....do you have a hot water circulating system on this particular water heater?

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1. When you opened the faucets, specifically the one that had really hot water trickle, did the hot water come out of the cold water side of the valve?

Not really sure on this one ... the one with crazy hot, I think it was straight up (it's a lever) and I probably went hot and cold and could not make it anything but hot and so I decided to just turn it off. It absolutely was the closes to the hot water heaters. The others that were getting a trickle had been on cold, I also probably moved them to hot and cold ... they were cold or tepid, not scalding hot, and if it was flowing I left it flowing. If nothing was coming out I think I shut it off.

2. Was the hottest faucet also the closest to the water heater?

Yes.

3. Was the rupture upstairs on the cold side of your system or hot side? (not sure I understand this one)

I have two supply lines under the house with shut off valves the rupture and the hot water heaters are on the same side. We had a toilet upstairs not refilling and cold water on a faucet not too far away (same bathroom) running and we had a sink in the adjacent room that stopped running cold. I think we let that one trickle hot.

4. Did the trickle continue for a long time, and did you leave the valves open all night?

I shut off the scalding hot trickle. And on the rest of the shut off side of the house, if there was a trickle I think I left it open but I don't think all were trickling. Upstairs on the ruptured and shut off side of the house ... nothing was coming out of anything ... so I shut those off. Downstairs on rupture side, I think there was some that were moving water and so I left them open ... it was cold or cool water. If it stopped flowing I shut it off. And not he side still supplied with cold water, we ran cold water all night.

5. Circulating system.

Yes and I nun plugged that a short time after shutting off water.

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Did I completely drain the hot water tank by opening valves?
If I had not shut off the scalding hot trickle would it have drained itself?
Is this a problem?
After the rupture and shutting down supply ... should I have simply left all my cold sides opened and turned the heaters to pilot?
Would the hot water in the lines run back to the tank or did I need to empty those lines?
I don't think there is any question about continuing to run cold water on the still working side of the house given the cold.
There was no new hot water on the working side of the house bc that is supplied through the hot water heaters that had been shut off ... I opened and then later closed the hot water on that side... I think that was the call right?

Thanks for the education on this stuff. Next time we have 140+ hours of freezing temps in Dallas I'll be ready.

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Did I completely drain the hot water tank by opening valves?

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No, I seriously doubt it, but I can't say for sure. Even if you did, with the burner set on pilot, you didn't damage the heater by letting the burner kick on with the tank dry....that's the key.

Since you have a hot water circulating system, you have a pretty large supply of hot water that stays hot in the piping. That is exactly why I asked the question on the circ system. Since you have a single handle faucet that you went straight up with the handle and the water coming out was very hot, that means you had hot water coming out of the cold and hot supply simultaneously most likely. That means you had some water siphoning up the cold water dip tube in the heater when the system drained down. The fact that you saw this at the closest faucet to the water heater is no coincidence. That siphoning should stop once the hot water system drains down, which would be a good bit of water since you have an upstairs....all that piping will gravity drain down prior to air being able to get in the top of the hot water heater. That air getting into the top of the heater is what is supposed to stop the siphoning, assuming you have that little hole in the cold water dip tube near the top.

One thing you could do to prevent a repeat is to have a plumber install a check valve at the hot water heater on the cold water side (inlet), along with an expansion tank. Don't install a check valve without the tank....heated water expands and can build up pressure in a closed system. The expansion tank absorbs this expansion without letting the pressure spike. This isn't absolutely necessary, but when I was doing plumbing work professionally, it was required by some municipalities to install a check and expansion tank. My opinion is that it adds mechanical components to a system, and all mechanical components eventually fail. By the time we have another freeze like we just went through, the check valve could have enough corrosion or calcium build up that it wouldn't even work as intended anyway.... There are no perfect solutions unfortunately.

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If I had not shut off the scalding hot trickle would it have drained itself?

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Not likely, as described above. The siphon should break once you get some air in the top of the hot water heater. I can't speak to the design of every dip tube for modern heaters (it's been 15 years since I did plumbing work professionally), but I would think ALL of them have the anti-siphon hole in the dip tube.

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Is this a problem?

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Even if it did virtually empty your tanks, you prevented damage by turning your gas valves to 'pilot.'

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After the rupture and shutting down supply ... should I have simply left all my cold sides opened and turned the heaters to pilot?

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No, I think draining both sides is the right move. Any stagnate water has a MUCH greater possibility to freeze, plug, and rupture. Even if you did siphon the tank dry, that's a much better outcome than another rupture. Not much argument there since you protected your heaters by turning the heat source off.

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Would the hot water in the lines run back to the tank or did I need to empty those lines?

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No, the water won't run back into the tank. By design, there is typically no air at all in your hot water heater. If you can picture that, you can see there's no room for water to run back in. Emptying the lines is the right move.

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I don't think there is any question about continuing to run cold water on the still working side of the house given the cold.

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Agree. When it's that cold, any pressurized water system needs to be 'moving.' It doesn't have to move fast, but it does have to move. By dripping your faucets, you are basically keeping the water moving, not allowing it to freeze.

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There was no new hot water on the working side of the house bc that is supplied through the hot water heaters that had been shut off ... I opened and then later closed the hot water on that side... I think that was the call right?

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Yes, you should keep the hot water OFF in this instance, except to initially drain as much water from the lines as possible. If you have pressure on the cold water side of a faucet, and no pressure on the hot side.....if you open both sides of the faucet (which is really easy to do with single handle faucets) you can and will back feed water through your water heater. Best case scenario is that the back-fed water comes out of an open faucet on the shut off side of the house. Worst case is your ruptured line starts leaking again and inflicting more damage to the house.

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Thanks for the education on this stuff. Next time we have 140+ hours of freezing temps in Dallas I'll be ready.

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You're welcome! I think, as a whole, you made the right moves. The rupture is bad news, I hope it didn't do too much damage. If you need anything else, I'll try to keep an eye out.

Your delta chi name now is Dr. Magnum ...

Dr. the ruptured pipe is on the second story where the floor there overhangs a small porch on the first floor so cold air underneath and on the outside wall ... a good test. The copper pipes had, what looks like to me, basic foam insulation ... not super thick foam insulation which I've seen. I'm looking on line for perhaps a better insulation solution ... fiberglass or something high tech. Is there a product? Any ideas?

Also, would PEX or another type of pipe be a way better solution here? The supply lines come up the lower level wall and then turn out under the floor of the second story and then go up the second story wall and then into the house. Not gonna rip anything out but would consider cutting in PEX or something else if they would dramatically reduce the odds of this happening. Thoughts?

Thank you!

Mr. Frodo said:

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Your delta chi name now is Dr. Magnum ...

Dr. the ruptured pipe is on the second story where the floor there overhangs a small porch on the first floor so cold air underneath and on the outside wall ... a good test. The copper pipes had, what looks like to me, basic foam insulation ... not super thick foam insulation which I've seen. I'm looking on line for perhaps a better insulation solution ... fiberglass or something high tech. Is there a product? Any ideas?

Also, would PEX or another type of pipe be a way better solution here? The supply lines come up the lower level wall and then turn out under the floor of the second story and then go up the second story wall and then into the house. Not gonna rip anything out but would consider cutting in PEX or something else if they would dramatically reduce the odds of this happening. Thoughts?

Thank you!

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Ha! Pretty sure I don't deserve that moniker.... Happy to help though.

Copper pipes are awesome for water supply in every situation except freezing weather (and the occasional electric discharge corrosion issue). Besides the thin foam insulation on the pipe, was there any insulation for that ceiling, like blown in, or fiberglass batting? If so, your probably going to tell me that you lost power long enough that that part of the house got really cold, making that insulation useless to protect the pipes. I've seen situations where the copper pipe was run in the middle of the trusses/floor joints, but the insulators came in and shoved the fiberglass batting above the pipe, leaving it exposed basically to outside temps. If your pipe is below the insulation, the first thing to do is correct that by adding another layer of insulation spanning the entire porch ceiling below the water pipe (I'd be a little surprised if this was the culprit, and fixing it would likely require even more demo work ripping the porch ceiling out). If this was a prolonged power loss issue, the only solution that might have helped is either draining all water from the system, or dripping ALL faucets, both hot and cold, for the duration of the power outage. That includes flushing the toilet every couple of hours whether it needs it or not. Long story short, if you lose power drip those faucets and any faucet on the outside wall first and foremost.

In this situation, PEX is a better solution than copper. I have a feeling your plumber will be suggesting ripping out all the copper and installing PEX, at least in this area. I would do the same if it were my house. Don't let him run off with all that copper unless he pays scrap value for it....another tid-bit. It's worth a trip to a scrap dealer. Not trying to scare you, but this undertaking may get a little adventurous. Copper does not shrink back to size after thawing out like PEX does. This means the plumber may have to seek out pipe that has not 'grown' in order to properly solder fittings on to convert to PEX (or even replace with new copper). Hopefully the frozen area is isolated.

There are other potential solutions, like heat tracing/heat tape, but I'm assuming you don't really have permanent access to each piece of pipe. I wouldn't bother with this investment unless you have a way to monitor that they are working and replace when they go out. Otherwise its a false sense of security. Power loss obviously kills that heat source too, putting you right back in the same situation.

The only other thing I can think of is to ask your plumber if its possible to install a pair of shut off valves somewhere that is accessible. The idea would be to isolate that particular bathroom that is prone to freezing if we get this level of cold again with power outages. The hard part is knowing a good place to install the valves, and putting in a way to drain down the lines. I don't necessarily suggest doing this unless you can drain it down. Another false sense of security....lines that have no pressure, but are still full of water can rupture copper easily.

EDIT: Sounds like you've already had a plumber out to repair the rupture, which I wasn't thinking about. I can only assume that there is still some porch ceiling damage to repair that may go through insurance? If so, I'd make sure the adjuster that comes out knows that you want the pluming (or lack of insulation) adequately fixed as well. If no insurance will be involved, I would suggest dripping the faucets as described above as a last line of defense if/when we get a repeat of this weather in the future.

No power outage. Was not dripping hot ... just cold.

Cold water was running in that bathroom the whole time with cabinets open.

I guess I should I have jimmied the flap on the toilet to make sure it was constantly running and been dripping hot too?

The space was double insulated above and below the line and the line itself had the smaller black foam not the thicker 1" variety I'm seeing.

Fortunately I got to the shut off valve quickly (I was on the lookout) and it does not seem to have gotten into the lower wall. There is sort of a natural cubby created by the trusses and a blockout and the rupture was pointed up. I had the ceiling and insulation out of there within 20-30 minutes of the rupture an really just one bay of insulation was wet. If I'd been more surgical with my ceiling demo and less enthusiastic it could have been a pretty small area.

I was going to block between the trusses close the first floor wall and paint and caulk and seal to create something like an upside down sink to contain any water, add at least 1" k flex insulation and build an access hatch/service door into the ceiling that gives you access to these pipes so that I don't have to pull down cedar planks and be done.

You've got me thinking on the PEX though. You think replacing all the horizontal lines that run from the lower wall to the upper in that ceiling/floor space would solve it?

Mr. Frodo said:

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No power outage. Was not dripping hot ... just cold.

Cold water was running in that bathroom the whole time with cabinets open.

I guess I should I have jimmied the flap on the toilet to make sure it was constantly running and been dripping hot too?

The space was double insulated above and below the line and the line itself had the smaller black foam not the thicker 1" variety I'm seeing.

Fortunately I got to the shut off valve quickly (I was on the lookout) and it does not seem to have gotten into the lower wall. There is sort of a natural cubby created by the trusses and a blockout and the rupture was pointed up. I had the ceiling and insulation out of there within 20-30 minutes of the rupture an really just one bay of insulation was wet. If I'd been more surgical with my ceiling demo and less enthusiastic it could have been a pretty small area.

I was going to block between the trusses close the first floor wall and paint and caulk and seal to create something like an upside down sink to contain any water, add at least 1" k flex insulation and build an access hatch/service door into the ceiling that gives you access to these pipes so that I don't have to pull down cedar planks and be done.

You've got me thinking on the PEX though. You think replacing all the horizontal lines that run from the lower wall to the upper in that ceiling/floor space would solve it?

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Ah, ok. I made an assumption that you lost power, my apologies. With this new info, I'm a little surprised the line froze. I asked this question earlier for a different reason, but it's worth revisiting. Did the freeze/rupture happen on a hot water line, or a cold water line? This will all make more sense to me if it was the hot water line that froze and ruptured, which may seem counterintuitive. Was it a main feed, or a smaller 1/2" line off to the side?

If you had cold water running/dripping the whole time, did it ever stop (like it would if it froze)? You may be guessing why I'm asking....if the cold water was moving, but the hot water was stagnate, it was probably the hot water supply that froze and ruptured. I don't know exactly how your circ system is set up. My first thought is that your circ system should have kept all that water hot and nowhere close to freezing, but that greatly depends on the circ system routing (the hot line run into that porch ceiling may be stagnate, even with your circ pump running). The answer to that will give me a little more confidence that dripping the hot side along with the cold side will prevent this from happening again. If it was the cold side that froze and broke, even with you running water, I'm a little baffled!

This may seem crazy, but having the pipe between the layers of insulation is not ideal, although it is MUCH better than the pipe being below the insulation for obvious reasons. If you can picture the warmth from the house being above the insulation, the insulation between the pipe and the sub-floor is actually preventing the house's heat from getting to the pipe. It's easy to forget that insulation is there to slow down heat loss....it doesn't provide any heat by itself. If there is a way to easily move the floor's insulation below your piping, that is best preventative action by itself. If you are planning to and willing to reroute with PEX, you should be able to get it above the insulation. The thicker insulation will slow down heat loss, but won't prevent stagnate water from freezing. You'll still have to drip your faucets with multiple days of freezing weather, with PEX, copper, or anything else.

Going back to dripping faucets....you don't have to rig the toilet flapper necessarily, especially if you have another fixture further down the main line. The rule of thumb on preventing freeze is to have a solid stream, not a drip, drip drip, on the furthest faucet from the water inlet. Not sure how your bathroom is oriented and piped, but sounds like you may be getting a good look at it and can make a mental note for future reference. If some of my assumptions above are correct, and the hot water circ system does not keep water moving directly under this bathroom, you should drip the hot side as well. This is fairly easy with single handle faucets....just go straight up to split the flow, instead of to the right for cold water only.

EDIT: I'm trying to decide if I agree with damming up between the trusses to prevent water from running down the wall and inside the house..... On one hand, that seems like a good preventative measure, but it seems like you'll have to pull a lot of ceiling down to pull that off adequately. I think the other changes discussed above will serve you better honestly. I also want to be clear that my opinion is that PEX run only on the horizontal feeds in this ceiling won't be a cure either. Any copper not replaced that freezes will still have a high likely hood of rupture. You're best bet is to keep the pipe above freezing temps with insulation improvements and keep the water moving in as much of the piping as possible (dripping your faucets). I'm still really surprised you had heat in your house and still had a pipe rupture. I would have lost that bet.

I appreciate the know how ... and hope others are learning from this ... as I am.

I think this is end of line and nearly the furthest point on that side of house.

And, the hot water up in this room always seems a little delayed vs instantaneous in most downstairs fixtures.
Maybe my recirculating pump is undersized???

I'm gonna pull down my awesome poly staple job and take a picture so you can see this exactly.

The tip on the furthest point with a good flow makes a ton of sense.

Mr. Frodo said:

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I appreciate the know how ... and hope others are learning from this ... as I am.

I think this is end of line and nearly the furthest point on that side of house.

And, the hot water up in this room always seems a little delayed vs instantaneous in most downstairs fixtures.
Maybe my recirculating pump is undersized???

I'm gonna pull down my awesome poly staple job and take a picture so you can see this exactly.

The tip on the furthest point with a good flow makes a ton of sense.

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If the hot water is delayed to this bathroom, that lends a little credence to my theory that the circ system just doesn't pump water as close to these fixtures (the circulation loop doesn't flow directly under the bathroom). Doesn't mean the pump is undersized, but it does mean its very likely that the hot water feed to that bathroom is stagnate just above your porch ceiling and prone to freezing just as much as the cold water feed. It all depends on how that loop is routed.

A few good pictures would be fantastic.

Honorable Dr Magnum, here you go











Wow ... you are good.

As I tell the kids, it's usually not just one thing that defines winning or losing or the answer to what caused a particular outcome. Quite often, it's a number of little things that add up and build on each other to get the desired or un-desired result. Seems like that's what we have here.

It indeed was the hot line that busted.

Do we have all the contributing factors?

140+ hours of below freezing.

Not only cold outside the exterior wall but cold air below from the porch.

Two layers of insulation but the plumbing between them so less heat from house.

Plumbing lines are closer to bottom of truss so further from heat of house.

And actually, the space between the insulation has a feed back to the cold air.

Hot water not circulating at this far end of the run for some reason so hot lines are not hot at all.

Add all those compromises up and you get a freeze.

Maybe running hot water the whole time would have prevented. Maybe one or two of them done differently without running the hot water would have prevented. Who knows.

I think I'm gonna do the following: replace the horizontal parts with PEX and move it up below the floor, block between the trusses to prevent the soffit air from getting back into the insulation, investigate why that part of the house does not get good hot water circulation and run hot and cold next time it gets anywhere near this cold.

Let me know what you think.

Mr. Frodo said:

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Honorable Dr Magnum, here you go











Wow ... you are good.

As I tell the kids, it's usually not just one thing that defines winning or losing or the answer to what caused a particular outcome. Quite often, it's a number of little things that add up and build on each other to get the desired or un-desired result. Seems like that's what we have here.

It indeed was the hot line that busted.

Do we have all the contributing factors?

140+ hours of below freezing.

Not only cold outside the exterior wall but cold air below from the porch.

Two layers of insulation but the plumbing between them so less heat from house.

Plumbing lines are closer to bottom of truss so further from heat of house.

And actually, the space between the insulation has a feed back to the cold air.

Hot water not circulating at this far end of the run for some reason so hot lines are not hot at all.

Add all those compromises up and you get a freeze.

Maybe running hot water the whole time would have prevented. Maybe one or two of them done differently without running the hot water would have prevented. Who knows.

I think I'm gonna do the following: replace the horizontal parts with PEX and move it up below the floor, block between the trusses to prevent the soffit air from getting back into the insulation, investigate why that part of the house does not get good hot water circulation and run hot and cold next time it gets anywhere near this cold.

Let me know what you think.

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Excellent pictures and explanation. It's all making sense now.

I didn't have my head quite wrapped around the soffit vents and cold air access, but I see what you mean now. I think the #1 priority is to get batting insulation between each of those trusses that will block the cold air from those soffit vents. I don't think you need completely block/caulk that area, some breathability is a good thing. Double layer the insulation with the paper side toward the house space, and staple it well. Fill in any gaps with great stuff foam. Not sure why those gaps between trusses weren't insulated to begin with, but any protection the lower layer of insulation was giving you went right out the window due to that being open. The good news is you'll have a more energy efficient house in winter and summer as well. Probably not a big enough change to notice on the electric bill, but will still help.

If I'm seeing things right, your water piping is all pretty low in that space. I hate to see you have to drill all new holes to reroute with PEX higher up in the space, but I'd be lying if I told you that it wouldn't help if you need to do it to fit another layer of insulation below the water pipe. I want to say that the #1 priority above will be enough preventative measure, but it's hard to say. If you can fit two layers of insulation below the water piping without re-routing, that's probably what I would do..... Getting the cold air blocked off, extra insulation, and dripping both sides of that lavatory above are all going to give you a much better chance at prevention during the next arctic blast.

You mentioned in a previous post about removing the cedar and installing a different ceiling. If you end up going that far, you could put a layer of foam sheet insulation between the ceiling and bottom of the floor joists. That would help too. I wouldn't necessarily rip out the whole ceiling just for this, but if you end up doing it anyway.....why not.

As usual......us plumbers get a bad name because the insulators did a crappy job.

I think there was batting insulation stuffed out there that I pulled out but that still seems like a liability. Since I have a good portion of the ceiling down, I'm gonna have it blocked and insulated ... that will cover the bathroom and the bedroom. The soffit vents should keep that structure vented ... not sure of the proper architectural term ... but in section it's just a triangular structure on the side of the house with roof on top and the soffit underneath. Thanks for helping me think through this. The cold air was most certainly outdoors.

One final question ... where exactly would you splice in the PEX? Given what I read about the joints, I'm thinking let the copper come out of the wall and run a little across the ceiling and cut in there-- so the joint is in the ceiling out form the wall a bit. Splicing directly into the vertical runs out of first floor wall and into second floor wall seems like a bad idea. Thoughts?

Mr. Frodo said:

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I think there was batting insulation stuffed out there that I pulled out but that still seems like a liability. Since I have a good portion of the ceiling down, I'm gonna have it blocked and insulated ... that will cover the bathroom and the bedroom. The soffit vents should keep that structure vented ... not sure of the proper architectural term ... but in section it's just a triangular structure on the side of the house with roof on top and the soffit underneath. Thanks for helping me think through this. The cold air was most certainly outdoors.

One final question ... where exactly would you splice in the PEX? Given what I read about the joints, I'm thinking let the copper come out of the wall and run a little across the ceiling and cut in there-- so the joint is in the ceiling out form the wall a bit. Splicing directly into the vertical runs out of first floor wall and into second floor wall seems like a bad idea. Thoughts?

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I wouldn't stuff the batting insulation all the way out into the eave, as you mention it's not doing anything but soaking up humid air at that point. If you can get the batting flush with the plate line, and run up to the roof decking, that will block that cold air. Blocking it is fine too, but my opinion is you don't have to....it'll help hold the insulation in place. Either way you go, your on the right track and will have a much better chance at weathering the cold next time.

The biggest threat of failure, even with a PEX to copper transition, is going to be the freezing weather, assuming a good solder and crimp job on the joints. Mechanical failures are rare without outside influence like ice. With that said, if you are going to go forward with PEX installation, I would replace as much of the copper as possible. I would tie into the vertical runs. The threat of a future freeze failure in the copper you leave is much higher than having a problem with the PEX over that wall. Use good crimp connections, don't use Sharkbite. Viega has the best system that I've worked with if you find a contractor that has their tools....but I've used Apollo as well with no issues. Make sure to well insulate (duh...) and strap the lines down to prevent water hammer. I like brass fittings as opposed to the plastic ones, and they really don't cost much more.

Good luck with your project!! Hope all this helps.