Emergency Water Turn-Off?

Probably a better method, but I'll bet it's much hard to implement. IIRC, the flow rate on my water meter is pretty coarse. By the time it indicated a leak, you could have some serious damage. I assume you can get ones that measure to the tenth of a gallon, but the expense might start climbing into the prohibitive range.

Agreed that there are profiles to various uses, but IMHO there are SO MANY potential water use profiles that there are going to be an awful lot of false shutdowns. Consider a guest (worst case, a MIL) brushing her teeth and letting the water trickle slowly from the faucet. Bang! Off goes the water. That will get tired *very* quickly. Maybe if you had a flowmeter on both the water main and the waste line you could really differentiate leaks from a MIL brushing her teeth.

Not mine! Some guy comes around with a plate puller. The company rounds out usage to the nearest 1000 gallons. I'm not sure you can get the kind of readings from existing meter that would be useful in detecting small leaks.

I agree with the theory, but in practice, I think you could spend an awful lot of time futzing with such a system only to eventually abandon it because the exceptions became too bothersome.

Yeah, you'd have to have a MIL cutoff that killed the function completely. I don't think an override would be very effective for guests unless you mounted some sort of controller over each faucet. In my experience it's the "guest test" that really makes or breaks a lot of neat HA ideas.

The problem I see is that if a leak matches a valid usage profile, you've got a flooded basement. Unless you go about putting pinhole leaks in pipes, cracking old solder joints, rupturing washer hoses and letting tubs overflow you're only profiling half of the equation. I don't think it's possible to build a system with a high confidence of correct operation if you only model the proper behavior and not the actual leak cases that you're hoping to find.

It reminds me of the gentleman here a while back who built the cat door that used imaging to process "go/no go" rules. The camera picked up intrusions by racoons, birds and unknown other creatures and allowed the neighbor's cat to go in and out freely as well, since it, too, had a "cat" profile. The problem I see is that house leaks happen maybe 5 times in a lifetime. Too few to accurately model or to spend lots of time or money to prevent.

Agreed that there are many ways to counter the power problem, but it's one of many that need to be dealt with it. I'm just not sure it's worth it. If I decide to equip my next house with automatic sprinklers, that will even further complicate the issue for me.

Unfortunately, my experience is that the simpler the system the more likely it is to be used and not end up in some extended "forever testing" mode. I suppose that's why WaterBug and WaterCop are as popular as they are. There's a lot of engineering smarts embedded into the units that aren't apparent at first glance.

-- Bobby G.

Anyone made their own emergency water-turn-off system? Like a WaterCop or WaterBug? Something like a ball valve with an attached drive wheel and motor to turn the water off.

Also have you tried to get water flow information from acoustic transducers on water pipes? I can "hear" the water flowing inside a pipe with a stethoscope, but I wonder if I can get quantitative enough flow information from a strapped-on "mic".

I'd like to use the HA computer, multiple-acoustic sensors, and an smart algorithm to watch for the acoustic patterns that could uncover a running toilet (or other undesirable water flows), and turn the water off. This flow monitoring, as opposed to the usual alternative of looking for undesirable water accumulations.

Sound possible, or have you done it?

Thanks,

Dick

I'd wonder, besides issues with lawn and plant irrigation what negative impact would a shut-off have on the typical residence? Granted, beyond the tedium of having to go manually turn it back on again. I'd much rather have something that just cut it off, sounded some sort of alert (to a security console, PC or whatever) and left it off.

What, if anything, would happen to a hot water heater that needs to refill but can't because the main has been shut off? Just curious.

No, but I've looked into this before and been sent to Grainger's to look for automated valves. IIRC, they are available for $25 to $50 but it's been a while since I've researched this particular HA facet.

I'm going to install one of those valves just to be able to shut off the watermain without have to go downstairs. There are a lot of issues to consider. The valves I looked at were 24VAC. For a leak system to be reliable, it would have to work during a power failure. That alone makes the problem considerably more complex than appears at first blush. You might be able to design a system with a solenoid valve that always closes upon power loss, but that means another 24x7 current draw and the probability that the valve will start humming when things loosen up.

Again, if I recall correctly there's already a commercial product that did this. But when I started to set down and really think about it, the only time you want an acoustic transducer to trigger a shut-off is when no one is home. Even then, a mike would cause a system to shutdown in any empty house because an icemaker caused a brief water flow. Evaporation of water in the toilet tank will trigger water flow if the float drops below a certain level.

(Speaking of toilets I saw Smarthome flogging a new toilet overflow sensor. It's a device that I am sure has one of the lowest Spouse Approval Factors in the world because part of it sits within the bowl itself and the other part gets hung from the shutoff valve. As a person who has faced some significant opposition to various HA gizmos, I think wiring up the toilet just won't be popular with the ladies. Back to your problem.)

The problem is manifold. Water pressure varies in a typical home based on concurrent water usage by neighbors, the amount of water in the local water tower, etc. That means that the sounds created by various fixtures would be different depending on the water pressure and depending on whether someone was operating two different fixtures at high flow rates.

I agree that by the time a sensor detects that your basement carpet is wet, it's too late. But the real rub lies in separating the sounds of legitimate use from a leak. Are you going to be able to design a sound processor that's able to separate all the variants of a toilet flush or a dishwasher run and act accordingly? I really doubt it.

I had a washing machine hose rupture recently. Fortunately I was home. But I can't think how I could have differentiated that event from normal water use without moisture sensors of some sort. There's just too broad a range of events to trap for with an acoustic sensor to make it really workable. At least that's MHO.

With all that said, I know that there are commercial leak detectors that operate in the ultrasound range. But I think all of the same problems listed above apply.

-- Bobby G.

Yeah, I gotta agree, Robert.

But, I think it would be fun to play around with!

I once worked for an industrial automation company - that company sold some major clients on some cool stuff that worked well (automated tracking sides of beef from the kill floor to the freezer) - to stuff that was an absolute multimillion dollar failure for the poor companies that bought them (using a machine vision system to determine if a keg of beer was leaking).

I dunno, I think if you could get a fairly accurate flow meter, combine it with reliable indicators of whether or not people are in the rooms that should use water, and combine that with a schedule... I think the problem could be solved to a reasonable degree of accuracy.

Maybe that's part of the problem for the folks like watercop - it's designed to be used on it's own; it doesn't have the benefit of getting the data that a mid to upper class HA system can provide.

Oh well, I dunno either way. I do think I can safely say an acoustic solution can be ruled out. I was thinking about that on the way home, and given the number of different materials that can be used (copper, pex, galvanized) for water supply, and the fact that their accoustic properties _must_ change over their lifetime, and probably over the seasons as well, just make it seem infeasible.

But if the OP gets something going, and wants a house to beta on - I'm game.

I just think it would be great fun to putz around with.

Then again, I'm putting in an old 1A2 multiline telephone system in my house next week..... with only one actual phone line - just so I have a phone(s) with blinking and flashing lucite buttons.

Matt

Good question; I've often wondered that myself.

I do know that the cost of water heaters recently went up about 30% because the gov't mandated that the pilot and flame be enclosed in the hopes of preventing an explosion in the presense of flammable vapors.

But I don't know of any safeties on a water heater for an out of water condition. Seems like to me the thermostat is going to call for heat in an empty situation, and the burner will simply continue to run; I suppose until someone notices or the bottom of the WH burns up, what follows that I don't know.

On the other hand, I'd like to believe that there is either some sort of safety built in to prevent this, or a logical reason why it isn't an issue. I don't recall of hearing any horror stories of water heater burn up; but I have seen videos of water heaters shooting off like rockets, before the PRV was standard issue; blowing through 2 or 3 floors and finally the roof, continuing their journey into the sky......

No doubt about that! I've got a bunch of fun projects. I want to be able to tell when FedEx has pulled up to the curb. If I can sense their arrival when I am in the basement, I can get to the door before the "We tried to deliver" tag gets looped on the handle. I set up cameras, shot gun mikes, all sorts of stuff. Eventually I settled on putting a microphone and a camera on a lamppost by the front walk. When I thought I had it working perfectly, the FedEx guy delivered a package to my neighbor and then walked across the lawn between our houses to ring my bell. That's when I gave up! You can't imagine how PO'ed I was to see the truck driving off, knowing my system had failed me.

Sounds fascinating. I think anyone who's been involved in the automation field has similar stories. The real world will apparently do what it pleases, no matter what engineers or automators expect of it.

That's the problem. Accurate flow measurement. Perhaps the mike on the pipe will turn out to be just as good for that because water does make noise going through a pipe. I suppose I would start by strapping a mike to the main valve's feed pipe and running that into a PC recording program like CoolEdit that has an elapsed time indicator. Then I would run around the house with a pad and a clock, open various faucets just enough to fill a gallon bucket about an hour and log various flushing, bathing and kitchen water use events. Then I would see what I could match on the CoolEdit log to my own test log.

I think you're right. In order to have mass-appeal, and, I expect to increase reliability and predictability, they've gone with the water leak detectors in critical areas.

I wouldn't rule it out until I performed the above test. I just happened to have moved a old PC with CoolEdit to the basement. It would be simple enough to try. I also have an outside spigot with a leak that's shutoff from the inside valve. That would make a good "real world" sort of test of an actual leak.

Hmm, hadn't thought about that complication! It's just a reminder that there's very little that's really trivial in the HA field.

OK. We'll use your house, Matt, to make sure it can detect someone smashing the outside water spigot to simulate a car crashing into it. "Can you hand me that 15 pound sledge hammer?"

Yeah, this thread might inspire to do a little testing with the acoustic method. It may turn out that a truly sophisticated system will model human leak detection: Looks wets, sounds wet, feels wet. There's a leak! By that I mean having moisture sensors, acoustic sensors and a flowmeter all working together to determine if a leak has occurred:

IF FLOW > 10 minutes AND floorwet=.t. THEN CLOSEVALVE!

I've still got many of those floating around along with a dozen or so punch down blocks and loads of the 50 conductor phone cable from when an office I worked in got remodeled. Bell didn't want it back so I took it. The wire makes great ties for plastic bags but at twice the diameter of RG6, it's not useful for much else. It's hard to believe how much phone wiring has changed.

-- Bobby G.

I think various things happen depending on whether they are tank or tankless types and whether they can truly be emptied accidentally. My impression is that unless it leaks out, a lack of pressure (i.e. the main valve is shutoff) means the water that's in the tank will stay in the tank. Unless there's some sort of siphon effect drawing it out to a lower level but there have to be open valves above the tank and a way for it flow out for that to happen. I think. :-)

-- Bobby G.

If the thermocouple in the tank, won't it heat up VERY fast in a dry tank (vs one filled with water), and therefore the burner will not burn that long?

I have an electric WH, in my garage, in Phoenix, and it barely runs in the summer. When the garage is 110, and the thermostat is set to 140, doesn't take much to bring water up to the proper temp!

(of course, the cold water is also 90 degrees that time of year....)

Ah yea, AZ!

Hmmm more questions - I dunno....

But doesn't the thermocouple only sit in the pilot flame, not the burner flame?

There ya go!

I'd still volunteer for beta test - sledge on my hosebibbs or not!

If you do the acoustics tests, can you post a summary?

Thanks Matt

I've been doing a lot of plumbing work and in my house, killing main water causes the water heater really shake rattle and roll. Depending on whether someone opens up a valve or flushes a toilet, and where, you'll have a lot of effects. You'll have faucets spitting rusty water HARD if the water drained out of those lines. I've had a massage showerhead in a clip holder blow off the wall in one case and go flying around the room soaking the place before I caught it. Probably something to consider in the overall plan of a water killer - the cure being worse than the disease!

I guess that's the best solution. But I worry about false alarms inducing air into the system. It's never happened to me, but I'll bet you could get an icemaker into trouble with too much cycling. De/Repressurizing is a fairly serious event for a plumbing system. I think if you have a shutoff without *serious* warning capabilities, people will turn on the water and discover it's shut off that way. And if they open up the right valves, you'll get a lot of air in the pipes with the very MIL-unfriendly start-up spitting. It's very startlingly.

We probably should crosspost this thread to alt.home.repair, as that's where I found a wealth of useful plumbing data. There ARE legitimate uses of crossposting. It's just too bad we haven't been seeing them lately. )-:

-- Bobby G.

There's one in the pilot flame that won't allow gas to the main burner if there's no pilot, but there's another to check the water temp. How else could the temp of the water be determined? Not by the heat of the flame....

The "Thermostat" (which, IIRC, uses a thermocouple - with a lesser range - inside the tank) setup works for both gas and electric, and (we all hope) that there is no flame in an electric HW!

The "Thermostat" instructs the heat to go on/off.

That's a mighty big IF. :-) I have a lot of projects running so it might take a while to get the pieces in place. I thought about it some more and the best thing to do is keep a pocket voice recorder to record the plumbing usage, since it automatically dates stamps each recording. I can upload those messages and the index via USB so I'll have at least part of the diary of flushes and leak tests created automatically.

Of more concern is the placement and nature of the microphone. I have quite a collection, from desktops to flat plate to clip ons to little electrets for PCB's. I'm wondering how best to affix and whether to surround the contact area with foam pipe wrap to try to restrict the pickup of extraneous sounds.

I also wonder where it's best to place the mike: close to the entry point in the basement or at the first tee, which I think is at the water heater? What about right on the valve or close to it? I'm no marine engineer but I would assume the most noise in the pipe would be created where the valve assembly narrowed the flow of water.

-- Bobby G.

Yeah, but that's probably a good thing. It's likely to be one of the primary combustion triggers in a serious gas leak. Unlike dryers and ranges, the water heater is likely to follow a pattern of waiting an hour or two, even in an empty house and then lighting up for a few seconds. Probably couldn't design a more efficient way to allow gas to collect in a basement and then ignite it! :-)

I've found one site that says this about electric WH's:

|Remember that with an electric water heater, you must turn the |power off! Even a partial drain down may expose the upper |heating element to the air and permanently damage it!

I found some really interesting information at another website that counters everything I had heard up until now about water heaters:

|Temperature control. On commercial tanks, they're set in |degrees, but on residential tanks, expect warm, hot, very hot, or |something like that. There is so much variation on what those |settings mean, heater to heater, that all we can tell you is that the |right temperature is at least 130 degrees at the tap, which you can |test with a meat or candy thermometer.

|Why 130? Well, at 120, legionella bacteria that cause |Legionnaire's disease can grow. Then when you take a shower, you |catch it by inhaling the mist. Anything above 130 vastly increases |scalding risk, energy use and sediment buildup. Truth is, 130 is a |compromise temperature. You can be scalded there, too, if you |spend long enough under the water, but it is sufficiently hot that |you'll probably draw back, but not so hot that you'll JUMP back. |Most bathing injuries are not from burns, but falls.

Well, that's news to me. I am going to jack that temperature up the next time I go to the basement!

Well, I haven't seen any sites that detail any "empty tank" safeties but if they are enclosing the combustion chamber and mandating earthquake strapping in CA, then SOMETHING's got to be in there to prevent a burnout. I hope.

That's why they have so many stickers attached to them. In case they reach escape velocity and travel to another solar system. We used to have a few fire safety engineers hanging around that could give us the real scoop on WH safety.

-- Bobby G.

Heh, I've seen exactly the same thing happen. Like sumpthin' out of a comedy skit.

Not as much trouble as serious water damage. I can replace an ice maker a heckua lot easier than dealing with destroyed drywall, wiring, stud walls, flooring, carpets....

Yes, as is water hammer. Not something to ignore. Pipes and various plumbing fixtures are a LOT more sensitive to these problems that people thing. If during the course of normal use anyone's got banging pipes they should get them looked at and SOON.

Got that right, sad to say.

-Bill Kearney

It managed to crack the plastic nut that holds the head to the flexible hose. So even when I got it back in place, there was a stream of water hitting me right in the face. I was not a happy camper THAT day.

Yeah, that's true. A woman I worked with lived in a four story townhome. She went away for two weeks and when she came back she found that a toilet tank on the top floor had cracked. Total damage was over $80K and she never felt that they did a good job drying out and cleaning up the place.

I would recommend looking around to make sure that no 500 pound bureaus are placed where plumbers might need access. We had redesigned the kitchen without paying enough attention to that issue. When I had a serious problem with a corroded shower valve assembly, it was hell's bell's getting to it.

I read an interesting description of how water heaters can bang from the accumulation of sediment. They also talked about how some HW heaters expel air from the HW taps. Lots of interesting information at:

ately. )-:

Well, it just means we all have to be super-careful not to fall into a deliberate crosspost trap meant to rekindle the flamewars. The problem is that a lot of newsreaders don't make it easy to detect a crosspost in progress.

-- Bobby G.

How dare they invent something so quickly after reading a usenet postulation post!!!!!!!!

What I don't understand is how they got the fancy website up so quickly

- this thread is only 1 day old.

But.... notice the availability - sometime in 1Q of 05. Whats up with that?