need ideas for finding a plumbing leak.

So here's the deal. I am building a new house which is basically done, sheetrocked, finish floors, etc. The only problem is that we can't get a plumbing final passed--seems like there is a fitting that has come apart in the vent portion of the DWV. I am looking for some brilliant ideas to find it, short of filling the system with water and looking for the leak.. We have tried the "peppermint test" --dumping peppermint down the vent, follwed by hot water, and can't smell peppermint anywhere. We also tried a camera, but were unable to fish it in the lines smaller than 3".
A few ideas I've had are--
1) devising a hillbilly smoke test--setting a shop vac to blow. Put a little water in the tank, and add dry ice, and hook this up to pump "smoke" into the system.
2) Hiring a guy with an infrared camera. Attach a heat gun to the system. Pump heat and look for heat.
Anyone have any other ideas?
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marson wrote:

Hi, You're doing it backward. After plumbing is done, you had to check the possible leak pressurizing the entire system with compressor. Your plumber did not do it? Now retroactively, pros use super sensitive microphone to pinpoint even a slightest leak. That's all I know.
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marson wrote:

Pressurize with compressed air. ~20 psi. That requires tight sealing of all openings. Listen for telltale whistle. Or, as suggested, use a pro listening mic for even ultrasonic signals.
You could introduce faux smoke from a smoke generator or "smoke" candles if it's likely you could see the smoke where it exits. Or introduce mercaptan odorant (used in natural gas).
Jim
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wrote:

Is this a two story home?
The first years or so of owning my last house; it seemed like on Monday there was a wet carpet spot on the first floor. It so happens the master tub drained right down/angled to the first floor. The bride used to tub on Sunday evening.
A rubber sleeve was not coupled correctly to the ABS and the water from the tub drained through the wall studs.. about four foot from the floor.
You will need to open the sheetrock to fix this.
-- Oren
"The voices in my head may not be real, but they have some good ideas!"
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My friend says all houses are two story homes. There's the story the realtor tells you, and then there's the truth :) (Sorry, couldn't resist)
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wrote:

Well that just ticks me off. I will forever live in a single story house; henceforth and so on!
-- Oren
"The voices in my head may not be real, but they have some good ideas!"
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Well, I haven't had a chance to follow up on this. Of course, the DWV was air tested after rough in. But something happened between then and the final manometer test. Either the plumber added a fixture after the fact (which he did) or one of the HVAC guys got a little wild with the Sawzall. It's no pinhole leak--you can't even begin to get any pressure built up on it even with an air compressor.
The water test is the final resort. With my luck it'll spill out onto the HO's computer. The people are living in the house under a temporary certificate of occupancy.
The sound test sounds interesting. Who has such equipment? My experience in listening for leaks is that the whole system hums and it is hard to pinpoint exactly where?
Right now, I got a hold of some smoke pellets. I've got plans in my head to pinch down the outlet of a shop vac and blow smoke into the system with that.
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Found it! Wound up putting a smoke cartridge in a vent, then putting a continuous 20 PSI on it (enough to blow out the hole but not enough to blow water out of the traps). Found it next to a tub access hole-- someone had widened the access hole and got a little wild with the sawsall!.
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20PSI!!??? that much pressure would surely blow the water out of the traps.
s

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wrote:

Correction, I had the regulator on the compressor set at 20. Never got that high in the pipe I suppose because of the leak..
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marson wrote:

What is wrong with filling it up with water and looking for the leak? That is one of the tests that is required for plumbing topout around here. You can either use water or compressed air, but with compressed air you have to seal everything up including caps on the vents on the roof, so it is much easier to put a test plug at the main drain and fill with water until it comes out the lowest roof stack.
--
Robert Allison
Rimshot, Inc.
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