Gas Pipe Install

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I'm installing a tankless water heater at the opposite side of my house from the natural gas meter. I have a dedicated pipe-run going directly from the meter to the appliance. My primary problem is getting the approximately 65 feet of new black pipe to COMPLETELY hold the test pressure. All the inspector cares about is 15 psi for 10 minutes, but this is my family's house! More details are below.
Sun at 4pm - 15 psi Wed at 4pm - 15 psi Thurs at 9pm - 13 psi Fri at 9pm - 12 psi
I'm guessing the delay in the leak was caused by the extra time needed to force the pipe dope out of the threaded connection. Once the seal finally broke, I'm guessing the leak rate will be more constant until that point when the operating pressure gets down to the 1-2 psi range. Then the leak rate would slow.
Bottom line, I suspect I have not totally tightened a jont well enough and that is the source of leak. I started this job by using Harvey's Pipe Thread Compound, then I started using Rectorseal on the last couple joints. I'm beginning to wonder if I should have used Harvey's TFE past since that stuff does not appear to be nearly as runny as the other two products.
Anyway, I'm interested in hearing about similar installation experiences, and I'm always open to suggestions regarding installation, pipe dope, pressure testing, etc. Thanks
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All I can suggest is to put as much pressure in the line as you can get, then check every connection with soap bubbles, Larry
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Use Teflon tape in place of pipe dope, it doesn't fail like dope and helps you to be able to tighten that joint just a little tighter. Clean all the dope off, ues a wire brush if needed, When looking at the end of the pipe wrap the tape clockwise around the threads 4 times, then hold it in place with your thumb and pull to break. Hope this helps. Ron
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I have had the reverse of your experience.
For my money, Teflon tape isn't nearly as reliable as high quality (teflon filled) pipe dope.
Our dishwasher was installed by a "professional" who used Teflon tape on a 1/4" brass elbow. About a year later I noticed the floor was "swelling." Check and found that the Teflon join was leaking. I did the connection over using pipe dope and no problems.
When I had to replace the "Air level control valve" on my water tank I first tried Teflon tape. (This was a 1 1/4" thread.) The tape just would NOT seal. Used teflon filled dope and no problem.
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The pro's I watched do it used pipe dope, and REALLY tightened the joints hard. They were working at it.
Bob
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With pipe threads that definitely is part of the secret. The threads are tapered as as you tighten you deform both male and female threads to make the connection.
The "dope" helps with ordinary joints by making it slightly easier to really, really tighten down and then sealing the tiny residual leak.
Like it or not, some joints can't be tightened down until they can't be turned anymore. Elbows and "T"s must be oriented. The plumber has to judge by the resistance when he only has "one turn" left and then stop when the fitting is "pointing" in the right direction. It's when you can't really tighten things "properly" that you need the high quality pipe dope. That's not the case, of course, for joints in a long string of course.

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1.1/4" on my 117000 btu unit is needed over I believe 30 ft. I dont know what btu or lenght run you have but I hope you followed a piping sizing sheet, One came with my Bosch . These units will easily double your home gas usage, a manometer is the only way you will be able to predict if when on the coldest days of the year when Ng pressure might be lower if you will be ok with competing apliances on. I can measure a temp drop when only my 70000 btu furnace kicks in. Who knows, even your main supply could be poor. Testing is the only sure way to know, you can buy a manometer for maybe 40$
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Fortunately, there is a pressure regulator at the gas meter. Unless you have a real problem with the supply, you actually will get MORE gas delivery after the meter during cold weather.

Frankly, that's not a big deal. Today, just about every gas consuming appliance has its own regulator. The "local" regulator accepts the gas from the meter (regulated to perhaps 11" to 20") and reduces it to what the appliance jets require which might be at little as 1/2" (H2O) gas pressure.
I grant your point that when a 120 BTUs/hr furnace kicks in it's a MAJOR drawn on the gas supply.
Gages that can read pressures equivalent to a few inches of water can be both expensive and delicate. If you are comfortable around gas lines you can just put a plastic tube on a tap and either partly fill a "U" with WATER and observe the difference or just stick the end of the tube into a deep container of water and observe how deep down the tube is when things start/stop bubbling.
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I know the problem I had when I first started working with threaded metal pipe was; it is hard to get it through your head just how tight those things really have to be. I'd give a pipe joint a good snug, (if it was a suspension bolt, I'd have been confident that it would hold for the life of the car), I'd go back and tighten it, it would still leak, then I got a 3' long pipe wrench, no more leaks.
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snipped-for-privacy@gmail.com wrote:

ahh why are you installing a tankless? they rarely save any money, that is the initial cost is so high and the cost of repairs over its lifetime so great these costs wipe out any savings till your past year 15 or more, when you will likely need a new unit.
the endless hot water if done right is nice, but the trouble is some will use it as a excuse to take endless showers raising your enerfy bill:(
perhaps someone will post that review of tankless, its not flattering. from people who have lived with them.
incidently the energy lost by a regular tank in the winter goes to indirectly help heat your home.
so if you heat your home in the winter cut your tankless savings by 1/2 or thereabouts.
I would disassemble everything and use teflon tape with a little dope. fewest leaks this way, minimize number of joints.
use 20 foot lenths of pipe or longer wherever possible rather than 4 5 foot lengths joined together.!!
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Trac pipe
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snipped-for-privacy@gmail.com wrote:

changes in temperature will affect the pressure of the air in the pipe...........
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I assume when the pipe dope fails like I've described, sounds like the best option is to disassemble, redope and/or tape, and assemble again. I'm guessing, but i bet simply trying to tighten the joint (and skipping the disassemble/redope part) won't be as effective.
Instead of taking every joint apart, I think I will pressurize the system to 60 psi and then hunt down the leak(s). I'll probably end up finding more joints that need tightening once the system is pressurized to 60 psi. Thanks
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I think you will find the more you disturb things the more they leak, starting over is better, but hey why not try, its your back as a friend says.....
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You're probably right. I can't wait until this thing seals for good!
By the way, if you were doing a similar install on your house, how would you do the pressure test and when would you be satisfied that the system was completely sealed. The truth may not come out at 15 psi for 10 minutes!
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Your real concern and a common cause of people saying Tankless dont work is pipe sizing. You need to test gas flow with a manometer with other gas apliances on to insure your tankless outputs its maximum btu, or in winter when its real cold your showers might be cold.
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m Ransley wrote:

1" depending on number of fittings. Just a guess as I'm used to working with propane.
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Tha'ts right...I went with 1 1/4-inch just to play it safe. I think part of my original problem may have been that I was using 14-inch pipe wrenches. I just picked up two 24-inch wrenches to help with the 1 1/4 joints.
Tom Lachance wrote:

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snipped-for-privacy@gmail.com wrote:

pipe dope is a lubricant and not a sealant...the seal is from metal to metal contact of the thread surfaces...the pipe dope merely lubricates the joint so it can be tightened without having to fight the friction of the steel against steel.
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Pump the pressure up to 25 psi then use a soapy mixture to check all joints for leaks.
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