Gas line under slab...

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zimm0who0net

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Can someone clarify a few things for me. I have a poly natural gas line coming from the meter to a guest house about 120 feet underground. It needs to get to an outdoor water heater on the opposite side of a structure. Easiest path is underslab starting with the poly line and running completely under the building (yet to be built), surfacing beyond the building. I called the inspector ( a really nice and knowledgeable guy), and we read the International Fuel Gas code and it seems 404.14 applies here (Piping Underground Beneath Buildings). However the ONLY two exceptions are for lines where both ends terminate inside the building (no sealing the sleeve), and for lines where one end terminates outside the building (seal both ends and vent the sleeve outdoors). There's no option for BOTH ends terminating outside the building. Clearly this is an oversight on the Fuel Gas Code, right? They wouldn't want me to bring gas inside a building that doesn't need it, right?

Anyway, reading the code with the inspector, it appears that the only option that works for me is to surface the gas line INSIDE the structure and then pop through the wall to go to the outdoor water heater.

Next issue here was what piping is allowed inside the sleeve. I obviously wanted to continue the poly, but again, the inspector said that wouldn't be allowed because I can't bring poly above ground, and I have fittings inside the sleeve, so it's a catch-22. One manufacturer rep suggested I put the transition fitting from poly to black pipe right at the seal (i.e. have the threads stick out the seal). The inspector didn't like that because technically there was still PART of a fitting inside the sleeve, with isn't allowed.

Next option was CSST. Again, a no go because you can't bury any of the CSST fittings, so I can't transition from poly to CSST underground without surfacing, transitioning to CSST, and then going right back underground, which seems insane. Why surface a gas line that doesn't need it? How is that "safety"?? Another option was to keep the transition "underground", but in an accessible valve box. That option is bad because it's a patio right there and aesthetically we don't really want a valve box in the middle of it.

So, the last option here is to transition from poly to coated black pipe, run that under the slab through the sleeve, make a right angle at the far wall, bring it above the slab inside the wall and then outside. I object to this because I think it's crazy that the only option here is to use old school black pipe underground with lots of fittings that can fail and theoretically rust. Not to mention the fact that should something fail, I'll absolutely never get the black pipe out because there's an elbow buried inside it as we curve up under the wall. Ugh. I'll do it if it is really the only option, but I think it's crazy. (it also happens to be the cheapest option....go figure)...
 

zimm0who0net

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Incidentally, the poor plumber is watching from the sidelines, essentially saying "I'll do whatever you and the inspector decide".
 

Dj2

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" It needs to get to an outdoor water heater on the opposite side of a structure. "
What about going around the structure to where the WH will be located?
All in one long CSST pipe.
 

zimm0who0net

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" It needs to get to an outdoor water heater on the opposite side of a structure. "
What about going around the structure to where the WH will be located?
All in one long CSST pipe.
Not really an option. Going one direction would require going under a driveway and open up the whole same can of worms. The other direction would be about 80’ and it would have to run right next to the base of a wash.
 
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