[DesertHawk]

I need to tap into the existing natural gas line under my house in the crawlspace to power a tankless water heater. The problem, of course, is I have a fireplace and a range that are downstream from the point at which I need to tap in. It's impractical to unscrew every single fitting after the tap in point because one rises through the fireplace's firebox, and the other through a wall. I'd like to avoid tearing up stuff just to unscrew and reattach all the fittings. The alternative is to cut one of the lengths of pipe feeding both appliances and use a union, but that wouldn't be to code. So what's the correct solution? Should I just rip off the band-aid now, cut the wall open and redo everything?

 

[DesertHawk]

Here's the point at which I need to tap in. That may actually be a L/R connection there, but I can't tell from just looking at it. Unfortunately I can't simply tap off the bottom of that capped tee, as the new run of 3/4" pipe needs to basically continue off the main 1" line to be high enough to clear some stuff that's not visible in the photo.

 

[lenaitch]

Certainly not a gas guy and I avoid playing with because I don't like loud noises, but you might want to consider whether that piping diameter will be adequate. Perhaps the installation manual for the heater will help. Also, I'm not sure that 'mud dump' is adequate. I don't know the rules but around here they all seem to be around 6" long.
Just thoughts.

 

[DesertHawk]

Certainly not a gas guy and I avoid playing with because I don't like loud noises, but you might want to consider whether that piping diameter will be adequate.

It should be. The main supply line is 1", and the specs for the water heater call for a 3/4" gas supply, which is what you see there. That 3/4" piping goes to the old water heater location, then reduces to 1/2" for the fireplace and range. All the connections after the point in the photo are the ones I'm concerned with.

Also, I'm not sure that 'mud dump' is adequate. I don't know the rules but around here they all seem to be around 6" long.
Just thoughts.

It's not. That's actually just temporary. I removed a bunch of frivolous piping that was coming off the bottom of that tee, so I needed to cap it. That'll be gone once this install is completed and a 6" trap installed on the other side of the wall before it goes into the water heater.

 

[DesertHawk]

Here's a close photo of the threads on that coupler. It does seem like the bottom nipple is a L/R thread type. If so, this should simplify everything as I should be able to separate the top and bottom pipes pretty easily. A second (and third) set of eyes on this would of course be appreciated!

 

[SeniorSitizen]

Rt hand left hand

 

[Bondo]

If so, this should simplify everything as I should be able to separate the top and bottom pipes pretty easily.

Nope, couplers don't work that way,.....

'bout the only way I see to do what you want is to come out from where the cap is, to a "T", with a drop-leg down, 'n elbows to go back up to where you want to go too,.....

 

[TarheelTerp]

'bout the only way I see to do.....

What about cutting in a union somewhere on that 1"?
Then set the TEE wherever it works best for the new WH...

 

[Joeywhat]

It's not clear which way this new run is supposed to go, but how about removing the elbow and replacing with a tee, then running the new pipe where it needs to go?

 

[TheEplumber]

I'm going out on a limb here and saying that your line will be undersized once you add the tankless. Have you actually ran a load calc using gas charts? Saying the heater is a 3/4" supply is not a proper way to size a fuel line....

You may be better off running CSST from the meter directly to the new WH. I'm sure there is ample space to put a tee there

Sent from my SM-G970U using Tapatalk

 

[roughneck]

That coupler

 

[bfrabel]

L/R couplings are pretty rare. I doubt that's what that is. It appears to be a non-tapered "merchant coupling", or what some people call a "thread protector". These aren't supposed to be allowed because they are threaded all of the way through without a taper, which means it doesn't get tighter and tighter the more you go like a normal tapered coupling would. Well, actually it would because the pipe is still tapered, but it's still not right.

As far as I know, a union would be allowed in this spot. Could you could cut that coupling right in the middle, unthread it, and replace it with a union?

An alternative and much easier option would be to unthread that cap and install a tee right there, and then put a short nipple and that cap back onto the bottom again.

Of course the point that TheEplumber is a very good one. How many btu's is your new water heater, how far of a pipe run is it from the point where you want to tie it into the piping, how far is it from there to the meter, and what gas pressure are you working with?

 

[roughneck]

That coupler

I don’t know why this posted like that......supposed to say that coupling is illegal.
Can’t use straight thread couplings.

 

[DesertHawk]

I'm going out on a limb here and saying that your line will be undersized once you add the tankless. Have you actually ran a load calc using gas charts? Saying the heater is a 3/4" supply is not a proper way to size a fuel line....

That's a valid point, and I considered that. It may be the case that due to the length of the run, the gas supply will be a bottleneck. Fortunately, it's a one bathroom house so the water demands are low.

If I make additions to the place in the future and add another bathroom with a shower (this is something I want to do), I will definitely have the gas line replaced as it's a fairly long run.

 

[DesertHawk]

L/R couplings are pretty rare. I doubt that's what that is. It appears to be a non-tapered "merchant coupling", or what some people call a "thread protector".

I'll have to confirm with my own eyes, but looking at the photo close up it appears as though the bottom nipple going into the coupler is L/H threaded, at least on one side.

As far as I know, a union would be allowed in this spot. Could you could cut that coupling right in the middle, unthread it, and replace it with a union?

It's possible it's allowed, but unions from what I understand must be preceded by a shutoff valve. Which, I think, is why plumbers usually say they should be used at the applicance only. Since you'll be using a shutoff anyway. Someone please correct me if I'm wrong.

An alternative and much easier option would be to unthread that cap and install a tee right there, and then put a short nipple and that cap back onto the bottom again.

Well, that would work, but the problem is I would need to raise the new piping back up again to clear a bunch of stuff that's off-camera, to the right of the photo. The "correct" way to do this really would be to tee off the bigger 1" pipe (instead of the elbow that's in use now), then continue it on past the point where all the stuff in the photo drops down. I need to go about another 27" inches to make the turn I need to get out of the crawlspace through a vent without making a hole in the rim joist and stucco.

Of course the point that TheEplumber is a very good one. How many btu's is your new water heater, how far of a pipe run is it from the point where you want to tie it into the piping, how far is it from there to the meter, and what gas pressure are you working with?

It's a 6.6 GPM heater, 160,000 BTU if I recall correctly. It's probably a bit oversized, but I got such a good deal on it due to a subsidy from the gas company, I couldn't turn it down.

 

[SeniorSitizen]

DesertHawk Quote:I'll have to confirm with my own eyes, but looking at the photo close up it appears as though the bottom nipple going into the coupler is L/H threaded, at least on one side.
*********************************************************
Previously mentioned L/R couplings are rare. Try rotating the pic 180° then look again at that end which will then be up top.

 

[TheEplumber]

That's a valid point, and I considered that. It may be the case that due to the length of the run, the gas supply will be a bottleneck. Fortunately, it's a one bathroom house so the water demands are low.

If I make additions to the place in the future and add another bathroom with a shower (this is something I want to do), I will definitely have the gas line replaced as it's a fairly long run.

If you starve the appliance, it will not perform properly and in some cases, it may go into lock out mode due to low gas volume.

IMO- Size your line properly (run the calcs) then you will know your location is a good choice. If not, consider running a branch from the meter. It can't be that much further since you say it's a small house....

 

[roughneck]

Excluding the tankless, how many BTU are being supplied by that gas line now?

 

[Ghostmaker]

https://fire-boulder.com/wp-content/uploads/2016/09/Gas-Line-Pipe-Sizing-Chart.pdf

 

[DesertHawk]

Excluding the tankless, how many BTU are being supplied by that gas line now?

The only other thing that would get any regular use off that 1" pipe run is the range/stove. The furnace on the roof has its own 3/4" line that's teed right off the output from the meter.