Rinnai Tankless

[DoctorPepper]

Hey there, new to the forum here. I just ordered a Rinnai RU199en and it seems I’m going to need to run a new 1-inch line to it. The Rinnai has a 3/4 inch fitting for the gas line; would I just use a 1-inch reducing coupling at the point of entry? Or can I run the 1-inch line to the wall where it’s mounted then use 3/4 flex line from the wall to the gas inlet on the unit?

Thanks in advance!

 

[Jeff H Young]

you could stub out wall 3/4 use a big enough flex for the btus. if your close within a few feet if its more than 5 foot I'd reduce at the shut off valve. sometimes I'll use a reducing 90 exposed at the wall that way anyone can tell in the future what size piping I had run. might be some technicalities

 

[Sponsor]

 

[DoctorPepper]

you could stub out wall 3/4 use a big enough flex for the btus

Thanks Jeff! So run the 1-inch line to the stub out, then 3/4 from the stub out to the tankless?

 

[Bannerman]

I expect the manufacturer's installation instructions detail how the gas line is to be configured.

 

[Jeff H Young]

I expect the manufacturer's installation instructions detail how the gas line is to be configured.

not really that detailed

 

[Fitter30]

How long will the 1" and numbers of 90s (ells) and is it comming. off 3/4" ?

 

[DoctorPepper]

How long will the 1" and numbers of 90s (ells) and is it comming. off 3/4" ?

The 1” run will be about 20 feet and will have 3 or 4 90s coming directly off the 1” line off the meter.

 

[John Gayewski]

Yes it'll be fine.

 

[Jeff H Young]

Thanks Jeff! So run the 1-inch line to the stub out, then 3/4 from the stub out to the tankless?

Sure Doctor , thats what I would do you wont starve it for gas the flex connector will be less than 1 inch or even if you are running solid gas piping with no flex its pretty standard practice around here

 

[DoctorPepper]

Yes it'll be fine.

One other question for the thread. I’ve read mixed comments about flex pipe vs black pipe. I’m assuming the 20-foot run should be black pipe? I’m working in a crawl space, so flex pipe would be a little more forgiving, but if it creates other issues I’ll just tough it out with the iron. Thoughts?

 

[Fitter30]

Short 3/4" flex should be ok. Some of the flexs use smaller tubing then use 1"

 

[John Gayewski]

You'd have to look it up. What's your pressure at the meter? If anything the CSST might need up sized, but CSST will work.

 

[DoctorPepper]

You'd have to look it up. What's your pressure at the meter? If anything the CSST might need up sized, but CSST will work.

That’s a good question, I’ll have to get a read on it first. But I’ll probably just end up running black pipe. Once I’m through the wall it will only be two 90s. The rest is a straight shot. Thanks again!

 

[Reach4]

If your gas company will provide 2 psi gas, you can use a regulator at each gas appliance to drop down to 7 inch water column (about 1/4 PSI). Some will. More won't do that, but if you can, a given size pipe can carry a lot more gas.