Do I need 12” vertical brass stubs on this Rheem Water Heater?

[Borisj]

The thing your mistaken on is "no one knows" best practice is 18" of metallic pipe to and from the water heater. What Terry said is that they use flex connectors, which are metal.

Best practice is known. Metallic hard pipe to the water heater. If earthquake area metallic flex connectors with the water heater strapped to the wall. That is best practice. I'm surprised no one has given you a link, but the metallic flex comnectors are becoming the go to. Pretty much no pro plumber would hook PEX to a water heater, but it takes all kinds.

Thanks John. I appreciate your perspective. I will start with 18" of LF brass since I can't use copper here. In your opinion, is there any potential downside to me starting the run with an elbow? I.e. screwing an elbow directly to the inlet/outlet. Any risk of bottleneck, whether for water pressure performance or safety reasons?

Also, "Pretty much no pro plumber" in your neck of the woods = "pretty much every pro plumber" in mine. I'll gladly/sadly take you on a tour of 200 $50k-$2m houses around here and buy you a beer if more than 2 meet your hard pipe requirements. 90% of "best practice" stuff I've learned on FHB, JLC, Terry Love, Mike Holt, whatever... is from people on the coasts or, sometimes, in high-end builders in left-leaning major cities like Matt Risinger (in no way representative of TX average practice). I'm born and raised in TX and work here. I'm trying to do better than what I see around me. That's why I'm asking you questions.

 

[Jeff H Young]

Are your lines grossly undersized if so it might be an issue but almost no chance a single 90 is going to ruin your system. kinda like having a 1000 studs in your house and one is notched down an 1/8 inch past the minimum . Not gonna hurt a thing

 

[Sponsor]

 

[Reach4]

Terry I can't use copper here (water composition)

Regarding copper, what problems happen? If you are talking pinholes after many years, note that type M copper (red ink) is thinner than the others. Type K (green ink) is significantly thicker.

Copper Tubes - Pressure Loss vs. Water Flow

Water flow and pressure loss <i>(psi/ft)</i> due to friction in copper tubes ASTM B88 Types K, L and M.

www.engineeringtoolbox.com

 

[Borisj]

Are your lines grossly undersized if so it might be an issue but almost no chance a single 90 is going to ruin your system. kinda like having a 1000 studs in your house and one is notched down an 1/8 inch past the minimum . Not gonna hurt a thing

Nah the lines are sized fine, I just thought this one elbow might make a big difference because it's right on the water heater. Kinda like how using <1/2" pipe from mixing valve to tub spout will cause problems even though it's a short run (I know that's a different situation just clarifying what I mean)

 

[AdamBC]

Hello, I’m installing a Rheem Marathon 50-gal water heater, in a 2nd floor, where it’ll service only the 1st floor (so it kinda has a “built in” heat trap since the pipe only goes down). Been trying to contact Rheem for 2 weeks with no response. There’s no code official here for me to ask either (unincorporated area). I want to follow best practices to ensure safety and performance.

1) The manual says "pre-solder 12" minimum stub pipes before installing to unit." We don’t use copper here due to water composition. I could use a brass nipple, but I want to be sure I understand the purpose of this requirement. Is it:

-(a) to ensure vertical clearance (which I’ll have regardless)

-(b) to ensure that a plumber does not melt plastic components while soldering < 12" from the inlet/outlet (irrelevant to me)

-(c) to make sure there is not a pressure "bottleneck" at the tank whether for safety or water pressure issues (good reason!)

-(d) some other reason?

2) If I *do* need to put 12” of brass here... does it have to be vertical? Or could I instead attach a brass street elbow directly to the inlet/outlet, then put the brass nipple horizontal? Again I don’t want to mess with water pressure or safety.

--And if it *does* have to be vertical, then why Terry ok here?

(I trust him over the manual that came with my heater, which is generic for all Rheem tank models). Thing is, my installation will be all hard piped.

3) The unit is being plumbed with PEX-A (Uponor) which is rated for direct connection to a water heater. Manual p. 8 says "Hot water connection fitting must have an ID > 0.725”." I can accomplish that with a 3/4" brass nipple, which I will then adapt to PEX-A (0.681" ID) - but is there a minimum length required for that nipple?

Not trying to cut corners at all – just want to do what’s best in this situation. Thanks!

Check with your local codes, I know here in BC Canada we require 18" of metallic pipe off the top of the water heater.

 

[Chefwong]

I just took a deep dive into these flex lines. Isn't the main difference the outer composition is SS or Copper. The inside of at least the BC lines I looked at - all appear to be the same *pex lined*. so the exterior is more cosmetic relative to the -core- of the hose itself