Rheem Marathon 40 Gal. Tall

[not-a-plumber]

I will be replacing the water heater in my Daughter's house. The existing tank was manufactured and installed in 2009. It actually looks new on the outside and shows no signs of leakage, but...
It is installed in a first floor water heater closet with no pan and no drain for the T&P relief valve, so any problems will result in flooding the main floor of the house. Based upon what I know of the previous owner, I assume that it has never been flushed and that the Anode rod has not been changed, so kind of a ticking time bomb.

I have a Marathon water heater (50 gal short) in my home that I installed 21 years ago and am very happy with.

I have purchased a Rheem Marathon 40 Gal. tall for my daughter's house and have a few questions before I tackle the project.

The cold water connection is a 3/4" tee due to the factory installed vacuum relief valve - so 3/4" FIP or 3/4" female NPT.

The hot water connection is a rubber seal ring seated inside a union hex nut.

Actually the hot, cold and T&P relief valves all start at the tank as a rubber seal ring seated inside a union hex nut.

I don't know for sure, but I assume that if I loosen the hex nut, I can reposition the orientation of the tee or T&P relief valve and then retorque the hex nut to 35 ft-lbs.

Could use some feedback on this assumption.

I planned on using Rheem (Preferred) 3" heat trap nipples and 18" SS corrugated (not braided) flex connectors before connection to Pex.

My concern is that I will have three dissimilar metals. Brass to steel to stainless steel. The heat trap nipples are plastic lined, but...

I think I might like to use brass nipples instead so I would be going from brass to brass to SS.

But then I give up the heat traps and I will be depending upon the brass nipple face being perfect in order to seal to the rubber seal ring inside the union hex nut.

The steel heat trap nipples appear to have a smooth plastic sealing surface, but they are not available in anything but zinc coated steel.

I'm sure that I am overthinking this, but I'd like to do one installation that can last the life of this water heater which should be a long time since it has a lifetime warranty on the tank itself.

Thanks

 

[Twowaxhack]

Get a couple 316L stainless steel nipples. Don’t use those crappy heat traps.

 

[not-a-plumber]

Get a couple 316L stainless steel nipples. Don’t use those crappy heat traps.

Thanks.
Good advice.
Is there an advantage to using SS nipples vs good brass nipples made in the US, like Everflow?

 

[Twowaxhack]

Brass is fine. It’s not as good as 316L in my opinion.

Look up dezincification of brass.

 

[not-a-plumber]

I'm familiar with the dezincification of the brass Pex crimp fittings in my son's house (well water) which fail regularly and will eventually be replaced with Boshart SS crimp fittings. I make sure that the brass pex crimp fittings that I use in my Daughter's house (city water) are DZR rated.
I assumed that lead free brass nipples would be OK since the wall is so much thicker, but SS it is.
Thanks

Anyone have experience with the Marathon "rubber seal ring seated inside a union hex nut" connections?

Can the union hex nut be loosened from the tank and retightened in a different orientation?

 

[Twowaxhack]

I can buy stainless for nearly the same cost as brass. Easy choice for me.