Water heater drain mod - would this cause problems?

[Tunce the traveler]

Originally Posted by dpi7800

As a somebody that was a plumber for 17 years the only real problem with the brass into the aluminum , especially with teflon tape is easily over tightening and splitting the aluminum. I would recommend a plastic nipple or use pipe dope.

Good advice and it never entered my mind.

[norty1]

It is a valid point. It's been discussed much for years. Personally I would use a non metallic fitting in the tank and consider removing it at least once a year to get the scale out of the tank bottom.

[Camper_bob]

Originally Posted by North of 49°

This mod is now on my to-do list. Last fall I forgot to relieve the pressure on the tank as I was winterizing, and as I was loosening the cap, the geyser of water blasted the cap out of my hand, never to be seen again. Good thing the water was only warm and not at full temperature. Instead of being wet and embarrassed, I'd be scalded and screaming.

I did the same thing, except I found my plug ... 15 feet away in the side-yard. It almost made it into my neighbors yard! That's why I stressed the "wait for the tank and water to cool down" before you remove the plug. Luckily no one saw me, but DW did ask why my shorts and shoes were all wet. Then she looked at my face and said "never mind, I don't want to know."

[Lolead]

Camper Bob, Thanks for posting, I thought I was the only one that received a free instant shower when winterizing this past fall. For some reason I totally forgot to release pressure first but it only took a second to be reminded !!! I was soaked from head to toe but the pug was captured by the carport we store under. And I did have a great laugh at myself.

[oldmanAZ]

I let the tank cool down and made sure the pressure was off by opening the outside shower valves. I removed the drain plug, no pressure. All good. The water 'gurgled' out slowly... until I opened the pressure relieve valve... Air rushed in and WHOOSH! my shoes got soaked!

[North of 49°]

My wife knows better than to ask when I come into the house soaked and cursing. I think she derives some form of amusement from it. But that's another reason why I think it's a good mod. The end of the hose can be pointed in a safe direction before the valve is opened, just in case.

[SteveMM]

Originally Posted by dpi7800

As a somebody that was a plumber for 17 years the only real problem with the brass into the aluminum , especially with teflon tape is easily over tightening and splitting the aluminum. I would recommend a plastic nipple or use pipe dope.

I hunted around Lowe's and on Amazon today for a plastic version of the male-to-male adapter that I currently have, with no luck. If anyone has any ideas of where to find one, I'd be grateful!

[oldmanAZ]

Have you checked Ace Hardware? I've been amazed at the 'odd stuff' I find at my local Ace store when I have a problem.

[01tundra]

Originally Posted by SteveMM

I hunted around Lowe's and on Amazon today for a plastic version of the male-to-male adapter that I currently have, with no luck. If anyone has any ideas of where to find one, I'd be grateful!

What size is the threaded connection - 1/2" NPT?


https://www.grainger.com/product/THO...1-2-Pipe-1VTJ4

https://www.freshwatersystems.com/p-...FRY9gQods5EM_w

[norty1]

1/2 to 1/2 NPT nipple should be readily available. It does not have to be nylon.

Just something that will hold up to hot water.

[01tundra]

Originally Posted by norty1

1/2 to 1/2 NPT nipple should be readily available. It does not have to be nylon.

Just something that will hold up to hot water.

I wouldn't use PVC for sure, too high of temperature. CPVC might work, but I'd stick with Nylon. I just ordered two from the second link that I provided above.

[North of 49°]

Interesting... I didn't think that PVC or even ABS pipe was that susceptible to high temperatures. I found this at The Engineering Toolbox website. There might be a case for using a properly installed brass fitting. Or, as 01tundra said, CPVC. What temperatures are our water heaters set at from the factory?

[01tundra]

The International Plumbing Code limits the water temperature to a shower to a maximum of 120F, I would imagine that the RV industry would comply to the same code.

Keep in mind that the temperature/pressure charts for PVC and other non-metallic pipe materials are not linear in most cases, meaning as the system pressure rises, the maximum allowable temperature decreases exponentially.

PVC is rated for a maximum temperature of 140F, even under no pressure.




We know that Nylon will handle the duty, the only caveat is that there are several different formulations of "Nylon". I'm still searching for a maximum operating temperature at 50 psig pressure, but no luck so far. I may have to do a field engineering experiment for this one and report back..........


Here is another source for Nylon fittings -


Threaded Nipples | U.S. Plastic Corp.

[JFlightRisk]

The checklist that came with our PDI listed the actual hot water temp at 140 degrees from the tap. I'll check the Atwood manual later tonight to see if they list "normal" settings.

[01tundra]

Originally Posted by JFlightRisk

The checklist that came with our PDI listed the actual hot water temp at 140 degrees from the tap. I'll check the Atwood manual later tonight to see if they list "normal" settings.

That surprises me, not only does that go against IPC, it also goes against ADA - unless you have mixing valves at the fixtures limiting the maximum to 120F, which is common practice in residential, commercial and industrial applications. A lot of times I'll design to a 150F-180F delivery temperature to mixing valves and then knock the mixed temp down to 120F. This reduces the required hot water storage capacity for the usage factors, which would make sense in the RV industry with such limited space and storage capacity.

[01tundra]

Ok, this gives me enough comfort level to roll the dice and go with the Nylon fittings that I ordered.

For 140F (60C) max temperature and 50 psig (3.45 Bar) max operating pressure (using the max pressure of my Camco PRV) every size of Nylon tubing in this chart is good to go, so even with the derating between tubing and fittings I'm feeling OK about it.

I'll let you know if we end up with a geyser spraying out of the side of our TT .

[Mark Geer]

I use a 4" x 1/2" brass nipple and brass cap very simple and cheap under $5 at home depot . Water misses the bottom of heater easy cleanup. Have installed on 2nd camper with on problems with daring .

[SteveMM]

After all of this discussion, I'm not 100% sure what to do about the hookup I built. A number of people here are saying not to worry because the risk of corrosion is extremely minimal, and would only happen over decades. However, it sounds like to minimize risk it would be best to replace my brass male-to-male fitting with a plastic or nylon one, which I can't seem to find.

[Camper_bob]

Could you just tap and thread the existing nylon plug? I know the nylon is pretty flexible, and the cap might not be thick enough to get a decent thread depth or count, but I just wonder if it's possible? I suppose you could also just go all the way through the nylon plug and attach using a washer and nut on the inside? Perhaps put rubber washer(s) on to prevent leakage?

[SteveMM]

Originally Posted by Camper_bob

Could you just tap and thread the existing nylon plug? I know the nylon is pretty flexible, and the cap might not be thick enough to get a decent thread depth or count, but I just wonder if it's possible? I suppose you could also just go all the way through the nylon plug and attach using a washer and nut on the inside? Perhaps put rubber washer(s) on to prevent leakage?

That sounds like beyond the amount of trouble I'm willing to put into this.