I know it's been discussed before but if the drain plug on an Atwood HWH is plastic so as not to create a metallurgic reaction to the aluminum tank then why doesn't the pressure relief valve or the thermostat coming off the gas valve cause the same reaction?

The PRV will......it's just that 1) it isn't removed as frequently as the drain plug should be 2) nobodies makes a plastic prv3) Drain plug is nylon which can handle the pressure/temperature and will not destroy the drain plug threads when you remove it. They come in a 2 pack for a reason.The thermostat just touches tank wall..not in contact with water.

Thanks for the reply Bisquit,you helped me a couple of weeks ago with my gas valve. I think what I called the thermostat isn't. What I mean is the long copper looking rod that is attached to the gas valve. #2 My drain plug broke off in the tank I got it out but my new nylon plug will not thread into the tank? I thought the threads my be bad so I threaded in a brass fitting that went in perfectly. Any thoughts on why the nylon ones won't catch?

Drain plug is nylon, the others are probably brass. Neither will corrode but nylon is much less expensive than brass.

pigman1 wrote:How do you spell cheap??I don't think it is a matter of cost. Atwood was actually quite smart when the specified the nylon drain plug. If you cross thread the drain plug when you install it, it's much better to sacrifice a nylon drain plug than the threads on the hot water heater. And it's one heck of a lot less expense for an owner to replace the nylon drain plug every 5-10 years than having to fork over $15 for a Suburban anode rod/drain plug once or twice a year. I've owned rigs with Atwood and Suburban, and I'll take the Atwood version any day.

Atwood Hot Water Drain Plug | Good Sam Community

mobeewan
Explorer
Apr 28, 2014
Suburban water heaters have an over pressure and temperatures relief valve and a steel tank and steel plug with anode rod.

Atwood water heaters have an over pressure and temperatures relief valve an aluminum tank and a plastic plug. If it was true about the plug being designed to blow out if over pressurized, why would the relief valve be needed. Someone needs to recertify the RV course. Plastic plug vs aluminum tank threads equals no damage to threads. I actually replaced my pastic plug with a brass nipple, ball valve and hose barb on an older trailer I have.
Tequila
Explorer
Apr 25, 2014
Actually it was at okanagan college where they teach 2 year certified RV tech courses. I was allowed to sit in since I was teaching another non RV course at the same college. They refered to it as extra insurance.
Tequila
Explorer
Apr 25, 2014
Actually it was at okanagan college where they teach 2 year certified RV tech courses. I was allowed to sit in since I was teaching another non RV course at the same college.
PenMan
Explorer
Apr 24, 2014
Tequila wrote:
That plastic plug is designed to blow out if the presure is too high. I took an RV tech course and they told me not to replace to with the butterfly valve.

Probably should take a different course. They took your money and ran. That's what the relief valve is for. Add a drain valve and don't worry about it.
pianotuna
Nomad III
Apr 24, 2014
Hi,

I guess they never heard of the pressure relief valve in the course.

Tequila wrote:
That plastic plug is designed to blow out if the presure is too high. I took an RV tech course and they told me not to replace to with the butterfly valve.
Old-Biscuit
Explorer III
Apr 24, 2014
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Tequila
Explorer
Apr 24, 2014
That plastic plug is designed to blow out if the presure is too high. I took an RV tech course and they told me not to replace to with the butterfly valve.
GrandpaKip
Explorer II
Apr 24, 2014
hogcard wrote:
I didn't know about this reaction thing you are referring to. I replaced my plastic plug with the metal one that has the center little helicopter valve you can open and close to drain the tank without removing the entire plug. An RV service guy actually recommended it. Any issues here?

Yep, put one in, too. Open it before leaving camp to drain while traveling. All the sediment washes out while on the road. No problems so far.
PenMan
Explorer
Apr 23, 2014
I used a Close Nipple and a Ball Valve. All brass. Works great.
pianotuna
Nomad III
Apr 23, 2014
Hi,

What is a full port plug valve?