Change in Atwood drain plug size?

[Scott_P]

I have a 2005 Dutchmen Lite 18B and the drain plug was spraying water. IT has the Atwood water heater. I bought the replacement plugs at the dealer, but they seem a tad too big to fit. Any effort to screw it in causes the plug to get crooked and almost cross thread. The stock plug still threads in easily.

Did they change the drain plug size over the years? I can run to Lowes for a replacement nylon plug or two, but it would be easier if I knew the actual size.

[Scott_P]

I ended up using a wire brush to clean up the threads a bit and the new plug went in better. It seems to be holding. Thanks for the help. That one threw me for a loop.

[Old-Biscuit]

Atwood drain hole is 1'2" NPT

Hex head has changed sizes.........7/8" or 15/16" socket

Should be able to start using fingers until hand tight then just snug up with a socket. Tapered pipe threads.

You can easily 'chase' the drain hole threads by screwing in a 1/2" NPT pipe nipple. Cleans/straightens threads.

Nylon is used due to temperature rating.
PVC is not high enough temp rating (never use) and CPVC just meets temp rating (OK for emergency until OEM nylon can be found)

[rcmiller32]

You might have to take a thread chaser to the threads. Or at the least a pipe wire brush to them. A new plug will go in less then 1/2 way. Each time you remove it and install it will go in a little deeper.

[Scott_P]

I have the Atwood part (91857) in a two pack. It just seems too big for the drain. There isn't much of a taper to the new one. I can hand tighten the old one all the way in, but the new one stops after a thread or two. If I tighten it with a wrench or socket, it gets crooked.

[SoundGuy]

Scott P wrote:
Did they change the drain plug size over the years? I can run to Lowes for a replacement nylon plug or two, but it would be easier if I knew the actual size.

Thread size is and always has been 1/2" NPT ... however, if you look carefully at the authentic (white) Atwood version it does have a slight taper to it so that's what I always make sure to use, normally sold in a blister pack of 2.