Forum Discussion

JoshInReno's avatar
JoshInReno
Explorer
Sep 21, 2017

Water Heater Pressure Relief Valve Outlet Size?

I have a stinky (mild rotten egg smell) water heater on my trailer that I need to deodorize with hydrogen peroxide. I am thinking of filling the water heater through the pressure relief valve. But I don't know the thread size to buy to appropriate fitting.

This is what I am trying to avoid doing:



Unfortunately I can't do much by trial and error because the trailer is at a remote campsite. The nearest hardware store is 80+ miles each way. The campsite is also 4 hours from my home. I am going up this weekend to get this and a few other projects done but time is very limited. I really don't want to pull the valve from the water heater if I can avoid it.

I guess the question is: are the outlets a universal size or should I bring a selection of sizes? I'm guessing 1/2"? NPT I'm assuming?

Thanks!
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    There are two sizes common 1/2 and 3/4. but on RV's only the 1/2 is used.
  • wa8yxm wrote:
    There are two sizes common 1/2 and 3/4. but on RV's only the 1/2 is used.


    Not so....
    Suburban uses a 3/4" NPT

    Atwood used two sizes......1/2" NT & 3/4" NPT depending on year/model
  • Just replaced one, Atwood 1994 model, 1/2 in, newer one's can take 3/4 in and that was from a RV dealer in Whitehorse this summer, $39.00 for the 1/2 in one.and that was in my 5th wheel.
  • wa8yxm wrote:
    There are two sizes common 1/2 and 3/4. but on RV's only the 1/2 is used.


    Mine is 3/4".
  • cpaulsen wrote:
    wa8yxm wrote:
    There are two sizes common 1/2 and 3/4. but on RV's only the 1/2 is used.


    Mine is 3/4".


    Shot that in the foot.... 2 times., make it 3. My Sub is 3/4 as well.