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Pex elbow to water heater leaking

Go to solution Solved by Frank Bergamo,

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A week ago we found water leaking and traced it to the Pex elbow as shown at the top left of the picture, below. The water heater is an Atwood 10 Gal unit. The fitting was loose and I tightened the screw connector to the copper to stop the water leak. I thought I was done but this evening I heard a drip and found the fitting leaking, again. When I removed the fitting (after turning off the water and relieving the pressure), I found that the fitting was in fact broken thus causing the leak.

Looking at the post below for info, I assume, not having any calipers with me) the Pex pipe should be 1/2 or 5/8 inch and the Female threaded connector is 3/4 because it is much larger than the 1 inch garden hose female fitting (I know, it is a terrible way to measure).

Several members ran into plumbing issues at the water heater recently and I was hoping for guidance on which size elbow fitting to purchase. My best estimate is that it is, as mentioned, 1/2" ID and 5/8 "pex OD and 3/4" female threaded elbow that I need. There were other post(s), related to the back-flow preventer valves such as:

Any help primarily with the Pex size and threaded fitting would be greatly appreciated. 


waterheater elbow 2024-02-15.png

Edited by Martinvz
correcting the pex size
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Here is a picture of what I needed for mine. It threads onto the 1/2" pipe threads and gets crimped in the 1/2" PEX hose. Yours is different on the bottom end and uses what I believe is called a Flair-it fitting to attach to the PEX hose. Mine came from the hardware store but I'm not sure if they'll have a Flair-it to FNPT fitting at the hardware store or if you'll have to try an RV supplier.


I think this is it.


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I agree, the pex size is nominal 1/2" which is 5/8" OD.  Based on the scale of the picture I'd be surprised if that copper/brass T is 3/4"NPT it sure looks like 1/2" NPT.

Did you mean it's SMALLER than garden hose fittings?  Garden hose female couplers will start to thread onto male 3/4" NPT threads, but only one or two threads.

I'd try to find a 1/2" female by 1/2" pex sharkbite fitting for that, unless you have the crimping tool already.  You can cut the pex with a utility knife, carefully, if you have to. 

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Thanks to Tom Wallis and Frank Bergamo for pointing out the Flair-it brand and that was what pointed us to the part. I did not find it in the stores we visited and had to draw the line some where. We found the part on Amazon as Flair-it elbow part number 16816 as in the photo below. I also found that the seals on the ftp side are available on Amazon.

I had purchased a brass pex to ftp connector but it was not the correct fitting. A friend had the correct Flair-it elbow which I installed and we have been free of leaks. The photo is of the purchased part in the packaging to keep (and hopefully never to be used). the part number is visible at the bottom.

I suggest that the part be added to the Monaco parts list, if it is not already there.

Flair-it 16816.jpeg

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