Water Heaters - Need immediate advice on "an in-demand water heater"

I have an on demand water heater for an apartment that is rented out. My husband installed it over a year ago. My husband suddenly passed away not long afterwards so I'm trying to fix what I can on my own. We ourselves built this apartment in the above part of our remodeled barn. About 2 wks ago, the copper or brass pipe that the water flows thru started leaking. I found a very small split in the line and bought JB weld. Of course I drained all the water out and used an air hose to force air thru the crack to clear water out. I sanded, cleaned with acetone and once dry I applied according to directions, the JB weld. The problem was gone, and I thought I'd taken care of it. This morning I found the same area was leaking water. It was seeping from the edges of where I applied the JB weld. I have taken a drimmel and sanded off the weld around the area of the split. Before I try the same process as before I wondered if anyone had any other suggestions. I can't afford to buy a new one and have no idea about the warranty as my husband took care of all that. Any other product I read on won't hold up to the pressure or the heat. This room that the water heater is in is heated so the cold shouldn't have been the problem. I know a couple of friends who weld but didn't know if whatever this line is made of can be welded. I am desperate for suggestions. This has been a rough year and I've had to face so many challenges, I'm beginning to feel beaten down. My husband was such a smart and wonderful guy, I know he would have known what to do.

If this split is inside the water heater itself it is likely you need to replace the entire part or maybe the entire water heater. Can you take a picture of the split and post it? To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected.

http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear058.jpg


http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear059.jpg


http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear060.jpg


http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear061.jpg


http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear063.jpg


http://i697.photobucket.com/albums/vv336/davenglo/waterheat.jpg


http://i697.photobucket.com/albums/vv336/davenglo/Rangerwithbear062.jpg

I think you would be best to get an authorized representative from the water heater manufacturer to look at that split. It may (or may not) be a covered warranty issue. If not covered under warranty then it may be possible to just replace the heat exchanger (that's what the part is called) instead of replacing the entire heater.

At any rate, while a competent person may be able to braze the split it would likely fail again in a short period of time.

The room it is in may be warm, however on these lower priced atmospheric units freezing from air spilling down the vent and over the exchanger, compounded by negative pressures is common. Induced draft units address this with sealed combustion, dampers and heaters on the block.

Even if warranty is still in effect, once looked at freezing will be the determination and void the warranty.

As said earlier, the return bend can easily be brazed shut, no applied glues or epoxies can stand up to those temp swings.

If you are dead set on doing the JB weld thing again you have got to get the JB INTO the crack so it can grip on the inside of the pipe. It may very well hold up to the expansion/contraction but it has to have a good hold. Putting it on top of the split is not gonna work.

To me it looks more like a defect than a freeze problem but that doesn't really help you any.