mystery leak

On our last trip I noticed that our 2011 3124KB had an occasional, slow leak. It was leaking from the bottom trim piece around the external shower (see photo 1), but the ext shower seemed just fine. The leak was slow and I didn’t notice it every day. I had previously noticed that items in our external rear storage were damp.

After landing back at home I tried to reproduce the leak. No leaks when using the fresh water tank and the pump. Hooked it up to city water for days - no leaks. Ran all the faucets, cold and hot taps - no leaks. Thought maybe it was the shower given the proximity, but no leaks in the fresh water nor from the drain.

Figuring it had to have been water from the shower that somehow ran behind the splash board (which I did have to re-calk), or the leak self healed for a while (wishful thinking), I went on to the next task which was replacing the anode rod and flushing the water heater. Finished that and proceeded to test the hot water heater. The hot water heater works just fine, but the leak is back. Now the water is coming from right where the bottom trim piece meets the wheel well.

Now I’m suspecting the hot water heater, though it would need to have a slightly bizarre path to leak at the rear portion of the wheel well. Crawl under the kitchen sink – nothing. Under the bathroom sink – nothing. Confirmed again that the leak only happens when the hot water heater is running – electric or gas. Once the water is hot and the heater is just sitting idle, the leak eventually stops. ..and when it’s leaking, the water is not hot.

After several more trials and contorting my body to get a view of the plumbing behind the exterior and inside showers via the “service” hole in the rear cargo compartment (photo 2), I spotted a the drip. It looks like it’s coming from exterior shower connections (90% sure). I’ve noticed other posts on here that indicates the ext shower as a point of failure.

So…..
Any theories or similar experiences with why a leak might occur there only when the hot water heater is running? My thermodynamics knowledge is not so good! I would have thought being hooked to city water (I do use a pressure regulator) regardless of the heater being on would make a leak deterministic.

Second question: Any experience on repairing a leak behind the external shower? There’s no way to get at it via the rear cargo area. Looks like I’d have to remove the entire shower to get to at it from the inside. It almost looks like a hole was cut and later patched in the TM underside to get at this area (~ 1 sq ft area encompassing the 2 drain valves.) Hopefully there’s enough maneuvering room if I take out the ext shower itself.

Appreciate any guidance.
-mike

If you open the external shower door there should be four screws holding it to the body. You can gently pull it out AFTER cutting the caulking. The lines are attached but you can pull it out a little to look and possibly repair. I got rid of my outside shower the thing to me was kind of useless with that stiff hose. You can look at one of the pictures I posted after the removal of the external shower in the sealand toilet thread. I took a saw zall and or saber saw and cut out the guts and left the frame and door. Robert

Thanks Robert. I was able to get the exterior shower out fairly easily.

Once the shower was pulled out I confirmed the leak was coming from where the cold water connected to the ext shower. The hot water connection was leaking too, but to a much lesser degree and stopped when I tightened the plastic swivel nut.

I’ve never worked with this PVX stuff before. I’d like to start by just replacing the beveled washer in the plastic swivel connector. Can someone recommend where to find parts for this PVX stuff? I tried the Depot but they only had a few random Shark Byte parts (brass, not the white plastic). The guy in the depot told me these were not compatible with RV plumbing, but I suspect he may be wrong. Anyway, I’d like to avoid cutting out the existing elbow to just replace a washer.

If I do need to replace the elbow connector, do I need to cut the old one out or is there a way to undo the black connector band and get the barbed end out? Like I mentioned, I’ve never work with this PVX stuff. How do I properly install, or remove the coupling connectors?

Thanks

-mike

The water heater part of the mystery deepens. I capped off the hot and cold feeds to the external shower and decided to retest the system. Again, with the water heater off and shore water on (with a regulator) the TM sat overnight with no leak other than a few drops where I capped the external shower. When I turned on the water heater, the drip at the cold connector to the external shower picked up some, but not as bad as when the shower was connected (again, I suspect it’s the beveled rubber washer.) After running the hot water out a few times and letting it reheat, I was about to call it done when I noticed there was a fair bit of water under the kitchen sink by the hot water heater. It looks like the water leaked out the plastic connector where the cold water enters the hot water tank. I checked the rest of the connections around the TM and also found some water had leaked out from the pipes feeding the internal shower.

Does anyone have any ideas why I’m getting leaks when the water heater runs? It’s like it imparts back pressure on the cold water input line. (as far as I can tell, all the leaks are on the cold lines.) Help!

I don't know what swivel connector you are talking about; is it in the exterior shower?

I've only worked with the PX stuff once while doing the toilet change out. I made a mistake connecting up the piping and had to remove the black band so I could use the fitting again. I used a grinder to grind off the band. It took some time and also damaged the plastic hose. I don't know if there is a better way. Cutting the hose at the fitting may be the only way. You need a shark bite crimping tool to crimp on the new bands. There are some fittings that don't need a crimping tool. I just broke down and paid sixty dollars for the tool because it makes for easy connections. I bought everything at the Depot. Maybe you need to try another store or buy online at a RV store.

I wish I could tell you why the cold water lines are leaking. Does the water seem hotter than usual? If the temperature isn't excessive I guess you just have to repair the leaks and see if they hold. It's great your looking to find every leak and repairing them.

The shark bite tool also comes with a calibrating tool to make sure it is crimping correctly. One end of the tool should slide over the band and the other end of the tool should not. If the leaks are coming from the hose connections to fittings maybe the tool wasn't crimping enough. If the leaks come from threaded connections maybe they just need to be tightened slightly, don't over tighten. I just noticed you have a new trailer, it MAY have just been an installation problem. Hopefully other may give you more ideas. Robert

I just thought of something else, maybe the regulator isn't working correctly or is there a way to put it on backwards. I'm just trying to eliminate all possibilities, not insult.

You could put water in the fresh water tank and turn on the trailer water pump with the city water DISconnected and see if there are leaks. If it still leaks you know it's not an excessive water pressure problem from the city water hook up because I doubt the water pump in the trailer can put out excessively high pressure. Robert

As long as you are stumped and trying things. Try the same experiment with WH running on gas then on electric. This will eliminate the possibility that the heating method is causing some expansion in a fitting and causing a leak.

[commodor47]

Something else to consider: what is the relative humidity in your area? Condensation can occur on cold, metallic surfaces when the relative humidity is higher than normal. I've experienced a slight amount of water below our hot water heater and also thought it was coming from the cold water input. A closer inspection revealed a small hole at the bottom of the hot water heater Styrofoam jacket which had indications of a water leak - due to condensation between the water heater and the jacket.

Dick

[Bill]

Trish -

Just a side note. I'm under the impression that PEX-to-PEX fittings require a special crimping tool to make the connections. Shark Bite fittings are expensive, but they do not require a tool, and they are easily removable/reusable if you buy the little plastic remove-tool collar (sold separately, cheap). They also work on all kinds of rigid and semi-rigid pipe, including copper, PVC, and PEX.

I believe that the pipes and fittings in the TM are the standard household size, and many of our members have used them in the TM, so I'm not sure what the Home Depot guy was talking about. On the other hand, I don't know what PVX plumbing is.

As you said, it sounds like the pressure in the system is rising as the water heater comes on. Assuming you don't get to the boiling point (and you would know it if you did), water doesn't expand very much when it heats. On the other hand, the air in the head space of the heater will try ferociously to expand as it heats up. One thing you might do is blip the temperature/pressure release valve when the water gets hot, and see if the leaking stops. The t/p valve is intended to operate automatically to release excess pressure, so we are seldom even aware that it has done its job. It could be that the problem is a faulty t/p valve. They are not adjustable, but replacement is cheap and easy - or at least easier than what you are doing now.

Viewed from the outside, the t/p valve is located in the upper right corner of the heater. Just lift the handle a little bit, for just a moment, and drop it back. CAUTION - HOT WATER MAY SHOOT OUT - DON'T BURN YOURSELF!

Bill

Thanks for all the input. To answer a couple of questions in the previous replies:

• The swivel connector I referred to is the connector to the exterior shower cold input (the white plastic elbow that is barbed (presumably) on the PEX end and ½” hose thread on the other.
• I confirmed the shore water pressure, post regulator, is 32-35 psi.
• I hadn’t noticed the leaking when using the pump before, but I’ll give that a shot again since I have the TM pretty much emptied out at this point.
• The leaks do occur with either the electric or gas heater in use.
• I live in the SF Bay area so no humidity to speak of 
• I’m intrigued by the t/p valve concept Bill mentioned. I’ll try that this weekend.
• My bad with the PVX. Meant PEX. I’ll need to search around a bit more for parts. So far the local Depot and OSH only have a spattering of Shark Byte parts and I haven’t seen the beveled washers or the full elbow connector that I would replace first. (Tons of HW stores around here but the nearest RV supply store with any sort of inventory is 45mins away  )

Would still be interested to hear if anybody knows a good source for the PEX parts and/or any other theories on why the leaks occur when the hot water heater is running.

Thanks