PEX Size - Page 2 - Fiberglass RV


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Old 07-20-2020, 02:41 PM   #21
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One of the things that repeatedly stresses trailer piping is the pressure increase associated with the water heater.

When all the air is out of the system, and the water heater is started, the expansion caused by the temperature rise will push the system pressure up to the pop point of the relief vale, or about 110 psi. Probably many of you have noticed some dripping from the pressure relief when the water heater is running. This is the cause of that drip.

The remedy is to put in one or two RV accumulator tanks. This will reduce the pressure increase to about 10 to 20 PSI above the pump cut-off pressure. If you are connected to shore water, you can leave the faucet dripping until the water heater shuts off, but that is not a fix.

Using a pressure regulator on the shore water supply assures you will have this situation because they have check valves in them that do not allow water from the trailer to go back into the shore water system.
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Old 07-20-2020, 02:48 PM   #22
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I actually try to not use shore-water too. We rarely get a sewer hookup, so I try to use pumped water as it's more trouble to fill the fresh water tank and I figure this helps discourage use.

We indulged last week and used the campground water supply as we had a sewer hookup.

We use a little Camco (40055) pressure-reducing fitting on our water hose. It was sustaining 40 psi while the campground supply was at 80 psi, so it was doing a good job. But, still 40 psi is still enough to make a mess of things quickly.

I wish you good inspection results.
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Old 07-20-2020, 02:54 PM   #23
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Quote:
Originally Posted by Raspy View Post
Using a pressure regulator on the shore water supply assures you will have this situation because they have check valves in them that do not allow water from the trailer to go back into the shore water system.
Oops, Imma gonna check that out!

Normally, we run the pump, and stingily at that. But, we might be doing us as much harm as good with the PRV.
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Old 07-20-2020, 03:16 PM   #24
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An easy way to see the pressure increase is to get all air out of the water system, just by operating it normally, then put a pressure gauge on the shore water connection, that is typically a hose connection. A water test gauge with a hose connection is easy to find, or adapt at the hardware store. Then start the water heater and do not run any water. Watch the gauge rise.
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Old 07-21-2020, 07:38 AM   #25
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I’ve definitely noticed the high pressure when the water heater is on. I only turn mine on 15-20 minutes before a shower, then back off again.

I’m almost done, assuming no leaks. This is definitely one of those jobs that would have been really easy if it hadn’t been so hard. Know what I mean?

I somehow got one less PB->PEX fitting than I needed and our hardware stores close at 5:30 so I have a little work to finish this morning. But, in the end, to get the gigantic PB crimper in there, I had to remove the sink. To remove the sink, I had to remove the furnace. I guess this is where a small child comes in handy...but there were none around.

Anyway, one more fitting, two more crimps (two men enter, one man leaves?), the re-attach the sink drain, connect the furnace, and hope for no leaks!
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Old 07-21-2020, 11:15 AM   #26
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Zack. What a hassle! Sheesh! You poor dog.

Remember, the stainless cinch ring works just as well as the copper crimp ring. They are interchangeable with either PB or PEX and the cinch ring tool fits into very small spaces.
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Old 07-21-2020, 01:00 PM   #27
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Ah...well too late. That would have been nice...I didn't know I could use that cinch ring on the PB.

It's done now; tools returned; deposits refunded. Turned on the water and so far no leaks. You can bet that I'll be de-pressurizing the system every time I turn off the water pump for a while though...

Not a lot of space
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I mean really
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Much better view/work angle from the top with the sink out
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Surprisingly enough, once I could see what needed to happen, it wasn't a big deal. I've had the furnace out so many times...I had it out in under 5 minutes. Sink was kind of a pain. But none of that was worse than trying to get those rings cinched in the cramped space I was working with before removing them.

If you've never had your sink trap out, you're in for a treat! You know how grey water smells? Imagine that, but super-concentrated and in solid form. Basically black water with a tang. But I cleaned out a lot of accumulated gunk, which feels good.
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Old 07-21-2020, 06:35 PM   #28
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If it makes you feel any better.. I prefer the crimp rings, as long as the tools have the room. Looks like a professional job to me. Did you use the go / no-go gauge? I always do but I have seen plumbers who trust that their crimp tool is properly adjusted and they dont stop long enough to check the crimp (at least until the leak test).
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Old 07-22-2020, 10:22 AM   #29
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Thank you.

Yes, luckily the rental tool came with the go/no go gauge, and I did use it. I definitely don't trust my first-time skills enough to assume I did a good job.
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Old 07-23-2020, 06:50 AM   #30
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Did you use the go / no-go gauge? I always do but I have seen plumbers who trust that their crimp tool is properly adjusted and they dont stop long enough to check the crimp (at least until the leak test).
Having done many thousands of crimps over the years, using that gauge would have cost me a heck of a lot of money in time. What is done at the most in the trades is to just check a crimp at the start of a job and if good just go, and if for some reason not good double check with another crimp, and if still bad go get a new crimper.

I have 3 different styles of PEX crimpers, the regular longer handled one with 1/2" and 3/4", one 1/2" only with much shorter handles, and a small block for 1/2" and 3/4" for really tight spots where there is no room for handles.
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Old 07-23-2020, 09:40 AM   #31
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Having done many thousands of crimps over the years, using that gauge would have cost me a heck of a lot of money in time. What is done at the most in the trades is to just check a crimp at the start of a job and if good just go, and if for some reason not good double check with another crimp, and if still bad go get a new crimper.
..
My understanding (correct me if wrong) is that the crimp tool can get out of adjustment over time with much use. So it seems reasonable to use the go -nogo gauge the first time, and then check again every 50th crimp or whatever number you like. The crimper I have can be adjusted if needed. Since I use it so infrequently, I use the gauge every time but if I were doing an entire house it would be different.
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Old 07-23-2020, 09:46 AM   #32
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My understanding (correct me if wrong) is that the crimp tool can get out of adjustment over time with much use. So it seems reasonable to use the go -nogo gauge the first time, and then check again every 50th crimp or whatever number you like. The crimper I have can be adjusted if needed. Since I use it so infrequently, I use the gauge every time but if I were doing an entire house it would be different.
After much use I have never had one fail on me, though have heard of plumbers that have had them go.

Only my largest crimper is adjustable, but even after owning it for 20 years now it is still doing just fine.

I still do you use the gauge once every few hundred crimps just to be sure, or like I said at the beginning of doing a whole house.
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Old 07-23-2020, 10:17 AM   #33
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The large ones I rented were adjustable. I could definitely see them getting out of adjustment after dozens of crimps. But yeah, if you're doing a whole house or doing it for a living, you'll learn real fast what the right balance is.
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Old 07-23-2020, 10:32 AM   #34
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I've done a lot of PEX and PB connections too. And I've never had a crimper get out of adjustment. I suppose it could if it got dropped or something. The over-centering nature of the tool gives good feedback as to what is going on and the consistency of the crimp. I have never had a crimp connection fail. And I can say for certain there is a lot of tolerance on the actual crimp without leaking. Out of necessity, I've made a number of crimp connections with 12 X 9 mm polyurethane tube onto 3/8 PEX fittings and not had any leaks with them either. In that case, the cinch ring is the best choice.
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Old 07-25-2020, 12:32 PM   #35
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quick fix

Lowes sells a stretch silicone self adhesive tape (I carry a roll in the rig), depending on the type/location of leak, wrap with silicone tape and compress with hose clamp. If your fitting, elbow, tee or the like is cracked this won't work. If the leak is seep between the hose and the compression band, remove the band and try a small hose clamp.
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Old 07-25-2020, 01:08 PM   #36
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If the leak is seep between the hose and the compression band, remove the band and try a small hose clamp.
The first thing to do in that case would be to re-crimp the ring.

Removing a copper compression ring is hard to do, especially in tight spaces. Hose clamps do not work well on PEX because it is such a hard material and hose clamps do not apply an even force around the fitting. Best to just snip off the offending joint and re-do it.

Crimp ring joints don't leak unless they were crimped incorrectly or boiling water, under pressure softened the tube.

The plastic barbed fittings can crack, but that can only be fixed by replacing the fitting.
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Old 07-25-2020, 02:07 PM   #37
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..
Removing a copper compression ring is hard to do, especially in tight spaces. Hose clamps do not work well on PEX because it is such a hard material and hose clamps do not apply an even force around the fitting. ...
I can attest to that because I did it... used a small dermal wheel to cut the ring almost to the pipe, then pried it off. I needed the entire length of pipe or it was going to be a much bigger project so I gave it a shot. And it worked.. the pipe was not nicked, new crimp ring went on and no leak. But its not easy.

As for hose clamps.. I tried that once on PEX in an emergency situation at night far from any store.. it did not work at all.. not even for a minute.
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Old 07-26-2020, 09:04 AM   #38
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I was wondering whether there were any bandaid fixes to stop the leak long enough to make it through a camping weekend or through the work week until I could find time for a real fix.

Sounds like not really? Or maybe it depends on where the leak is. Fittings seem hard to temporarily fix.

As of this weekend, I’m pretty confident my new crimps aren’t going to leak. Things are dry even with the water heater on.
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