Air system install details

[Roses]

I bought one of those air line systems with the blue nylon tubing and push to connect fittings. I'm having some issues and was wondering if someone else had the same and fixes.

First of all, that blue tubing has a significant thermal expansion rate. If you cut everything to fit perfectly and have clamps for the tube and fittings, and the temperature drops significantly, the tube will pull back and leak. Something in the assembly has to float. Part of my system is indoors, where the low temp is typically 40. Other parts of it are outside, where the low temp is 20-ish, and as soon as it got cold (I cut and installed the system at 60-ish) it started to leak. Cut the lines a bit longer and that worked - for a while.

Second, I'm having issues with small leaks at some of the outside fittings that become bigger leaks as it gets colder - I assume its o-ring or line diameter shrinkage as all my lines are now a tad over-long. The fittings seem to be built for some assembly/disassembly without degrading, but I'm wondering if the only solution to this problem is a compression fitting.

 

[finn]

Haven’t noticed leakage on my Amazon knock off of RaidAir.

did you try retightening the nut. Mine called for 3/4 turn after snug, I think, but if the tubing is taking a set, you should be able to detect that.

I don’t have any outside, though.

My pex floor heat has been in place for years. I think the 50 foot runs of copper expand more than the Pex, but again, it never gets cold on those circuits.

 

[PopcornSutton]

I'm no fan of these push on fittings, whether pex or copper. There is no free lunch. For expansion, it's not hard to provide for expansion depending on how you have it supported. We're not talking inches of expansion distance.

 

[finn]

I'm no fan of these push on fittings, whether pex or copper. There is no free lunch. For expansion, it's not hard to provide for expansion depending on how you have it supported. We're not talking inches of expansion distance.

The kit I bought doesn’t use “Shark bite” style fittings, but I suspect the op’s kit does.

 

[racecougar]

OP, exactly what kit are we working with here?

The kit I bought doesn’t use “Shark bite” style fittings, but I suspect the op’s kit does.

Is your kit PEX-AL-PEX or just nylon tubing like the OP?

 

[finn]

OP, exactly what kit are we working with here?



Is your kit PEX-AL-PEX or just nylon tubing like the OP?

It’s HDPE-AL, or something like that. I don’t recall the exact name, but if you dig deep enough into the specs, every kit I found has an aluminum layer, but doesn’t strictly meet the definition of pex, as pex has a rather strict cross link composition. I think even the genuine Rapid Air Maxline systems aren’t strictly pex+al, although they too have the aluminum layer. It’s a close relative to Pex.

i spent some time digging into this last summer, but don’t recall the details. My kit came packaged exactly like photos of the RapidAir system, and I mean exactly, except the box was brown instead of white, and lacked the RapidAir labels on the outside and one page instructions

 

[racecougar]

It’s HDPE-AL, or something like that. I don’t recall the exact name, but if you dig deep enough into the specs, every kit I found has an aluminum layer, but doesn’t strictly meet the definition of pex, as pex has a rather strict cross link composition. I think even the genuine Rapid Air Maxline systems aren’t strictly pex+al, although they too have the aluminum layer. It’s a close relative to Pex.

i spent some time digging into this last summer, but don’t recall the details. My kit came packaged exactly like photos of the RapidAir system, and I mean exactly, except the box was brown instead of white, and lacked the RapidAir labels on the outside and one page instructions

Likewise (I use RapidAir Maxline), but it seems that the OP's arrangement is nylon tubing (no aluminum layer) with sharkbite-type fittings.

 

[Roses]

This is a Rapidair home garage system. Mix of their fittings and other stuff from Amazon - but they are so visually identical I don't believe there's any appreciable difference, but neither have any identifying information on them, so its hard to tell which pieces were made here, and which ones were made in China. But the distribution blocks I've had to use automotive RTV to get the plugs to seal and on the fittings an enormous and abnormal amount of tightening with teflon paste - teflon tape was insufficient. The tubing is straight up nylon.

 

[racecougar]

Others here have tried mixing/matching RapidAir parts with off-brand parts in the past with similar results (leakage).

It looks like RapidAir calls for two wraps of thread-sealing tape PLUS pipe paste/sealant on all of the NPT connections.

https://www.rapidairproducts.com/wp-content/uploads/2019/05/RAPIDAIR-INSTALLATION-3-2013.pdf

 

[finn]

Others here have tried mixing/matching RapidAir parts with off-brand parts in the past with similar results (leakage).

It looks like RapidAir calls for two wraps of thread-sealing tape PLUS pipe paste/sealant on all of the NPT connections.

https://www.rapidairproducts.com/wp-content/uploads/2019/05/RAPIDAIR-INSTALLATION-3-2013.pdf

I used the fittings in the kit plus some I bought separately from amazon that are a little different. No problems so far.

I did the tape and paste for the first several joints, then dropped the paste, as it seemed redundant. I suspect the paste is there mostly to reduce friction up to the point the fitting reaches “snug” and you start counting turns to finish the job.

I have less than $100 in my three drop system, and enough left over material (less outlet termination blocks) to add another forty or fifty feet.

 

[racecougar]

I used the fittings in the kit plus some I bought separately from amazon that are a little different. No problems so far.

Again, you're talking about the Maxline setup, not the Home Garage setup. The fittings are completely different.

I did the tape and paste for the first several joints, then dropped the paste, as it seemed redundant. I suspect the paste is there mostly to reduce friction up to the point the fitting reaches “snug” and you start counting turns to finish the job.

You mention counting turns; did you put tape/paste on the compression fittings? Those should be dry, or if anything, a drop of oil on the threads. The tape/paste is for the NPT threads.

 

[Roses]

WRT the teflon tape, some of the holes in the blocks seem to be overbored and the plugs just sink in them. I could put five turns of tape on and it just didn't matter. Permatex ultra grey fixed it. Now it could be the plugs and fittings are out of spec, its not like I have a go/no go gauge sitting around for different NPT threads, you kind of take that stuff for granted.

For the regulators and the various plugs and piping that make up that part of the system I built an adapter to allow me to test it all under pressure before it is mounted, and some of the stuff I had to assemble/disassemble three times to stop all the leaks.

 

[racecougar]

They likely are out of spec. I don't know that you can expect that system to ever be entirely leak free. The fittings are budget parts made overseas by whomever provided the cheapest quote. What is the leakdown rate currently?

 

[finn]

Again, you're talking about the Maxline setup, not the Home Garage setup. The fittings are completely different.


You mention counting turns; did you put tape/paste on the compression fittings? Those should be dry, or if anything, a drop of oil on the threads. The tape/paste is for the NPT threads.

The instructions, limited as they are, called for both tape and paste. I found that odd, and contrary to everything I was taught. Those fittings, best I can tell, don’t seal on the threads anyway. Like I said, the tape and dope likely just reduce thread friction.

I didn’t write the instructions, though.

You’re correct, though. The home garage has push to connect fittings.

My knockoff kit has nickel plated brass fittings like the Maxline. Some of the Amazon fittings are nicle coated brass but have a little different sealing mechanism. Both interchange, at least for me.

I have no or limited experience with push to connect or sharkbite fitting.

 

[racecougar]

The instructions, limited as they are, called for both tape and paste. I found that odd, and contrary to everything I was taught. Those fittings, best I can tell, don’t seal on the threads anyway. Like I said, the tape and dope likely just reduce thread friction.

Just on the NPT threads. Not on the compression fitting threads. https://go.rapidairproducts.com/l/9...X0J3RQ..*_gcl_au*MTY0NjQzMjc2OC4xNzcwNjQ4NzQ5

 

[Roses]

I did have one visually different elbow fitting left over from a beer bottling machine and it worked - now if I only kew where to get more!

 

[finn]

Just on the NPT threads. Not on the compression fitting threads. https://go.rapidairproducts.com/l/9...X0J3RQ..*_gcl_au*MTY0NjQzMjc2OC4xNzcwNjQ4NzQ5

That’s how I ended up doing it, but not what the one page instructions included in my kit called for, nor what several YouTube videos showed.

The knockoff kit I ended up with was otherwise identical, including the cutter and eveling tool.

My 100’ kit with fittings for three drops was less than $70, cheapest I found at the time.

 

[racecougar]

The instructions in the knock off kit were likely originally written in another language by someone completely unfamiliar with how things are supposed to go together.

 

[finn]

The instructions in the knock off kit were likely originally written in another language by someone completely unfamiliar with how things are supposed to go together.

Maybe, but the usual clues were there.