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Author Topic: Will PEX pipe work in the engine compartment?  (Read 1754 times)
belfert
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« on: September 30, 2012, 11:50:13 AM »

I installed my Proheat heater in the engine compartment in the same spot the long gone Webasto heater was mounted at from the factory.  I used 3/4" PEX pipe to connect the heater to the fan heaters inside the bus.

When I stopped to check fluids the PEX pipe was pretty soft from the heat in the engine compartment.  Am I going to have issues with the PEX pipe bursting or something?  I didn't even run the heater at all this trip, but it is likely we will run it while rolling down the road in the future.  Would I be better off using copper pipe or silicone hose inside the engine compartment instead?
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #1 on: September 30, 2012, 01:08:06 PM »

PEX will not burst, but it will get very soft, and maybe deteriorate and separate. (Will then look like a burst). Having used PEX all through my coach, I prefer to use copper (best choice), or run the PEX inside a metal pipe (if copper is totally impractical), when in a compartment or area where there is engine or generator engine heat.

Just my opinion.
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luvrbus
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« Reply #2 on: September 30, 2012, 01:15:46 PM »

If you used the orange color Pex you will be ok all the different grades are temperature, pressure rated I doubt there would be a problem with any grade just keep it away and off the exhaust system pressure is not going to be problem with a Pro/Heat
« Last Edit: September 30, 2012, 01:58:53 PM by luvrbus » Logged

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belfert
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« Reply #3 on: September 30, 2012, 02:10:34 PM »

The PEX I used is not orange.  It is oxygen barrier though.  It is not PEX-AL-PEX because that style won't work with the Sharkbite fittings I prefer.  I did a quick Google search and some orange PEX is PEX-AL-PEX and some is just oxygen barrier.

I suppose I can use copper, but I absolutely hate soldering copper.  Maybe two out of ten of my copper joints work and I end up making the copper fitting manufacturers a lot of money.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #4 on: September 30, 2012, 02:22:03 PM »

Brian,

I'm the world's worst plumber but I've found that getting the copper really clean at the joint (Both pieces) and using lots of flux does the job. I often use way too much solder but no leaks so far!

One problem most of us amateurs have is using too much heat, once the solder starts to melt into the joint that is usually enough heat.
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« Reply #5 on: September 30, 2012, 02:23:29 PM »

If you used the orange color Pex you will be ok all the different grades are temperature, pressure rated I doubt there would be a problem with any grade just keep it away and off the exhaust system pressure is not going to be problem with a Pro/Heat

I had forgotten about RF-PEX (used in fire sprinkler applications) - thank you for making sure all the info was presented !!
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« Reply #6 on: September 30, 2012, 02:27:40 PM »

Your pex should be fine it is probably rated for 180* or 200* .I use the 200* for solar hot water systems and have never had a problem.inside motor compartment should be fine just not near exhaust .I wood rent the pex crimper at homedespreat for $8. a day and use pex crimp rings more permanent (never had one leak yet)          dave
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« Reply #7 on: September 30, 2012, 02:30:58 PM »

How much copper do you need 1/2 inch was 21.00 bucks for a 10 ft section at the supply house Friday and why Sharkbite fittings wasted money there you bus people are the only ones buying those $$$ fittings 

They have new fittings for the Pex (black) 33 cents for a fitting crimp it with the stainless rings it's there for ever if you ever need to remove it cut the ring and reuse the fitting the cutter cost less than 15 bucks 

I sure would not use sharkbite on hot water supply in a engine compartment
« Last Edit: September 30, 2012, 02:40:07 PM by luvrbus » Logged

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« Reply #8 on: September 30, 2012, 02:53:33 PM »

I second luvrbus I would not trust the sharkbite,great for a quick fix but not for the long term                        dave
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« Reply #9 on: September 30, 2012, 03:43:51 PM »

To be clear, I'm not against changing materials.  It seems almost inevitable that the PEX isn't going to work inside the engine compartment.  I'll probably have to go to copper and deal with soldering it.  I am almost certain I am getting things too hot when soldering, but I have no idea what the proper amount of heat is either.

My first go around at plumbing my bus I used Oetiker clamps.  They were used in my first travel trailer and they worked great.  I bought the special Knipex tool for Oetiker clamps and used them in the bus.  Almost every joint leaked!  Folks here recommended Sharkbite connectors so I used those and they work great.  Sharkbite connectors are the only PEX connector allowed to be sealed in a wall.  The copper rings are probably better than the Oetikers, but the tools are so darn expensive.  $70 for the crimper and another $20 for the removal tool.

I'm not worried about the cost of copper.  The only reason I would rather not use copper is the darned soldering.  That, and the fact it would take fives times as many fittings since copper is not flexible like PEX.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #10 on: September 30, 2012, 03:48:21 PM »

What would be the reason not to use Sharkbite fittings in the engine compartment?  Will the heat kill the o-ring?  They are probably all going bye-bye anyhow.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #11 on: September 30, 2012, 04:17:25 PM »

Soldering is not hard heat the copper touch the solder to pipe if the solder melts it will suck into the fitting if not apply a little heat, clean both pieces good with emery cloth till it shines and use a good flux and don't worry about building the copper up on the outside of the 2 pieces it serves no purpose that is why is it called a sweat joints takes very little solder to be leak proof 

Me I just heat till the copper changes to a blueish tint and then touch the solder to pipe and go to next one
« Last Edit: September 30, 2012, 04:27:10 PM by luvrbus » Logged

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« Reply #12 on: September 30, 2012, 05:21:27 PM »

Pex is good because it withstands the vibration in the engine compartment.

Your solution is simple:  insulate the Pex hose.  The same insulating material they sell at home depot for house pipe insulation will work on your Pex-- pipe wrap, split foam, bubble wrap, etc.

I wouldn't tear the Pex out, I would insulate it.

--Geoff
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luvrbus
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« Reply #13 on: September 30, 2012, 05:43:58 PM »

You guys go know Pex sells a cover shield for the pipe you use it when bury the Pex in concrete or dirt comes in roll you slide it over the Pex and tape the ends
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belfert
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« Reply #14 on: September 30, 2012, 07:47:30 PM »

Insulation simply slows heat transfer.  Won't the PEX eventually get just as warm if driving long distances?  I would need to find out how much heat the pipe insulation can take before it burns.

You have a good point about copper being too rigid.  I was wondering about that since most don't use copper in conversions for that very reason.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #15 on: October 01, 2012, 04:49:06 AM »

I can relate to not being able to do certain things. But the internet has changed some of that. Youtube has some really great instructional videos (and some not so great) on many subjects.

 
How to Solder Copper Pipe
Go and check out several on soldering,maybe you will see what you are doing wrong.  If not try your wife, kids, grandkids they seem to have a knack for welding and maybe soldering.
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« Reply #16 on: October 01, 2012, 05:12:36 AM »

The pex I use is rated for 200* but I was told by my supplier it is tested to 350* .The solar water systems I set up can get to 300* at the collector  ,I use 2 insulation wraps     ( ac pipe insulation x 2 ) and have never had a problem.In the bus is the same pex for in floor heat but I used 3/4 auto heater hose in and out at the proheat for 12' to the manifold then to pex .I used the heater hose as I was unsure about constant vibration from road,motor . Over 6 years and counting no problems             dave
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belfert
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« Reply #17 on: October 01, 2012, 05:27:52 AM »

The pex I use is rated for 200* but I was told by my supplier it is tested to 350* .The solar water systems I set up can get to 300* at the collector  ,I use 2 insulation wraps     ( ac pipe insulation x 2 ) and have never had a problem.In the bus is the same pex for in floor heat but I used 3/4 auto heater hose in and out at the proheat for 12' to the manifold then to pex .I used the heater hose as I was unsure about constant vibration from road,motor . Over 6 years and counting no problems             dave

I'm only concerned about the PEX in the actual engine compartment.  It is getting soft from the heat from the engine.  It sounds like you used heater hose in that area.  I have no issues with the PEX in the rest of my system.
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« Reply #18 on: October 01, 2012, 06:27:57 AM »

I would use coil copper tubing not rigid, if you dont like soldering use flare type, stay away from shark bite or compression, I prefer soldering Ive been a plumber for 42 years its very easy to solder. clean the fittings and the pipe with emery paper, do not touch the cleaned area once cleaned, body oil will cause the solder not to take, use self cleaning flux like laco brand apply to both the fitting and the pipe, heat till it smokes, apply solder till it drips then the joint is full, it is very easy once learned, lol

    John.
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« Reply #19 on: October 01, 2012, 06:09:50 PM »

I connected my engine preheat system of my Aquahot to my DD in the engine compartment using 3/4" PEX. It circulates engine coolant through my aquahot heat exchanger.
Been working that way for about 7 or 8 years now. Not a single leak or problem with it.

As for the cost of the crimper for the copper rings, they make a smaller version which has two sizes of holes and clamps by tightening a couple bolts with a wrench or socket.
It's about $15 if I remember correctly.  No need to buy a special tool for removal of the rings, either. A small hand held hacksaw blade holder will cut through the ring, and I've
even used the points of side cutters to snip through the ring.

Some things just don't need to be complicated.

craig
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« Reply #20 on: October 01, 2012, 06:13:41 PM »

There is flexible copper and it uses flared fittings. No soldering needed.
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« Reply #21 on: October 01, 2012, 06:42:50 PM »

Type k soft can be soldered or flared stick or roll fwiw  the 15 dollar removal tool is worth the money once you use one you will never go back to hacksaw gumpy lol
« Last Edit: October 01, 2012, 06:49:39 PM by luvrbus » Logged

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« Reply #22 on: October 02, 2012, 01:30:21 PM »

A tool for 15 bucks I have used a die grinder for years, now you tell me.I have the crimpers but  Home depot ( home desperate ) rents them for $8 a day.Its time to buy a removal tool .                           dave 
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« Reply #23 on: October 02, 2012, 02:16:35 PM »

Flex copper is for easy of installation. If it is exposed to vibration it will work-harden and probably crack, all copper does.

I prefer hard copper lines with rubber hose at flex spots like curves.
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« Reply #24 on: October 02, 2012, 07:52:08 PM »

one thing the pex wont hold up to is the steam from an overheating situation. unlikely but be aware. If you support it enough it wont droop. i only use pex for water. wasent sure how antifreeze would affect it
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« Reply #25 on: October 03, 2012, 01:26:31 AM »

PEX is used for radiant heat all the time in buildings.  Antifreeze doesn't hurt it.
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