PEXing thoughts

[Geom]

OK, as we continue to work through a list of items for our mechanic to checkout, one item on the list has been the ability to get heat, and more importantly defrost, working up front.

Some background,

The floor in this bus had been lowered quite some time ago.
In order to accomplish this, several lines were cut and/or rerouted.
In discussing the heater with the previous owners, they believed that the loop going to the heater core was still intact and that I could just open the valve in the engine bay to allow coolant to pass to the front.
After checking out all of the cut lines, I saw coming out of the engine bay and into the backbay, I was really hesitant to open that valve for fear of making a huge mess if the lines were indeed left cut; so I left it closed until I could get someone with a better understanding (and a pit) to look at it with me.

Fast forward to today,

The lines were indeed cut, but were rerun.
Here's where it gets... Interesting.
Instead of running the makeup lines (the area that undoubtedly needed removal to accommodate the floor lowering) in new copper, whoever did the floor lowering used 1/2" (possibly 3/4") PEX instead. And this is old-school gen1-ish type pex, not the fancy sometimes color-coded, with higher tolerances, type pex.

Where it gets even more... Interesting, is the connection from the cut original copper to the new pex. It goes like this: Original Copper, to Rubber hose piece with hose clamp, to a grey PVC?? threaded fitting, to a threaded steel pipe piece, to a (quite rusty) threaded steel pipe reducer, to a threaded pex fitting, to PEX pipe. The other end comes out as pex back to the original copper (but not in the same as the former). It just seems to come out of there directly into the copper.

Ok, so now I'm a bit concerned.
What do you guys think? I realize this is "out of the box" types design so there's probably no set answer.

I think the pex will be able to handle the temps and certainly the pressure. From my research pex easily handles 180 degrees with tolerances (albeit non published) in the 200s.

I'm not certain what that grey threaded piece is. If it's pvc, then I think it's a problem since pvc is only rated to something like 140 degrees. If it's cpvc, then it's a bit better since that's rated to about 170-180 degrees.

That rusted steel piece is also concerning. Not sure if it's also rusting on the inside and could push rust into the coolant. Not to mention the possibility of it corroding to the point of failure (considering it's just attached to plastic).

I believe a lot of this can be decluttered if I could go more directly from the old copper to pex. The old copper looks like 1" (or more?) and I'm not sure such an animal exists (copper to pex fitting).

Since this whole assembly will be under 190-200 degrees, constantly, but under fairly low-ish pressure, what do you guys think?

I definitely think defrost is important, but so is not dumping 12 gallons of coolant into my bays, not to mention the rapid loss of coolant to the engine.

Your thoughts are greatly appreciated as always.

Thanks
George

[luvrbus]

Gray PVC is sch 80 it can handle a lot fwiw

[scanzel]

Sounds like an area of future failure to me. Copper reducers are available so you should be able to find a 1" to 3/4" copper reducer to the 3/4 pex fitting. I would never leave something like that.

[luvrbus]

JMO I would not plumb any Pex into the engine system that would be asking for problems

[Oonrahnjay]

Sounds like an area of future failure to me. Copper reducers are available so you should be able to find a 1" to 3/4" copper reducer to the 3/4 pex fitting. I would never leave something like that.

     I agree with Clifford and Steve.  PEX isn't good for coolant, heat, pressure, vibration in motor vehicle us.  If you're going to join a replacement line  to copper, make it the simplest and sturdiest connection possible (not the mess you have on there now).   Something like that always fails at the worst possible time (rainy weather, in the dark, when you're in a hurry, miles from service assistance and spare parts/supplies ...).  Don't take any unnecessary chances.  

[bevans6]

I would think about this for a while, and not leap to any conclusions.  I have had copper lines fail on a vehicle due to vibration stress, I've never had Pex fail in the tube for any reason.  I probably would not use Sharkbite type fittings - but then again DOT air lines use push to connect fittings...  I have a nagging feeling that Pex is actually a really good choice for this, in contiguous runs well supported with good fittings and adaptors, if protected from cuts and abrasion (which you need to do for copper anyway, it is really quite susceptible to physical damage).  I would redo the funky adaptor.

Brian

[luvrbus]

I tried Pex on my engine pre heat from the Webasto, maybe because of the heat in the engine compartment but it didn't work out for me cost me 200 bucks worth of antifreeze 

[gumpy]

I used PEX between my engine and AquaHot. Short lengths on either end. 12 years or more and no problems.

[Gary Hatt - Publisher BCM]

Something to consider regarding questions about any lines to and from your Aqua-Hot, Hydro-Hot or Webasto heating systems; you may want to call Lloyd DeGerald.  He has been servicing these units for years and has fixed problems caused by folks who had made bad choices in plumbing and other things regarding these products. He can be reached at 501-258-8426 or lloyd.degerald@gmail.com.

He has seen it all so a call or email to him may save you a lot of money and headaches down the road.  He services my Aqua-Hot system every year in Quartzsite and he has been a huge help in getting my system back in service after sitting unused for three years, which of course is the worst thing you can do for not only your Aqua-Hot but your bus in general.  Lloyd says you should run your Aqua-Hot system at least once a month whether you use it or not.  He sent us an article about servicing your unit which will run in an upcoming issue of BCM soon.

Check him out at http://lloyddegerald.com/locate-me-calendar.  Who knows, he may be coming to an event near you soon where he can look over your system and do a yearly tune-up on it so it will continue running for years.

[pabusnut]

George,

I don't think I would use PEX, but at this point I think it would be a major rebuild for you to replace it, especially if it is in the tunnel under the floor and the bus is finished.  I would think changing out all the PEX connections to brass, using the solid crimp rings would be a start, and using flexible copper for all the easily accessible places.

I am more curious about which part of the floor is lowered?  I have a 4905, and can't imagine the work to lower the rear part, unless the 4107 is substantially different than my 4905?

Steve Toomey

[Cary and Don]

If all else fails, how about this? The defrost blower works. Why not remove the heater core and install a 12 volt electric heater in there and use that for the defrost?

Our Eagle has little electric heaters on the dash for defrost. They may not be pretty, but they aren't ugly and work great.

Don and Cary

[goldgiter]

If all else fails, how about this? The defrost blower works. Why not remove the heater core and install a 12 volt electric heater in there and use that for the defrost?

Our Eagle has little electric heaters on the dash for defrost. They may not be pretty, but they aren't ugly and work great.

Don and Cary

I'm glad you posted that Don, earlier today I was wondering what I was going to do about my defroster and you may have solved my problem. Thanks

Wes

[TedCalvert]

 
FWIW; I believe schedule 40 PVC is grey, also.  PVC is tough stuff. but I don't know about using it in this application. 

There's a lot of room for improvement in many of the house systems, but I would have to look long and hard at re-engineering the vehicle systems.  True, its only coolant; it won't make the wheels fall off; but it will shut you down!  In your case, I would probably remove the improvisations and replace to OEM standards.

HTH

Ted.

[sixtyseven]

Don't worry about the pex. It can handle the heat & pressure & vibration.  I have pex from the engine compartment to the front.   No problems in 15 years.  The gray PVC is another story.  It WILL fail.  PVC will not hold up to that temp.  Happy plumbing

[sledhead]

I have infloor heat in my coach and it is pex . works great and is rated for 200 f . no problems at all and I installed it in 2005 . I used regular green auto anti freeze in the system to keep it simple . I have used the same pex in water solar systems and the temperature can get very hot ( above 300 f ) and have not had any problems .
I like pex and use it all the time on any plumbing projects

dave