Roadtrek Water System - Winter Design Issues

[markopolo]

Copied from the Roadtrek Yahoo Group - Very Interesting.

THE QUESTION:
I have a 2004 Chevy Versatile 190.

I set up my plumbing system today for winter usage by cutting off water to the outside showers and draining the exterior water lines, draining the front exterior water tank and the hot water tank.

There is no cutoff, therefore no freeze protection, for the "tank fill water line" that runs between the EXTERIOR city connection and the tank selector valve. When the rear (interior) tank is selected for moderate winter usage, there is water in the entire "tank fill water line" and it will freeze and burst because this line leaves the motorhome and is exposed directly to the exterior temperatures.

I would appreciate your comments and advice.

Thanks,

Tim Frazier

THE ANSWER:
Dear Mr. Frazier,

Thank you for your note. It is important, for the Roadtrek Engineering Dept, to receive this type of feedback from our RoadTrek owners and better still that you have a technical background that can address these concerns knowledgeably.

Anyway, you are right about your comments regarding the tank fill line and yes there will be water in this line between the inlet side of the pump and the city fill ball valve on the exterior of the van. This was certainly a serious concern when I designed the water system for winter use.

So I did some research and testing of various PEX based water systems; The water line clamping system we selected is manufactured by Oetiker, specifically for use on PEX water systems. This is a stainless steel, stepless, ear clamp. Unlike solid copper clamp rings and similar clamping systems, typically used on PEX line, these clamps maintain their clamping pressure regardless of expansion and contraction (freeze/thaw) cycles.

And of course PEX line itself is very resilient and will not burst, even in extreme freeze/thaw conditions.

Additionally, all our PEX fittings are made out of a high impact engineered plastic that has performed remarkably well in destructive testing of various kinds.

But of course the proof is in the pudding:
Testing, of various shapes and sizes, of closed loop test pieces, filled with water, pressurized to 80 PSI, and frozen to -18 deg C were carried out.
Result: Even with prolonged and repeated freeze/thaw cycles there were zero failures in these test sequences!

But what about the real world, you might ask? Well, although we couldn't justify shipping one of our Engineering test units to an Arctic test facility, further testing of the actual water system was indeed carried out, on a finished van, at the Environmental Test Chamber, at Dometic Industries in Elkhart Indiana. Result: Our water system, in winter use mode, survived; without leaks!, without burst lines!, without incident!

Your owner's manual states that this Roadtrek, in winter use mode, can be operated in moderate sub-freezing temperatures as low as -10 deg C (obviously there are limits to how low ambient temperatures can be before you will begin to experience problems). Our environmental testing, which was considerably more severe than the recommended operating temperature, produced no failures in the water system as it is configured in your vehicle.

You are correct in observing that water is present in this line but, this line is on the inlet side of the pump and so never sees working pressures in Winter mode. This fact minimises the effect of freezing since, for all intents and purpose, this is an open water system.

I hope this addresses your concerns, and if I can answer any of your questions regarding the design and engineering of this system I would be pleased to hear from you.

Regards,
Christopher Boileau
Engineering
__________________________________________________ _________

Hi Tim,

I have to write this on my lunch break since this in not generally a part of my normal duties. I was asked to address the technical question you had regarding the design of the water system but generally these are addressed by our Service Dept. However, I feel that I do benefit from this type of direct feedback from owners so I will respond to this one question.

Roadtrek switched to a PEX based water system in November 2000. However this first generation PEX system used brass fittings and copper clamp rings (which were pretty much the standard at that time).

Over time, more and more suppliers entered into the PEX product market, due in large part to the growing popularity of radiant heating systems in the housing industry. With increased competition
there were many innovations and improvements to the products made available with the result that we at Roadtrek made a change to our fresh water system, using high impact plastic fittings and a clamping system that maintained a constant hoop stress on the fitting barbs. This revision was made effective in May 2003. Jim's 20PC falls between these dates so although it has PEX lines, they would not survive a freeze thaw cycle as well as the present design does. Even so, they should provide years of trouble free service under the design conditions they were made to meet.

I am personally very pleased with this product (both 1st & 2nd version). It is robust, cost effective and has virtually eliminated leaks at fittings. That is not to say they are perfect, but compared to any system used in the past, problems have been greatly reduced. We also benefited by improved productivity since these newer systems are quick and simple to install effectively.

We, as an organization, have strived to avail ourselves of improvements in technology, when they make sense and offer value and utility to our customers. This has paid off very well in many areas of our current design, from our Auto-tracking satellite receiver, Flat screen TVs & DVD players, to our water systems, and right down to the waste discharge pump on our latest model, which, by the way, has finally made one of the banes of RV'ing manageable if not down right...........well, OK lets face it, you still have to draw straws for the pleasure of dumping the waste tanks.

Owners have a right to, and certainly ours do, expect more in exchange for their custom and as part of our Mission Statement we aim to delight them in this, with unrivalled product value. Don't get me wrong, we all know there can be challenges for any company in endeavoring to offer an automotive quality product in a relatively small specialty market. We truly do rely on the hard work of our dedicated employees and the generous feedback (good and bad) from our customers. But nothing pleases us more than success in our mission. Of course it’s nice to put food on our children's plates too.

With every new Roadtrek model we build, there is the desire to make it the best Roadtrek ever. And that's what I like about this place.

Thanks for your help.

Regards,
Christopher Boileau