Pressure Water Plumbing - PEX, etc.

[s/v Jedi]

My Webasto manual says: "The temperature limiter is a thermostat that responds (opens) at a temperature of 95° C (203° F).

Christian: Which puts it right on the max temp. published spec as long as the pressure is under 80 psi. Not much margin...
Ah, my first language: You ain't much if you aren't Dutch ;-)

My Isotemp water heater has a manual mixer on it.
Its a simple thing....the cold water supply has a tee before entering the tank, it has a flexible braided line that tees into the hot discharge side with a small valve.
This allows the water in the heater to be as hot as possible but tempered as it exits.

James: but that setup will always mix in the same amount of cold water. For safety it'll have to be adjusted for maximum water temp. in the water heater. So, if the water heater is below max. temp. you get colder water. There are thermostat controlled mixing valves that would adjust automatically. In Europe, almost every shower has those too but I see very few of these in the US or Caribbean. They do exist however, our boat had one in bronze when we bought it.
This stuff is very different around the world. In the UK I mostly see electric thermostat valves in showers! The type I mean has no electric connection at all, I think it's controlled by a bi-metal spring.

cheers,
Nick.

[Christian Van H]

Originally Posted by s/v Jedi

Christian: Which puts it right on the max temp. published spec as long as the pressure is under 80 psi. Not much margin...
Ah, my first language: You ain't much if you aren't Dutch ;-)

Well, I doubt my Webasto system operates at a quarter of that pressure, and that thermostat is the OVERTEMP cutoff. So, I believe we are ok. This stuff is used for hydronic heating all over the world, every day.

BTW, English is my FIRST language, and I do believe Nick can express himself more eloquently than I.

[lookoutnw]

The Hurricaine II is below 210F, and at 7-8 PSI

[Maine Sail]

As an individual who actually used to rep, over a number of years, two different lines of PEX tubing (actually three but that was just brand name badging by US Brass the parrent company). I also sold two lines of commercial/industrial & residential hydronic & high pressure steam boilers, control systems, HVAC systems, valves and many other products sold to the plumbing & heating wholesalers all I can say is you guys are WAY, WAY, WAY over thinking it.

I was selling radiant tube hydronic heating systems well before most anyone had even heard of it and well before PEX had even one approval for domestic water use in the US.

The vapor barrier for hydronic systems is to prevent air from being sucked throught the walls of the pipe and into the sealed system as the water cools from 180-200f down to a stand by temperatures. As water is heated it expands as it cools it shrinks. This shrinking can cause air to permeate a non-vapor barrier tube and induce air which leads to corosion. This was a big problem with low mass steel boilers as air & steel don't mix well. even with cast iron boilers the air caused problems with rust and scaling.

The bottom line is this. Yes, Wirsbo/Uponor (still think the name change was dumb) makes a great fitting as does Rehau and both are very good companies. Wirsbo, along with Rehau, were the early pioneers in the US for PEX and both got a lot of arrows in thier backs being pioneers.

The reality today is that ALL the systems work and work quite well when properly installed. All the fittings have been well vetted and throughy tested. The Sharkbite style has been perhaps the most tested and vetted product of them all simply because of disbelievers like many on this forum.

Even Watts, one of the most respected companies in the P&H industry, now has PEX quick connect fittings in both brass and plastic. I can assure you that Watts, of all companies in that industry, would not release a product with their name on it without it being able to live up to the Watts reputation.

I used to sell both Rehau and what is now called Zurn Pex (actually Quest too but we won't go there). All these fittings are strong when properly installed. The Rehau fittings are now even certified to be burried in Gyp-Crete, which they were not when I sold them. The key word here is PROPERLY. We used to run two & three day training seminars for the trade and still we'd find bad fittings, by properly trained licensed plumbers/HVAC technicians, in floor splices, A HUGE NO, NO back then, and many other issues that would lead to potential failure.

Having personally supervised the instalation of well over 100,000 feet of PEX tubing, we used to sell millions of feet per year, I would advise anyone considering the use of PEX crimpers on a boat to think twice. There are places where it will simply be impossible to make a good crimp or to get the expanders into, even hand expanders. The Wirsbo or Rehau expander is a slightly better option than rings but again there will be situations where you simply can not get the expander into.

Shark bites, Watts Quick Connects or any of the other o-ring types are very, very reliable (I never even sold them and I am saying this).

The worry about your fresh water supply being supported by only an o-ring is WAY over blown IMHO. Hell your entire boat is probably floating on crappy & cheap junk Ideal perforated hose clamps. I mean really, how many here actually use T-Band or AWAB hose clamps on thier sea cocks??? I'd bet not all that many.. Hell, I'd worry more about the T&P valve and the operating temp of your marine engine than I would about anything else of you don't want to lose water. For safety's sake it's good practice to always turn off your 12v pump when not using it anyway.

How many of you guys have a fresh water diaphragm/accumulator tank like a Jabsco or a 12V fresh water pump? Both of these also utilize o-rings. Your engine is loaded with o-rings & rubber seals. Your fuel supply is protected by an o-ring too. Racor fuel filters and many on engine filters.. o-rings.. Faucets.. o-rings/seals... How many have a PSS Shaft Seal? Again, the stainless collar uses... you gussed it.. o-rings... LPG cylinder valve.. o-ring...

Wirsbo/Uponor, Rehau, Zurn and many others make great products. Rehau & Wirsbo are by far the most experienced and have the longest history though US Brass/Zurn, at last check, was the biggest and largest volume seller in the US..

So what does someone who does actually own the tools, who has trained the trade, spent 12+ years selling and designing hydronic radiant systems in the very early days of it, and who is familiar with most all these companies products use on their own boat?

I'm actually using the Cash Acme Shark Bites..... Let's not forget that they are rated for 200 F and 200 PSI. The water system on my boat barely pushes 40 PSI. Sure I cold have used my Rhaupex expanders and the brass fittings but it's overkill and I just could not physically get those expanders where I needed them in certain locations. Also with the quick connects I can take the fitting apart and re-plumb or make changes without wrecking a length of tubing by cutting the ftting off and having it wind up 2" to short. I personally think the quick conects are the ideal fittings for the tight quarters we experience on boats. Crimp band conections can be screwed up fairly easily but the expanded fittings are less apt to be screwed up.

For anyone considering this job on a boat I highly recommend 3/8" PEX vs. 1/2" as it is MUCH easier to work with, both for snaking and bending..

[James S]

Originally Posted by s/v Jedi

Christian: Which puts it right on the max temp. published spec as long as the pressure is under 80 psi. Not much margin...
Ah, my first language: You ain't much if you aren't Dutch ;-)



James: but that setup will always mix in the same amount of cold water. For safety it'll have to be adjusted for maximum water temp. in the water heater. So, if the water heater is below max. temp. you get colder water. There are thermostat controlled mixing valves that would adjust automatically. In Europe, almost every shower has those too but I see very few of these in the US or Caribbean. They do exist however, our boat had one in bronze when we bought it.
This stuff is very different around the world. In the UK I mostly see electric thermostat valves in showers! The type I mean has no electric connection at all, I think it's controlled by a bi-metal spring.

cheers,
Nick.

You're right Nick...as the water in the tank cools....so will the discharge hot water....and not proportionately at all.
But it’s the only non electrical option I know of and it does allow the maximum storage of hot water for the tank....fortunately for us, we can be pretty flexible with hot water temps...

[Christian Van H]

Maine Sail, thank you for your response. It's good to hear from experience. I fully understand your approach, but I'm not actually over-thinking. I'm just doing research, and logging info incase I want to write an article on installing these systems in a boat. As for my installation, I can use the wirsbo expander, as my interior is removed and I have access to all areas for swinging a cat. Oh, about those hose clamps...EVERY clamp on board IS AWAB, thank you very much! What are the chances you found the one person in the world with a boat like that!?

[Maine Sail]

Originally Posted by Christian Van H

Oh, about those hose clamps...EVERY clamp on board IS AWAB, thank you very much! What are the chances you found the one person in the world with a boat like that!?

The one other person...! I have LOTS invested in AWABS and T-Bands & those buggers are expensive. Every single last hose clamp on my boat is either AWAB or T-Band. I have seen too many Ideal type perforated clamps fail..

One other thing many boat owners lose sight of is true below water line rated hoses. I have seen clear un-reinforced PVC attached directly to seacocks on a fair number of boats.

[TAREUA]

Main Sail, I didn't mention Rehau because I knew they were abandoning the potable water market. My concern with shark bite type fittings wasn't just with the o-rings but with the little teeth that hold the fittings in place in situations on a boat that have far more vibration than a house. It is good to hear they work well for you. I would certainly have a supply on hand for quick repairs.
My own old used boat when purchased had cockpit drain lines leading to a below the waterline seacock. The hose was so pitiful it was leaking at two different points where it was hung with hose clamps to a bulkhead. My 'surveyor' didn't even make a note of it. Scary.

[Maine Sail]

Originally Posted by TAREUA

Main Sail, I didn't mention Rehau because I knew they were abandoning the potable water market. My concern with shark bite type fittings wasn't just with the o-rings but with the little teeth that hold the fittings in place in situations on a boat that have far more vibration than a house. It is good to hear they work well for you. I would certainly have a supply on hand for quick repairs.
My own old used boat when purchased had cockpit drain lines leading to a below the waterline seacock. The hose was so pitiful it was leaking at two different points where it was hung with hose clamps to a bulkhead. My 'surveyor' didn't even make a note of it. Scary.

Don't even get me going on surveyors and SAMS or NAMS.....

I am readdressing insurance on my own boat at the moment but all the insurance companies want an accredited NAMS or SAMS surveyor.

My buddy Tim has been building boats since the age of eight and knows piles more than ANY surveyor I have ever met. The guy is a walking encyclopedia of all things boating, construction, plumbing, engines and all ABYC codes, yet they won't accept a survey by him and they will by a semi-retired apprentice with four total years of lake boating experience because he's a NAMS associate???

The whole survey industry, in large part, is a half scam IMHO. The last surveyor I hired, and who is a very well respected one, insisted I had a foam cored hull and deck on my boat. We argued for about five minutes then I just agreed to disagree. Later I sent him a note with facts showing that it was in fact a solid glass hull and balsa cored deck. You could tell just by the soundings it was a solid not cored hull but I digress....

P.S. Last night I fired of a CD with 400+ photos of the upgrades and systems on my boat to hopefully overwhelm the insurance company to avoid being raped of $600.00 clams on a BS "legit" survey when my buddy Tim can send a better more detailed report for a case of beer. I also sent them a link to my "how to" web site.. I'm sure I'll still have to bend over and hire someone with who likely has less knowledge than either myself or my buddy...

[Christian Van H]

Originally Posted by Maine Sail

I also sent them a link to my "how to" web site..

Well....WHERES THE LINK???

[Maine Sail]

Originally Posted by Christian Van H

Well....WHERES THE LINK???

Sorry I thought I had it in my signature but I guess I don't..

My How To Section (LINK)

[lookoutnw]

1/2" PEX & Sharkbites for potable. Blue & Red
3/4 " PEX & Sharkbites for hydronic system and raw water to galley sink & water maker. Using teh 3/4" NPT sea water strainer 1st after teh thru hull, a 3 way valve (to teh potable so I can flush teh galley & watermaker systems with fresh water) then to the 'T'- On demand pump for the sprayer in galley sink, and LC-3-cp march 'lift pump' for the watermaker feed. Then a bunch of filtration before the water maker. Complex, expensive, simple to do and maintain with PEX & Sharkbites

[s/v Jedi]

Originally Posted by James S

You're right Nick...as the water in the tank cools....so will the discharge hot water....and not proportionately at all.
But it’s the only non electrical option I know of and it does allow the maximum storage of hot water for the tank....fortunately for us, we can be pretty flexible with hot water temps...

They are mechanical, no electric needed and I just learned they are widely available, ie:

https://www.ez-flo.net/?page=catalog...egory_id=61165

thermostatic control valves - thermostatic valves by amot controls

cheers,
Nick.

[James S]

cool....thanks

[seapup]

Wicked good thread on PEX..thanks. Which of the manifolds (say 8 cold and 4 hot outlets) would be best in a marine install if you want to stay with the expander fittings throughout?