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Author Topic: Pex or Silicone Hose for Webasto  (Read 3470 times)
CindyandJohn
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« on: September 04, 2008, 05:06:14 PM »

I am getting ready to order some parts for my Webasto install and have a few questions... first i am concerned about the heat for tubing. I have read to use Oxygen Barrier Pex but all the papers for it only rate it at 180 degrees at 80 psi... Silicone is rated at 350 degrees or more but is real expensive. I will have a couple of heat exchangers in the system one between the engine and one between my generator. I am full electric and run the generator whenever not connected to shore power. So I figured I could use some of that heat in the hydro system. How hot does the Webasto actually heat the antifreeze? Is Oxy PEX sufficient? My next question is - how hot does a Webasto unit get? I have a DBW 2010 inside of an enclosure. Could it be put inside of a somewhat confined space - in with my fresh and grey water? I have an insulated Plywood enclosure within my water bay. Last question is - How noisy do the system run? should i be thinking of installing back with the engine? i have room there as well as in my generator bay, but that is in the middle of the bus and it would be on the passengers side of the bus - so we would be sitting next to it when sitting by the camp fire - not a problem in the summer and we don't sit outside much in the winter. It will mainly be used for heat and engine preheat while out and about in the winter.

Sorry for the long post. I searched a bit for some of the answers but still have many questions...

Thanks,
John
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Ednj
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« Reply #1 on: September 04, 2008, 05:29:31 PM »

John,
Use automotive heater hose.
It should heat the water to 180°
It will generate enough heat to keep your tanks from freezing.
They are noisy, you don’t want it under your bed, best spot is behind the front bumper.
Mount any side and run the exhaust out the driver’s side.
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MCI-9
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« Reply #2 on: September 04, 2008, 05:43:10 PM »

John, Dick Wright uses 3 ply heater hose but most people use CPVC pipe.I don't know about the 180 all I have been around are about 120 degrees.The Oais and Hurricane systems use PEX,copper,cpvc and rubber heater hose  good luck
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lostagain
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« Reply #3 on: September 04, 2008, 05:47:23 PM »

I have the service manual that a dealer emailed me last year when I had to fix ours on the hockey team bus. It says that it shuts down at 165F and back on at 68F. Rad hose should be OK. Yes it makes a noise, mostly from the fan for combustion air. It is not bad at all from inside the bus, just don't install it under your bed. It is a great heater!

JC
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JC
Invermere, BC
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makemineatwostroke
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« Reply #4 on: September 04, 2008, 06:06:34 PM »

My Hurricane unit (proheat) is adjustable from the 120 to 145 heat range and has PEX.With the price of fuel today I am looking into a different type of heat this winter at the ski resorts using 4 gals per day at $3.79 it is going to be expensive to heat,the grandkids may have to get a firewood permit and cut their own wood   have a great evening
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Jerry Liebler
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« Reply #5 on: September 04, 2008, 06:06:53 PM »

John,
     I went with what Dick Wright recomends, heavy duty radiator hose (3/4"), to get the same Id would require 1" Pex and I didn't trust it at 180 degrees, the coolant temperature.  Either location sounds fine.  You'll also want to onsider the exaust location.  I put mine in my engine compartment so my exaust is below my rear bumper.  Mine is real close to the head of my bed, just on the other side of the firewall yet form inside the bus I can hardly hear it running, certainly much quieter than any air conditioner.  However outside there is a sound sort of like a distant jet plane when it's going.  One more thing if you use radiator hose, don't use ANY nylon hose fittings, strictly brass.  I used a couple of nylon hose to pipe thread fittings & they leaked till I replaced them with brass.
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Jerry 4107 1120
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Brian Diehl
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« Reply #6 on: September 04, 2008, 06:54:21 PM »

I have a DB2010 as well and it is setup to come shut off at 180 and come back on at 160.
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Skykingrob
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« Reply #7 on: September 04, 2008, 06:56:50 PM »

John
I just finished my install. I talked to Aquahot people and the recommendation is for 3/4" premium radiator hose. I have a 40' Prevost with 5 heat exchangers and used 75' of the hose. As Jerry says, buy brass connectors, I got mine at Lowes but any good plumbing shop will do and used steel hose clamps from an auto store, like O' Reillys/Autozone, etc. Strongly advised by Aquahot to buy radius tubes for the curves to keep them "gentle". Aquahot has them, kind of pricey at $7 each plus shipping but saw a new Prevost, sure enough they were on it so gave in and bought them from Aquahot. Aquahot also said I could use radius brackets to snap the radiator hose into rather than the radius tubes but the were more expensive.

BTW, I have an extra brand new never used box of  50', 3/4" premium gates hose that I was able to buy at store cost of 70 cents per foot. I would sell it for this plus shipping, if interested.

Rob
91 LeMirage XL
Missouri
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gumpy
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« Reply #8 on: September 05, 2008, 04:52:11 AM »

I guess I did mine all wrong. I used all PEX and copper in the install of my AquaHot.  Used 3/4" PEX to connect the engine to the AquaHot engine preheat, and to connect the heating system to the manifolds. All the heating system runs are 1/2" barrier PEX.

I'll let you all know when it fails from the heat. Heating system has been in for about 4 years now. The engine preheat has been in for a couple years. Don't hold your breath too long, it may be a while till you hear back from me on this one.

craig

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Craig Shepard
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« Reply #9 on: September 05, 2008, 05:38:17 AM »

Rob, I'd like to buy your hose. Can you email me at bottomacher at hotmail dot com please? Thanks
Don
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Brian Diehl
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« Reply #10 on: September 05, 2008, 06:11:17 AM »

I used 95% pex in my install as well.  It is working great with not a single leak in the pex.  On the other hand, I have had a few leaks in the radiator hose I used to make a couple of small connections.  Go with the PEX.  You won't be dissapointed.
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luvrbus
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« Reply #11 on: September 05, 2008, 07:03:24 AM »

My system is about 90% copper because i have radiant heat on each side it does have the molded rubber bend and that is the only place I have ever had a leak.Go with Pex it is used for floor heat poured in concrete it's good stuff and easy to work with but I have seen a lot of systems with CPVC and never had problems. No matter what you decide to use make it accessible for repairs   good luck
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CindyandJohn
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« Reply #12 on: September 05, 2008, 12:06:02 PM »

Thanks for all the great input. I will come to a decision soon. I will let you know how I make out.  I will definitely keep things accessible, that was in my plan already.  I kind of siding with the install in the generator bay. It is the most convenient spot and an area where the unit will mostly be protected from the weather and will still have venting if needed. Do you think the exhaust could be tee'd into my generator exhaust system? I have a flexible steel hose to a floor mounted elbow out under the bus - i have heard that these units have restrictions though on the exhaust length, etc... just a thought to throw out there. I will most likely run it out to the side near my generator's exhaust. Here is one more question to ask you guys - can I tee into my generator's fuel supply and return? rather then trying to access my fuel tank... Does it pay to install a separate tank just for heater fuel - I know this opens the door to that debate on heating fuel vs. on road fuel... I don't want to get that one going again, but I could do something like that for the heater...
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makemineatwostroke
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« Reply #13 on: September 05, 2008, 12:16:46 PM »

My Hurricane unit is restricted to max exhaust length of 8ft(no bends)  some of the diesel units are 5 ft max me I would use a separate exhaust the unit produces a lot of exhaust heat and shorter in my opinion would be best to get it away from the coach as fast as possiable 500+ degrees is hot  with a separate fuel line these units use about the same amount of fuel as a generator if not more
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Brian Diehl
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« Reply #14 on: September 05, 2008, 01:54:23 PM »

My unit is rated for .33 galons per hour.  That is very low fuel flow!
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Homegrowndiesel
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« Reply #15 on: September 05, 2008, 02:33:14 PM »

Hello John

My 2 cents worth.
   Pex is made for these temps 160-180 & heater use. I used equal pex and regular heater hose, some copper & a Little Silocone which can be a pain to seal at the joints even with the best clamps.

Dont forget the circulation pumps on the heat exchangers (of either engine you want to heat) if your keeping everything (coolant systems) seperate. And do not forget a heat exchanger for your potable hot water, that one you will never regret.

Drill a 3" hole out the bottom in either bay, run the exaust straight thru & the rest is the makeup air for combustion. I like the wet bay as it keeps the tanks from freezing without a heater in that bay.

Do Not put it in the engine compartment if you are going to be sleeping overtop (the noise from a dead quiet to the webasto burn makes for a fitfull sleep). Do mount it on rubber isolation mounts to lessen the high pitched gear noise.

I ran my fuel line seperate, I have seen some that used the same line work.

I do not find many spots that have off road fuel easily available but your situation may be (is) different.

Decisions Decisions Smiley


Bill Glenn
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CindyandJohn
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« Reply #16 on: September 05, 2008, 09:40:31 PM »

Hi Bill,

Thanks for the insight. I haven't heard from you guys in a while... We need to get ourselves back down there. Cindy and I have a case of some great Vino for Roberta! We hope to come around in a couple weeks or so.  Cindy said to say hello to you guys too....

I'm leaning towards the pex... At this time I am not going to plumb in the hot water heater... I have a tankless propane that has been working well since I worked out my kinks in the feed lines.

 If the exhaust from the heater is quite high - do you think some capture of that heat could be cycled back into the system? I have been kicking the idea of mainly using the generator as my heater since I run it most of the time. The webasto is more or less a secondary heater, block heater, and a reason for me to fix my dash defrosters... I was thinking of installing in a water bay area for the heat capture, but it will most likely be inside the open area with my generator... it is a much more accessible space. so many ideas - so little time....

Thanks,
John
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rv_safetyman
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« Reply #17 on: September 06, 2008, 02:53:07 AM »

Ski, I am very surprised at the Aqua-Hot recommendation.  When I got my system from them, it came with PEX.  If you look at the Aqua-Hot installation in most new premium coaches, I think you will find that it was done with PEX. 

I used PEX on mine for the domestic and heating systems, with a little heater hose for connections.  I made some 90 degree bends with copper and hooked them in with heater hose - some heater hose over the pex (using internal ferrules).  For the engine connection, I used some very premium heater hose (did not want to take a chance there).

We are still in Europe, so I can't contact my top level Aquahot application person by phone, but I think he would confirm that they still recommend PEX.  I have written him an email with this tread link.  If he does not reply to the thread, I will post his email reply to me.

Jim
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Jim Shepherd
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CindyandJohn
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« Reply #18 on: September 06, 2008, 08:55:06 AM »

When using Pex - is the larger the diameter the better - 1" vs. 3/4" ? I read somewhere that the larger the Pex the higher the BTU's produced? At least that was my interpretation of the thread. Thoughts on this?

Thank you for all the greart input.

John
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JackConrad
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« Reply #19 on: September 06, 2008, 10:21:16 AM »

Not sure about producing more BTUs, but most of the diesel fired boiler systems, require a minimum amount of coolant to prevent the pump from short cycling.  Don't ask how I found out about this. Larger diameter would increase the system capacity. With 1 engine to proheat heat exchanger, 3 heat exchangers inside the bus and 1 heat exchanger in the water bay, we still had to add a reservoir.
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CindyandJohn
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« Reply #20 on: September 07, 2008, 08:05:54 AM »

Thanks for that insight Jack... I will take that advice to heart... and as with most things in a bus - Bigger is Better!!!

John
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« Reply #21 on: September 07, 2008, 05:11:27 PM »

Don't be afraid to tie the Webasto fuel lines into your generator lines, and keep its exhaust seperate.

I know a coach based command vehicle application that ran two 8k generators and a 300 BTU Webasto off the same length of plain old skinny fuel line.

A Webasto doesn't need to run through a muffler, not really much sound there to muffle, and you'll introduce restriction that is verboten.

The Webasto in with the water tanks is a mixed blessing...the Webasto needs air to breath, introducing the frozen air to the tanks... and if you are tying in the generator waste heat, your goal will be to keep Webasto burn to a minimum, so it might not do the job?

I'd consider losing the heat in the exhaust from the Webasto as the cost of doing business, the generator waste heat is far more readily captured without a penalty and is available for longer amounts of time.

Adding a water bed electric heater to the water tank compartment so as to give the generator some load...and add some redundancy... how to keep the tanks from freezing under various inconvenient circumstances, or failures...

Lots more for a cold weather busnut to have fun with in the calculations!

happy coaching!
buswarrior
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« Reply #22 on: September 09, 2008, 01:24:13 PM »

OK, we are back in the good old USA (over 24 hours of travel yesterday Shocked)

I did receive a reply from Aqua-Hot and it has some good information. 

Here is a synopsis of the reply I got from the lead Technical Sales Representative at  Aqua-Hot Heating Systems Inc.

1)  PEX is rated for ***80 PSI ***at 180 degrees. It doesn't mean that the PEX is rated at 180 degrees.  It is a qualification for pressure rating.

2)  The Aqua-Hot 675 to 375D models use a 0 pressure system. The pre 2008 units use a 13 lbs system. PEX is JUST fine!!

3)  If heater hose is used in an  enclosed living quarters AND is heated above 180 degrees, it will give off a smell and may cause headaches. (physical). The silicon heater hose is designed to resist abrasions but with temps over 180 degrees, water starts to permeate the hose and it sweats creating the same conditions as heater hose in a enclosed living quarters but more noticeable.
 
4)  The Webasto cycles between 145 to 167 degrees. The Webasto uses engine coolant which will be heated to engine temp. which can exceed 200 degrees. For the engine connection a good quality heater hose with 3/4 ID is just preferred  because of  the vibration of the engine along with the twist of the coach.

5)  Aqua-Hot uses heater hose in connections inside the cabinet of the unit and the transitions between the PEX tubing is 5/8 ID x 3/4 OD and Cozy exchangers.

6)  They recommend 5/8 ID x 3/4 OD PEX tubing .

I questioned my contact about the heater hose smell and the silicone hose issue.  In a subsequent email, he mentioned that in one coach had used silicone hose and, because of a customer complaint of headaches when the Aqua-Hot would come on, they did a thorough investigation using what sounds like a sophisticated "sniffer" and found that the silicone hose was "off-gassing".  They replaced it with PEX and the problem went away.   He has also seen the silicone hose change color from the coolant permeation.  As a longtime hose guy, I have not seen that, but my contact is very reliable and I will defer to his experience.

Jim
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Jim Shepherd
Evergreen, CO
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CindyandJohn
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« Reply #23 on: September 09, 2008, 01:52:21 PM »

Jim,

Thank you very much for this information. I too will accept your contacts professional information... It sounds like some good Oxy Pex is the best way to go.  I agree with the connection to engine using a quality hose... that makes a lot of sense.

I will let you know how I make out.

Thank you,
John
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« Reply #24 on: September 09, 2008, 02:40:58 PM »

How are folks dealing with the transition from PEX to heater hose connections on the heat exchangers and at the diesel heater itself?  I physically looked at Brian Diehl's system and he uses heater hose the last few inches, but he is also saying that is where the leaks are.
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« Reply #25 on: September 10, 2008, 04:37:47 AM »

Brian, a short piece of stainless steel tubing is inserted into the PEX.  That keeps the PEX from collapsing.  The heater hose is then placed over the PEX and clamped.

The inserts that Aqua-Hot sells are really neat.  I ran out and ordered some from another source (can't remember who) and they were not as good.

Aqua-Hot uses constant tension clamps (the type you apply with pliers).  I have used them with no problem and also worm clamps.  I have had leakers in the past.  I go back and make sure the PEX is clean with no burrs and then sometimes double clamp those, or go to worm clamps and tighten them pretty good.   With worm clamps, you have to go back and tighten them periodically, as the rubber in the hose tends to "creep" a bit.

Jim
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Jim Shepherd
Evergreen, CO
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Somewhere between a tin tent and a finished product
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CindyandJohn
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« Reply #26 on: September 10, 2008, 12:22:59 PM »

Is it possible to use those shark bite compression connectors to go from PEX to a barbed hose nipple? Then use hose clamps... or to use a threaded end if the heater is so equipped. Does anyone know if the shark bites are good for the heat of the system? Just more thoughts to make it easier. I know they aren't cheap but they sure are easy to install.

John
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« Reply #27 on: September 10, 2008, 12:56:05 PM »

John,
I have them threaded right into my hot water heat exchanger and they are working just fine.
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MCI-9
Sussex county, Delaware.
See my picture's at= http://groups.yahoo.com/group/busshellconverters/
That's Not Oil Dripping under my Bus, It's Sweat from all that Horsepower.
----- This space for rent. -----
luvrbus
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« Reply #28 on: September 10, 2008, 01:08:32 PM »

John, find a plumber and see if he will lend you his expander and you can slip the PEX over the pipe on the exchanger and crimp it I watched a RV dealer do this because of leaks with adapters.Oh yea Jack another tool for Pex
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