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Author Topic: Water heating diagram. Will it work?  (Read 3173 times)
Chaz
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« on: November 14, 2006, 11:17:37 AM »

Hey gang,
  Here is what i came up with for my water heating schematic. Sorry there is no written explanation, but I think you can tell that I can heat various things at various times by the use of the solenoids.
  As far as I can tell, it should cover everything I want to do, but I am open for suggestions. I would also be open to any particular ways you all might think it would work best and how to plumb it.
  By the way, I called Luke this morning - GREAT GUY!!!!!! - and ordered a windshield and block heater. He thought it wasn't a bad idea to have it as a back up "just in case".
 
  I also have my floor plan drawn out and if I could shrink it, I would post it. But I did figure out how to do that "dogleg" in the bathroom to get natural privacy and utilize the space better. If I can get it shrunk, I want to start a new post of interior shots and floor plans. I feel that would be EXTREMELY helpul to us newbies and even neat for others to see how others did cool things.

  Thanx for all the help!!
     Chaz
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« Reply #1 on: November 14, 2006, 11:50:48 AM »

Hi Chaz

This is very interesting to me as I am just trying to design a similar system (received my Webasto for Germany last week. Yippee!). I will be following others' comments on your circuit very closely, but some initial questions from me to help my understanding:

- What will you be using to pump the water around the circuit? And, where in the circuit will the pump go? (even more than one pump?)
- Are you using a pressurized cold water system? (and hence pressurised hot water through the heat exchanger?)
- As there doesn't appear to be a 'hot water tank' as such in your system, do you think the heat exchanger will be able to 'instantly' heat sufficient water for decent hot showers etc? I had ruled this out as an option on my system, but it may be your Webasto output and heat exchangers are much bigger than mine.
- Do you know what type of solenoid valve you intend to use? If so I would be interested to know the make etc
- Will you be using temperature guages to know when the water in the various pipes has reached the right temperature to open or close the various valves? (or will you even have automatic values?)
- Will the Webasto be running on veg oil as well? If so, presumably you will also have an electrical heating element on the veg oil line to heat the oil before you can light on the Webasto?
- Is heating the veg oil supply line, rather than the tank itself, satisfactory?

Sorry to hit you with a list of questions rather than useful comments, and sorry if some of those questions are dumb, but I am on a steep learning curve with all this too.

Jeremy

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« Reply #2 on: November 14, 2006, 12:04:54 PM »

Ow, my head hurts now.

I don't see a pump.

Suggest you put valve manifolds in the system before and after the Webasto and a pump on the output side between the webasto and manifold. Then rework the circuits to come off the output manifold and return to the return manifold. I think it'll end up being a cleaner drawing and installation.

You'll be sharing coolant with the engine, but there will be times when you don't want to circulate through the engine (no sense heating the engine when boondocking for 2 weeks). In this case, you'll need to provide an expansion tank on the webasto side.

craig


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Craig Shepard
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« Reply #3 on: November 14, 2006, 12:24:10 PM »

Not to repeat anything said before: You have indicated all three way valves in your system. I think you will have trouble locating anything suitable in a 12 or 24 volt valve. You will be using at least 3/4" pipe and pilot operated valves are not suitable if there is back pressure or flow in two directions. I am sure it is possible if you spend enough money but not practical.

If you are planning to run more than one circuit at a time, you have to have some way to split the flow. An open flow circuit such as the engine would take aknost all the flow and little would go to the heat exchanger. Like electricity, water goes to the least resistance.

Contrary to what gumpy says about a surge tank, if you leave one line from the Webasto (either hot or cold) open to the engine, there will be no circulation but room for expansion.

I can't make any further comments until you provide details on the components you plan to use, We need info on BTU capacity, pipe sizes, pump info, etc. etc. etc.
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Chaz
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« Reply #4 on: November 14, 2006, 01:36:52 PM »

Sorry about your head Craig!   Grin

This is basically the drawing of what I want to do. Since I am new at this (Hell, I didn't even know there wasn't a pump on an aux heater!) I just wanted to get my drawing out to you guys to see where i may be going wrong BEFORE I get too far along. And as far as components, I am also open to that. Again...... I just don't know. I'm sure I could wade thru it and make the same mistakes many have before me, but I would rather not. (I will also stop and ask directions before I starve to death, too!  Cheesy)
 
Can the motor water pump do the circulating thru the system for me when I use the heat from the motor?

Sorry I don't have more info for you Jeremy, but I'm just getting started. There will be a pump in the fresh water side, obviously, I just didn't put it in there as I wasn't worried about that line. Just the hot water circulating.
I was hoping the aux. heater would be able to heat the shower water fast enough but it may need a different set up than what I have it looks like. (I haven't even seen one in real life!)
Temperature controlled valves are a cool idea. I had planned on just manually operating them, but I like that idea.
The aux. heater will run on diesel. I am not versed enough yet to do that. I think diesel would probably be best anyway.
I seen on the wvobus site that they put a copper coil or even a small heater coil in the tank to heat the oil. That was something I was going to do on a seperate line, but I think I am going to use a plate heater just before it goes into the engine also.

No problem with the questions bud, I am learning here too!! All I really know is what I want to do. These guys on this site have been a boat load of help!! Hopefully this will help both of us!!

Thanx
  Chaz
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« Reply #5 on: November 14, 2006, 02:05:05 PM »

Chaz:

Here’s a few thoughts from one who has done a similar install using an Espar coolant heater:

Your Webasto probably has an inlet and outlet pipe or hose size of 1 inch or more and a pump to match.  This setup is fully capable of providing adequate flow characteristics through two parallel loops of ¾ inch diameter pipe or hose.  Yours plan appears to employ an either/or choice of one loop at a time.

You will find it advantageous – and perhaps cheaper – to dispense with the heat exchanger for domestic hot waster and replace it with a marine type tank heater with its own built-in heat exchanger and a 110 volt electric element.   You won’t want to be running the Webasto to heat shower water when its 95 degrees outside and you’re plugged in to shore power.

I don’t see any provisions for a generator and the use of its coolant heating capability in your system.

You will surely also need a coolant loop to supply your defrosters, and another means of controlling the flow through it.

Last, but not least, you will find it best to limit the use of valves and additional pumps to the extent possible, and to include the capability to run the Webasto coolant pump independently from the heating section.  I use this feature in mine frequently while driving in cool weather to improve the use of engine heat.

KISS principal always applies.  I have a box of valves and controls in my garage that I ended up removing from the bus because the system didn’t work the way it was designed. It was too complicated and had too many components.

tg
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Jerry Liebler
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« Reply #6 on: November 14, 2006, 02:26:10 PM »

Chaz,
     If you chose, as the diagram indicates, a single coolant loop system combining the Webasto  and engine you'll have to heat the engine to heat the bus or the hot water, this could take a while and under most conditions waste a lot of heat.   The usual practice is to use two isolated coolant loops, one for the engine and another for the Webasto with a recirculating pump in each and a heat exchanger between them.  The two loop system also requires the addition of a coolant resivoir(sp?)  tank for the Webasto side.  With the two loop design the Webasto's coolant can be non toxic and make a leak in the domestic water heating less dangerous.  Also you'll need to choose the flat plate heat exchangers carefully (way oversized)  as the recirculate pumps used with Webasto systems don't tolerate much pressure drop.  Also the Webasto dealers highly recomend a bypass water filter in the coolant loop.
Regards
Jerry 4107 1120
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Jeremy
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« Reply #7 on: November 14, 2006, 03:25:31 PM »

Hi Chaz

Thanks for the info; it's just occured to me that the following 'official' Webasto water circuit diagrams that I came across the other day may be useful to you:

www.batmanuk.com/pdfs/circuits.ppt

I haven't got my head around them myself yet, but I expect the comments other people are making will be easier for both of us to understand when referenced to these circuits.

The issue regarding the 'built-in' Webasto water pumps is an interesting one. My unit doesn't have one, but an integral pump was (is) available as an option depending upon how the Webasto was to be used (ie. if the Webasto is just used as an auxillary coolant heater when the vehicle's engine is running (for emissions and passenger comfort etc), the Webasto doesn't need it's own pump). On my model Webasto, the optional pump is a plastic device bolted to the outside body of the unit - it doesn't look to me like it would really be capable of pumping water around lengthy and convoluted water circuits in a bus conversion, so I was expecting to fit an entirely seperate circulation pump somewhere in the hot water system anyway.

You're right about the pump in the cold water system not really being relevant at this stage; I was just interested to know whether you were going for a simple on/off type pump, or a fully pressurized system. (I'm leaning towards the latter, but it is a slightly more involved installation, and the components are more expensive).

Again it's a more involved installation, but like 'akbusguy2000' I am planning to fit a hot water tank in my system, principally because I like the idea of having a tankful of 'free' hot water (heated by the engine) available as soon as I have arrived anywhere. The tanks I have been looking at come complete with an electrical element, so although I will never be connected to shore power whilst travelling I can use excess generator capacity to heat water if I want to. I'm not yet sure how to decide how big the hot water tank should be, though - too small and I'll run out of hot water before I've finished my shower, and too large and it will take too long to warm up.

The bits of the system I am most unsure of is are how to arrange and operate the various valves, especially those separating the 'engine circuit' and the rest of the system.

Jeremy

Jeremy
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« Reply #8 on: November 14, 2006, 03:38:05 PM »

The pump I was talking about is for circulating the coolant, not the fresh water pump. The webasto might have a high capacity pump, but not necessarily. Yes, you can use the engine pump when driving. If you use a March circulating pump, it can go inline and will not impede coolant flow.

If you use separate antifreeze systems, be aware that rv antifreeze won't hold up to the heat produced by the webasto (BTDT). The standard rv mixture will also freeze at about -10*F, and won't pump (again, BTDT). You also must separate your glycol system from your fresh water sytem with two separate layers off metal. In other words, you can't just run a loop of hot coolant through the hot water tank.

For domestic hot water, consider the following: A friend of mine bought a new electric water heater from Home Depot. He got the smallest one they had. Then he stripped the outter jacket and insulation, wrapped it with two layers of 1/2" soft copper tube, re-insulated over it, and connected the copper to the engine/webasto loop. Now he can heat water with electric, or with the engine/webasto system, and he always has several gallons of hot water available. You'll want to put a tempering valve on the domestic hot water as the engine/webasto could produce temps up to 200*F in the tank.


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Craig Shepard
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« Reply #9 on: November 14, 2006, 03:40:08 PM »

I found that the webasto pump was not enough to circulate when idlling.  I installed a circulation pump from my FishBowl parts bus it is under the bed and plumbed from the engine to the pump then to my webasto etc...  I figure if the GM engineers designed that pump to pump all the way up to the front drivers heater it would work as a booster pump to my webasto.. I also have a loop that will heat my electric hot water heater while I'm driving down the road.  Note while driving down the road once all the air is out of the system the engine water pump seems to maintain engine water tempature at the  electric water heater  (18 ft away ). I have yet to need the booster pump when driving down the road.  Idling the booster pump keeps the water moving..... paul
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« Reply #10 on: November 14, 2006, 10:39:06 PM »

Chaz- one thing that will increase the effieciency of the system-mainly not letting cooler water mix with the warm water where not needed-every place you have a T and/or a solenoid, you should use a ball check valve to keep the fluids moving in the right direction.  Otherwise you could get a back feed, or worse create a loop where the water won't flow to where you want it.  Otherwise it looks good.  On my transit, my big engine pump is enough to get the coolant up to the front of the bus without the use of a booster pump.  I still have the booster pump in line just in case, though.  Good Luck, TomC
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« Reply #11 on: November 15, 2006, 10:02:03 AM »

Chaz,
Keep asking questions, I'm taking notes.  Cool

Lee
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Lee Bradley
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« Reply #12 on: November 15, 2006, 10:14:49 AM »

A pretty good diagram at http://itrheat.com/hydronic.html
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Chaz
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« Reply #13 on: November 15, 2006, 12:53:56 PM »

 Grin Grin Grin Grin Grin
  Thanx Lee!!! lolol I am going to, but I got a little busy in my studio.
  But I'll tell ya, I'm loosin my steam on this hot water project. I guess I am just a little too ambitious for my own good. It seems that this was not all that good of an idea. BUT, I haven't given up.
  I just get these big ideas and don't know how to implement them. And I hate to keep bothering others with what ends up being a dumb idea. I don't really have a problem with asking, if it pans out to be a good idea, then everyone can benefit, but so far my inexperience is REALLY showing itself.
  But, I still want to do something along this line so stay tuned!!  Roll Eyes I may just have to redesign it a bit. Jerry Lieber called me (really good guy) and offered me some insight also.
  More questions to come!
     Chaz
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« Reply #14 on: November 15, 2006, 12:59:32 PM »

You should see all the dumb ideas in my bus - some even worked!.  Sometime its good to "not know that you can't do something".
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Chaz
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« Reply #15 on: November 15, 2006, 01:08:31 PM »

Thanx Jim,
  I appreciate that. 
  I try to live by my signature line:
 
  "Imagination is more important than knowledge" - Albert Einstein

But I would rather pay the price than somebody else.

Chaz
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Homegrowndiesel
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« Reply #16 on: November 16, 2006, 06:08:05 PM »

Not Bad Chaz, close to everything you will need? Smiley

WOW alot of good advise, Grin concider all. It is always nice to get interesting opinions and good advise. Huh

OK now MINE, everybody has one, OPINION which I hope will also be good advise. Wink

As noted missing generator circuit, input(take asprin).  Cool
Most all diesel boilers are ordered with coolant pump.
As expressed, when idiling you will need it.
Good advise on the supply and return manifold ( use regular on-off valves)3 ways are expensive.
Good suggestions on the summer and winter valve.
As noted no need to close both, supply and return.

Think, Detroit supplying manifold, generator supplying manifold, webasto supplying manifold.
Of course if you have supply you need return (cold in your drawing).
Some circuits can be run in parrallell and some can be series depending on use.
Full 3/4" minimum, (prefer1" pex) from and to the manifolds. 3/4" or 1/2" pex or heater hose from there, depending on btu of the heat exchanger and load. Shocked

" It is beautiful for an engineer to shape and design the same way that an artist shapes and designs. But whether the whole process makes any sense, whether men become happier - that I can no longer decide."

                                                                                              Rudolph Diesel

Grand Pops Saying was " There is technology today to do anything the human mind can imagine." I live by that.

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                                    "    WHO SAID CAN'T?
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Bill
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