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Date:         Mon, 19 Nov 2012 16:13:19 -0800
Reply-To:     Alistair Bell <albell@SHAW.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@SHAW.CA>
Subject:      Re: Rear heater control
Comments: To: mcneely4@cox.net
In-Reply-To:  <20121119172819.O40VA.217794.imail@eastrmwml108>
Content-Type: text/plain; charset=us-ascii

oh for goodness sake's Dave, you never get challenged at home? Does asking you to explain your hypothesis constitute an insult?

:)

I'm not getting excited, just curious if you know what comes out of the coolant when it it left standing.

But how about a little thought expt, ok? Suppose stuff does fall out of solution in the isolated, and now cool, rear heater. That stuff would be limited to the amount in solution in the volume of the isolated coolant, lets be generous and say 1 litre. And why does it fall out of solution? Because it is cooler than it was when it picked up the solutes (whatever they may be) in the first place.

Now lets imagine the heater not being isolated, but rather it being used. In this scenario all the engine coolant will at some time pass through the heater. And because the heater works by transferring heat from the coolant to the air in the van, we can conclude that the aluminum fin/coolant interface will be cooler than the engine/coolant interface, right?

So now we have 17 litres of coolant and its dissolved stuff passing through a cooler region and this temp drop must cause some of the solute to drop out of solution. It might not drop out at the same rate as it would if the coolant were cooler (mind you ii does get cooler in the heater when the van is not running) but on the other hand the entire coolant supply is passing through the heater.

So I would say you would see more ppt. in the heater that was in the loop than a heater that was out of the loop.

Look at the radiator, I have. It gets clogged up over time with stuff and it doesn't get turned off in the summer does it? :)

alistair

On 2012-11-19, at 2:28 PM, <mcneely4@cox.net> wrote:

> ---- Alistair Bell <albell@SHAW.CA> wrote: >> what the heck exactly do you believe is suspended or dissolved in the coolant that will drop out of solution, or settle, or what ever, upon standing? > > Corrosion products? Not all coolant is created equal, and certainly not all water is chemically pure. I use distilled water, but it is not reagent grade. Many people use tap water, which in some parts of the country is pretty rough stuff. We all know that the waterboxer cooling system is corrosion prone. Some folks just use whatever coolant is on the shelf and cheapest. > > Good grief, Alistair, there is no need to get excited. If I am wrong, I am wrong. A little politeness rather than insults thrown at me because you perceive me to be more ignorant than you would be appreciated. Does it do any harm if someone leaves the valve set in "winter" position in summer? I actually don't have a rear heater, so maybe your complaint is with those who do and advocate the winter setting in summer. > > I was just trying to offer a rationale, one that I am still not convinced is wrong, given all the possible variables in the mixture present and operating conditions. If chemical processes were not possible in the cooling system, manufacturers of vehicles and coolants would not go to all the trouble they do to minimize the possibility. For example, VW recommends a phosphate free coolant, but many coolants sold in the market are simply labeled as being compatible with all vehicle makes and all coolant types. Whether they are phosphate free or not is a part of "let the buyer beware." Yet I have seen advocated on this list that any ethylene glycol based coolant is suitable for the waterboxer. > > mcneely > >> alistair >> >> >> On 2012-11-19, at 1:05 PM, <mcneely4@cox.net> <mcneely4@cox.net> wrote: >> >>> Alistair, I do not mean such suspended materials as the silt in a sample of river water, but rather chemical suspension including solution. My term was precipitate, not settle. In a perfect world, I would not expect the dissolved materials in coolant to precipitate out, but since they interact with several different materials in the coolant system, I am not convinced that precipitation will not take place. I do know that that was one of the problems some folks had with early generations of the coolant sold by GM and the brands intended to substitute for it. Maybe you are correct, that this would never be a problem. Certainly, fresh, clean coolant solution should behave better than old, contaminated coolant solution. And maybe flow would not matter. In my system, I have obviated any problem of static coolant in the rear heater by removing the thing. If it is a problem, it should apply to the front heater as well, of course. >>> >>> BTW, when I mentioned to my mechanic recently that I intended to flush the cooling system and replace the coolant this winter, he asked me why. I said that the coolant was more than two years old. He said if I do it, save the coolant and give it to him, that he would run it in his vehicles if it looks clean. It does look clean, in fact, quite clear. mcneely >>> >>> ---- Alistair Bell <albell@SHAW.CA> wrote: >>>> Dave, >>>> >>>> my point it that I can't see, or have seen proof, that closing the rear heater valve will cause any harm to the heater, given that the van has a good charge of coolant. There is no proof that anything will precipitate out as you think it would. What suspended matter is there in the coolant? If you can tell me that then we can have a discussion. Perhaps take a sample of your coolant and let it sit for a while and see what drops out? >>>> >>>> alistair >>>> >>>> >>>> On 2012-11-19, at 12:38 PM, <mcneely4@cox.net> wrote: >>>> >>>>> Alistair, while I agree that chemical environment matters to chemical processes, I am not sure that the facts you cite would prevent precipitation of suspended matter in a static setting with tiny passages. But, I (like others) have been wrong before. mcneely >>>>> >>>>> ---- Alistair Bell <albell@SHAW.CA> wrote: >>>>>> Dave, >>>>>> >>>>>> the comparison you make between a car's cooling system: >>>>>> - closed loop, low O2 (if not anoxic), water, ethylene glycol, corrosion inhibitors >>>>>> >>>>>> and a dishwasher: >>>>>> - open loop, O2 rich, water, caustic cleaning solution >>>>>> >>>>>> doesn't warrant much more thought than just how bad an analogy you made . >>>>>> >>>>>> :) >>>>>> >>>>>> alistair >>>> >>> >>> -- >>> David McNeely > > -- > David McNeely


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