Boiler Anti-freeze

[Paul]

Boiler Antifreeze

Want to save some Money on this stuff.

The unit holds five gallons plus the piping and heat exchangers for a total of eight gallons.

Camco makes a 32 oz concentrate that makes ¾ gallon mixing it 2 parts distilled water 1 part concentrate for a total cost of $9.50 for the ¾ gallon. Or over $100.00 to fill the System.

any ideas you might have

Paul

[rv_safetyman]

Paul, when I had my system serviced at the Aqua Hot factory, I asked them about antifreeze.  The book has a spec. (can't recall details), but they said that good old cheap automotive antifreeze is fine.  In our area, I use a 50/50 mixture and whatever was cheap at Wally World.

Jim

[Sam 4106]

Our Aqua Hot was leaking antifreeze on our recent trip. I finally discovered that the radiator cap seal was cracked and pushing antifreeze out rather than into the overflow tank. I got a new cap and 4 gallons of antifreeze at a chain store called Blain's Farm & Fleet. Antifreeze was $7 a gallon plus $4 mail in rebate. Distilled water that day was 83 cents a gallon. The cheapest antifreeze at Walmart that day was $8 a gallon. The 50/50 premixed was $7 a gallon so you are also paying $7 a gallon for the water in the premixed stuff. The price of convenience is pretty steep. I know, I'm cheap and always will be. LOL YMMV

[gus]

Sam,

You're actually paying $14 a gal for for anti-freeze, the water is free!!

I can't help admire a person who can think up such a rip-off, almost as bad as paying $1+ for a pint of tap water in a plastic bottle!!

Probably the same guy who thought of charging $250 for a pair of tennis shoes!

[James77MCI8]

Regular automotive antifreeze is fine as long as there are no heat exchangers in the lood that come in contact with domestic hot water.

[NewbeeMC9]

Have you ever thought about using oil?  It'll transfer heat better than the mixture

Here is one I found on google.

http://www.radcoind.com/600prop.html

[bottomacher]

What is the problem with domestic water heat exchangers and antifreeze?

[NewbeeMC9]

What is the problem with domestic water heat exchangers and antifreeze?

Ethlene Glycol is poisonous,  if you should have a leak in your HX,  potential for death.


Propylene Glycol is supposedly not poisonous,  you actually see it on food ingredient labels.


They have oils that claim safe for food but I don't want to imagine what happens in case of leak.

[Tim Strommen]

What is the problem with domestic water heat exchangers and antifreeze?

Ethlene Glycol is poisonous,  if you should have a leak in your HX,  potential for death...

You can get a double/dual-wall heat exchanger for EG-heating in potable (freshwater) systems.

..Propylene Glycol is supposedly not poisonous, you actually see it on food ingredient labels....

Evans Cooling has a Propylene Glycol coolant called NPG+ for use in engine cooling etc (even Class-8 diesel).  The nice thing about this type of coolant is that there is no water content – so no freeze risk (it turns to slush at -40 due to the corrosion inhibitor pack, but it's still pump-able).  Another nice thing is the boiling temperature at atmospheric pressure is around 375F – way beyond the operating limits of any engine or domestic boiler out there.  Also, because it's a waterless coolant – it's a lifetime coolant (assuming no external contamination...).

[bottomacher]

I have an Atwood marine water heater with engine coolant heat exchanger. I don't believe that the engine water line passes THROUGH the domestic water, but AROUND it, which would eliminate any chance of contamination by antifreeze. I could easily be mistaken, since I looked at it a long time ago. I have no experience with other w/h models. I'd like to hear from anyone who knows for sure.

[Paul]

Ethylene Glycol is a Poison and if it leaked into the domestic water system that would be bad.

On our Aqua-Hot unit we have, the domestic water-heating coil is inside the boiler unit with direct contact with the anti-freeze in the system. 

The engine preheat coil is around the out side of the boiler unit.
Thus engine preheat leak would not leak into the boiler but would leak out side the boiler unit.

The way this Aqua-Hot was built, there is no way that I would use Ethylene Glycol in this system.

Propylene glycol based "boiler" type antifreeze deemed "GRAS".  Recognized safe by FDA

Look into home water system at all the lime and scale in the pipes. That is why to use Distilled water.

Not all Aqua-Hot units are built the same.  This post is about our Aqua-Hot unit.


Paul

[gumpy]

Ethylene Glycol is a Poison and if it leaked into the domestic water system that would be bad.

On our Aqua-Hot unit we have, the domestic water-heating coil is inside the boiler unit with direct contact with the anti-freeze in the system.  

The engine preheat coil is around the out side of the boiler unit.

Your Aqua-Hot is hooked up backwards. The outside loop is supposed to be for domestic hot water, and the inner loop is for engine preheat.
There should be a tempering valve on the domestic side.

I'm not aware that Vehicle Systems ever built a unit that is hooked up the way you indicate yours is. There is a code somewhere that requires a domestic hot water exchanger must have two layers of material between the coolant and domestic water. In the Aqua-Hot the first layer is the tank. The second layer is the copper coil around the tank. If yours is connected with the domestic hot water going through the inner coil, you are at risk of contamination. Plus, that inner coil will not sustain continuous use of the domestic hot water like the outer coil will.

Do you have a manual for the unit you have?  I'd like to see it if that really is correct.


By the way, I run Prestone auto antifreeze (Ethylene Glycol) in my Aquahot. I tried RV antifreeze (Propylene Glygol premix) but it slushed at about -10*, and no it would not pump!

craig

[Paul]

Glade you jump in Craig.  I know that you hade trouble with the propylene glycol antifreeze about three years back. Thought that you might have found a source for propylene glycol at a good price. I see you switched to ethylene glycol. I do not think this is right for us.


Our Aqua-Hot is A Model H2E-200-01E.  This is one of the first units with out a pressure cap. I have an installation manual and they never printed a parts or repair manual. They sent me a draft for a parts and repair manual for a model 525-D.  This manual is not like the one on there web site.

The unit works great but has two leaks.

One in the boiler tank stir pump piping and fill / drain valve.  Will be changing this to a system like on the newer units where the valve easy to get too.

Then second, one is in the engine preheat piping / pump in the unit.  This one has not been found. Will pressure test this as soon as the snow is out of the way.

The domestic water coil is in the tank. I will try to send you a service / parts manual
The file is to big to send

Paul

[gumpy]

Well, if that's the case, it's the first time I've ever heard of them putting the domestic hot water loop on the inside.

I see the manual 525-D on their website. I noticed that none of their new manuals indicate how the loops are configured, but on
page 7, the flow diagram says, "The engine's coolant is circulated through the Aqua-Hot's internal Engine Preheat System where the heat
from the Boiler Tank is transferred to the engine's coolant."  This would seem to indicate that the engine preheat is on the inside of the tank
for that model, but then again, it could just mean on the inside of the box.

I really find it hard to believe that they would have changed their design so as to not provide the 2 layers of separation between the antifreeze
and the domestic water. But, I admit, I have not looked closely at their units for several years, nor have I talked to them for several years.

I would not use a unit that was built that way. It's too risky, even with propylene glycol in there.