Hydro Hot Antifreeze ??????

[Joel Ashley]

This is from the AquaHot link I (and Bill) provided above, for those that didn't access the link or didn't read it:

" ... In 2002, Aqua-Hot changed the system design and in 2003 systems started using Propylene Glycol-based boiler antifreeze rated Generally Regarded AS Safe (GRAS).

 All Aqua-Hot Systems manufactured after 2002 must use Propylene Glycol antifreeze, including Hydro-Hot™, Aqua-Hot®, Aqua-Hot 375D™, Aqua-Hot 375LP™, Aqua-Hot 400D™, Aqua-Hot 400LP™, Aqua-Hot 450D™, Aqua-Hot 525D™, Aqua-Hot 600D™, and Aqua-Hot 675D™.  DO NOT use Ethylene Glycol or Propylene Glycol automotive antifreeze in these Aqua-Hot systems.

 ... Ethylene glycol antifreeze is toxic, does not have the GRAS label and is not suitable for an Aqua-Hot system manufactured after 2002. Ethylene glycol was used in pre-2002 Aqua-Hot systems with the exterior domestic hot water loop design. Ethylene glycol can be used in these pre-2002 systems, as well as GRAS-labeled propylene glycol boiler antifreeze."

David, your 100-02S model is apparently from the previous era but installed in a new era coach.

-Joel

[Dick Simonis]

Interesting discussion.  My 100-1s has regular anti-freeze in it and holds 11 gallons or so.  At ~$50.00/gal for the boiler fluid I would be hesitant to spend close to $600.00 to change it out.  Looking at Roger Berkes website the model chart indicates EG for older models and PG for newer ones.

Just guessing but the main reason for using PG may be the toxicity of EG in the case of a coolant leak through the heat exchanger into the fresh water.  Perhaps the older models have a double tube configuration the prevents this type of contamination.  I recall that the Hurricane used such and arrangement which allowed for the use of EG.

[Jerry Carr]

Dick the red boiler fluid runs about 18/gallon at BCS in your own bottle they stock it in 55 gallon drums

[Joel Ashley]

Yeah, as I recall the fluid was $15-$18/gal. the last I bought at True Value a few years back.  It was a lot more than that at Guaranty RV when I first found it, which got me started shopping around.

Boiler fluid has a higher boiling point than regular propylene glycol so it can transfer heat better, and as per the website its viscosity is higher presumably increasing lubricity too.

Joel

[Orman Claxton]

Dick
Your A/H holds approx. 16 gal fluid, That would be 8 gal. coolant, 8 gal. Distilled water, a 50/50 mix

[Dick Simonis]

Thanks Omar.

Question for the expert, why is EG OK in the older units but not OK in the newer.  I can speculate but that doesn't take the place of knowledge.  What was actually changed in the construction.

[Orman Claxton]

Dick
From what I was told, it was all health concern,   

[Edward Buker]

Dick,

My understanding is if the copper tube that heated the hot water was wound around the outside of the boiler then ethylene glycol was considered safe given any boiler leak was still isolated by the external coil. In cases where a coil was run inside a boiler it was not. I'm not sure which of their units heats water inside vs outside of the boiler envelope. Orman probably has the answer.

Later Ed

[Larry Dedrick]

Jay:
           If you get the Camco Boiler antifreeze in the Gallon container for your AH, use caution in diluting the gallon. This antifreeze is already diluted to give -100. This is too low for proper heat transfer. The antifreeze does need dilution, but not 50/50. If this gallon of antifreeze is mixed with one gallon of Distilled water, using a refractometer, the reading will give you a freeze and burst point that may not be sufficient for the climate you are in. There is a bit of misunderstanding on the mix ratio, because, once again the gallon container is already diluted.
            What I discovered in the mixing with distilled water, is a gallon of boiler antifreeze to approximately a 1/2 gallon of distilled water will get you close an acceptable ratio. Aqua Hot recommends 35%  to 50% propylene glycol to water. I don't have my numbers handy right now, so I apologize for not providing that. I have received so much misinformation in mixing that I ran my own experiment in mixing and used a refractometer to check my freeze point. I then called AH to confirm this dilution process and finally got the validation on mixing. This only pertains to the gallon boiler antifreeze. There is a smaller container that is Concentrate, this is a different mix ratio than what I am explaining.
              Bottom line, you need to use a refractometer to know for sure where your freeze point is. Refractometers are not expensive and easy to use. The Ball type testers are not for use with this type of antifreeze.
               Also AquaHot.com provides good information.

                  Hope this helps, good luck.

                   Larry D.

[Steve Huber Co-Admin]

Larry,
The freeze point numbers for a 50/50 mix and your target would be informative. Also, it would seem to follow that the concentrate would have the same characteristics e.g. don't go with the recommended 2/1 mix w/o checking freeze point protection.
The FAQ sheet from AH also is informative re this point.  http://www.aquahot.com/FAQs.aspx

Steve

[Dick Simonis]

Steve, thanks for the link.

It confirms that our older units use EG and we can use the Hydrometer for measuring the freeze protection.

It also confirmed that the construction changes after 2002 required going to PG.

One more thing off my "worry" list.

Dick

[Larry Dedrick]

Steve:
            I was checking out my boiler antifreeze with my refractometer, which will give you a reading for ethylene glycol or propylene glycol and a 49% (which is displayed on the refractometer) results in a freeze point of a -20 degrees. Unfortunately mine was only at a 34% glycol to water providing me with a +5, so I will be adjusting this. Don't really want to be anywhere I will need -20 protection, but you never know. Also the 50% ratio provides for the ideal hear transfer and keeps the antifreeze from causing sticky valves and problems with pumps.

Jay:
           A refractometer that will measure Battery/ Ethylene and propylene will give you the mix ratio and freeze point through the display. That way you know exactly what mix ratio you have. This may not be what you were asking about, but I thought I would put it out there.

                         Larry D