AquaHot Coolant

[Gary.Jones]

Let me begin by pointing out that my coach is a 2015 Anthem, built in late 2014 and early 2015 and equipped with an AquaHot 450D DE4. I have spent the afternoon with an AquaHot (AH) tech who has swapped out all four pump motor provided by AquaHot (on a 5 month old 450 D), and managed to spill some of the coolant in the process). There are a lot of issues here but the one I am writing about is the Transfer Fluid. The boiler fluid in my AquaHot is "yellow" and it is made by Century Chemical Company of Elkhart IN. They call this Transfer Fluid and although it might look close to "green" (old style Prestone anti-freeze), this is clearly yellow. The Century TF1 transfer fluid should never be mixed with Prestone Antifreeze! It is different chemically and incompatible. Its purpose is to efficiently pick up the hot fluid in the AquaHot and move it through floors and radiators. Now, the interesting thing is that it is virtually not available through any normal source. Amazon shows that they carry it, but even with Prime, it says available to ship is usually two to four weeks. A call to all big box RV retail outlets showed none of them handle it. A call to Century Chemical revealed they have "no retail outlets as of this time". They hope to develop some. However, there is one source at Elkhart Industrial Sales (574-276-2000) and they have it in gallon jugs, and 5 gallon pails (I think it is pails). I do not know the cost. I am told that Century Transfer Fluid is used in Entegras, and Winnebagos, and two other major brands (but not in many others who use the "pink"). I am told that it retails between $19 and $25 a gallon. My problem is that no one had it and although Century's chemist said he felt that Camco's Boiler Fluid was the same chemically except for the color (pink) he thought it was OK to mix, but the resulting combination would be brown, which is apparently also an indication of problems if the coolant has not been mixed (if all yellow turns brown, then that is diagnostic of a problem). However, when I called AquaHot, their opinion is that CamCo would say to not mix their coolant with the Century, so with AquaHot not coming on board, we had only one option.

My problem was we could not get some anytime soon, and I needed to leave so the decision was simply to add about a half gallon of distilled water. This would reduce the concentration, but Entegra and AquaHot CS felt that a half gallon of distilled would reduce the boiling point a little, and raise the freeze point a little, but that would be acceptable. So we added distilled and when i get home, I will drain the AquaHot and fill it with the concentration of Century that is required, but until that time will try to avoid temps above -10 degrees. So, now you know. If the overflow tank in your AquaHot is yellow, it is Century and not Prestone (Green) or Camco Boiler Fluid (pink). I will also try to buy my supply at Amazon ($30 delivered) or in 5 gallons pails (retails somewhere between $19 and $25 I am told). If I am wrong on anything, correct me..

If anyone knows of a good economical source, I would be happy to get the information.

Now, you coach may be different.... so look at what you have and plan accordingly, however, if it is yellow, it is Century TF1.

Gary

[Ann n Gene]

I think you have it nailed 100% Gary and explained very well. I ordered a gallon that I carry from Amazon and got it in less than a week. That was in January right after we got the coach home and figured out we had different fluid. It has not only got scarce but gone up in price since then. All JMHO


2016 Cornerstone 45B on order
Formerly 2011 & 2013 Anthems
2014 Lincoln MKT towed

[xtechgeek]

I replaced a couple of motors and flushed the system early this year. Aquahot recommended switching the system back to the Camco pink, but I stayed with the yellow Century Transfer fluid. I liked having a different color than the engine coolant which I believe is why Entegra went that route; albeit difficult to source and expensive.

[BrianGlenn]

Have you tried Roger over at RV Hydronic Heater Repair?

Sorry - just looked - he is not carrying the Century transfer fluid.

Brian

[Mr_D]

Yep, went to an AquaHot maintenance seminar at a GS Rally in Phoenix and they cautioned against mixing the two types due to the color change. You can purge the old stuff and change over to the Camco. Luckily we have the Camco in our 600D system as it's available more places.
Prestone is not approved for use in the newer systems as per AquaHot and Federal requirements due to it not being rated for boiler use.

Types Of Antifreeze In Aqua-Hot Heating Systems

Propylene Glycol Boiler Antifreeze 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 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-labeledpropylene glycol boiler antifreeze.
<Back to Top>

Why Does The Aqua-Hot System Use Boiler Antifreeze?

Unlike automotive antifreeze, boiler antifreeze has a higher boiling point and higher viscosity that helps lubricate the system, as well as the rust, scale and corrosion inhibitors. When properly used, it is capable of efficient and high heat transfer.

Aqua-Hot heating systems use either the Camco (pink color) or the Century (green color) brand products. The color your system has depends on the coach manufacturer and the model year of your motorhome.

What Brands Of Boiler Antifreeze Are Recommended For Aqua-Hot Heating Systems?

Aqua-Hot heating systems typically use either the Camco (pink color) or the Century (green color) brand products. The color your system has depends on the coach manufacturer and the model year of your motorhome. TIP: Don't mix colors in your Aqua-Hot system. Mixing pink and green boiler antifreeze produces a brown color that maybe confused with corrosion, creating unnecessary service expense.

[Gary.Jones]

I made a mistake. The name of the place that I got from AquaHot is Fleming Sales, and the number is 574-276-2000 and the contact person there is Steve Murphy. No commercial connection to them.

Gary

[Gary.Jones]

Mr. D.

I notice in your quote that your quote says that the Century Transfer Fluid is green. However, everyone I talked to today referred to it as yellow, and yellow is the color that I could call it. I wonder if maybe there was some confusion between the Prestone (green) and some earlier version of Century, and the manufacturer moved to a pure yellow. Mine is clearly yellow to my eyes. Also, strangely the Amazon and even the Century web page does not refer to the Transfer fluid as Propyline Glycol, but that is clearly what it is. Strange they don't reference its type.

My tech acknowledged what a previous poster on this thread asserted.... he bet that Entegra chose the yellow to distinguish it from the pink that circulates as engine coolant, and is what circulates through pump 4 which is on the back of the AquaHot and not inside the front cover. If you get a leak, it is clear which is the problem... yellow versus pink.

Gary

[Mr_D]

That quote is a direct copy and paste from the AquaHot website. I'm assuming (and you know what that means) that they would know the colors. But, as I remember it is yellow when mixed. They also show a container of the Century fluid and it is yellow too. Although green would change to yellow when diluted so maybe that's where the confusion is?
Here's the link: Aqua-Hot - Frequently Asked Questions

[Ann n Gene]

I THINK Century calls it green also, at least the Amazon ad I bought from in January did, but the gallon I have is very definitely Yellow.


2016 Cornerstone 45B on order
Formerly 2011 & 2013 Anthems
2014 Lincoln MKT towed

[Cruzer]

Mine is a light faded lime green. I guess it's borderline between calling it yellow or green. But it is the same stuff.

Also, I got mine on Amazon and it came within a few days, even though they state a few weeks.

[waterboy10]

I got ours on Amazon. It is yellow for sure and it took only a few days to arrive at our me home.

[Marcosdad]

If you go to camp Entegra, take a jug and they will sell you as much as you want and you'll know its the right stuff.

[rogelling]

I also got a gallon from Amazon in about a week.

[Rotis]

Same here, it took about a week from Amazon.