Aqua - Hot 450-D Service Question.

[Adam Hunter]

Hello All!

Was wondering if someone could answer a couple of questions regarding our Aqua-Hot Boiler?

Our unit is in a 2008 Scepter 42', we live in Canada so currently the entire coach is winterized and in storage in our shop. I would like to flush and replace the boiler coolant as the system has not been done since new. Obviously I need to energize the system and bring the coolant up to temperature when I remove and replace the antifreeze - but....

1. The manual states that "The Hydro-Hot can still be used for interior zone heating even if the domestic hot water system has been drained and winterized".
How is it that I can run the boiler and not do damage or "transfer heat" to the domestic water side of the loop (Which is currently filled with RV antifreeze)?

2. Since I have never replaced the antifreeze before does anyone have any suggestions on how to refill the system via the drain valve? As the manual states the boiler must be refilled through the drain valve - Would I use a hand pump with a brass fitting to put the new coolant in?


Any input would be greatly appreciated.


Thanks
Adam Hunter

[Roger Berke]

Adam

Check the model number on the data plate on the top of your Aqua-Hot.

Depending on which model you have will determine which is the easiest way to replace the coolant.

Why do you want to replace the coolant? Per Aqua-Hot, coolant does not need to be routinely changed.

- Roger Berke -
www.Forum.RVHYD.com

[rvrepairnut]

Originally Posted by Adam Hunter

Hello All!

Was wondering if someone could answer a couple of questions regarding our Aqua-Hot Boiler?

Our unit is in a 2008 Scepter 42', we live in Canada so currently the entire coach is winterized and in storage in our shop. I would like to flush and replace the boiler coolant as the system has not been done since new. Obviously I need to energize the system and bring the coolant up to temperature when I remove and replace the antifreeze - but....

1. The manual states that "The Hydro-Hot can still be used for interior zone heating even if the domestic hot water system has been drained and winterized".
How is it that I can run the boiler and not do damage or "transfer heat" to the domestic water side of the loop (Which is currently filled with RV antifreeze)?

2. Since I have never replaced the antifreeze before does anyone have any suggestions on how to refill the system via the drain valve? As the manual states the boiler must be refilled through the drain valve - Would I use a hand pump with a brass fitting to put the new coolant in?


Any input would be greatly appreciated.


Thanks
Adam Hunter

http://www.aquahot.com/eSource/ecom/...nual_REV_E.pdf

Open the repair manual site I have provided and go to page 113.It explains all u need to know and more.YES u need a transfer pump
Paul

[Adam Hunter]

Thanks for the replies.

I will pick up a transfer pump to replace the coolant.

As far as why....boiler antifreeze has a shelf life too, just like engine coolant.
In our case this coach is new to us and the original owner had put it in storae after only 9000mi of use.

We replaced the burner jet, the fuel filter but the old antifreeze doesn't test very well with the refractometer and visually its black in colour & full of debris. Time for new coolant!


Regarding my other question - Any ideas on the heating loop operating while my domestic water system is winterized? Is that OK?


Adam

[Dr4Film]

Roger Berke is the Aqua-Hot Guru. He is the most knowledgeable person to talk to about Aqua-Hot units that I have ever met.

He has worked on thousands of units and has performed excellent service on mine many times.

If you have not joined his Hydronic Heating discussion forum, I would highly recommend it.

Forum Rv Hydronic Heater Repair - Welcome

The solution used in the AH unit may not be the same as used in an automotive engine depending on the AH unit you have, therefore it does not need to be changed like is does in an engine. Some units use the same solution as engines but it doesn't need to be replaced like it does in engines.

if it is black in color, that is not good. It should maintain its original color which can be either green or some other color depending on what was used.

The loop for the domestic water supply is a separate internal loop within the coolant box. it will transfer heat to the RV Water Anti-freeze and that's all it does. Since you are not drawing any water, it just sits there.

However, the coolant/distilled water mixture inside the AH unit is being heated by either the electric assist or the Webasto burner and is useful to use for the different zones within the coach for heating purposes during the winter.

Dr4Film ----- Richard

[Roger Berke]

Adam

Again, provide your model number for model specific help.

You do not have to pump coolant through drain valve unless the model is an AHE-450-D02 or later (zero pressure system). I don't think that this model was available in 2008.

In your 2008 model, if you replace the coolant you need to use the Camco -100 boiler coolant or equal. This coolant is hard to find.

Did you check the PH of the coolant? What was the refractometer reading?

Thanks for the kind words Richard. I don't think that I have worked on thousands of units... just quite a few.

- Roger Berke -
www.Forum.RVHYD.com

[rvrepairnut]

Regarding my other question - Any ideas on the heating loop operating while my domestic water system is winterized? Is that OK?

as u well know and have been told.its perfectly safe to do so.as u yourself posted
Quote:
The manual states that "The Hydro-Hot can still be used for interior zone heating even if the domestic hot water system has been drained and winterized".

[rvrepairnut]

Originally Posted by Roger Berke

Adam

Again, provide your model number for model specific help.

You do not have to pump coolant through drain valve unless the model is an AHE-450-D02 or later (zero pressure system). I don't think that this model was available in 2008.

In your 2008 model, if you replace the coolant you need to use the Camco -100 boiler coolant or equal. This coolant is hard to find.

Did you check the PH of the coolant? What was the refractometer reading?

Thanks for the kind words Richard. I don't think that I have worked on thousands of units... just quite a few.

- Roger Berke -
www.Forum.RVHYD.com

thanks roger for that information.I was wondering why that manual stated to use a pump because the couple older ones I have worked on I always added fluid through the RAD cap sytem located on top of the AH.I thought maybe when draining the complete system the pump made sence because it would guarantee a full airless system which I think will make good sence though and make it a much quicker fill process as some(most) units I have worked on the MH builder had no sence of humor when locating the unit in the MH
the only one I have seen mounted in a correct location was a 2007 beaver contessa.Very very good ease of access

[Adam Hunter]

Thank you,

My AH is the AHE-450-DEI.

My dealer has the -100 coolant available in bulk. The reading was -10 and the PH showed 6.4. Would that not be considered low??

Again this coach was neglected by the first owner and it sat for some time before we aquired it. As to the colour of the coolant it must have been contaminated in some manner, the fluid is dark (think Guinness) and has "growth" in it and sediment.

Thankyou for your input Roger.
-------

Regarding the water loop and my concern about energizing the AH - I was simply trying to increase my system knowledge & understand how I could do that without affecting the household RV antifreeze - Sorry to get you so worked up "rvrepairnut".

[rvrepairnut]

Originally Posted by Adam Hunter

Thank you,

My AH is the AHE-450-DEI.

My dealer has the -100 coolant available in bulk. The reading was -10 and the PH showed 6.4. Would that not be considered low??

Again this coach was neglected by the first owner and it sat for some time before we aquired it. As to the colour of the coolant it must have been contaminated in some manner, the fluid is dark (think Guinness) and has "growth" in it and sediment.

Thankyou for your input Roger.
-------

Regarding the water loop and my concern about energizing the AH - I was simply trying to increase my system knowledge & understand how I could do that without affecting the household RV antifreeze - Sorry to get you so worked up "rvrepairnut".

Sorry but Iam not worked up at all and it sounds like you definately need to change the fluid.Its just U asked and answered your own question and then reasked a question that you had already had the correct answer to ?its was just my take on it is all. I must have missed the Rv antifreeze part of it that you just now included?
sorry my bad

[Roger Berke]

The AHE-450-DE1 has radiator cap. Simply remove the cap and pour the coolant in that way.

If your PH is 6.4 then coolant SHOULD be replaced. PH should remain between 7.5 and 9.3; if it tests lower than 7.5, galvanic corrosion may be accelerated.

-10 gives you 40% coolant / 60% water. Recommended concentration is closer to -20 (50% coolant / 50% DISTILLED water).

You should probably also flush heat exchangers / supply and return lines. Drain coolant. Fill with tap water. Bring to operating temperature. Drain and fill with correct coolant / distilled water. The system holds around 5 gallons in the boiler tank + around 3 gallons in the interior heat exchangers / supply lines.

The bulk Camco -100 Boiler coolant will work just fine. Just verify that you are using the correct product or equal. The Camco is a non-toxic boiler coolant that is designed for use in the Aqua-Hot system. Expect to pay around $25 - $35 US for the coolant.

Make sure that the electric is turned off (@ circuit breaker). If you drain the coolant and the element turns on, it will immediately fail.

The shop manual for your model is on the Aqua-Hot website, here: http://www.aquahot.com/eSource/ecom/...ice_Manual.pdf Your AHE-450-DE1 is almost identical to the HHE-500-09M except that it has a white painted case instead of the galvanized case.


- Roger Berke -
www.Forum.RVHYD.com

[rvrepairnut]

Rogar
what is the main cause for coolant to turn black and go bad? consistant high thermostat temps or ?
Or just many many muti heat/cool cyccles?
Thanks

[Roger Berke]

I am not sure why the coolant changes color. No one has been able to give me a satisfactory explanation. It is very common for it to change color to look like Coke-Cola.

It could be that the wrong coolant has been added. Lots of mis-information out there about which coolant should be used. The RV water line anti-freeze is NOT an equivalent product, even though it is propylene glycol based.

It could be that tap water was used instead of distilled water.

In my opinion, so long as the correct coolant has been used, diluted with distilled water and the PH is in the acceptable range, there should be no reason to routinely replace the coolant. The Aqua-Hot is a closed system. No engine / diesel burner contaminates get into the coolant.

Not every Aqua-Hot uses the Camco coolant. For information about different Aqua-Hot models RV Hydronic Heating Repair - Hydronic Heater Model Information The proper coolant should be in the right hand column, unless there is label on the unit itself overriding what is listed. Some coach manufacturers started using the Camco earlier than recommended.

- Roger Berke -
www.Forum.RVHYD.com

[Adam Hunter]

Thank you Roger,

And thanks is little reward for such a dedicated, knowledgeable reply to the rejuvenation of my Aqua-Hot system.

I will most definitely follow your detailed instructions. Armed with your input it is quite obvious that the previous owner of our Scepter made some poor choices with the Aqua-Hot upkeep.

The new coolant will help me sleep better on our cold winter nights.


Sincerely

Adam Hunter