Community Forums

PitMan51 · 03-29-2023, 03:40 PM

We have 09 40MDTS with the Aquahot 450 D system. We have developed a major water leak coming from the back side of the unit. It appears the only access to repair the leak is from the back side. Unfortunately there is no access. I can barely get a picture of where the leak is, let alone do any repair. Does any have experience in what’s involved in removing the whole unit?

Bill and Sonia
09 40MDTS

shootist · 03-29-2023, 03:45 PM

There are hoses and pex lines all around these things. Get a snake camera for your phone and find where the water is coming from. A nine foot snake with a light is about 40$ on Amazon.

Cinequip · 03-30-2023, 10:18 AM

Hi Bill,

There is an opening in the floor, behind the unit, which can be accessed from under coach. First time you access it, you have to feel around to locate it, and then cut the black barrier which covers the underside. You can then get to everything you need back there.

I think you will find you have an engine coolant leak - that is the weak point. You will probably have to replace a section of the 5/8" coolant hose. I use my phone to take a picture of the rear of the Aquahot to keep tabs on the condition of the hoses, from time to time. Most I've done so far, is to tighten the hose clamps.

Bking · 03-30-2023, 11:37 AM

I have very personal hard knocks experience with this. I had the (likely) very same leak. I did not know about the above access panel under the black screen fabric on the under side of the coach. That would have been HUGE.
Sooooo I removed mine by disconnecting all fittings necessary for removal with lots of coolant everywhere, many new colorful words recited and three days, repaired the fitting on the back, then reinstalled it. Mine is no longer bolted down in the back. Yes there is one fastener that holds down the flange in the back to the floor. It took all I had to remove it by feeling and using lights and mirrors. The only other access I could see would have been to remove the tanks on the other side of the coach to be able to just fix it in place.
Boy do I wish I had known about the access panel!!!! What would be a good way to re-seal the black fabric once finished?

Dieselboy · 03-30-2023, 11:43 AM

I'm not a mechanic, but I can try to give you some general guidance on removing the Aqua-Hot 450D system from your RV. If you're not confident in your ability to do this, I would highly recommend consulting a professional or contacting Aqua-Hot for assistance.

1. Turn off the system and disconnect power: Before you start, make sure the Aqua-Hot system is turned off and disconnected from any power source. Also, ensure that the unit has cooled down to avoid burns or other injuries.

2. Drain the system: Drain the coolant and fresh water from the Aqua-Hot system. There should be drain valves for both the coolant and fresh water lines. Be sure to have containers to catch the fluids and dispose of them properly.

3. Disconnect plumbing connections: You'll need to disconnect the plumbing connections on the unit. This will typically include the fresh water supply and return lines, as well as the heating loops that supply heat to the various zones within the RV.

4. Disconnect electrical connections: Locate and disconnect any electrical connections to the Aqua-Hot system. This may include power connections, control connections, and any sensors or switches associated with the system.

5. Remove mounting hardware: The Aqua-Hot 450D unit is likely mounted to the RV using brackets or other hardware. Identify and remove any bolts, screws, or other fasteners that secure the unit in place.

6. Carefully remove the unit: With all connections disconnected and mounting hardware removed, carefully slide the Aqua-Hot system out of its location. This may require the help of another person or the use of equipment to support the weight of the unit during removal.

7. Repair and reinstallation: Once the unit is removed, you should be able to access the leak and make the necessary repairs. After the repairs are completed, follow the above steps in reverse order to reinstall the Aqua-Hot system.

Again, I'm not an expert, so please consult a professional or contact Aqua-Hot support for assistance if you're unsure about any of the steps involved. Good luck!

Cinequip · 03-30-2023, 12:11 PM

Quote:

Originally Posted by Bking

Boy do I wish I had known about the access panel!!!! What would be a good way to re-seal the black fabric once finished?

4" wide industrial gaffer's tape to seal the cutout section back on.

vito.a · 03-30-2023, 12:41 PM

I removed our Aqua Hot system last week. I also had a leak in the back side of the system and our coach does not have an access port.
It is difficult work in a tight space.
I removed two engine heater hoses, two fuel lines, two Pex water lines, six zone coolant hoses along the top, one over flow hose, dozens of DC control wires, a set of 120v AC wires, and two angle brackets bolting it to the floor.

The tough part is the exhaust port under the coach. I used a very large pipe wrench with a 4' cheater bar to unscrew the 1 1/4" NPT exhaust.

I used a set of silicone tapered rubber plugs from Amazon to stop the hoses from leaking. https://www.amazon.com/dp/B00XYD2760...roduct_details
I used a 5/8" brass hose barb union to reconnect the heater hoses so I could run the engine and a 1/2" Pex hose cap so I could turn the water back on.

I slid the unit out onto a furniture dolly to work on and replaced the boiler assembly.

Bking · 03-30-2023, 05:41 PM

Quote:

Originally Posted by Cinequip

4" wide industrial gaffer's tape to seal the cutout section back on.

Thank you Scott. I'll get some to have on hand for "incidences" ....

EngineerMike · 04-06-2023, 05:20 PM

Some coaches were made w/the cutout in the floor and some were not; I've felt around for that hole in mine and can't find it. However the floor can be sawn thru to make the hole, that's how the 1st guy did it. Measure carefully from outside to the back of the unit, there are full height flanges on either side to get a full dimension without much trouble. Add 1/2" for safety sake & trim away. Don't go nuts above the floor line for obvious reasons.
The original engine coolant line material was iirc 5/8"i.d. heater hose of the cheapest junque grade known to humankind that barely passed a 5-minute test, and fails at the brass nipple into the tank where it gets hottest w/the blow torch going. Those that have replaced it with premium heater hose have never had the problem again.
There is also a mixer valve in the back that should probably be adjusted down in temp from the OEM setting when you get there.
If you replace hose back to the engine, just strap new hose to the existing bundle as you will never get the bundle undone w/out a lot of torture.

DrDaveMA · 04-11-2023, 09:13 PM

One other improvement I made, I did not like the exhaust exiting directly under the bedroom slide, so I extended the pipe to the rear of the Coach. Now it does look a little strange, a 38’ Coach powered by that small an exhaust, but with no diesel fumes drifting in through the slide, I don’t care what others think.