Aqua Hot Failed

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Aqua Hot Failed

December 10, 2019, 10:30:20 pm

Over Thanksgiving I had to make an emergency trip to the Chicago area to pick up my grandchildren. When we left Florida the Aqua Hot was working flawlessly. No sooner we arrived to our campsite the Aqua Hot failed to start. When I fired it up it had a weird smell. I went outside to see smoke coming out of the exhaust and a weird sound in the motor operation. The sound of the system was not the normal whinning sound. I had my wife shut it down, waited a few minutes and asked her to start it up again. It started normal as usual, then the motor was winding down and smoke started coming out again and then the system shut down on its own. Waited a few minutes and the system would not start again. I called Rudy and by my description he thought something was going on in the burner. He told me not to start it anymore till I can look into the burner or have someone check it out. Luckily it was in the low 30's and I survived with the Aqua Hot electric element and some cube ceramic heaters till I got to Florida.

Now that we are situated back in Florida I was able to remove the burner and opened it up to discover that the the plastic clutch driver between the motor and blower was cracked and caused the system to fail and bog down. The smell was the melting plastic from the motor shaft spinning in the plastic clutch.

We were able to bench test the the rest of the system. Blower and fuel pump are spinning freely and I put power to motor and it ran flawlessly. We are ordering the plastic clutch and we will service the nozzle and filter at the same time. Hopefully the $12 plastic clutch will solve my problem. Since the plastic clutch was so cheap I ordered a second one to keep on hand.

Taking the burner apart was very easy with the advice from Rudy and using the service manual. In figure 23. Item #4 is the clutch in question and attached is a picture of the damaged clutch.

We will follow up on the repair and operation after recieving and installing the new clutch.

John M.

Re: Aqua Hot Failed

Reply #1 – December 10, 2019, 10:40:05 pm

Good job on DIY repair. I'm sure Rudy's expert technical guidance was a big help. Good thing he doesn't charge for "Service Calls".

Re: Aqua Hot Failed

Reply #2 – December 10, 2019, 11:00:12 pm

John, Take several pictures of where the wires go.

Take from different angles. I always wish I took more than I do.

Re: Aqua Hot Failed

Reply #3 – December 11, 2019, 12:59:45 am

John, I had a post about adding a 4 connector plug to the wires going to the thermostats and a single plug for the red wire going to the bay thermostat. Now might be a good time to add them. Makes the next time pulling the burner easy.

Re: Aqua Hot Failed

Reply #4 – December 11, 2019, 08:35:01 am

Thinking about it...kinda strange failure mode. Plastic parts like that are usually designed to be a "weak link" sacrificial item. The plastic drive gear/drive cog is supposed to break before more expensive bits come apart. Same basic principle as the plastic motor drive cogs on old clothes washing machines. I've replaced a bunch of those...

But, you have already determined that the motor, blower and fuel pump are turning freely, so I just have to wonder why the plastic piece failed...?

Re: Aqua Hot Failed

Reply #5 – December 11, 2019, 09:08:25 am

Quote from: John Morales – December 10, 2019, 10:30:20 pm

Item #4 is the clutch in question and attached is a picture of the damaged clutch.

We will follow up on the repair and operation after recieving and installing the new clutch.

John M.

The ~~clutch~~ is properly called a high misalignment coupling.
And sometimes an injection molded plastic part just fails.
Nice job!

Re: Aqua Hot Failed

Reply #6 – December 11, 2019, 09:09:00 am

Quote from: craneman – December 11, 2019, 12:59:45 am

John, I had a post about adding a 4 connector plug to the wires going to the thermostats and a single plug for the red wire going to the bay thermostat. Now might be a good time to add them. Makes the next time pulling the burner easy.

Link to craneman's post Aqua Hot plug addition. A previous owner had already installed a connector on the red wire on mine. I will consider installing the other connector the next time I have to service it.

I add my praise for Rudy who gave me phone diagnostics and service support too. It was blowing a lot of while smoke and would cycle off after about 15 minutes. Even blew two fuses. Re-seated the nozzle per Rudy's instruction, cleaned the chambers and re-installed. Also replaced the clamp on the fuel line as it was leaking some fuel. Ran it for over an hour with no issues and no visible exhaust.

Re: Aqua Hot Failed

Reply #7 – December 11, 2019, 09:45:24 am

The red wire coming from the harness to the C-plug of the Control Unit and going to the pump connection on the load side of the middle clear relay is called the "Diode Wire". This wire is energized any time the burner motor is running. It turns on the number 2, middle, pump to stir the coolant tank during heating of the coolant tank by the burner.

But, this wire is also energized anytime the bathroom thermostat calls for interior heating. Without the diode, the bathroom call for heat would back feed the control unit, not a good thing. So bravo for the diode wire doing its thing.

I too, put a disconnect on the diode wire to make moving the burner into a workable position doable.

Re: Aqua Hot Failed

Reply #8 – December 11, 2019, 10:27:04 am

Quote from: Old Toolmaker – December 11, 2019, 09:08:25 am

The ~~clutch~~ is properly called a high misalignment coupling.
And sometimes an injection molded plastic part just fails.
Nice job!

We used a lot of these when I worked in an industrial setting--and yes they break down over time. when you consider that most of the coaches on the forum are 20years old or over, I am surprised we haven't seen more of these break.

John, where did you order your part from?

Chris

Re: Aqua Hot Failed

Reply #9 – December 11, 2019, 10:35:24 am

Where do you purchase a four connector plug? Sounds like something I want to do.
Put it on the "list!"

Re: Aqua Hot Failed

Reply #10 – December 11, 2019, 10:52:18 am

Quote from: GleamB – December 11, 2019, 10:35:24 am

Where do you purchase a four connector plug? Sounds like something I want to do.
Put it on the "list!"

A couple years ago, I purchased connectors, pins and the crimping tool from a motorcycle shop in NY. Great service and prices...especially for the Toyoto fuel injector connectors. I will try to find that website, but you can probably use a kit like this one Connector Kit. You will also need a crimping tool to install the pins.

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Re: Aqua Hot Failed

Reply #11 – December 11, 2019, 11:45:22 am

Chris,
I bought the clutch through Roger Berke at RV Hydronic Heater Repair. I posted in my original post $14, but they are $12.
John M.

Clutch, Half, 6MM

Re: Aqua Hot Failed

Reply #12 – December 11, 2019, 12:19:49 pm

Quote from: GleamB – December 11, 2019, 10:35:24 am

Where do you purchase a four connector plug? Sounds like something I want to do.
Put it on the "list!"

Glen,
I just used an RV flat 4 trailer light connector extension I had laying around. Just cut the extension in half and labeled the plug with the corresponding wire colors. I'm going to strip, soldered and shrink wrapped the wires to eliminate the use of bulky butt connectors in the harness. I'm going to use a Bullet Butt connector on the individual red diode wire. If you wanted to, you can use Bullet Butt connectors on all of the wires. You can purchase a pack of assorted colors and use a different color for each wire. They work great. They have them on Amazon.
John M.

Amazon.com: Bullet Butt Connectors, Sopoby 100pcs Assorted Insulated Female... mlm

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Re: Aqua Hot Failed

Reply #13 – December 11, 2019, 12:23:13 pm

Quote from: GleamB – December 11, 2019, 10:35:24 am

Where do you purchase a four connector plug? Sounds like something I want to do.
Put it on the "list!"

This is what I used.

Amazon.com: Cable Matters 2-Pack ATX Power Supply 4-Pin CPU Male to Female...

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Re: Aqua Hot Failed

Reply #14 – December 11, 2019, 12:48:12 pm

Quote from: GleamB – December 11, 2019, 10:35:24 am

Where do you purchase a four connector plug? Sounds like something I want to do.
Put it on the "list!"

Knock your self out. One of the connector names you want to know is Molex. And yes, you should buy the crimping tool and the pin removal tool.

Molex Pin & Socket Connectors | Mouser

Art

Re: Aqua Hot Failed

Reply #15 – December 11, 2019, 05:53:41 pm

Chuck what are the wire sizes on your plugs?
Chris

Re: Aqua Hot Failed

Reply #16 – December 11, 2019, 06:53:46 pm

Chris,
If you scroll down towards the bottom of the link page it says it's 18 AWG.
John M.

Re: Aqua Hot Failed

Reply #17 – December 11, 2019, 07:05:19 pm

Quote from: Chris m lang – December 11, 2019, 05:53:41 pm

Chuck what are the wire sizes on your plugs?
Chris

John gave it,
They carry 80 watts have had no problem since installing. Wires looked the same size as the thermostat wires

Re: Aqua Hot Failed

Reply #18 – December 11, 2019, 09:00:38 pm

Thanks for the info John. Glad to hear it worked out.
When Rudy serviced our AH I remember a red wire. Will look at it tomorrow when we get to the coach.

Re: Aqua Hot Failed

Reply #19 – December 12, 2019, 08:24:12 am

thanks guys
Chris

Re: Aqua Hot Failed

Reply #20 – December 16, 2019, 09:53:05 pm

Well I recieved the new clutch and I was able to finish the Aqua Hot and it runs great! The material of the new clutch is different from the old one. Maybe a better material. Working on the burner was pretty easy and not rocket science. If you are handy you can do whatever needs to be done. My main advice is to take pictures and label everything. Nowadays I try not to rely on my memory to put things back together and with digital phones it is easy to document everything.

It is easier to work on the burner in the shop, especially if your aqua hot is in what I call, the belly of the whale. When working on my aqua hot I always remove the three zone relays and clips and set them aside. It never fails, I always bump them while working on the burner and knock the off.

To remove the burner you will need to unplug the connectors from the control box, slide the control box from the burner, disconnect the fuel lines and cut 5 wires. Make sure you power down all ac and dc power to the aqua hot and cut each wire separately. There is a harness that comes off of the burner and you need to cut the white, light blue, orange and purple wires. Then you will need to cut the individual red diode wire. Loosen the mounting bolts and take the burner into your shop.

To aid in the assembly I used a click style center punch to mark the correct index location of each section before taking it a part. I marked the outside cover, motor base, blower housing and fuel pump section. While waiting for parts I seperated the fuel pump section from the blower and I cleaned and greased the pump shaft gear and the blower drive gear and checked the blower bearings. I used a heat and freeze resistant grease on the gears. Carefully assemble the pump section and mate the shaft gear with the blower gear. They should fall right into place. The gear on blower is plastic. You can lightly spin the blower while mating the two sections together and they should fall into place.

When putting things back together use the witness marks you punched to align each section and remember that everything is aluminum so don't overtighten the screws. You are working in inch pounds not foot pounds. Before replacing the case you can spin everything to make sure it is all spinning freely. You can also power the drive motor by applying power to the brown and black leads. I used my drill battery to power everything and it all spun perfectly.

Whenever replacing the burner case you should also replace the large o'ring that seals the case. You will also need to make sure you replace the case to the correct index and align the case screw holes. You may need to compress the o'ring in order to get the case screws in. I used my center punch in the case mounting holes to pry on the case while pushing on the backend of the case. You will hear it go into place and the holes will line up. Replace the nozzle while you have the burner on the bench and check the igniter electrode alignment with the alignment tool.

Before installing the burner I installed a 4 pin connector on the 4 wires and a bullet butt connector on the red diode wire. I also installed the mating half of the connectors in the aqua hot compartment. Just make sure all of the wires are in the correct alignment on the connectors. I soldered and shrink wrapped all of my wire connections. Install burner reconnect all fuel lines and electrical connections and fire up the unit.

I was able to successfully accomplish the job with the help of Rudy, the Aqua Hot Service Manual and a Youtube video of a guy rebuilding his Aqua Hot Burner because his fuel pump was leaking. The video was very helpful. It was nice to see how it all comes a part and he had a lot of great advice and information. Here is the link to the video.

https://youtu.be/eVsvDgRhRk4

Attached are pictures of what I did. Hope this helps the next person.

John M.

Re: Aqua Hot Failed

Reply #21 – December 16, 2019, 11:15:59 pm

John, That is a very good write up.

Re: Aqua Hot Failed

Reply #22 – December 17, 2019, 08:35:45 am

John, excellent job and write up. I have to remove my AH this winter to do some work on it so I'm sure this will help not only myself but many others in the years to come.

Thanks,
Larry

Re: Aqua Hot Failed

Reply #23 – December 17, 2019, 10:08:18 pm

John as always a great write up from you. Hope that I don't have to do it but if I do I know where to refer to. Thanks for the pictures, always helps, alot!
👍

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