Aquahot shuts down after ignition

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Aquahot shuts down after ignition

March 24, 2021, 01:30:13 pm

Trying to get aquahot running. Just replaced fuel lines no air that i can see in filter. Starts right up, clean exhaust, runs great for maybe minute or minute and a half then shuts down. Exhaust clean at start and stop. Where do I start?

Re: Aquahot shuts down after ignition

Reply #1 – March 24, 2021, 06:01:27 pm

Replaced nozzle with spare. Flame sensor was black, cleaned and will ohm test tomorrow. Will also try to clean burn pot tomorrow. Any tips or suggestions to look at while apart. Printed 105 page service manual from internet. Will look over tonight. Any tips or tricks appreciated

Re: Aquahot shuts down after ignition

Reply #2 – March 24, 2021, 07:21:53 pm

I would suspect a crimped fuel line if it worked before changing the lines. It can be either one of the lines. Been there done that.

Re: Aquahot shuts down after ignition

Reply #3 – March 24, 2021, 07:23:31 pm

While bunner is out and flame sensor is clean, disconnect it from the harness paying attention that the green wire to the sensor is plugged into a green wire in the harness. Connect your Ohm meter to each plug and measure the resistance.

In bright light of a flashlight, the resistance should be less than 200 ohms. The dark, the resistance should be very many meg-ohms or even OL (0pen line). If it fails either test, replace.

Let know what you find.

And, I agree with Red Tractor

Re: Aquahot shuts down after ignition

Reply #4 – March 24, 2021, 07:39:47 pm

Is the coolant full to the lip on the main unit?

Re: Aquahot shuts down after ignition

Reply #5 – March 24, 2021, 08:38:45 pm

Did not work before fuel lines. I fired it up it blew cloud of black smoke ran for minute or so then stopped. Examined fuel lines and dry with lots of cracking. It was final motivation for changing fuel lines. Before starting pulled several gallons fuel from main tank with pump connected to supply line at AH unit. Most air was gone. Dont think lines pinched. Fought that battle many times trying to get fuel tank back in. ROYAL PIA! I think flame sensor was sooted up and couldn't detect burn. Will check ohm tomorrow. Would like to check burn pot not sure how. How is the best way to tighten down back bolt to secure burner. It didn't seem tight enough to me. Almost finger tight. Could it have not been tight enough and burner was sucking air

Re: Aquahot shuts down after ignition

Reply #6 – March 24, 2021, 09:45:18 pm

"Could it have not been tight enough and burner was sucking air".

I use 10" extension and yes if not tight enough it will suck air and grey smoke comes out the exhaust. (Ask me how I know). Black smoke is caused by fuel not burning You then need to pull out burner tube and clean out the soot.

Re: Aquahot shuts down after ignition

Reply #7 – March 24, 2021, 10:05:18 pm

Just be carful to NOT over tighten that nut!

Re: Aquahot shuts down after ignition

Reply #8 – March 25, 2021, 12:56:58 am

The torque on that nut is measured in in-pounds. If you over-tighten, the "J" bolt will break and it is a pain to replace.

Also make sure you don't catch the wires between the burner and the combustion chamber. It will blow black smoke into the storage bay and you have to take it apart again.

I was told to leave the stainless cover over the burner area at home. Apparently there is a lot of heat trapped around the parts, which is not good for the stuff there

Re: Aquahot shuts down after ignition

Reply #9 – March 25, 2021, 07:32:12 am

Quote from: stevec22 – March 25, 2021, 12:56:58 am

.

I was told to leave the stainless cover over the burner area at home. Apparently there is a lot of heat trapped around the parts, which is not good for the stuff there

Just curious if Rudy recommends this? I know if the AH is running that bay gets toasty.

Re: Aquahot shuts down after ignition

Reply #10 – March 25, 2021, 07:50:57 am

I have left mine off for the last 2 years per Rudy-- the control box has problems when too much heat
Chris

Re: Aquahot shuts down after ignition

Reply #11 – March 25, 2021, 11:25:04 am

Quote from: Chris m lang – March 25, 2021, 07:50:57 am

I have left mine off for the last 2 years per Rudy-- the control box has problems when too much heat
Chris

Ive bought a new control box, sounds like I better get mine off! Those things are expensive!

Re: Aquahot shuts down after ignition

Reply #12 – March 25, 2021, 11:32:31 am

Tommy, if you have the new one with the pig tails check with Rudy they might not be heat sensitive as they are solid state no contacts.

Re: Aquahot shuts down after ignition

Reply #13 – March 25, 2021, 11:36:02 am

I bought my solid state from Rudy. He told me to remove the cover. It's been at home for two years, now.

Re: Aquahot shuts down after ignition

Reply #14 – March 25, 2021, 11:45:02 am

Our cover has been off for over 2 years as well, per Rudy! Also, just a tip for those of us who had cracking fuel lines, especially to the Aqua Hot. I cut the bad ends off and secured them back with a hose clamp. Just the supply line, not the return. Easy to do and the short lines inside of the box, I just replaced them with new. Works like a charm now. Oh, I also installed another Racor filter inside of the AH box to further filter the fuel. When we had issues with the AH originally, I found the cracked lines, so ran a new line from the supply inside of the bay to the main fuel tank. Took a clean rag and stuffed it around the hose to allow the AH to work. When we traveled, I pulled the fuel hose out and installed the cap again. You gotta do what you gotta do when in freezing temps! Now, all lines hooked back up and working great! We will get our fuel lines changed out sometime next year when we get back to civilization. Being full time has it's perks and issues.

Re: Aquahot shuts down after ignition

Reply #15 – March 25, 2021, 12:40:59 pm

Quote from: Tommy D – March 25, 2021, 07:32:12 am

Just curious if Rudy recommends this?

Yes he does, I've rode with him on many service calls and hear him say it every time. Rudy does not like covers on anything...

Re: Aquahot shuts down after ignition

Reply #16 – March 25, 2021, 01:52:41 pm

The cover and other pretty panels make things in the basement look finished. You have to remove and replace to check on anything like fuses. They do not add to or take away from heater operation. Plus the heat gets into the compartments away from the control unit making its environment better for an electronic device.

If I want my basement to look good, I close the door.

Re: Aquahot shuts down after ignition

Reply #17 – March 25, 2021, 02:03:26 pm

I too removed my AH cover per Rudy's recommendation but observe my inverter cooling fans constantly running (even when inverter not being used during the winter). Rudy are AH's burner control unit module "extender pigtails" available such that the AH cover can be installed and the AH module be somehow mounted outside the AH enclosure? I have not traveled during the summer with the AH cover off and the inverter running but think it might get toasty enclosed in the bay when traveling west this summer. Looking for some expert advice Mr. Rudy when also factoring in the other electronics in the coach bay.

Re: Aquahot shuts down after ignition

Reply #18 – March 25, 2021, 03:06:58 pm

Feeling pretty stupid. How do I remove burn chamber to clean

Re: Aquahot shuts down after ignition

Reply #19 – March 25, 2021, 03:20:57 pm

You have to move the burner/ignitor out of the way and it just pulls out

the burner tub is on page 12 and I believe it just pulls out then clean with brake cleaner and wire brush

Re: Aquahot shuts down after ignition

Reply #20 – March 25, 2021, 03:23:11 pm

Pull pump back out like you did for nozzle replacement then reach in to chamber and pull put burn chamber- I was told the seam needed to be on top when going back in. You might check to see how yours is oriented, once out take a steel brush and clean the ribs inside the outer chamber.
Chris

Re: Aquahot shuts down after ignition

Reply #21 – March 25, 2021, 04:06:37 pm

You may have to use a thin screwdriver to get the burn chamber started if it has been a long time since it was cleaned. Use a light touch and be careful. Replacement chamber/swirlers are a couple hundred dollars

A long handled wire brush helps when cleaning the actual sides of the burner chamber. There will be a lot of black soot. It will blow out the exhaust when you start the AH back up

Re: Aquahot shuts down after ignition

Reply #22 – March 25, 2021, 08:28:48 pm

Needed screwdriver to persuade burn chamber to release. Cleaned everything up and put back together. Flame sensor was black. Fired up, burned clean blew out chamber carbon. Believe loose bolt on burner and leaking fuel lines caused carbon buildup. Seems good. Must say i was a bit surprised by how loud it is when running. Dont know if its pump or fan but its whatever it is that runs after burner shuts off and completes the cycle. I would think it may be a blower or circulator. Is this to be expected? At least its not as bad as the dash blower fan was

Re: Aquahot shuts down after ignition

Reply #23 – March 25, 2021, 08:45:38 pm

Spiderhitch, it is fairly loud when you are in the bay next to it and that is normal at least for mine. I just finished going through my
blower and burner. Replaces the bearings on the blower, I had noticed a couple of hard stops and then when I got in the bay while it was running it sounded like the rpm was changing it wasn't a constant smooth run like it had been. So I pulled the unit out and replaced the bearings SKF 608 zz , check fuel pressure, replaced nozzle, checked spray pattern, cleaned combustion chamber and swirler then put back together. I've ran it yesterday and again today --starts up smooth and winds down smooth--
One more project finished!!!
Chris

Re: Aquahot shuts down after ignition

Reply #24 – March 25, 2021, 09:22:39 pm

My learning curve is still still very steep. Great feeling as projects get completed successfully. Thanks to all for advice, knowledge, patience and encouragement.

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