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AquaHot Noise

August 18, 2015, 11:18:42 am

This is a "newbie" question, but we'll appreciate any insights.

It's summertime and we are parked at a 50 amp site. So we keep our AquaHot on the "115VAC" setting. However, we exercise the "Diesel" setting every 30 days for 24 hours.  We were told that if we do not, we risk getting the injector nozzle gummed up.

This month, there seemed to be more noise when running AquaHot on diesel — more noise, at least, than we remembered.  We've only owned the coach three months (hence "newbie question"), but we used the system a fair amount while dry camping in cold, rainy conditions in May.  The sound was almost like a small aircraft flying overhead (think Cessna 172 with prop in climb pitch rather than cruise).  Outside, the system was quiet.  Combustion looked good; totally clean/invisible exhaust.  Inside the coach is where the sound was more noticeable.

Could this be a pump?  Anyone had this experience?  Is it possible we're close to failure on some part?  I'm taking the coach to Tennessee RV for some other work next week, so I'd rather have this looked at now than on some cold December night (we're full-timers).  Thanks for any thoughts!

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Re: AquaHot Noise

Reply #1 – August 18, 2015, 12:35:34 pm

Richard,

The plastic clutches that connect the motor to the blower and fuel pump shaft make a high pitched whine normally, some more than others.  So I am not too concerned by your comments.

Sometimes the fuel pump will whine.  But its failure is normally a shaft seal leaking fuel that causes its replacement.

As long as the exhaust is clear, no visible vapor, and not smelly, you are most likely good to go.  You only need a single heating cycle once per month to keep fresh diesel on the nozzle to ward off burner service.  Running for 24 hours is okay but more than necessary.

Having a experienced tech check it out is fine too.

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Re: AquaHot Noise

Reply #2 – August 18, 2015, 02:36:58 pm

AquaHot really isn't difficult to work on for a competent mechanic with the proper manuals however seems like there's not a lot of shops that do quality work on AquaHot. The most tell tale signs of trouble is smoke, uneven running burner, shutdown for no apparent reason or diesel in the bay. I've had two controllers fail over the years and they're ridiculously expensive. They can be repaired, search previous posts for a source. My first coach smoked and melted the air swirler in the combustion chamber due to low air flow, ended up being too much clearance in the air impeller which was an easy adjustment. FOT didn't fix it for the previous owner so he lived with it, I inherited the problem. I've had one fuel pump leak that put a lot of diesel in the bay, don't like hydrocarbons loose in a bay. Had one flame sensor fail causing the unit to shut down immediately after lighting.

Pulling the burner and replacing the nozzle seems to be all some shops do for annual maintenance, not enough.

If you don't understand how the system works don't attempt to work on it, find someone qualified. It can be a fire hazard and there is 120VAC for the electric element.

Never had any problem with the nozzle plugging and I don't change it very often  (3-5 years). It won't plug as long as the fuel is clean, change fuel filters regularly. We rarely park more than a few weeks at time and usually leave the diesel burner turned on. The electric system should maintain a higher temperature than the diesel fired system. The diesel system should only fire when hot water is used and demand increases.

When the fuel pump failed we were in Alaska. I had Rodger Berke ship one to our next stop and I replaced it. Since disassembly was required I went ahead and replaced the bearings and coupling. Webasto recommends replacing the fuel pump every 5 years due to possible fuel leakage from the shaft seal. Mine was 8 years old when it failed. Cost of parts is high especially if it's something from Webasto (makes the mechanical and electronic controls for the diesel system).

I pull the blower assembly every year, the combustion chamber should be clean with minor soot. Inspect the air swirler, motor and fuel pump for condition and leaks, adjust the spark electrodes. If full timing you may want to do this twice a year. Really not much else to do if the system's running well. Read the service manual!, do not over tighten the nuts that hold the Wabasto blower in position.

There's several sources for parts, I've had good service from RV Hydronic Heater Repair - Home and Aqua-Hot Heating Systems for RV, UTV, RTV. If you have a problem call Rodger Berke for advice, he's very reputable. Manuals are available online from AquaHot. There's several highly qualified Techs that make the rounds to RV rallies but they're usually very busy. Failing electronic control modules can be frustrating to diagnose without the proper tool, new controllers are over $800. Paying an experienced guy with the tool could save a lot of time and headache if the problem is erratic.

AquaHot is great when working but a real pain when it quits - limited hot water, really bad news during cold weather.

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Re: AquaHot Noise

Reply #3 – August 18, 2015, 03:57:03 pm

Thank you, Rudy and David, for the quick answers re: the AquaHot.  I'm less concerned now.  We'll keep an eye on it (ear on it?) next monthly cycle.  But the exhaust is clear/no smoke, no visible vapor, burner seemed to run fine (super-hot water), no shutdowns over the 24 hours, and no diesel smell in the bay(s).

Much appreciated.  The Foretravel Forum is first-rate and is one of the reasons we purchased a Foretravel coach.  Good to know, Rudy, that one cycle is enough.  We'll just do that next month.  And David, thanks for the pointers to additional tips and resources. 

Big thanks to you both!

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Re: AquaHot Noise

Reply #4 – August 18, 2015, 04:56:46 pm

And to add, if you get a new controller, save your old and have rebuilt, carry as a spare - $350 vs. $800+ - that is what I did.  had a buddy have his go, I grabbed his old one and gave to JohnS when I saw him a few weeks back.

YMMV - but works for me

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Re: AquaHot Noise

Reply #5 – August 18, 2015, 05:36:31 pm

Richard,

If you are good with your tools, you can service the burner just fine.  There are a few tips that make it go better but nothing a good mechanic can not sort out.

I have had a number of owners hire me to train them to do the service which I am happy to do.  I work myself out of a job that way but they get a thorough hands on look at how to perform the service, why you do what you do and how not to skip any steps (I agree with Tim that lot of shops do).  But again, a good mechanic with a shop manual can do a good job.  It is not rocket science.

I am on the far east side of Houston but travel all over southeast Texas servicing Aqua Hots should you come my way.

Wish you all the best with your Foretravel.  Hope you like yours as much as we do ours.

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