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Aquahot issue on 03 U320 - could it be the fuel filter?

October 28, 2020, 03:47:29 pm

Our aqua hot has not been working properly for the past week.

We have replaced the aqua hot nozzle, cleaned the exhaust, the photosensor, and the electrodes, but we have not changed the fuel filter.  We have a replacement fuel filter on order from Foretravel, but it has not yet arrived.  As soon as it does, we'll install it.  Not sure when it was last changed.  We paid to have the aqua hot serviced 12 months ago, but it doesn't look like they changed the filter.

When we turn on the aqua hot on diesel the light comes on, but it goes out after a few seconds.  The whirring sound spins up and down like it's trying to purge, but the sound never stops and we have to switch off the master power to get it to stop. 

Is it likely our issue will be resolved by changing the fuel filter, or does it sound like another issue?  If you think we have another issue we'd like to attempt to fix it while we wait for the fuel filter to arrive.  If you think it's likely the fuel filter, we'll hold off on troubleshooting further.

Does anyone have the specs on the spacing of the electrodes?  Is this something that needs to be exact?

Thanks in advance!

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Re: Aquahot issue on 03 U320 - could it be the fuel filter?

Reply #1 – October 28, 2020, 04:20:07 pm

For the electrodes there should be a stainless sheet metal gauge attached by a screw to the burner case.  You use this to set the electrodes.
For the other stuff it could also be the control box going bad.  There is a way to jumper wires so that the burner works.
Best bet is to always give Rudy a call.  I'll pm you his phone #.  He's the aquahot guru!

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Re: Aquahot issue on 03 U320 - could it be the fuel filter?

Reply #2 – October 28, 2020, 04:22:19 pm

On my original set up, the fuel filter looked like a cheap lawn mower filter that can be bought at any auto parts store, Walmart etc. It shouldn't be 5 bucks +/-. The spacing on the electrodes is important. Did you use the spacing tool which is mounted on the side of the burner? I didn't the first time. Didn't notice it even though I had my hands all over it. It ran as was, but smoked somewhat. When I redid the AH this spring, Rudy told me where to look for the spacing gauge and right there it was all the time. Used it and the unit fired right up and no more smoke.
Cant say for sure if this is your problem, but the filters should be local and cheap, and the gauge should be bolted to the side of the burner.
Hope this helps.

Larry

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Re: Aquahot issue on 03 U320 - could it be the fuel filter?

Reply #3 – October 28, 2020, 05:45:44 pm

Thanks, everyone for the suggestions & help!  We adjusted the electrode gap but that didn't solve the issue.  We called Rudy (thanks for the referral).  Rudy said that the aquahot should one make sound only (on or off) and the sound we are hearing (whirring up and then down) is indicative of a failing control unit.  He was able to put a replacement control unit in the mail for us today so we should have it tomorrow.  Hopefully, that will resolve the issue.  Thanks again everyone!

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Re: Aquahot issue on 03 U320 - could it be the fuel filter? SOLVED

Reply #4 – November 05, 2020, 01:40:57 pm

The control unit arrived and we installed it, but it didn't solve our problem.  Called Rudy again and tested the thermostat (working) and the ignition coil (not working).  Rudy shipped us out a replacement ignition coil.  We installed it and everything is working great now.  The aqua hot starts up properly and so far the whirring up and down noise has gone. 

Thanks again for the referral to Rudy.  He was fantastic to work with.  I highly recommend him if you need help troubleshooting your aqua hot.

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Re: Aquahot issue on 03 U320 - could it be the fuel filter?

Reply #5 – November 05, 2020, 01:46:27 pm

Rudy is da man!

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