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Aqua Hot motor surging

October 08, 2012, 08:48:31 pm

When my aquahot goes into the cool down mode the motor makes a surging sound.  It does not seem to do it with the burner lit but if it is I cannot hear it over the roar of the flame.  Anyone have this happen? Remedies? Thanks, David

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Re: Aqua Hot motor surging

Reply #1 – October 08, 2012, 09:28:22 pm

David,

The Control Unit, the brain box, should start the blower for a 20 or 30 second start up purge.  At the end of this purge, the fire should ignite and burn with a smooth even rumble.  When the control thermostat reaches set temp or the Diesel On/Off switch is turned off, the Control Unit stops the flame and starts a 2 or 3 minute shut down purge.  All during this time the blower runs at a smooth even sound.  At the end of the shut down purge, like a light switch, the blower abruptly stops.

Having said all this, if at the end of the shut down purge, the blower begins to surge or no longer runs at an even smooth sound, the Control Unit is failing.  If one has his ear near the Control Unit, many times the surging is accompanied with a clicking sound from the box.  The burner may eventually stop but not abruptly like it is suppose to.

Does this describe the operation of your burner?

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Re: Aqua Hot motor surging

Reply #2 – October 09, 2012, 11:37:56 am

Rudy, That sounds exactly like my symptoms.  I have yet to remove the cover and listen for clicking, but I will and post results.  Thank you, David

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Re: Aqua Hot motor surging

Reply #3 – October 10, 2012, 11:01:52 am

The unit is now not even running a cool down.  I have shut the unit down as I don not want to overheat anything.  Do you think I need to order a new control board?  Thank you,  David

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Re: Aqua Hot motor surging

Reply #4 – October 10, 2012, 03:41:15 pm

David,

Yes Sir, I believe it is time to replace your control unit.

The best place to order an new control unit is from Roger Berke at roger.berke@gmail.com.

Roger's on-line order for a control unit is Control Box - Webasto 12-Volt

Till the replacement gets there you can run the burner till it cycles off and goes into the never ending cool down purge.  Just be there and after two minutes of cool down disconnect the power.

I do this by pulling the smaller "B" plug from the control unit.  When it stops, you can replace the plug and the control unit resets itself till the next time it is allowed to run.

So if you plug the "B" plug back in - turn the diesel burner switch to OFF so it will not start till you want it to and you will be there to shut it down manually again.  But you will have hot water till the replacement arrives.

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Re: Aqua Hot motor surging

Reply #5 – October 10, 2012, 05:13:37 pm

Snip: [The best place to order an new control unit is from Roger Berke at roger.berke@gmail.com.]

I agree with Rudy; talking to Roger Berke is a great idea. Regards the replacement control unit you also might benefit from talking with Jim Frerichs at Frerichs Electronics about a overhauled/tested replacement control. The price is right and the reliability also; I've been using one for several years since Roger installed it.

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Re: Aqua Hot motor surging

Reply #6 – October 14, 2012, 03:23:47 pm

Well, with very quick shipping, Jim Frerichs saved the day sent me a rebuilt control unit and volla my aqua hot is up and running as engineered.  Thank you Jim and all others that assisted me.  David

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