Aqua-hot burner not starting after Racor Filter change.

[Mike Sulley]

As some of you may remember, my Aqua-hot quit working on our last trip of the season.  We found the Aqua-hot system very low of boiler fluid.  Eventually found connections leaking on forward most heat exchanger connections. Tightened.   Refilled system with 6- 8 gallons of boiler fluid.

Since I had not preformed an annual maintenance, I replaced the Racor filter and the burner nozzle.  The Racor filter would not gravity refill,  so I attempted to fill the filter by installing a primer bulb on the outlet of the filter and was able to fill the visual filter bowl and out flow line.  Removed the primer bulb and reconnected line to the diesel manifold.  Attempted to restart the burner but no luck.

I loosened to the Banjo bolts on the burner fill and return lines.  No diesel!  Can someone enlighten me on the correct filter priming method?  Without a dedicated pump from the main diesel tank, I assume one must rely on initiating a siphon thru the Racor and burner lines.  Once the burner lines are full, can I apply 12 volts to the burner pump to establish circulation back to the system?

Going forward, am I better off replacing the Racor with a spin-on filter element?  The guys in the videos never seem to have this problem.

I thank you in advance for your responses.

Respectfully,
Mike Sulley

2001 Beaver Marquis Amethyst

[Eric Maclean Co-Admin]

Mike
The Aqua hot has a gear pump in it that during the purge cycle is constantly pumping fuel through the system and back to the fuel tank via the return line .
In this system everything between the burner and the tank is on the suction side of the pump which means any small leaks in the fuel line or filter will allow the pump to suck air rather than fuel .
If this is a result of a fuel filter change that is the first place to look . In that raycor filter there should be to O rings one on the outer ring of the filter and a second on the threaded portion of the base .if there inner one on the threaded portion is missing or has two O rings on it the filter will not seal properly and the system will suck air .
Another thing to look at is the supply fuel lines if they have become dry rotted with age and are full of cracks they call cause the same problem.
If the fuel tank is below 1/4 tank the fuel pickup for the Aquahots may not be in the fuel anymore this is set up to keep you from running the coach engine out of fuel.
If the tank is lower than half a tank a dry gear pump may not be able to lift the fuel from the tank and may require you to prime the system.

Use your squeeze bulb primer but this time connect to the return line and suck fuel through the burner assembly then reconnect the lines and cycle the burner it should light but it may have to be cycled  two or three times to allow the pump to move fuel around the system and build pressure.

It is best to do your Aquahot filter with a near full tank of fuel.

Eric

[Mike Sulley]

Eric,  Thank you so much for your response.  Very helpful.

My tank is full.  I have replaced all the diesel lines except for the one from the tank to the filter.  As I understand,  I would have to drop the tank in order to access the top of the tank to replace that line.  The line is hard but no apparent cracks.

I will do as you suggest.  Installing the primer bulb in the burner return line and see if I can prime the system.  If no success, I will look into the filter itself for leaks.  I kept the Racor housing and replaced the filter and clear plastic bowl as a unit.

My Aqua-Hot is a very early model AHE 100-01S ( sr # 01-047).  So I do not have all function controls of the later models.  I believe the only way to cycle the burner is to turn on the thermostats in the coach.  Do you know if I can cycle the burner by applying 12 volts to the control board itself?  Perhaps after disconnecting the ignition wires.  Or perhaps by applying 12 volts to the burner pump.  I see that it has +and - ( ground) designations on the pump.

One other question.  The only manual that I can find is for a model AHE 100-02S.  I purchased an Aqua-hot pressure gauge to be installed in place to the nozzle.  But I do not see a pressure adjustment screw on my pump.

Once again, I appreciate all your ideas and guidance.

Respectfully,
Mike Sulley

[Eric Maclean Co-Admin]

Mike
On the early systems you will something Aqua Hot switch in the kitchen this switch turns on the diesel boiler powering up the control board two things have to happen to make the boiler burner operate first the thermostat has to be set at a temperature requiring heat second the boiler temperature has to be below the thermostat cutting switch on the boiler this won't happen if the boiler electric element is turned on or working as the thermostat for the electric element is set at 190° whereas the cutout for the diesel boiler is set at 180°. Therefore the system will work on electric with the diesel turned on the diesel will not work until the temperature drops below approximately 160° and then cuts off at 180 when the boiler has brought it up . The theory here is that with both the electric and the diesel turned on the diesel only operate when the electric cannot keep up.
To test your diesel operation with a cold boiler set the thermostat above the temperature it is inside the coach and turn on the kitchen switch the switch should light up telling you that the board is live at this point the temperature in the boiler should be below the cutting point of the diesel thermostat on the boiler once this is achieved the control board will try to run the boiler diesel burner. By first going through a purge cycle and then an ignition cycle with fuel if the photo cell does not see light from an ignition or burn the controller will shut down the fuel and go back through a pericycle before shutting off.

The pump that pumps the diesel fuel through the boiler is driven by the main motor in the burner it is the same motor that drives the blower so if you hear the scream of the blower the diesel gear pump should be pumping , in order to do the pressure test the nozzle must be removed and the gauge installed but without the specialty electric controller tool to allow you to run the boiler without the ignition you will have to disconnect the wires going to the ignition coil located under the ignition coil  they are the smaller wires not the high tension leads ,now to do the test install the gauge , disconnect  the ignition coil primary wires and activated the kitchen  boiler switch the burner will start to run however there should be little or no pressure showing on the gauge until the controller has completed the purge cycle approx 2 minutes after that time the controller will activate the diesel solenoid which allows high pressure fuel to be delivered to the nozzle or in this case the gauge then watch the gauge there will be a small flat headed screw on the side of the gear pump below one of the fuel line banjo housings that is the adjustment for the fuel pressure. If you look up the manual for any of the Aqua Hot 100 series units you will find they are using a DBW 2010 wabasto burner any one of the manuals will walk you through the adjustment of the fuel pressure 145 PSI .   the pump is not electric the pump that you are looking at that is electric is the circulation pump that circulates the hot boiler fluid to each of the radiators in the coach.

https://acrobat.adobe.com/id/urn:aaid:sc:VA6C2:181eaee0-3cf9-480b-ba36-2d917bc6ec56


Hope this helps

[Mike Sulley]

Eric,

I really appreciate your patience.  You have been more than kind with your time and sharing your knowledge.

The diesel fill and return lines are in a "pile of snakes" that disappear thru the wall behind the Aqua-Hot.  So I was confused.  If I am understanding correctly, the diesel system is like the fuel injection system on your car.  The fuel is pulled from the coach main tank, thru the filter and burner, and then returned to the main tank.  I only see the line coming from the tank.  The return line is buried in the pile of snakes.  So I will install my primer bulb in the return line from the burner to the manifold.  I don't want to cut into the tank return line.  I can't even see it.

Once I have the burner lines full, I will try to restart the burner.  The only "Kitchen switch" (burner control) I have found is the on/off switch on the thermostat switch located on the glass cabinet.  I do not have the burner monitoring panel " Aqua-Hot by Vehicle systems" shown on Figure 4 page 12 or Figure C4 on page 84 of the AHE-100-02S manual.  The only feedback I get is the fans coming on behind the coach heat exchangers.  Then to wait and see if it gets warm.  Or I can go listen to the scream of the burner blower.

If the burner doesn't ignite, then I will follow the "Burner Controller Component Test" on page 68 in the above referenced manual.  Checking DC voltages on the B and C plugs.

Thanks again Eric,

Mike Sulley

[David T. Richelderfer]

I can tell if our AquaHot ignites by seeing its exhaust (usually a bit white until it warms up, then clearing) through the rear-facing streetside dining room window. I can also run outside, on the streetside, and feel the exhaust. If it's a warm/hot exhaust, then it's burning diesel. With interior audio components off, I can hear the burner operating.  Ours is an 02S.

[Steve Huber]

Mike,
The "kitchen" switch Eric is referring to is located in  the panel just below the kitchen sink (usually on the left side of it). Most have 3 switches: Diesel, Electric, Preheat. For your testing you want to select Diesel.
Steve

[Mike Sulley]

Hello David and Steve,

 I thank you for trying help me out and add to my knowledge.  When I bought the coach a couple years ago, we received no explanations about the Aqua-Hot and what manuals we received were scattered everywhere.

David for first several outings with our "new" coach over two seasons, every time I started the coach engine,  I would always see the gray exhaust of the Aqua-Hot firing up.  I never had to do anything.  I always attributed this to the main thermostat on the cabinet above the couch being switched on.  I never turned it off.

Steve my wife tells me there is a single switch under the sink on the left behind the waste basket.  She thought it might have to do with the instant hot water fixture on the counter top next to the sink.  But the switch didn't seem to have any effect.  We never got any hot water out of it.  So she turned it off.  Evidently, that was about the time of our last trip of the season.  And curiously, we had no heat.  She just brought this to my attention after reading Eric's comment about the "kitchen switch".  Note we have always had hot water from the AH.  I turned it off with the breaker in the box on the back wall of the bedroom when I started trouble shooting the diesel fired AH.

It would really be helpful to find a manual for "our" AHE 100-01S Aqua-Hot system.  The 100-02S manual is the only one I have ever found.  I have never looked in the Beaver Forums Manual library.  The security sign on requirement has always intimidated me.  I did call AH in Colorado and they could only provide with the 100-02S manual.

I am still waiting for my 5/16" primer bulb.  Once it arrives, I will temperarily cut it into the diesel return line and circulate diesel thru the system back into the supply tank.  Then go from there.

Once again, thank you so much for your reply's.

Mike Sulley
 

[Gene Obie]

You should be able to find the manual for your unit here --> https://heatmyrv.com/pages/resources__manuals?

It's seems 01 and 02 are the same manual.

[Steve Huber]

Mike,
The switches I was referring to are not under the sink by the waste basket. They are on the cabinet panel in front and just below  the sink. Poor choice of words on my part. See figure 2 on page 4 on  this link for a picture of the switch panel. https://cdn.shopify.com/s/files/1/0851/3182/1360/files/AHE-100-03SAqua-HotOwnersManual09-03.pdf?v=1704856391
Coach Assist has links to the 01S service manual and as Gene noted the op manual for the 01S and 02 S is the same so your manual should be accurate.
If you are having issues accessing our documentation let us know and we can step you through the process as needed.
Steve

[Eric Maclean Co-Admin]

Mike
Does your coach have a water pump switch located  near the sink in the kitchen and if so is there not a switch right beside it marked water heater?
If so that water heater switch is the Aqua hot diesel control switch.

In the coach assist library the closest thing to an Aquahot wiring diagram is in the 1996 Patriot wiring diagram section ( second to last page)

[Mike Sulley]

Gentlemen:

Well I found the elusive Kitchen switch.  It was on the underside of the overhead cabinet with the coach monitor.  At the far end near the refrigerator.  Recall seeing it, but its function escaped me.  It is sort of similar to switch in the 100-02S manual, but it only has two functions-diesel and engine preheat.  No fancy green and orange lites.

So I cleaned off the carbon on the ignitors and repositioned them to the nozzle.  And reassembled the burner.  The burner fired immediately upon flipping the diesel switch and We Had Heat!!  Let it run for a while and circulated all the air out of the lines.

Wish to thank all you gentlemen for all your help.  It's been a long learning journey from finding the leaking connection to performing the yearly burner maintenance.   I have learned a lot.  In the future I will not be so intimidated by the mention of Aqua-Hot.

Again, thank you all!!

Respectfully,
Mike Sulley

[Dan Johnson]

Glad you found the switch. Sorry I missed your problem  because that is where mine is also. You got to stand on your head to read what the switch is for.  Another issue is the heater in the water bay. It is controlled by a button thermostat. It is hot all the time regardless whether the aqua hot is turned on. When the temp gets below the trigger temp it turns on the stir pump.  Not any more as I added a switch before the button thermostat

[Eric Maclean Co-Admin]

Good work Mike
As you become familiar with the systems in your coach things get easier to understand and troubleshoot.

Happy travels and hot water.
Eric