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Aquahot won’t fire


Max95428
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I am having a problem with my Aquahot system again. It has been working and I love it. 02 Monaco Executive, Aquahot model 100 02S 12vdc. I should have started a new thread but I posted it in the last post that someone had the same problem. I will wait and look for comments from that post before I enter all the information in a new post 

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This manual is good. I just finished servicing mine so now works great again. Looks like it needs to be done every year almost. I let mine go a bit until it started puffing smoke. A clean up and new injector did the trick.

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It helps to understand the Aqua Hot like all internal combustion devices needs fuel, air, and a spark to run.  With this in mind run through the troubleshooting steps in the manual.  

The usual suspects are the flame sensor, the ignition coil, or the controller.  

Best of luck!

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With the use of the “holy grail” I checked for continuity of the thermostats. First the 190* start up thermostat for 12vdc. Checks out good. The thermostat that failed is the 198* for the 120v part of the system. Any advice from this new information? Should I replace more than the faulty thermostat, perhaps buy all new thermostats but just replace the faulty one. I have never used the 120v part of the Aquahot system but when it failed I had it connected to shore power via an external generator 

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Did you try to restart the unit? It takes several hours for the side to get hot. In my case i had to jump the blue wire to purple ( 230 dc) bottom left control thermostat for the diesel side to ignite. Your problems sound similar to mine. Aquahot service dept is really helpful. 

Edited by Flyinhy
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Yes I turned the Aquahot switch under the kitchen counter to “on” , light lights up but diesel burner does not light. Every time I have the Aquahot switch in the “on” position and then turn on the bedroom (zone two) thermostat the 15 amp fuse (f) blows within 30 seconds or so. I believe that is when the thermostat is sending the signal for the Aquahot diesel burner to light via the automatic mode 

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The zone thermostat is only controlling the fans (and zone pump) behind registers, at least within this model. It does not control the AH firing and does not know nor care whether the fluid is hot or cold. Does it fire if you leave the thermostat alone? If not, the light should go out after 30s to tell you that the firing sequence failed.

Edited by Ivan K
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As stated before the light in the Aquahot switch below the  kitchen counter stays lit as long as I leave the switch in the “on” position but the burner will not ignite. This information I posted in the reply’s to the other monacoer having a problem with the Aquahot not firing (I should have started a new thread with my problem)

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 Max, the thermostat for the zones will not turn on the burner, no connection between the two. 

 What that thermostat will do is turn on the fan and the pump for its respective zone.  It will blow cold until the elect heater or burner comes on.         Both are activated by the kitchen switches and those thermostats inside the unit, which cannot happen when the 15amp fuse blows.

 When the 15amp fuse blows, is that only when using the bedroom zone?   Is that fuse inside the aqua-hot cabinet?  Do you have hot water? 

 I think you need to determine why that 15amp fuse is blowing first, that is probably where the whole problem lies.

Edited by Ray Davis
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I talked with Aquahot tech support this morning and the tech thinks my motor is bad because it keeps blowing fuse f when I turn on the zone 2 controller. Ray I do not have hot water, the diesel burner will not ignite and the light in the switch does not go out after 30 seconds to indicate the firing sequence failed. The 15 amp fuse only blows after I turn on the bedroom zone controller, about 30 seconds after the fans come on. At that moment I hear a signal being sent to the zone 1, living room, controller. I need to go into town for some more 15 amp fuses before I can test the motor 

Flyinhy when you say jump the purple and blue wires connected to the black dot 230* thermostat in the lower left corner position, I imagine I must first disconnect them from the thermostat and also have the Aquahot hot switch in the “on” position. Please clarify. What do you think is happening here, just bypassing that particular thermostat?

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28 minutes ago, 96 EVO said:

I would think it would have to be one of the heat exchanger fans.

Burner motor doesn't need the thermostat turned on to run.

When the unit is cold and the diesel sw is turned on the burner fan motor will come on.  If the thermostat inside ( zone 2 ) is turned on then that motor will run too.     The 2 motors are too much, one motor is bad that's why I wanted to know if zone 1 or 3 did the same thing.

We could get by without zone 2 most of the time if necessary.

Edited by Ray Davis
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Your observation is correct, my coach is an 02 executive with the AHE-100-02S. On my system it seems the zone 3 controls the bathroom heater which has a separate switch in the bathroom. I assumed that zone 3 was for basement heat so I don’t really know what zone 3 controls and I have never tried to operate the bathroom heater without the bedroom zone (2) operating. I imagine that zone 2 controller on the wall of the bedroom must be on for the bathroom heater to work, not sure never tried it. I believe the bay zone fan will operate depending on the temperature setting in the basement irrespective of the inside the coach thermostat/controllers being on or off. When I turn the diesel Aquahot switch on (under the kitchen counter) nothing happens. Fuse (f) is good and when I turn on zone 1 thermostat the cozy fans come on as normal, the diesel burner still will not ignite and fuse (f) does not blow. When I turn on the zone 2 thermostat the cozy fans come on and fuse (f) blows within about 30 seconds of the cozy fans coming on, at the same time as the fuse blows I hear something click (I think the sound is coming from the zone 1 thermostat/controller. The cozy fans in the bedroom are not affected by fuse (f) blowing.  The test I did to check the motor (that the Aquahot tech told me to use) was to disconnect one of the wires from the coil to the motor. Then turn on the Aquahot switch. The motor doesn’t start because it does not have power but the (I believe) combustion air blower comes on and after the purge cycle is over (approximately 3 minutes) the combustion air blower shutdowns and at the same time the fuse (f) blows. So I may have two different things causing the fuse (f) to blow. Believe me I don’t want to replace the diesel fire motor unnecessarily but I talked with an Aquahot certified mechanic and he also thought the motor was bad probably a result of worn bearings. He had another test procedure to do to check the motor, also described in the service manual pg 50. I have not used that test yet. 
 

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Ok I see that in the parts. What do I hear turning while one of the coil wires is disconnected, which happens when the purge cycle is in progress ?

I just completed the motor test described in the service manual, pg 50, with the C plug and I did not get a reading with my volt meter. I am unsure where my problem is 

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