Aqua-Hot Operational Differences for Dfferent Models

[Dr4Film]

I have now owned two different models of Aqua-Hot units. The first one was in my Windsor, model 100-01 which was replaced with 431/12. Now I have Aqua-Hot model 100-04 in my Dynasty.

Based on how the Aqua-Hot in the Windsor operated, I always had the Diesel and Electric Assist switches turned on. The Diesel is the primary heat source whereas the Electric Assist is the secondary heat source. That unit had four thermostats, two for the Diesel and two for the Electric Assist. There was a Control Thermostat for each plus a High Limit Thermostat for each. The Diesel Control Thermostat had a range of 175F to 200F where it would come on when the boiler fluid was at 175F and turn off at 200F. The Electric Assist Control Thermostat had a range from 185F to 210F where it would come on when the boiler fluid reached 185F and turn off at 210F. Each system had a High Limit Thermostat to prevent either one from overheating the boiler fluid. That was set at 230F for each. So when both switches were on, the Electric Assist would always kick on first but if the demand was greater than what the Electric Assist could keep up with the boiler fluid would drop to where the Diesel burner would kick on and bring the boiler fluid back to temperature.

I have been trying to understand how the Aqua-Hot model 100-04 operates with both switches turned on as that’s how I had used the 431//12 Aqua-Hot. Over the past year of owning this Dynasty, I have noticed that the diesel comes on quite regularly when there has been no demand for hot water or room heating. That has always baffled me as to why the Electric Assist wasn’t maintaining the boiler fluid temperature. However, after reading in the Aqua-Hot manual for the 100-04, that unit does NOT have four thermostats. It only has three, one Control Thermostat for both the Diesel and Electric Assist plus one High Limit Thermostat for the Diesel and one High Limit Thermostat for the Electric Assist. There is also a sensor wire that goes over to a Float Switch that will shut down the Aqua-Hot if the boiler fluid level gets too low.

I now understand why the Diesel has been coming on more frequently in the Dynasty than I would have thought especially when the demand hasn’t been there to cause the diesel to fire up. Both the Electric Assist AND the Diesel are activated simultaneously once the boiler fluid gets to its low temperature point and will turn off once the boiler fluid gets to 190F +or- 5F. So, now with the Aqua-Hot model 100-04, it no longer makes sense to have both the Diesel and Electric Assist switches turned on all the time. To save on diesel usage and if you are hooked to shore power or generator power it makes sense to always have the Electric Assist Switch ON but only turn on the Diesel Switch when the demand increases like showers, room heating or you have really cold incoming ground water, etc.

I have now turned off the Diesel Switch and only have the Electric Assist Switch turned on. I will operate like that for the time being to see if the Electric Assist can keep up with our normal water usage this summer. Once fall hits here in September I will most likely have to revert back to keeping the Diesel Switch on as temperatures will be turning colder here in the Northeast and we will be using the baseboard heat exchangers to keep the coach warm.

I do not understand WHY they would eliminate the fourth thermostat in the 100-04 model. Having the ability to leave the Diesel and Electric Assist Switches on all the time like what was used in the earlier Aqua-Hot models makes perfect sense versus having the Diesel running when it's not needed.

Once they came out with the Aqua-Hot 450D model which only has a 5 gallon boiler fluid tank they completely revamped how that system was controlled especially when you are using room heat and taking showers.

 

 

Edited June 29, 2023 by Dr4Film

[Georgia Mike]

Richard, I have the same model Aqua Hot and have found the electric has been enough most of time for my wife and I needs. We can both take a shower in the evening and have plenty of hot water. Even in cold weather if we just turn on the rear bedroom heat and the temperature isn’t below freezing it will keep up all night. If I turn on the other zones I have to fire up the diesel burner. We mostly use the electric only and fire the diesel burner once in while if we use a lot of hot water for dishes or just to exercise it.

[96 EVO]

HA!

I recall trying to tell you that about 9 years ago, over on IRV!

I guess you never believed me...... till now 😁!!

[amphi_sc]

As we are talking differences, I'll mention that with my 100-03s I seldom turn on the diesel ... typically only when boondocking for two or more days.  The 03s has enough boiler antifreeze that an overnight stop still has enough residual heat from the previous day's engine loop for a couple normal showers the next am.  I also can get away with electric only room heating when the temps are upper 40's or above.  Many times I lose track of time and forget to turn the diesel on for a cycle once a month just to exercise the unit.

[Dr4Film]

15 hours ago, 96 EVO said:

HA!

I recall trying to tell you that about 9 years ago, over on IRV!

I guess you never believed me...... till now 😁!!

I remember those discussions however, I don't believe anyone actually described the WHY exactly what I did in my post above. If they had specifically stated what I had discovered while using the 100-04 AND delving into the manual for answers, that would have made total common sense to me versus what I was experiencing with the 431/12.

Having been a "very technical" person in my film career is sometimes a curse and a blessing.

59 minutes ago, amphi_sc said:

As we are talking differences, I'll mention that with my 100-03s I seldom turn on the diesel ... typically only when boondocking for two or more days.  The 03s has enough boiler antifreeze that an overnight stop still has enough residual heat from the previous day's engine loop for a couple normal showers the next am.  I also can get away with electric only room heating when the temps are upper 40's or above.  Many times I lose track of time and forget to turn the diesel on for a cycle once a month just to exercise the unit.

Without going into the manual for the 100-03 I would assume that the 100-03 and 100-04 are identical in operation.

[96 EVO]

I guess the bean counters won out when they eliminated thermostats and extra wiring, and they turned a great system into a 'ok' system!

[Dr4Film]

@96 EVO

They really messed up when they came out with the 450D. That model is a total disaster in my opinion. Then they got a short reprieve when they introduced the 600D. That has to be their very best unit.

As stated previously, if this Aqua-Hot fails, another one won't be going into my coach. It will be the Espar Diesel System. Far easier to maintain than the Aqua-Hot.

[sg47619]

My question to this would be will it work on three zones and from what I saw it’s only 12V. Thanks for posting 

[Dr4Film]

Yes, will work on three zones and it is both 120 VAC for the twin Electric Assist elements and 12 VDC for the diesel.

[sg47619]

21 minutes ago, Dr4Film said:

Yes, will work on three zones and it is both 120 VAC for the twin Electric Assist elements and 12 VDC for the diesel.

 

21 minutes ago, Dr4Film said:

Yes, will work on three zones and it is both 120 VAC for the twin Electric Assist elements and 12 VDC for the diesel.

Thank you, lm having trouble with my Aqua Hot now. I made really look into this now

[Bill C]

2 hours ago, Dr4Film said:

@96 EVO

They really messed up when they came out with the 450D. That model is a total disaster in my opinion. Then they got a short reprieve when they introduced the 600D. That has to be their very best unit.

As stated previously, if this Aqua-Hot fails, another one won't be going into my coach. It will be the Espar Diesel System. Far easier to maintain than the Aqua-Hot.

Anyone ever converted the Aqua Hot 100-01 to another, better, system, perhaps the Espar Diesel System?

I wonder how hard it is, and how expensive it is.

[96 EVO]

8 minutes ago, Corkman said:

Anyone ever converted the Aqua Hot 100-01 to another, better, system, perhaps the Espar Diesel System?

I wonder how hard it is, and how expensive it is.

Doesn't the 100-01 have the 15gal boiler tank?

If so, I don't know if I'd consider the Espar a better system! JMHO.

[Dr4Film]

42 minutes ago, Corkman said:

Anyone ever converted the Aqua Hot 100-01 to another, better, system, perhaps the Espar Diesel System?

I wonder how hard it is, and how expensive it is.

Talk with @gene.howe who has had two installed in two different coaches, his previous Monaco Diplomat and his current Holiday Rambler Imperial.

[Jdw12345]

So of the three different systems that you have owned, which system do you prefer?

 

 Also, last winter in Az we lost the 120v side of our AH, the high limit sensor, I believe was original, timed out, here’s a picture or two, the contacts become loose over time, heat up and seem to fail, fwiw. I have the 100-4.

 

 

[Dr4Film]

2 hours ago, Jdw12345 said:

So of the three different systems that you have owned, which system do you prefer?

Basically, the 100-01 and the 431/12 were identical. My 100-01 failed in late 2005, 4 years after the coach was delivered to the OP in September 2001. I had a rebuilt from the Colorado Aqua-Hot plant installed which was the 431/12. I questioned the different model but Roger Berke stated that there were identical.

The 100-04 in my Dynasty is operationally different.

To answer your question, I like the Electronics package that comes with the 100-04 versus the 100-01 & 431/12 however I prefer having the four thermostats for controlling the Diesel and Electric Assist separately. There is no logical reason for deleting the separate control thermostat and combining them into one in my opinion.

I am learning to deal with the operational differences but logic tells me that you shouldn't have to. Basically, my beef is that technically, you should be able to leave BOTH the Diesel and Electric Assist Switches on ALL the time. The Electric Assist would not be operational unless you are on shore or generator power.

Keep in mind, ALL of the manuals state clearly that the Diesel is the PRIMARY heat source and the Electric Assist is the SECONDARY heat source. With the 100-04, if parked on shore power for a length of time like we are now, the Electric Assist has become the primary heat source with the Diesel switched turned off. It will stay that way until which time either the colder weather is upon us or the wife starts to complain, then I will turn the Diesel switch back on.

[Bruce S]

In our 03 Sig we have a 100-02s which has the 4 thermostats.  In case anyone is wondering, with this model the diesel control is set for 190F, the electric coil is set for 198F and the high temp for both is set at 230F hence the pressurized system radiator cap...  Apparently these thermostats will vary in their operation which is why the ranges are specified as well as the set points.  Either way the electric coil in our coach will suffice under lighter loads and under shore power.  If we only have a 30A supply then manual load management becomes mandatory.  

[amphi_sc]

2 hours ago, Bruce S said:

Either way the electric coil in our coach will suffice under lighter loads and under shore power.  If we only have a 30A supply then manual load management becomes mandatory.  

When we have hookups, we are on 30a quite a bit, so I automatically load share the front A/C heat pump with the AquaHot using the same type of Intellitec device as the washer & rear A/C heat pump use to share  the circuit. Thus when the front A/C heat pump starts drawing current the AquaHot is disconnected.  When the front A/C heat pump cycles off the AquaHot is automatically reconnected after a few seconds delay.

When back on 50a or generator I throw the switch the other way and they are wired independently again as per the factory.

[Bruce S]

Our 03 coach doesn't seem to have the same load shedding abilities as yours and I usually pay more attention when we are using the kitchen appliances.  Our roof air is seldom used as we generally prefer the windows open in our neck of the woods.

[amphi_sc]

Just to be clear, I re-wired and added the Intellitec AESS  https://intellitec.com/automatic-energy-selector-switch/ and a double pole switch to be able to load share the AquaHot/ Front A/C

[96 EVO]

15 minutes ago, amphi_sc said:

Just to be clear, I re-wired and added the Intellitec AESS  https://intellitec.com/automatic-energy-selector-switch/ and a double pole switch to be able to load share the AquaHot/ Front A/C

I figured that must have been something you added.

Good job 👍!

I'm also on 30A more often than I would like! I could see that modification being very handy!

Edited July 2, 2023 by 96 EVO