Aqua Hot Confused Newbie

[go2heaven]

My Unit 2009 Tiffin Allegro Bus 43QGP
Dont know if you can help me or not.

1. My owners manual describes a propane furnace and aqua hot as optional. It DOES NOT say that if I have aqua hot I probably DO NOT HAVE a propane furnace but only an aquahot. Is that true? I expect that my propane tank only runs my gas cooktop.

2. Materials say that activating the diesel burner gives great heat and continuous hot water. I do understand that. It also says that the "electric" switch, when connected to shore power, gives me light duty hot water and some heat.I don't know what that means?. Can I assume that this electric system does not use diesel at all and only uses the shore power? Ideally, if I am plugged in at a campground I would prefer to use their power and heat my coach instead of turning on the diesel burner to heat it. If I turn on the electric switch should I turn off the diesel burner switch. IE....is it one or the other? If I have the diesel burner switch on I would never have the electric switch on simultaneously?

I have my RV sitting outside now and plugged into 50 amp power. It is about 50 and the temp is going down. I would prefer to run the electric switch, use no diesel and run it off of my shore power just to maintain the temp in the unit. When I turn this on, it seems to hardly get warm at all. If the heat provided by it is relatively anemic, I don't know why it exists?

3. Lastly my 3 zone thermostat provides for each zone settings of "OFF, Electric and Gas". Since I think I probably do not have propane, does "gas" mean diesel? If I select electric" on the thermostat, does that correspond with the "electric" switch on the aquahot or is it intending to to access the electric AC/Heatpumps on the top?. I don't even know if there is a heat source on the top of the unit (Heat Pump??) or only the Aquahot.

Just bought the unit from a private owner and the second I bought it, he took off. Read the owners manual cover to cover, does not answer these questions adequately. I think I understand the diesel burner part and I assume that the appropriate selection would be "gas" on the thermostat. I just don't understand the Electric switch and whether or not my thermostat should be set to gas or electric when using the Aquahot Electric switch and whether or not that will heat the coach in any meaningful way or should be ignored.

Thanks if you are able to help me !


Utterly Confused
Kevin Adams

[brandss]

Kevin
You are not alone in being confused with all of the "stuff" with a new coach. I will try to give you my best answers and hopefully, will be corrected by a more experienced person than I. The wife and I are only 4 months into our journey.

From what I can tell from your message, you do not have propane on your coach. You have an all electric coach like we do. What that means regarding heat is that you have the AC units on the roof that can also supply heat as well as the aqua hot system which can also supply heat, and to confuse it more, can supply heat in two ways; electric and with the diesel fuel.

You stated you have 3 thermostats, we do as well. You have the settings of gas and electric. Now this is where I may be corrected but, I will give you what I think I know. If you set your thermostats to electric, it will supply heat from the roof ac units. If you select gas, it means the aqua hot will supply the heat. The aqua hot is like a furnace on a home. What took me more than a month to realize though, is even though you select "gas", using the aqua hot, it will only use electric when plugged in and give you roughly 1/3 of the total heating capacity. As I type, even I find it confusing.

In our coach (and you do as well) we have a control system over the drivers seat for the aqua hot. It has three switches that say, burner, electric, and pre heat or something, for pre heating the diesel engine. Our early mistake was thinking we were getting the best heat from the aqua hot by only turning the electric switch on. Thanks to the good people on this forum we discovered that the electric only switch can only provide a certain amount of heat. We are in below freezing temps and I went out and bought another electric heater because I thought the aqua hot wasn't enough. By turning on the burner switch it allows the aqua hot to use the diesel to fully utilize the aqua hot and provide more heat than you will ever need.

Since we are in a campground for a few months we leave the burner as well as the electric switch turned on. We leave the front thermostat on 66, mid on 66, and the rear on 64. Once we wake up we use the heated tile floors and sometimes the fireplace to supplement the heat.

I'm not sure I helped, it is a bit confusing at first. If I can help anymore, feel free to PM me. I swear, there is so much to learn.

[jzeurcher]

On our bus there are 3 thermostats. One for the front, one for the mid area and one for the back. The mid one is only for the middle heat pump/air conditioner. You should only have 2 zones for the aqua hot. Front and rear.
Not sure what you have for switches on your aqua hot. On mine there is a switch for electric and one for diesel. When plugged in I use the electric all the time and when it can’t heat the coach enough I also turn on the diesel function. I turn on the floor heat also leave it on all the time. It takes a long time to heat up the floor. The floor heat all by itself warms up the coach nicely when not too cold outside. With the aqua hot electric on all the time you will have enough hot water to wash dishes and so forth but you will probably need to use the diesel when taking showers.

[pbucha]

I found this info a couple of years ago and found it pertinent to my coach as well. Not sure who the original poster was, but kudos to them...I found this to be very handy.




Aqua Hot notes – 2015 Allegro Bus 45OP
We have 3 AC's/heat pumps, they work like this.
All three AC's have electric heat. So when you put the thermostat for each AC to Elec Heat, it will blow warm air from each unit. They are good down to about 45F.
The AquaHot system heats a fluid, much like car antifreeze, which then circulates through tubes to air exchangers, call Cozi Heaters, throughout the coach. These are similar to the heater core in a car. A fan blows the air through the Cozi core and warm/hot air comes out.
There are three ways the AH fluid can be heated:
1. The AH has an electric element to heat the fluid. That works for hot water fairly well when the water temp is not very cold. We use that for hot water during the spring through fall.
2. It also has a diesel burner to heat the fluid. It is very efficient and we use that for hot water and heat when it is cold. In our coach, we can actually have the electric element and the diesel burner on at the same time, giving additional heat to the fluid when it is very cold outside.
3. The third way the fluid is heated is by the Cummins engine, at least on our Allegro Bus. This is done automatically. There is no on/off switch for this.
We have separate switches to turn on the electric element and the diesel burner. They are part of the Spyder controls that are mounted under the rear thermostat in our coach. They both are marked "WATER HEAT", one with a lightning bolt (Electric) and the other with a flame (Diesel Burner). See photo below. So to get the AH fluid hot when the Cummins engine is not running, one or both of those switches need to be on.
Realize that if it is fairly cold, and/or the water coming into the coach is fairly cold, the electric AH element, if used alone, will not be able to keep up with the demand and the AH fluid will not be hot, so the performance of the heat/hot water will be poor.
The rear and front AC's thermostats are the ones that control the heat from the AH. The center AC's thermostat is not connected to the AH heat. For the AH heat to work, put the thermostat on Gas Heat. Kind of a misnomer but that is how it is labeled.
For the WET BAY heat, the rear thermostat has to be on Gas Heat. The AH has to be on Diesel Heat or both Electric Heat and Diesel Heat. The temperature in the wet bay is controlled by the thermostat in the wet bay
Realize that the diesel fuel for the AH is coming from the same tank that your Cummins engine uses. Tiffin has set the diesel line out of that tank for the AH such that the AH will not run once the tank is below about ¼ full. This is to avoid the unfortunate situation of having the AH use up all diesel and then your coach will not start.
An additional note: This is an all-electric coach. There is no gas/propane.

[les.warden]

We have a 2017 all electric Phaeton. Looks like the AH is pretty well covered here with previous comments.

Only thing I’ll add is being careful not to cover the exhaust vents. In ours, there are vents on the PS on each side of the couch/bed top, up by the wall. They make real good shelves and my DW tends to put small baskets on them. Always have to move them if I use the AH heat.

[TurtleKent]

Kevin,

You could well have a propane tank which supplies only a gas cooktop... along with AquaHot(no propane furnace)... that was standard from the factory. We had the same setup in our 2010 Bus. In the 2009-2010 Bus all-electric was an optional upgrade, which deleted the propane tank and furnished an electric cooktop.

AquaHot has two(not three) zones, front and rear... the mid-position on the triple thermostat controls nothing AquaHot, but the mid-position does control the middle rooftop heat pump. Heat pumps only function down to 40° or so. Lower than that if we wanted electric heat we used portable space heaters. They were much quieter than the AquaHot, and did not deplete your diesel fuel.

Always leave the AquaHot electric switch on, no harm in that. It draws 115v from the park pedestal, but does not draw from your batteries when unplugged. Electric output is only around 5000 btu, less than a space heater, so don't expect much heat. Good enough for dishwashing or for a single shower. Two showers or clothes washing requires diesel also. Supplement with diesel switch as necessary.

When driving, your engine will heat the AquaHot fluid automatically, and keep the entire coach comfortable, even with all three switches turned off.

Engine heat works in reverse, to heat your cold engine from AquaHot.

Finally, join TiffinRVNetwork for their forum. You'll get much better answers to your questions.

[BrianGlenn]

One last note - with both switches on for electric and diesel, they activate at the same time, boiler fluid lower than 158F, and turn off at the same time, boiler fluid higher than 190F.

I only run with either electric or diesel "on", not both. Electric is 1650W (about 5600 btu/hr) input rating and my diesel is 45,000 btu/hr. Diesel is much faster heating and can supply 10 times greater heat input to maintain high heat loads (shower, and cold ambient).

Brian

[jzeurcher]

Not sure about the older coaches but 2016 and newer you have to set your aquahot to diesel heat to have your coach engine supply the hot water for aquahot when traveling. The aquahot burner will not come on because the engine circulated water then provides the heat to operate it. This is the function for Tiffin coaches.

[jkorn]

Electric and diesel both provide hot water and radiator heat. The diesel has quicker recovery like a residential water heater. Diesel burn can provide unlimited hot water while electric has the recovery time after you drain all the hot water out.

[go2heaven]

Thanks for all your help!! I finally get it on the aquahot 😁 To top it all off, I just had a guy pull into the campground with an identical 2009 Allegro Bus . Better than Christmas morning !! I sincerely appreciate all of your help !

[les.warden]

When you talk with them, now you’ll be the expert!

Safe travels!!

[DFitz]

Kevin - glad you've got your AH figured out [emoji4] It took us a while when we bought our 08 bus a couple years ago.
A couple things that I didn't see mentioned:
Regular service on your A-H is important... If you are handy & patient changing out the fuel filter, replacing the nozzle and cleaning out the soot takes some time but is very doable. Look up your AH model (probably 450de) online and follow the service instructions. For 1st time service you may want to have an AH tech perform it while you watch!
When running correctly, your AH shouldn't smoke or smell excessively of diesel. (it will smell some...)
Other thing you may have discovered on the wall of the last storage bay, passenger side is a thermostat. This controls the heater that keeps your wet bay and tanks from freezing in very cold temps. I recently found that mine was not working! With your AH boiler ON & up to temp, you should be able to hear a click when turning the control knob back & fourth.
Congrats on your purchase - happy glamping!
Dennis