Tiffin Phaeton Aqua Hot -- 400D good enough?

[DazedNConfused]

In the process of picking out a motorhome...and I keep coming back to Tiffin. Drove an Open Road Allegro...and we really liked the coach itself...but after driving a diesel it would have to be the Allegro Red or Phaeton. Looking at 38QBA or 40QKH. Anyway...in comparing the two I found that Aqua Hot is now an option on the Phaeton which is part of their "All electric coach" option at $8,120. I know it includes the Aqua Hot system...but I'll assume that means it completely eliminates all propane from the coach -- including stove. It's already using a residential fridge.

I found an article this morning that talks about which Aqua Hot. The Phaeton uses the 400D whereas the Bus uses the 450D. A quick comparison shows them to be very similar units -- same BTU rating, about the same GPM, and the same fuel consumption. But...and here is where I'm trying to determine how important -- the 400D only uses two sources of energy to heat the water -- a 1650w heating element or a diesel burner whereas the 450D can use the heating element, diesel burner, and also heat from the diesel engine. So that means the 400D in the Phaeton cannot offer cold engine start assistance...or heat the coach while travelling without using the diesel burner or running the generator. Is what it is...but was more curious about the cold starts. Only diesel I've owned has been my diesel pickup truck....and cold starts aren't an issue for it...so was looking for some feedback on whether the 400D is worth the cost of admission.

Thanks.

[Dale_Traveling]

#@^%!!, I'm wrong. 450D does have the engine preheat. Wouldn't worry about not having it though unless you plan to camp in very cold areas. Needs and wants.

[BigSkyBob]

jorbill2or wrote:
???? my understanding is if the aqua hot includes a Engine coolant loop in it then that also includes a Aqua hot pump to pump the coolant through the engine for preheat! if the engine is running it cycles that coolant back through without the use of the separate Aqua hot pump That coolant then heats the boiler fluid/ coolant making it available to the hot water loop and the heaters

This is exactly how the 450DE functions. I've never started my ISL 400 cold, just makes me feel better.

[jorbill2or]

???? my understanding is if the aqua hot includes a Engine coolant loop in it then that also includes a Aqua hot pump to pump the coolant through the engine for preheat! if the engine is running it cycles that coolant back through without the use of the separate Aqua hot pump That coolant then heats the boiler fluid/ coolant making it available to the hot water loop and the heaters

[Ivylog]

I have both a block heater and A Hot with engine preheat and in 10 years I've never used either to get the engine to start. Having unhooked the block heater so I can have a outlet at the back of the coach I can't roll over and turn it on several hours before starting the engine. At 32 degrees my ISL will start at the end of the first grid heating cycle. Down close to 0 I'll cycle the grid heater a second time and then it starts just fine.
For those going "OH NO, you are hurting your engine" most of my heavy equipment do not have preheat and I use starting fluid to start them when it's cold. Only been doing this for 30 years since I moved to northern Georgia without a engine oil pre-heater.
OP, I would not worry about it but being able to get heat from the engine is really nice.

[DazedNConfused]

Yes....this makes complete sense. Thanks so much.

Dale.Traveling wrote:
I think you might be looking at this from the wrong direction regarding preheating the engine with the Aqua Hot. With the 450D a heat exchanger is added to pull heat from the engine coolant for use within the Aqua Hot system. Both systems are closed and do not exchange liquid so unless the engine coolant system has a secondary pump to circulate within the engine block using the Aqua Hot to preheat isn't going to work.

The additional feature of the 450D using waste heat from the engine is a benefit and will save you a small amount of fuel for the times you're on the road in cold weather. Show stopper? Not much unless your travel plans have you in cold areas on the road for extended periods of time. I wouldn't worry about it not having it.

What I would rather have is an engine oil pre-heater with an external auxiliary oil circulating pump. A pre-lube anytime, and a warm pre-lube on cold days, might be something I would consider paying for.

[Dale_Traveling]

I think you might be looking at this from the wrong direction regarding preheating the engine with the Aqua Hot. With the 450D a heat exchanger is added to pull heat from the engine coolant for use within the Aqua Hot system. Both systems are closed and do not exchange liquid so unless the engine coolant system has a secondary pump to circulate within the engine block using the Aqua Hot to preheat isn't going to work.

The additional feature of the 450D using waste heat from the engine is a benefit and will save you a small amount of fuel for the times you're on the road in cold weather. Show stopper? Not much unless your travel plans have you in cold areas on the road for extended periods of time. I wouldn't worry about it not having it.

What I would rather have is an engine oil pre-heater with an external auxiliary oil circulating pump. A pre-lube anytime, and a warm pre-lube on cold days, might be something I would consider paying for.

[jorbill2or]

The 400d can heat the engine ( thus the engine can heat the Aqua hot ) as an option ..its standard on the 450. Does tiffin not include that option ? If for some reason they order it without you would surely have a old school electric preheat.
After using a hydro hot I wouldn't have a coach without it . quiet even radiator fan heat and hot water that isn't limited .. One shower after another without waiting . I didn't know what I was missing.

[accsys]

I have owned my current Phaeton for the last four years and love it. It is not all electric and doesn't have the Aqua-Hot. I am familiar with the Aqua Hot but not enough to answer your question. However I can tell you that the Phaeton, and I assume all diesel Tiffins, come with an electric engine heater that works for nicely to alleviate any cold start problems. Naturally, you must be connected to shore power or running the generator to power it.

Not sure if you are aware of its existence or not but you may want to pop over to the Tiffin RV Network (TRVN) to gain more information. It's a great forum not part of Tiffin but has many, many very experienced users providing first class info on just about anything you wish. The link I gave takes you to the home page but there is a link on the left side for the forum.

[mike_brez]

For cold starting the engine could it have a block heater?

Looks like you type faster

[bullydogs1]

For cold starts, you should have an engine block heater to take care of that...and it plugs in (at least mine does) very easily and I use the circuit breaker for it as a switch. If you are staying new, these things are expensive enough...I think you are going to be just fine.