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.

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.

For cold starting the engine could it have a block heater?Looks like you type faster

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.

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.

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.

Tiffin Phaeton Aqua Hot -- 400D good enough? | Good Sam Community

Blaster_Man
Explorer
Jan 14, 2015
DazedNConfused wrote:
Blaster Man wrote:
One other point, if not already mentioned, the 400 is propane, not diesel.

The 400LP is propane, the 400D, which was stated in my original post, is diesel.

DNC

Correct...didn't see that.
DazedNConfused
Explorer
Jan 13, 2015
Blaster Man wrote:
One other point, if not already mentioned, the 400 is propane, not diesel.

The 400LP is propane, the 400D, which was stated in my original post, is diesel.

DNC
Blaster_Man
Explorer
Jan 13, 2015
One other point, if not already mentioned, the 400 is propane, not diesel.
meuryGMC
Explorer
Jan 12, 2015
Here is a thought guys. I have a 73 GMC classic coach. I want to set up my own hydronic. So instead of buying an hydronic system at 6 grand i'm thinking of building my own. Here are my thoughts and questions.

1. On Demand Water Heater (Because it has 50,000 BTU) with a small two gallon storage tank. (marine grade, only has a 110 element and heat exchanger) Instead of using water in the on water storage tank and on demand hot water heater i would like to use good old pink stuff or other antifreeze. The flow would work like this.

ON Demand Water heater heats antifeeze that goes directly in the "water side" of the storage tank. and is then fed to 3 loops.
a loop for my real hot water potable water,(which is a 6 gallon water heater heated by engine heat and 110) and two loops for heating my rv via hydronic radiators.

The heat exchange in the storage tank would hooked up to the engines heater loop. This way while driving the engine would heat the anitfreeze in the 2 gallon antifreeze storage tank that could then be pumped via a 12 volt pump to the rest of the coach. The RV Antifreeze and the Hyrdonic Antifreeze never mix.

So my question is can i run the pink stuff in say an Atwood on Demand water heater since it has no anodes.?
bluwtr49
Explorer II
Jan 09, 2015
A huge advantage of the engine coolant loop is that with the engine preheat switch on while driving, the engine coolant heats the entire coach by simply turning on a thermostat.

Personally, I thought that was standard on all Aqua Hots and I would certainly want one.
Blaster_Man
Explorer
Jan 09, 2015
DazedNConfused wrote:
StevenH wrote:
It is VERY important to PROPERLY winterize the AquaHot. You need to pump the pink antifreeze through the fresh water loop in the AquaHot. Just blowing it out can leave enough water in the loop to break it when it freezes. This will require replacement of the AquaHot (Big $$$$).

Steve

I just read the AH owner's manual. Seems straightforward enough.

Or you can drain the water and put a couple of 60w light bulbs in there. It's worked for me down to 10 degrees.

I think Tiffin is saving a couple of bucks by using smaller AHs in their coaches. Amer Coach uses nothing smaller than the 450DE and in the larger coaches uses the 650. One thing to keep in mind with the 450, if it is producing heat and you turn on hot water faucet, the heat function stops until the demand for water is no longer there. That's what my manual says, and that's how it works. The 650 can run heat and water at the same time.
DazedNConfused
Explorer
Jan 08, 2015
StevenH wrote:
It is VERY important to PROPERLY winterize the AquaHot. You need to pump the pink antifreeze through the fresh water loop in the AquaHot. Just blowing it out can leave enough water in the loop to break it when it freezes. This will require replacement of the AquaHot (Big $$$$).

Steve

I just read the AH owner's manual. Seems straightforward enough.
StevenH
Explorer
Jan 08, 2015
It is VERY important to PROPERLY winterize the AquaHot. You need to pump the pink antifreeze through the fresh water loop in the AquaHot. Just blowing it out can leave enough water in the loop to break it when it freezes. This will require replacement of the AquaHot (Big $$$$).

Steve
DazedNConfused
Explorer
Jan 08, 2015
Thanks for all the feedback. I know trailers pretty well...but motorhomes, while they share many systems, are a different beast altogether. The Aqua Hot may be one of those instances where I won't miss what I don't know. Heard many folks say they wouldn't own a coach after having a hydronic system. I've never used one...and yet with my 10gallon water heater in my fiver, I have never run out of hot water despite long back-to-back showers from three girls. I think the all-electric is pretty groovy, though. :) And I understand multi-zone from the hydronic systems is a very nice way to heat a coach. The Phaeton with Aqua Hot and heated flooring might be nice in the winter months. We have typically winterized our fiver...and said goodbye to it sometime in November...and hello sometime in late March. Hoping the motorhome will have us camping all year long. But...while I do have covered storage (storage facility with bays that provide roof, side walls, and back wall and open in the front), it isn't heated...so I'd have to re-winterize after each winter trip...and have read that winterizing with a hydronic system takes longer...and I can't used compressed air like I do now with my fiver. Looks like I have some more reading to do.
DSDP_Don
Explorer
Jan 08, 2015
We have the Oasis system in our coach. It heats while driving, off of diesel and has two electric elements (30/50 amp). On mine, the upgrade to engine block heating is an additional switch and a pump. The connections, both wiring and plumbing, are already there. You might check to see if the AquaHot is upgradable.

With that said, these systems heat water so fast, you won't be waiting long for hot water, especially if you turn it on when you first stop. One of the guys on the Newmar forum just added the pump and switch to do engine preheat, but he lives back east. I think it's a nice feature, but out west, not necessary for us. The couple of times it got cold while on a trip, I just turn the block heater on the night before.

Forum Discussion

Tiffin Phaeton Aqua Hot -- 400D good enough?

About Motorhome Group

Related Content

Tiffin Phaeton engine access?

Dependability of an older Tiffin Phaeton

Water ingestion in engine on 2011 Tiffin Phaeton 36QSH

2013 Tiffin Phaeton 40' Empty Weight ???

Phaeton Motorhome