aqua hot

The AquaHot on our '97
Dynasty works exactly as MrMark described it. On cold mornings I can run the diesel boiler on the AquaHot, hit the dash switch and the coolant will circulate through the Cummins to preheat the engine. I am not mechanically knowledgeable enough to explain how it works, or if it is the coolant or hot water, but I can tell you that it does. Perhaps not all coach builders provided this function, but it is included as an option in the owners manual which came with our coach way back in 1997.

It is all about heat transfer more than flowing through one or the other. The Aqua-Hot glycol and the engine glycol are two seperate systems that merely exchange heat one to the other.

The Aqua-Hot glycol system heats up in the boiler tank and has a loop that runs around the boiler tank that contains the "engine" glycol, similar to the domestic water loop only smaller. The heat is transferred to the engine loop from the boiler tank when the block heater switch is turned on and the circulation pump is activated.

When traveling down the road the opposite heat transfer takes place, meaning the engine glycol is circulated through the Aqua-Hot engine loop which transfers heat to the boiler tank and thus raising or maintaining the boiler temperature to allow the heat registers to continue to expel heat throughout the coach.

All that said and out of the way, we too are in the camp that we will not be without the Aqua-Hot system on a coach. It was on our "must have" list when we went looking for out current coach and we love it. Although I had to do some work on it when we first purchased the coach due to the previous owners neglect it has served us well ever since.

I have a friend who has one in a late 80's Newell and it is still functioning properly and he does stay current on the maintenance so they will last quite a long time when properly cared for.

Mike.

Ivylog wrote:
Another "once you've had one" and another one who does not do a yearly maintenance. We are half timers and our single electric element is all we need 90+% of the time so no need to change the nozzle every year or even three. Have not used the diesel boiler more than a few times in the last two years so why would I change the nozzle every year? With a lot of use the hole in the nozzle actually gets too big and starts putting too much fuel into the burner = smoke and smell.
It's nice to have enough "free" hot water at the end of the day of traveling for two showers. Even if it's really cold out, it's no problem to stay warm going down the road as 400 HP puts out a lot of heat that the dash heater cannot capture, but the AH can.
We will be spending three months out West this summer boondocking often so I'll change the filter and nozzle for the second time in 10 years as it's starting to smoke some on start up. The AH is not as fragile as you are lead to believe. Probably should not brag but I've never had to rap on a check valve to get a zone to work.
as mine has been very trouble free.

I hope you fire the Diesel a few times a month for 10 or 15 minutes. NON use is what causes the fuel nozzle to gum up. Unless you have the large Aqua hot with 2- 120 elements, there is no way you can get unlimited hot water on the single 120 element. The Diesel burner is required for unlimited Hot Water on the Single element Aqua hot units. Doug

Another "once you've had one" and another one who does not do a yearly maintenance. We are half timers and our single electric element is all we need 90+% of the time so no need to change the nozzle every year or even three. Have not used the diesel boiler more than a few times in the last two years so why would I change the nozzle every year? With a lot of use the hole in the nozzle actually gets too big and starts putting too much fuel into the burner = smoke and smell.
It's nice to have enough "free" hot water at the end of the day of traveling for two showers. Even if it's really cold out, it's no problem to stay warm going down the road as 400 HP puts out a lot of heat that the dash heater cannot capture, but the AH can.
We will be spending three months out West this summer boondocking often so I'll change the filter and nozzle for the second time in 10 years as it's starting to smoke some on start up. The AH is not as fragile as you are lead to believe. Probably should not brag but I've never had to rap on a check valve to get a zone to work.
as mine has been very trouble free.

"If you do the maintenance on one, could you reasonably not be exposed to the exspensive coil replacement? I have heard that could be a $6 to $7,000.00 dollar repair?"

This seemed to be the OP's main concern. I have NEVER, in over 20 years, heard or had the water Heater coil fail from standard use. They HAVE failed when the Aqua Hot has not been winterized correctly and the coil freezes. Once that happens, Aqua Hot does NOT sell that part and you must send the complete unit back for rebuild. THAT is the 6 to 7 thousand dollar cost figure. This has NOTHING to do with maintenance. Doug

Once you have a coach with an AquaHot, you'll never go back. As others have stated, periodic maintenance is required, but not overly costly. As the owner, your primary duty is to monitor the coolant level and ensure the unit is properly filled. I have not added more than a quart of coolant in 3 years.

If your coach will sit un-used for the winter, it is critical that the AH be PROPERLY winterized. If the coils freeze and burst, there is no fix. A new $10,000 unit will be your only option. The electronic control box is a component that can fail. Easy to replace yourself, but somewhat expensive (over $700). I had one fail the first year I had the coach.

Like anything else, the more you use it, the better it'll stay running. Letting it sit for months at a time can result in pumps and check valves sticking. Sometimes this can be fixed by simply rapping on them.

AquaHot has all the documentation available online for troubleshooting, maintenance and winterizing, so check that out to learn more.

The AQUA-HOT fluid can be run through the engine as we have a switch on the dash that allows us to do just that. We can heat the engine with the electric engine block heater OR we can heat the engine block with the AQUA-HOT system running the coolant through the engine to heat it.

It could be that not all AQUA-HOT systems have that option as ours has the two stage electric (110 and High), which involves two elements. On cool evenings, I can run the AQUA-HOT on just the electric alone.

So, you have to see which system that the coach has that you are considering.

MM.

There are a couple of caveats...the aqua hot need to be serviced...most people have them serviced yearly..about $100. I have mine done every other year as the nozzle wasn't bad and yearly seemed like a waste of money. That said, you can usually tell if your AH needs servicing by the smell and noticeable smoke as the nozzle becomes fouled. Ours burns with no smell or smoke so I will not service it this year. As with any mechanical item, maintenance is the key. There is a reservoir that needs to be periodically checked to ensure it's full. Similar to your coolant reservoir.

The nozzle assembly can be replaced as a DIY if you have reasonable tools and some mechanical ability. However, when I have mine serviced, they also check the pressure regulator etc. something I cannot do myself as I don't have the proper tools. IMHO, it is worth the small price to have someone knowledgeable with the proper tools to service it.

As far as whether it's a deal breaker....well, my wife would not even look at, let alone consider, buying a coach without one. I don't think I would go back to a water heater either. Long hot showers for as long as you want, and not having to wait for the WH to regenerate is worth it by itself. The fact that you can heat the coach while underway is a bonus too. The fluid is run through the engine and heated while driving so you have heat throughout the coach if you want it. The only "heater" are small individual fans that silently bring warm air into the living quarters.....yes, it would be a deal breaker for us....Dennis