Hydro Hot system Question - works sometimes?

[jbobst]

I have access to a 2006 Newmar Moutain Aire, and took it out this past weekend for only the second time in the past 2 1/2 years. This was my father in laws motorhome, but he passed away about a year and a half ago. My mother in law still has the motorhome in storage, so we decided to take it camping this weekend to exercise it.

My understanding of the Hydro Hot system is that it has a diesel burner "engine" in it that will heat up some sort of alcohol liquid and it will instantly heat water. Kind of like a tankless water heater. There is also a blower motor that when turned on with the Hydro Hot system, will provide heated air to heat the motorhome. There is also a 110v heating option for when using the generator or plugged into shore power.

While camping this weekend I had mixed results with they Hydro Hot system. All three evenings, we had hot water in the shower, but both mornings, the shower was cold the whole time. I don't think we ever got any hot water out of the kitchen or bathroom sinks, but we didn't try too often...it was mostly in the shower we wanted hot water. When I flipped the diesel burner switch to "on", the light on the switch illuminates for a minute or so and then the light goes off. I could hear the diesel burner running even when the light was off, but during those two mornings, there was no hot water. I tried the 110v switch while running the generator and there still wasn't hot water during the morning hours.

Before my father in law passed away, I remember him telling me that the Hydro Hot system should be "serviced" once a year. I don't know exactly know what "serviced" entails, but it hasn't been serviced in three years. But, keep in mind, during those three years we've only used the motorhome 6-7 times (for short weekend trips).

Any ideas on why hot water was intermittent?

Edit: My wife reminded me that one evening before dinner my son tried to shower and there wasn't any hot water then (before dinner), but after dinner my wife tried the shower and it was hot.

[steveownby]

Altern wrote:

steveownby wrote:
The diesel burner should be left on at all times and in the primary heating source for the boiler fluid.

This is a bit misleading. While driving, the engine will heat the boiler fluid. That boiler fluid heat can also be augmented by by the electric element.
With these systems, we normally use the diesel burner when starting from a cold tank or when heat is wanted quickly, say first thing in the morning. Or, if no electric is avail.
YMMV and you'll soon learn how to use it and under which circumstances.

What is misleading? I stand by my statement. The Diesel burning is the primary heat source. And the only heat source that will maintain temp during periods of heavy usage.

[Altern]

steveownby wrote:
The diesel burner should be left on at all times and in the primary heating source for the boiler fluid.

This is a bit misleading. While driving, the engine will heat the boiler fluid. That boiler fluid heat can also be augmented by by the electric element.
With these systems, we normally use the diesel burner when starting from a cold tank or when heat is wanted quickly, say first thing in the morning. Or, if no electric is avail.
YMMV and you'll soon learn how to use it and under which circumstances.

[steveownby]

The HydroHot is the smaller of two systems build by the AquaHot company. The system consists of a large pressure tank containing a type of boiler fluid. Inside that tank is a fresh water loop which heats water by heat transfer from the heated boiler fluid. There is an optional engine coolant loop also which can be used to preheat the engine and also for the engine coolant to heat the boiler fluid while driving. The diesel burner should be left on at all times and in the primary heating source for the boiler fluid. It sounds like yours is not lighting. The sound you hear is the blower motor that provided combustion air to the burner. The diesel burner can bring the boiler fluid up to operation temp in just a few minutes. The electric element is mostly to maintain temp after the diesel burner gets it up there. The electric element is just about 1500 watts so it would take hours for it to get the boiler fluid up to temp. The times there was warm water available may have been shortly after driving when the engine would have added heat to the fluid. Or the electric element may have been left on and kept the temp up. This system is also the furnace for the coach and provides heat in cold weather.

The normal service required is replacing the fuel filter and the burner nozzle. It would be worthwhile to find a AquaHot certified service tech to do a service on the system and explain its operation to you.

[kmowen]

Sounds to simple but I just purchased coach with that system and had same issues on maden trip. The electric element just didn't work and the diesel burner wouldn't work because low on fuel. Mine won't work come to find out with less than 1/3 of a tank.Fueled it up next day (like dealer was supposed to) and it worked fine. Good luck with yours, there is a ton of info online about these systems.

[Old-Biscuit]

Here is a service manual for Hydro-Hot......LINK

[Altern]

If you have the owners manual there is a trouble shooting section which covers most problems. Its priceless!

[paulcardoza]

The light going off indicates a problem. You need to have a qualified service tech look at your system. You can go to this site for lots of great info and if you are mechanically capable, you can try to troubleshoot yourself:

http://forum.rvhydronicheaterrepair.com/forum.php