Community Forums

Mike Canter · 12-13-2010, 07:23 AM

John, I don't think it is directly plumbed into the heater hoses. If it did then you would have the motor anti-freeze in the Aqua Hot and they are two separate systems. I believe they use what is referred to as a "heat exchanger" which is a tank that the engine heated coolant is flowing through and in that tank is either a coil of pipe or a small radiator looking device that the Aqua-Hot coolant goes through and one heats the other without mixing.

Iron Man · 12-13-2010, 06:13 PM

There are in/out fittings on the hydrohot for the engine coolant for engine preheat. Newmar does not use the pump that will circulate the engine coolant for preheat (someone added this to their coach and there is write up somewhere), but when the engine is running the engine's water pump circulates the water through a heat exchange in the hydro hot. I know for a fact that there are engine heater hoses going to the hydrohot because I had a friend who had a coolant leak at the hrydrohot and lost a gallon of engine coolant.
http://www.aquahot.com/eSource/ecom/...13RevA_000.pdf

Mike Canter · 12-13-2010, 08:32 PM

John, sorry you are correct in that the heater hoses do run from the engine into its own special loop within the Aqua-Hot boiler. The heat exchanger is actually the boiler and there are three separate loops within the boiler, one is the engine antifreeze loop and the other is the Aqua-Hot antifreeze heating loop, and then there is the fresh hot water loop. On mine I have the extra circulating pump for the engine preheat loop so I can put the heat back into the engine.

Cruzer · 12-14-2010, 06:54 AM

OUr '07 Allegro Bus came equipped the same way as your Newmar. We had HydroHot but it was the model without the engine preheat feature. It was plumbed up with the Motoraide feature which allowed the engine to supply heat to the boiler when driving so the heater hoses were in place. I contacted AquaHot and had them send me the parts required to add the engine preheat feature to my unit. They sent me the pump, the switch, and some connecting hoses. Details of my installation can be found at RVcruzer.com - Installing the HydroHot Engine Preheat System. All wiring harnesses include wiring for the engine preheat switch so you don't have to run any wiring. Just plug the switch into the existing connectors. If I recall, the parts ran around $300 for everything.

I have found that the AquaHot preheat system does a better and faster job than the 120 VAC block heater. The block heater gives you the temperature reading on the gauge before starting but once the engine is running the temp drops a bit because the block heater only heats a localized spot in the water jacket. The AquaHot uses a circulation pump to circulate the coolant. The overall temperature is the same as the block heater but the warm water is spread over a larger area so the engine retains more of that heat. It's also much faster to build up heat than the block heater. For boondocking or last minute warmup decision the AquaHot preheater is hard to beat.

G.Peter · 12-21-2010, 12:38 PM

I have not got enough heating capacity with just 120 element can you run the diesel in conjunction with the ac

Cruzer · 12-21-2010, 01:22 PM

Yes, you can. The electric element is only around 5,000 BTU. The Motoraide feature puts out around 12,000 BTU, depending on your particular engine. The diesel burner is rated at 50,000 BTU. You can combine any or all of these three heat sources. If you run the electric element it'll reduce the time that the diesel burner runs, saving you some fuel.