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AquaHot Question

How does the AH system distribute the coolant to the heat exchangers?  Is there a pump?  Can you hear it?  If the overflow reservoir is maintaining a consistent level, can I be assured that the fluid level is good in the system?
Thanks, Mike
Mike Brady
'97 U320 SE. #5137
'13 Honda Fit
Willow Springs, MO

Re: AquaHot Question

Reply #2 –
Mike,

The AH heater in Foretravel installations has two or three fan coils in the saloon, one fan coil in the bathroom, one in the bedroom and two in the utility compartment of the basement.

The fan coils are supplied hot coolant by circulating pumps located in the heater.  One pump supplies hot coolant to the saloon fan coils that are plumbed in series.  Another pump supplies hot coolant to the bathroom and basement fan coils that are also plumbed in series.  One pump supplies hot coolant to the bedroom fan coil.  A fourth pump will circulate the Diesel Engine coolant through a tubing coil in the hot coolant tank to preheat the engine before you start it in really cold weather.

The overflow tank allows the coolant to heat up and expand out of the heater into the overflow tank as the temp of the coolant tank rises.  The overflow tank level will rise as the heater heats up and fall as the heater cools.  So the overflow tank level does not stay at the same level during heater operation.

If the tank level stays the same during operation, check or change radiator cap and check overflow tube for brittleness and cracking rendering it no longer air tight.  If brittle, pull off of barb, cut off one inch and reattach.  Both ends need to secured with a clamp, constant tension clamp being the best choice.

You can be assured the fluid level in the system is good when the overflow tank level varies during operation.

A faulty overflow hose will cause the overflow tank to stay at the same level.  This does not mean there in no coolant in the heater.  But it does mean any expelled or lost coolant is not being replaced by the coolant in the overflow tank and the heater is probably not full of coolant to the neck of the radiator cap.

No coolant in the overflow tank needs looking at with the radiator cap and overflow hose being the most likely suspects.  Leaks in the coolant plumbing at the pumps or fan coils will lower the coolant in the heater and cause the coolant in the overflow tank to replace the lost coolant till the overflow tank is out of coolant.  Those leaks are fairly easy for the owner to notice.

Hope this helps you.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: AquaHot Question

Reply #3 –
Rudy, I thank you for the detailed description of the workings of the A-H system, much more clear now on the pumps and circulation etc.
Many thanks
Dave M

Re: AquaHot Question

Reply #4 –
Also make sure to check the pick-up tube inside the overflow tank.  If it comes loose, water flow to and from the tank will stop.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R