To Everyone reading this, use a creditable Aqua Hot Authorized Service Rep.
I am going to offer a few tips to all who are interested:
(1)A bit of smoke upon start and shutdown is normal.
(2)One thing I am seeing is Aqua-hot owners think that if they don't use their heaters, they don't need servicing,
You should run your Aqua-Hot on the diesel cycle at least once a month, this prevents stale fuel from fouling the fuel nozzle. By the way, DO NOT try to get by with cleaning the Nozzle. They have a list price of around $15.00.
(3) When servicing your A/H, wipe the photo cell to clean of soot, if it cannot be cleaned with a dry towel, just clean with brake cleaner.
(4)A proper service cannot be performed without a fuel pressure gauge, fuel pressure range is 145 PSI + or - 6 PSI.
(5) An easy way to clean the combustion area is a nice long handle toilet brush, After cleaning that and the combustion chamber, insert the combustion chamber back into position, (seam at the top) Do not worry about the vacuum cleaner, after installing the burner system, when you start the unit, soot will be blown out the exhaust (another tip use gloves).
(6) One cause of smoke is the rubber boot at the air intake, throw that away, use a 1/4 screen to keep critters out, the air intake is preset at the factory, no reason to change unless operation a high altitudes for long period of time.
(7) Coolant level will change as the internal coolant heats. Be sure the system is full. By the way the only positive way to check is at the radiator cap, if it has one.