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Winterizing and Atwood Water Heaters
Winter storage in unheated shop Alberta Canada, this is the procedure i followed to winterize the Marathon,
Lowest recorded temp was minus 39 Celsius throughout the winter.
Fresh water tank drained, Black and Grey Tanks drained and flushed.
Water heaters were not working but were drained and inlet and outlet pipes removed, water pump # 2 was removed and fittings capped.
Pump #1 was used to pump approx 10 LTS of RV antifreeze through the hot and cold water lines removed from water heaters, lines were fitted with isolation valves to trap antifreeze in system when finished, each manifold outlet was cracked open and checked for antifreeze and the re tightened, Shower head removed, all faucets opened until antifreeze flowed, toilet flushed until pink antifreeze was present.
Ice maker disconnected at manifold and line blown down with compressed air, same procedure was followed for Dishwasher and washing machine, antifreeze then poured into base of dishwasher and into powder mixing tray of washing machine, insta hot lines removed and blown out.
All water lines to accumulator removed and drained, all non required fittings non return valves in bays disconnected and drained.water filters removed, all of the above was completed with approx 10 lts of RV antifreeze and i could probably have used slightly less, pouring excess down shower and sink drains only puts it into the tank.
The Atwood water heaters were replaced in 2016 but were not working when i purchased the coach, i confirmed that the top thermostat switch was receiving 115 volts and then removed the heaters as one unit.
I removed both heating elements and bench tested, both good, heating elements are held into water tanks by 4 bolts, when removed the threads in tank retaining area pulled out, tank material is a soft alloy, i refitted both heating elements with nuts and bolts, nuts when reduced slightly in thickness will fit behind original threads to allow tightening.
Top thermostat switch had failed along with the lower hi limit temp switch , both items found on Amazon and replaced, total cost was $43.
The drain points on the Atwood tanks are above the lowest water level, approx 1.5 gallons of water is still present in tanks, i removed the heaters in march and both were still frozen, the tanks are cylindrical and seem to be able to withstand freezing when partly drained ?
After fitting the new thermostat switches i rebuilt the tanks as stacked one on top of the other, replaced the insulation, filled with water and bench tested for a day before refitting into coach, operation is interesting as top tank has to reach set temp of thermostat and then power is sent to lower tank, this then heats up and power is again transfered back to top tank, if water is drawn off top tank whilst lower tank is heating temp drops in upper tank and power is again sent to top tank as the priority unit, clever
Next winter my coach will be in heated shop so this will not be carried out again, i thought that i would post how i have done it as it may hopefully assist someone who may need to winterize, i have not been able to find a lot of available info on winterizing the Marathon as i guess most owners live in sensible climates !
Regards
Gordon
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1 Reply
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Well done Gordon…
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