Hot Water Heater Clean Out

[Kevin Erion]

Just wonder what the normal practice for cleaning the sediment out of the hot water tanks. Is there a time schedule one should follow to keep things under control? I know some of this will be based on the hardness of the water going into the coach but I assume everyone must need to clean these tanks?
Kevin

[bill&jody]

just how do you plan to flush this thing, kevin? i chlorinate periodically, circulate the water and then drain everything, but doubt it flushes out the tank jiz. i've also thought about changing the anode, but i couldn't get the fitting out and i was a bit anxious about breaking something. i will prob'ly be a bit more, er, aggressive with it when i get back to Fla. where i have better access to parts and a place to work.

my water heater a 20 gal model and looks just like a plain old round, household water heater with no enging jacket water connection. its a marine model tho, a raritan. no i don't think it was original.

[Kevin Erion]

My 99 Marathon has 2 10 gallon Atwood heaters. I asked them and they said to disconnect from the water supply and the feed to the bus and then add 6 gallons of white vinegar and 4 gallons of water to each heater, turn the 110 volt heat on and drain and flush after 24 hrs. I did not separate the 2 heaters but I did disconnect from the supply and the bus. I made some adaptors to hook to a garden hose so I can flush in either direction, what a pain! Before adding the vinegar I did a quick flush just to test and I was shocked at how much white sediment came out.
I am going to do the drain and flush today and then do it 1 more time. I will report back on how much I see on this flush. I am trying to get the heat transfer from the Wabasco to the tanks better, my hot water from the Wabasco is not as hot as when the 110 volt or when driving. Atwood said that the sediment inside will not allow the heat transfer to be very effective.
I also found that Marathon buys a dual heat transfer unit, you can run the coolant thru the tube that goes inside the water tank or the tube that runs along the outside. Marathon told me they always use the outside tube so they will never let the coolant mix with the house water in the event of a leak of the tube that goes inside the water tank. Of course on mine, it was plumbed to the tube that goes on the inside---No, I didn't have a leak but the flow of coolant was running to slow and was causing the Wabasco to shut down to early due to an overheat inside the Wabasco.
To try and find the blockage I bypassed the water heaters after trying other things as well as a new recirculation pump. When the water heaters where out of the loop, the Wabasco ran perfect, now I found that the Atwood water heaters had a nylon coating on the first 2 inches of these tubes and the nylon was breaking down and causing the restriction. The tubes the are on the outside do not have this nylon coating. Lucky for me I just moved everything back to the outside tubes and the Wabasco is much better but I am still not convinced it is perfect. I am not getting the water as hot as I think it should be which would be due to a heat transfer issue. I also am checking the Webasco to see how many times it cycles during the heat period. I have to get the tanks flushed out first before refiring the Wabasco for another test, that will be tomorrow--what a fun project!
Kevin

[Jon Wehrenberg]

Kevin....are not the heat exchangers used by the Webasto which limits its temps to 160 the same ones used by the engine coolant which will normally run 195 plus?

Also the electric elements are inside the tank itself so there is no exchange except right at the water contact on the element.

We also see water temp differences because the bus runs so much hotter than the Webasto.

[Kevin Erion]

Jon, yes they are the same however if the coolant flow is slowed down by a restriction the Wabasco has an overheat shutdown inside the boiler at 190 or 195. The water heater also gives you the option of running the coolant thru tubes that go inside the tank, heating the water just like the electric element or the tubes that are welded to the outside of the water tank. Not very efficient but safer than coolant mixing with your shower water if you had a interior tube fail.

I do understand that when you are driving the water will get much hotter but the Wabasco should still provide hot water that will allow a shower. I would think a water temp somewhere about 105 to 115 with the Wabasco, I never checked before but that sounds correct. I measured about 92 after the Wabasco was running for over 1 hour, not high enough.

I did flush the tanks today, I can't believe the amount of white build up that came out. I refilled the tanks again with 12 gallons of vinegar and the rest with water and will flush again in the morning. I will then hook the house back up, refill the tanks, fire up the Wabasco and see what happens. On these projects I seem to take one step forward and two backwards, I hope for a little forward progress, it's just not that complex--I think.
Kevin

[Jon Wehrenberg]

I think you have a restriction in the flow of coolant around the HW tank. Some owners would have the over pressure pop off valve open when the tank got up to engine coolant temperatures, probably because they failed to properly pressurize the bladder in the expansion tank. If there was no bladder, there was no room for the expansion of the hot water so hydraulic pressure opened the pop off safety valve.

Rather than correcting the root cause, some folks would close a valve on the engine coolant line to such an extent coolant flow was severly restricted.

You aren't hurting anything cleaning the tanks, but I would suggest you check the pressure on your expansion tank. On mine with the water system pressure at zero my pressure should be around 30 PSI. That makes your pump run less frequently (but for a longer time when it does run) and it provides ample expansion for your hot water if in fact you do have closed valves.

[Kevin Erion]

Jon, thanks, I have checked all valves to make sure they are open. I will check the psi in the bladder and see what it is, I will try 30.
Thanks again,
Kevin

[MangoMike]

Kevin,

You've motivated me to clean out my tanks. Thanks a bunch.;)

On the hot water heaters which ports are inside and which ones are outside for the webasto - top or bottom ports?

Thanks

MIke

[dalej]

Which bus Mike? :)

[Jerry Winchester]

Dale,

That was way harsh.

[Kevin Erion]

Mike, Middle ports go inside the tanks and bottom ports go along the bottom outside the tanks. another lesson I learned today, Marathon modifies the wiring on the top water heater so that it is the first heater to turn on and only after it gets to about 140 degrees then it turns off and the bottom heater turns on. The bottom heater uses all the standard Atwood controls and the top one uses some other control that Marathon installs.
I would be very curious to know which ports your coolant runs into from the Wabasco, for all the Marathon owners with 98-00 vintage units, please let me know.
Thanks a bunch, Wabasco-Atwood heater 101.
Kevin

[JIM CHALOUPKA]

Kevin, where do you buy the Vinegar by the gallon?

[Kevin Erion]

Smart & Final restaurant supplies.

[MangoMike]

Kevin,

I'm having trouble finding the right size connectors to hook up to the Atwood to flush the system. Can you provide the sizes you used. Went to Campers World, HOme Depot and plumbing supply with no luck.

Thanks

Mike

[merle&louise]

MM & Kevin,

Does Marathon install a water heater in addition to or as a back up to the Aqua Hot?

[MangoMike]

Tuga,

We have a Webasto and not Aqua Hot. So that the Webasto sends heated coolant to a jacket around the (2) 10 gallon water heaters, when in use. Otherwise you use 110v electric to power the water heaters.

mm

1801
sampling the Webasto