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Old 11-06-2002, 08:53 PM   #71
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2004 30' Classic Slideout
Fenton , Missouri
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Re: good question

Originally posted by john hd
i've always assumed that the compressed air got to it. since the accumulator is after the tee between the pump and city water. (the water plumbing is all common after the pump check valve)
It sounds like after water pressure is removed from the line, any water in the tank will be expelled by the air bladder in the tank. I would guess the key is to have proper air pressure in the bladder.

If you think about it, any residual water that freezes in the tank will expand and be accomodated by the bladder. Sort of like the ball that people throw in above ground pools when they close the pool for the winter. The frozen water pushes against the ball rather than the side walls of the pool.


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Old 11-07-2002, 09:23 AM   #72
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Acculator and other


Thanks so much for the explanation of accumulator. I bought an adaptor for city water inlet to allow use of an air compressor. At this point I intend to level the trailer and use compressed air to purge the lines, then suck the traps dry w/shop vac and add some antifreeze to the drains.

Last question....when I got the trailer it had compressed air in lines - when I would open a tap compressed air would come out. is this because someone used compressed air to purge, then shut taps with air still going to it? Once the air was on the other side of the pump check valve I assume the lines would remain pressurized. I think that water under pressure freezes at lower temp than water at lower pressure but I may be wrong. I'm just wondering if there was some rhyme or reason to keeping air pressure in the lines.

What do you think?

Thanks again,


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Old 11-07-2002, 12:52 PM   #73
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Neal, its not unusual to find air pressure in the lines. Especially in conjunction with the temperature. Air and water in the lines can expand due to temperature which can cause the hiss or some water flow.

Note also you don't need to suck out the traps, reverse the hose on your shop vac and blow the air into the traps. This will push any liquid down and out of the trap into the holding tank.

Let me see if I still remember 7th grade science. Water under pressure has a higher boiling point but I don't believe the inverse is true.

When water boils you are breaking the molecules that combine at normal temperatures to make up water. When under pressure the molecules are held together thereby keeping the water from boiling at 212 F. More pressure, higher boiling point.

Freezing does not break apart the molecular structure of water. Although one property of water is that it expands as it freezes. The part that many people forget is that water expands as it freezes but only to a point, then it contracts. So most freeze damage occurs at temperatures just below freezing. Maybe one of you science teachers knows the temperature at which the contraction starts. I've read that another property of RV antifreeze is that it contracts so even if it does freeze its volume is less that what it was in a liquid form.

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Old 11-07-2002, 01:02 PM   #74
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1999 25' Safari
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The residual pressure in your lines is probably hydrogen gas which is released from water that has been heated/cooled/heated, etc. It will pressurize your lines if the water has been in there for a while. Like leaving a hose partially full of water in the sun.

The good thing is that if your lines held the hydrogen gas, your you don't have any leaks in your lines.
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Old 02-19-2003, 03:33 PM   #75
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Well this is kind of after the fact but I happen to have the winterizing tips that came with our 1959 Caravanner.
It recomends opening all the line drains and purge the toilet valve while it's draing. I asume because it would cuase a vacuum and pull any water back out. tilt the trailer. My system is Air over water (no bladders) and I can easily hit it with an airline. I have not cycled the Grover air pump yet but it's good for about 50psi so I could close all the valves and let it pressurize then open the drain valves and let it blow out. The instruction indicate that the only ting I need to do is pour something down the shower drain because it's a castiorn peice and I otherwise don't have anything to worry about.

My only hope is that this was winterized this past season. I have only had possession for the last week. All the drain valves were open when we went and picked it up and if it wasn't it's too late now and I'll find out when I test the systems in a few weeks.

I'll see what I can do about scanning these instuctions for those of you with older A/S to have and those of you with newer A/S to laugh at
1959 22' Caravanner
1988 R20 454 Suburban.
Atlanta, GA
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Old 03-10-2003, 02:45 PM   #76
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Winterizing/layup list in Excel

To assist in laying-up/winterizing our 1988 Excella 25, I have put
my reminder list into an Excel spreadsheet. I've done this so that anyone can use it as a basis for creating a personalized list, thereby avoiding a lot of typing. If anyone wants the file, please e-mail me at nickandsandra "at", and I will reply with the file as an attachment. This site will not accept Excel files (.xls extension) as attachments. The list, with formatting altered on this site, is

Airstream laying-up procedure
1 Wash, dry, and Walbernize exterior of trailer
2 Have LP tank re-filled if one is empty.
3 Buy 3 gallons of potable anti-freeze.
4 Store load distribution bars and sway control in transverse underbody storage on kerbside.
5 Ensure trailer tire pressures are 50 psi
6 Fit wheel covers for UV protection.
7 Store outside chairs and table in rear roadside locker .
8 Lower aerials.
9 Remove all clothing, food, bedding, and "stuff", that will not be kept in trailer.
10 Fit sun protection cards in front and rear windows.
11 Turn off water heater in rear outside compartment.Heater has permanent bugscreen.
12 Remove battery from water heater re-lighter and store in trailer.
13 Turn off refrigerator, empty, and wipe interior clean. Carton of baking soda on shelf, leave door ajar.
14 Fit bug screen to outside refigerator access flap.
15 Turn funace thermostat (on wall) to "off", and remove batteries. Furnace has permanent bugscreens.
16 Turn off both gas bottles on A-frame by turning knobs clockwise.
17 Fit sun screen round gas bottle cover and A-frame.(Use old tablecloth from rear streetside locker.)
18 Ensure battery is fully charged, topped up, and clean on top.
19 Drain grey water tank and close dump valve.
20 Drain black tank,half fill with clean water, and dump again. Cl;ose dump valve.
21 Put a gallon of clean water in black tank via WC, and add a capfull of Eco-Save.
22 Remove sewage hose, wash out, and store in transverse under-body storage on streetside.
23 Turn off mains water supply at outside tap, remove hose from source and trailer.
24 Empty hose,clean exterior, join ends together, store in rear hatch.
25 Drain cold water tank by removing drain bolt in kerbside wheel arch.Replace drain bolt.
26 Add table-spoon of baking soda in a pint of water to tank. Insert plug in air vent by filler cap.
27 Open all faucets and shower head. Jam WC open with Leatherman tool above pedals.
28 Open two drain valves under flap below cupboard under sink.
29 Open drain valve in rear roadside locker. (lift handle, then 5 turns anti-clockwise.)
30 Press on valve on WC spray head for a few seconds to drain this line.
31 Turn water heater lever to by-pass. (access via rear roadside locker.)
32 Open pressure-relief valve at top of water heater, remove nylon drain plug (box wrench), drain tank.
33 Replace plug, close valve.
34 Tank water filter is under flap at base of left wardrobe. Remove top, drain, clean, and replace top.
35 Retract corner scissor jacks.
36 Lower front of trailer using front power jack until water ceases to drain from valves.
37 Lower rear of trailer using front power jack until water ceases to drain from valves.
38 Level trailer, and support with corner scissor jacks.
39 Close all valves and faucets, WC, spray head and shower.
40 Open cold water faucet in kitchen, attach tire pump to city water inlet using adapter and pump air.
41 When water stops coming from faucet, open another, then close the first.
42 Continue with all valves, faucets, spray head, and WC until all have been blown through.
43 Ensure one of these is always open, so as not to risk a burst pipe through excess pressure.
44 Stop the air pump. Close the final open valve/faucet.
45 Between the tank filter and the tank pump is a T-joint with an either/or switch. Switch to T supply.
46 Connect the attached pipe into a gallon of potable anti-freeze.
47 Switch on the pump via the rocker switch in the kitchen or bathroom.
48 Open one faucet, drain valve, WC, spray head at a time until pink anti-freeze runs steadily out.
49 Replace the anti-freeze containers as necessary.Return T switch to normal position.
50 Pour a cup of anti-freeze into each drain trap (3) and a capfull of cooking oil to prevent evaporation.
51 Dry all surfaces of sink, shower and WC.
52 Open WC bowl valve, apply silicon grease to dry valve surfaces, then close valve.
53 Place containers of drying agent at both ends of trailer, and one in sink.
54 Remove batteries from smoke detector and carbon monoxide detector.
55 Switch off LP gas detector by exit door near floor.
56 Switch off all interior and exterior lights and radio.
57 Disconnect city electric supply,store cable in rear hatch.
58 Turn off electic master switch behind sofa.
59 Disconnect cables from battery. Connect solar battery maintainer.
60 Clean interior and sweep floor.
61 Close windows, curtains and lower blinds.
62 Close both roof vents, and extractor vent in bathroom.
63 Lock all exterior storage lockers, water flap and battery locker. Replace these keys in inside drawer.
64 Lock exit door and raise step.

Best wishes. Nick.
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."
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Old 10-16-2003, 12:08 AM   #77
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Hi from the Great White North!

As the frost is now here each morning (ugh!), I winterized my '77 31' (center bath) by opening the drain valves (one under the stove area, and one at the very back where the city pressurized water hook-up comes in), opening the petcock on the water heater, and then using the big air compressor to blow the lines--during which I opened and closed all interior valves until no more mist came out of the faucets, etc. I picked-up fittings at H.D. to connect the quick-connect compressor hose to the water supply.

Being paranoid, as it can get to -40 (same in Celsius or Fahrenheit) here, I then added antifreeze by teeing into the inlet hose of the pump, adding an inline ball valve, and a hose connector in order to attach a three foot length of clear tubing through which the pump sucks the antifreeze out of the container (very fast too!). I run the pump until it comes out of the faucets.


1. Are there only the two drain valves that I've mentioned--one under the range/sink cabinet (the knob is just below the floor level, and its kind of hard to locate), and the other is at the back right next to the city water inlet? If there is one more, please tell me!

2. Does the water heater have a bypass valve from the factory, or do I need to put one in--it's very tight space between the toilet and the back of the water heater (center bath layout)?

3. Behind the bathroom sink (accessed from under the countertop) is a valve, and I can't figure out what it is for--open or closed doesn't seem to make any difference. The copper pipe seems to come from the water heater, but I can't tell for sure--only the valve is really visible.

4. Can someone please explain in quick terms how the city water pressure and the pump and water tank are compatible--why doesn't the water tank fill up when the city water line is connected? Is there a check valve somewhere? But yet, when I blew the lines with the drains open, air was escaping out of the drain tubes under the trailer--I'm confused, and my service manual doesn't show enough detail.

I hope someone has time to answer these questions, it will be much appreciated!

Gary Heebner
Prince George, British Columbia
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Old 10-17-2003, 11:54 PM   #78
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Exclamation Air compressor hazard

My old air compressor has just about given up the ghost, so I decided it was time for a new one. Shopping made me remember that air compressors that require oil shouldn't be used on fresh water lines or to provide air to anything that you don't want contaminated with oil. A small amount of oil will work its way past the piston in the compressor and become vaporized in the compressed air. Then if that air is used to blow out fresh water lines the oil vapor will condense on the inside of the pipes.

Perhaps most of you are not too concerned about this, but I strongly recommend that only oil-less compressors be used for this duty. Sorry, I haven't posted this information sooner, but it only just now occurred to me.

Out for coffee!
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Old 10-18-2003, 12:28 AM   #79
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Good point! I never thought about that--however, in my case it's okay as I have an oil-less unit. Any advice on the questions I listed?

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Old 10-18-2003, 07:11 AM   #80
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I had the same layout same year trailer. It has been a while, but this is what I remember.

1. The valve under the kitchen cabinet is the drain for the fresh water tank. Opening this valve will allow it to drain via gravity.

I think there should be a valve under your refer too. It depends if yu have rear twins or a rear double. I would look at the drain lines coming thru the belly to see where they are.

2. As far as I know there is not a water heater bypass installed from the factory.

3. No clue what this is for, it could be an additional cold water drain or the water heater bypass, but those usally are two valves. Just a guesss, but it could be a fill valve to add water to the fresh water tank.

4. The water pump is a one way pump/valve The pump pulls water out of the tank, the output of the pump connects to the plumbing coming in from the city water connection.

BTW I never winterized this unit myself, I had it done by my local brand X dealer.
Brett G
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome

Wise men talk because they have something to say; fools, because they have to say something. -- Plato

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Old 10-18-2003, 09:36 AM   #81
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water heater bypass

I just found out this past year that my sovereign has a factory installed water bypass valve. It is located under the bed and is hard to reach!
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Old 10-18-2003, 01:45 PM   #82
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Brett and Wayner1239:

Thanks for your information--I'll add it to the service manual so I don't forget for next year.

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Old 11-25-2003, 10:16 PM   #83
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An easy winterizing system

My '74 Argosy 24' had a true rat's nest of plumbing when I bought it. There was copper (in two sizes), plastic, some heater hose, corrugated metal tubing, a hodgepodge of short, a real mess. I couldn't make sense of it, so I ripped it all out and redid everything in PEX.

I wanted an easy way to winterize, too. Part of my solution is seen in the picture below (the water heater has bypass valves, which are not shown). I found this nifty 3-gallon holding tank at Boaters World. The pump selector valve is permanently plumbed to both the water tank and this tank, which is filled with antifreeze.

To winterize, I open the water tank drain valve, flip the water heater bypass valves and the pump selector valve, and run the faucets and toilet until pink flows everywhere. I keep the antifreeze flowing for several seconds to fill the traps, too.

Once I've drained the water heater, it takes me about five minutes to winterize, and about five minutes to reverse the process and clear the system for cold water use only. This comes in really handy because I use the Argosy for tailgating in the winter - I don't really have to have hot water for that. The 3-gallon tank holds enough antifreeze for 2-3 winterizing cycles.

Bob McKeown
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Old 11-26-2003, 05:30 AM   #84
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Bob, that is one slick setup. Very well done. I may have to do something like that to mine. Thinking of going down to Florida in the next few weeks, and wondered about winterizing on or before the trip back home. I think I found a solution!

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