Fresh Water Tank Removal Project 86 Limited

[dbj216]

I have a fresh water leak in the pump pressure circuit. I traced it to the "T" connecting the low point drain valve to the pump circuit. I call this circuit my "main water line". This fitting is impossible to repair as it is below the floor, and above the fresh water tank. Great. Photo 1 below shows the line under the microwave cabinet.

So this winter I have to remove my freshwater tank to gain access to the plumbing. I'll just make a project out of it and replace this grey polybutylene plumbing from bathroom to galley with PEX tubing red and blue. This will surly cause more problems for me.

I'll need your help with this project. Never start, never finish so here we go.

David

[HiJoeSilver]

I would replace as much of the PBX with PEX as you possibly can when you do the project. It gets brittle with age even without the chlorine component. There was even a class action recall but only for homes, ended a while ago. PEX is pretty easy to work with. Look at what's there and make a shopping list of fittings.

[dbj216]

Yesterday I jacked up the trailer. Then I disassembled the fresh water fill inlet hatch along with the little vent line. Today I loosened the 14 cap screws that hold the pan to the frame. I had to move propane line along the frame rail as it was in the way of the cap screws.

I had no idea how to drop the fresh water tank. I put my floor jack under it and let it down. And down it came. Only the pan holds this tank in place.

I also found the usual mummified mouse. He died right next to my dryer sheet I stuffed down there years ago. I gave him a proper burial, little cross and all. Mice love Airstreams. And Airstream does such a great job of making entry doors and hallways for them.

David

[dbj216]

Hi HiJoSilver. I did PEX from the fresh water inlet, water heater, bath and shower several years ago. Now I can finish the job.

I need some advice. I have a desire to plumb it in 1/2" PEX tubing instead of 3/8". I think I'll have less pressure drop, but realize it will take longer go draw hot water at the galley sink. I only hope there is room between the tank and the floor to do this.

David

[dbj216]

Here is how the plumbing snakes between the street side bath, under the fridge, under the floor, and over to the curb side 12v pump and freshwater tank inlet.

There are three lines; one for pressure supply, one for cold, and one for hot.

The second photo is the three low point drain valves. One of these tees was rubbing against the frame rail and started to leak. I'm thinking I don't need these low point drains or the plumbing that goes with them. I've had the trailer 11 years, mostly in Minnesota, and I never used them to winterize. I prefer the blowout method, and then pump full of RV antifreeze. I think low point drains are rather ineffective.

David

[HiJoeSilver]

Originally Posted by dbj216

Hi HiJoSilver. I did PEX from the fresh water inlet, water heater, bath and shower several years ago. Now I can finish the job.

I need some advice. I have a desire to plumb it in 1/2" PEX tubing instead of 3/8". I think I'll have less pressure drop, but realize it will take longer go draw hot water at the galley sink. I only hope there is room between the tank and the floor to do this.

David

I think you'll be able to route the 1/2" PEX ok. If you need to you could probably route it better than original.
Volume difference between 3/8" and 1/2" is not significant on water needed to draw. Definitely less flow resistance though.
Can't believe they ran that much under the floor. Only under floor pipe I had was pump suction from street side to curb side. Moving all above floor as part of my full monty.

[dbj216]

I imagine they ran it under the floor to save piping and improve drawing hot water from the heater. I don't know if under the floor fresh water plumbing is still done. All my drain lines are above floor except the dump valve manifold.

I'm planning on 1/2" PEX flexible tubing, the blue and red. Anyone know what the smallest bend radius I could use with this stuff? I would like to avoid a couple of 90 degree elbows if possible.

David

[dbj216]

Here is a photo of the tank and pan. The tank interests me some as I worked in a rotomolding shop for a while. The tank is 24 wide, 9 1/2 high, and 53 long and has a volume of 48 gallons. Let's see, that's about 380 pounds of water. Somebody tell my wife we don't need to tow with a full freshwater tank. A half a tank will last a long while. I don't like the extra weight. She never wants to run out of water for morning coffee.

The tank was molded by Inca Plastics in California. They are one of the original rotomolders and specialize in the RV industry. This tank has several spin weld fittings on it. The tank shape leads me to think other folks use this tank for other RVs as there are features that are not used in my trailer, like the square notch in the side of the tank. I'm sure the tank is molded from polyethylene material. Tough stuff that.

I purchased waste water tanks from Inca Plastics for my Trade Wind. Inca served me very well.

You can see the fresh water fill hose (green) and the water pump "vacuum" tube connected to the bottom of the tank. You can also see the infamous freshwater drain port on the bottom of the tank too. I have removed the nipple and valve that is mounted on the outside of the pan. Had to to get the tank out of the pan. You can see the access panel in the bottom corner of the pan.

One thing I don't like is plastic tapered pipe threads. They are very easy to cross thread, and they almost always leak. I think even a molded hose barb is better than plastic pipe threads.

Maybe this will give some folks a perspective of what is under that floor.

David

[cliffcharb]

Originally Posted by dbj216

I imagine they ran it under the floor to save piping and improve drawing hot water from the heater. I don't know if under the floor fresh water plumbing is still done. All my drain lines are above floor except the dump valve manifold.



I'm planning on 1/2" PEX flexible tubing, the blue and red. Anyone know what the smallest bend radius I could use with this stuff? I would like to avoid a couple of 90 degree elbows if possible.



David

Probably about 4-6 inches. The big box stores sells corner supports that the pex snaps into. We used these when we redid our plumbing on the 81 in a couple spots.

[dbj216]

Thanks for the information and the tip on the corner supports. I will have to look for them. I'm just interested in saving some 90 degree elbows.

David

[dbj216]

Here is a photo of the offending Tee in the fresh water plumbing circuits. It is the output pressure line from the pump.

I slobbered epoxy on it reaching under the floor from the galley in hopes of plugging the leak. And it seemed to work for a year or so. But it started leaking again this summer.

I don't know yet the cause of the leak. It was rubbing on the frame rail which is a suspect. But it could be a freeze crack, loose cinch clamp, or some other cause. I may never know for sure as the epoxy may have "covered up the evidence."

To get the fresh water lines under the floor, Airstream installed a 90 to head down, then a Tee with a shut off valve built in as the low point drain, and then another 90 to head under the floor. The same two 90 elbows are on the three lines going up and over to the bathroom. I'm going to try to snake PEX tubing in a "S" bend to avoid these 90 degree elbows. Or I might have to use one 90 elbow, and then radius bend the PEX once I get it above the floor. The street side goes over the wheel house cover to the bathroom. The curb side goes under the microwave cabinet to the kitchen sink cabinet and then to the kitchen faucet. The third line runs under the wardrobe floor to the pump.

David

[dbj216]

I spent some time "disconnecting" the poly plumbing runs from the PEX bath plumbing I did some years ago. I found the "push to connect" or PTC connectors I used did not want to disengage. You can see one of them in the photo.

It is a bunch difficult working behind the bath vanity, and will be even more challenging running new plumbing under the shower and over the wheel well housing, under the fridge, and then down through the floor. Kinda like building a ship in a bottle, or kinda like working on my old Lotus. Tight confines.

It is also difficult to break the PEX cinch clamps in tight confines. But I was able to disconnect the three lines I plan to replace. Tomorrow I will pull the old grey plumbing lines out.

David

[dbj216]

This is likely the most boring thread on Air Forums. No tow vehicle debates, no hitch debates, no travel logs, nothing exciting. Who cares about a plumbing leak?

I guess I'm doing it to give some fellow Airstreamers a little insight to the fresh water tank and the challenging plumbing routes.

Today I removed the last of the old polybutylene plumbing lines. It was a challenge pulling them from under the fridge. I found they were strapped to the wheel well cover, which is totally inaccessible. But I yanked hard and out they came. Whew!

With the old lines removed from galley sink to bathroom, I can now start plumbing new lines. I'm going to try to minimize fittings and joints to help eliminate leaks.

David

[dbj216]

I was sweating it, but I managed to thread three new PEX lines from the bath to below the fridge cabinet. The three lines are "main" from the 12v pump, hot, and cold to the kitchen sink. It is a tight fit, and it is essentially a job done in the dark.

I will bend them 90 degrees, then install an elbow, and route them down through the floor and under the fresh water tank.

David

[dbj216]

I got a little more completed today, after my nap of course. I now have new PEX from the bath to the galley. I was able to eliminate 3 of 5 elbows which should reduce the pressure drop a bit. I also eliminated the low point drains as after 10 years of ownership, I've never used them, nor would I trust them. One of the tees to these three drains was leaking, which was the cause of this project.

I did winterize my trailer with the usual compressor line blow and was please there was no water in the lines I removed. There was water in the two lines to the 12v pump but these two lines are not in play during a "city water" air blow. They get winterized when I pump RV antifreeze throughout the system with the pump.

I'm going to replace the old 12v pump too since I'm at it. I'm thinking a Surflo revolution 4048. I'm also going to move the pump closer to the tank to reduce the length of the suction line. Might help it prime a bit easier.

David

[dbj216]

Did a little more today, again after my nap. The nap is okay as we have an extra hour this weekend due to daylight savings time "fall back'.

Finished running the new PEX to the galley sink. I also ran the water "main" to the pump output port. Tomorrow I'm going to shop for a higher flow pump that might be a bit quieter. I'll use the old one in my son's trailer.

I'm going to move the pump closer to the fresh water tank. The previous layout had about 5' of tubing to the vacuum side of the pump. I'm going to reduce it to maybe 2'. I may not put the pump guard strainer back in. My fresh water is filtered going into the tank.

I have omitted the low point drains, and I am eliminating elbows where I can due to the flexibility of the 1/2" PEX.

Really boring stuff eh?

David

[woodfox45]

Not boring at all you are doing a great job .
Les Grace

[dbj216]

Thanks woodfox45. I'll know how good I'm doing when I test it for leaks.

It is a lot of work for an amature. I bet an experienced Airstream tech could do this job in 8 hours.

David

[woodfox45]

Originally Posted by dbj216

Thanks woodfox45. I'll know how good I'm doing when I test it for leaks.

It is a lot of work for an amature. I bet an experienced Airstream tech could do this job in 8 hours.

David

8 hours x $150./ hour you are saving a lot of money .
Les

[slowmover]

Need to do this on my vintage kin. Some of the same problems. Thanks for the detail and pics. The trouble taken to post it all.

I'll "cure" the boredom factor: towing with this fresh water tank full increases trailer stability. No ifs, ands, or buts. And there won't be any measurable MPG penalty.

Full water and propane are basics, IMO. Both systems substantially exceed the electrical system in importance.


1990 35' Silver Streak
2004 555 Cummins