Function of "blow off" pipe run?

[CA_Tallguy]

Hi all - in my trailer, the previous owner updated plumbing to pex/pvc but didn't run it all within the pan. I may be redoing some of it and I wondered if you can tell me what the function/need is for a pipe run that seems to just spurt water out under the trailer? Is this a standard pipe run on airstreams that the previous owner replicated?

In the attached photo you can see the incoming city water line and a couple valves. The first valve seems to turn on/off the city water. Just after that, there is another valve that I believe just outlets under the trailer.

What on earth would that be needed for? The only thing I can imagine is to release pressure in the plumbing system. Is it really necessary?

Or maybe it is to bleed air out of the system?

Thanks in advance.

[Lumatic]

It looks like a low point drain used for getting all the water out in the fall for winterizing and draining the antifreeze in the spring.

[CA_Tallguy]

Interesting. That may be what he was trying to do but I don't think it is low enough. Wouldn't it need to be below the fresh water tank? Being above the floor, it is also above that tank. I guess it could drain stuff above the floor in the plumbing though.

[Nuvite-F]

Originally Posted by CA_Tallguy

Wouldn't it need to be below the fresh water tank? Being above the floor, it is also above that tank.

Not sure how yours is plumbed, but in every Airstream that I have seen, the freshwater tank is above the floor. (Also, it has its own separate drain.)

Those are definitely low point drains.
.

[Lumatic]

There are usually 2 low point drains. One in the front for the water tank, and one in the rear.

[Lumatic]

Originally Posted by Nuvite-F

Not sure how yours is plumbed, but in every Airstream that I have seen, the freshwater tank is above the floor. (Also, it has its own separate drain.)

Those are definitely low point drains.
.

Since the 60s freshwater tanks have been below the floor in the bellypan, although I don't know about newer models.

[Nuvite-F]

Originally Posted by Lumatic

Since the 60s freshwater tanks have been below the floor in the bellypan, although I don't know about newer models.

Oh?

In our 1980 Caravelle the freshwater and blackwater tanks are above the floor. The greywater tank is below the floor so that the shower can drain into it.

Our 1960 Pacer was the same, except it didn't have a greywater tank.
.

[rogerdodger]

Originally Posted by Nuvite-F

Oh?

In our 1980 Caravelle the freshwater and blackwater tanks are above the floor. The greywater tank is below the floor so that the shower can drain into it.

Our 1960 Pacer was the same, except it didn't have a greywater tank.
.

So is my Argosy. However, since the freshwater tank has it's own drain valve, I would think one low level drain is enough for winterizing. But probably not a problem in Hollywood, LA area.!! Freezing?

[CA_Tallguy]

Originally Posted by rogerdodger

But probably not a problem in Hollywood, LA area.!! Freezing?

It has barely been getting into the 70's lately (I'm down camping in san diego) so YES! LOL My heater has been running at night. It's awful.

[CA_Tallguy]

Originally Posted by Lumatic

Since the 60s freshwater tanks have been below the floor in the bellypan, although I don't know about newer models.

Yeah, I'm pretty sure mine is in the belly pan. I've only owned it a few weeks so far and this is my first airstream. But I've explored the ol' girl pretty well, at least in the main cabin area. I suppose that I might have overlooked it. I would love to inspect it along with the other stuff that I am assuming I can't get to very well in the belly pan.

[jdalrymple]

Does the line coming from under the cover lead to the pump?

Not all early trailers had a fresh water tank drain.

In my '81 the only way to "drain" the freshwater tank was to pump it out with the water pump. There was a valve that opened to allow the flow of water to exit the trailer that did funciton in the manner you describe...it simply was an open pipe under the trailer.

Regards,

JD