A/C drain issue

Topic: A/C drain issue (Read 752 times) previous topic - next topic

A/C drain issue

July 12, 2012, 12:16:34 pm

I have posted this issue before and have not corrected it yet. This time I have pictures. My drains for all 3 a/c units are piped on top of coach such that they all leave the unit and then join into one long line running toward rear of coach then drains down into engine compartment. In high humidity while traveling we get alot of draining going on and when you decelerate or go down an incline all of the drain water comes forward in the long drain line and then re-enters the forward unit causing water to pur in. I have asked everyone at Foretravel how to correct this and the only suggest solution was to allow each to drain on the roof. This of course creates a new problem of water running down the side of the coach and I hate that. I was wondering if I were to insert a section of larger diameter pipe in the forward section of the long drain such that the front of the larger section had a bottom lip covering about half the opening and no such lip on the back side would this allow draining without it coming back.

Re: A/C drain issue

Reply #1 – July 12, 2012, 12:25:53 pm

I have a similar issue with my drain line. When braking or on an incline, the condensate backs up in the tubing but on mine it just goes on the roof and flow down the front left of the coach.

Is your coming inside the coach via the front A/C unit?

Re: A/C drain issue

Reply #2 – July 12, 2012, 12:30:51 pm

Gerard,

You might consider placing a check valve at each A/C to stop the forward surge but yet allow the rear ward movement of the condensate.

Another idea is to replace the forward elbow with a Tee in which the opening to the front of the coach has a 45 degree elbow to slightly elevate it and would only drain to relieve the forward surge of condensate. That water would go down the side but only when experiencing the forward surge situation.

I would like to know how you resolve this issue. All the best.

Re: A/C drain issue

Reply #3 – July 12, 2012, 12:36:15 pm

That is a good idea Rudy.

Re: A/C drain issue

Reply #4 – July 12, 2012, 12:37:56 pm

Rudy,

I like the check valve idea, but can't think of one that would work under virtually zero pressure and not "hump" above the roof (i.e. be in-line with the "on the roof" drain line). Lots of experience with them on boats, but have not run into a design that I think would work in this application.

Would be interested in one that might work.

Brett

Re: A/C drain issue

Reply #5 – July 12, 2012, 01:07:27 pm

Brett,

You are most likely right again on the check valve. Wishful thinking on my part probably.

I have used a similar system of 1/2 inch PVC pipe but I ran the drain on both sides of the units and headed for the outside edge of the roof to take advantage of the crown of the roof to promote draining. I did not get any surge into the A/C and into the coach.

The weep holes of the A/C unit dripped into PVC elbows and were not water tight to the unit.

I had the front of the drain pipes open and did once or twice get a surge out the front. When parked, all my condensate went out the back of the coach.

Re: A/C drain issue

Reply #6 – July 12, 2012, 03:00:44 pm

Maybe a ping-pong ball in a PVC fitting... tilt the fitting just enough that the ball stays aft but on deceleration the ball rolls forward sealing the inlet. Would take a little fiddling but at least it wouldn't be stick up very high.

Craig

Re: A/C drain issue

Reply #7 – July 12, 2012, 03:23:41 pm

A few thoughts.

As the flow of condensate is low perhaps restricting the outlet from the pan to a better size might work. IE: If you now have a 1/2" outlet sizing it at 1/8" might reduce back flow and still allow condensate to drain. Try it with a piece of tape over the outlet first.

Another solution might be a soft rubber flapper vale in the drain line. These will open and close at very low pressures.

Move the main drain line to the edge of the coach, by the trim rail, so that the laterals drain downhill more emptying the line faster and giving less chance of return flow.

Are you sure that it's not just the pan overflowing?

Keith

Re: A/C drain issue

Reply #8 – July 13, 2012, 12:09:37 pm

Thanks to all who replied. I believe but am not positive that it is not the pan overflowinf. My rationale is that if it were the pan, why doesn't it do it while parked. It only happens while traveling. I agree with Brett that there is not enough pressure for a check valve. I do not want an option that runs water down the side of the coach. Oh and yes it drips inside the coach through the forward a/c unit.

Re: A/C drain issue

Reply #9 – July 13, 2012, 12:20:29 pm

Gerald,

Clearly, the shorter the horizontal run, the less stored water would be in the drain system. If you have a roof refrigerator vent, it would be fairly simple to route the hoses from the forward two down through the the refrigerator vent with a hole in the refrigerator floor and basement floor to route the hose under the coach.

All that horizontal hose with water in it WILL be subject to flowing forward when decelerating and when descending hills.

Brett

Re: A/C drain issue

Reply #10 – July 13, 2012, 12:46:22 pm

Gerard,

I was just thinking about your situation and remembered a homeowner friend that had condensate leak into the house. Turned out the condensate drain through the hot attic was clogged with algae growth. A little bleach solved the clog.

Could your black piping be a warm humid habitat for algae? Just a thought.

Re: A/C drain issue

Reply #11 – July 13, 2012, 03:54:16 pm

Gerald,

I meant to move the front to rear line to the side so the laterals drain downhill into it.

Keith

Re: A/C drain issue

Reply #12 – July 13, 2012, 04:31:56 pm

Have you tried a small vane on the front edge of the pans to blow air across them when moving. At 60 mph the water may even miss the toad. Gam

Re: A/C drain issue

Reply #13 – July 13, 2012, 04:41:52 pm

Quote from: lavocat – July 12, 2012, 12:16:34 pm

I have posted this issue before and have not corrected it yet. This time I have pictures. My drains for all 3 a/c units are piped on top of coach such that they all leave the unit and then join into one long line running toward rear of coach then drains down into engine compartment.

As you know, Steve's also wanting to install something in our drain kit to prevent any flow-back. Haven't found anything yet, but we also haven't had a problem.

Interesting that our aftermarket drain kit (from Dometic) is quite different than your OEM installation. For example, ours is clear tubing and there are drain lines that run all the way to the back of the coach on each side of the A/Cs

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One of the problems we've had with ours is the nylon drain pans (they're just a little cup) becoming brittle with UV exposure. Steve's had to reglue on drain pan's pieces and replace a second drain pan.

Michelle

Re: A/C drain issue

Reply #14 – July 13, 2012, 05:39:40 pm

It looks like there is no pitch down hill with the tubing. When it first comes from the AC it should follow the crown of the roof and come as close to the outside edge of the roof as possible . Water likes to run down hill. The roof I think was built flat front to back, but crowned right to left with the high point in the center for rain run off. Gam

Re: A/C drain issue

Reply #15 – July 13, 2012, 07:42:21 pm

Maybe if the draining the condensate down over the roof is too horrible, one might consider installing a dry vac system to pull the condensate to a proper dumping area ?

Just a thought
Dave M

Re: A/C drain issue

Reply #16 – July 14, 2012, 12:17:32 pm

Another of my Rube Goldberg ideas: Why not make a slobber tube for the aft end of the tubing? Similar to the old oil sump slobber tube? Outlet end down low enough into the air flowing under the coach.
On the front end, up just aft of the front AC, install a small transparent funnel to direct air int the drain line while traveling, in effect pushing the water out the back with air and also assisting the slobber tube. The front AC could dribble into the tubing just prior to the funnel nozzle. Thus creating a venturi effect.

Re: A/C drain issue

Reply #17 – July 14, 2012, 12:43:57 pm

I agree with Gam, I think the tubing should run to the edge of the coach first then can run to the back or wherever the desired drain spot is. Would require even more pressure under deceleration and may provide the needed margin to prevent the back flow.

Another option pictured below. If you implement this, I would like to come see it!

Re: A/C drain issue

Reply #18 – July 14, 2012, 01:16:52 pm

I was at Detroit Dragway on a Tuesday when Bill Golden was buying and trying for the first time The Little Red Wagon . What a rush. Is it possible that when driving the back end of the coach is even a little high on the air bags, and there is no drainage? Gam

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A/C drain issue

July 12, 2012, 12:16:34 pm

Re: A/C drain issue

Reply #1 – July 12, 2012, 12:25:53 pm

Re: A/C drain issue

Reply #2 – July 12, 2012, 12:30:51 pm

Re: A/C drain issue

Reply #3 – July 12, 2012, 12:36:15 pm

Re: A/C drain issue

Reply #4 – July 12, 2012, 12:37:56 pm

Re: A/C drain issue

Reply #5 – July 12, 2012, 01:07:27 pm

Re: A/C drain issue

Reply #6 – July 12, 2012, 03:00:44 pm

Re: A/C drain issue

Reply #7 – July 12, 2012, 03:23:41 pm

Re: A/C drain issue

Reply #8 – July 13, 2012, 12:09:37 pm

Re: A/C drain issue

Reply #9 – July 13, 2012, 12:20:29 pm

Re: A/C drain issue

Reply #10 – July 13, 2012, 12:46:22 pm

Re: A/C drain issue

Reply #11 – July 13, 2012, 03:54:16 pm

Re: A/C drain issue

Reply #12 – July 13, 2012, 04:31:56 pm

Re: A/C drain issue

Reply #13 – July 13, 2012, 04:41:52 pm

Re: A/C drain issue

Reply #14 – July 13, 2012, 05:39:40 pm

Re: A/C drain issue

Reply #15 – July 13, 2012, 07:42:21 pm

Re: A/C drain issue

Reply #16 – July 14, 2012, 12:17:32 pm

Re: A/C drain issue

Reply #17 – July 14, 2012, 12:43:57 pm

Re: A/C drain issue

Reply #18 – July 14, 2012, 01:16:52 pm

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