Have you experienced a slow drain on your Quantum Kitchen sink?

[Bob Nodine]

Since we purchased our 2022 JM31 new the wife has been complaining about the very slow drain on the kitchen sink. I did a little investigating and on our coach the kitchen sink and the bathroom sink share the same flex drain into the gray tank because they are both in the big slide. My first thought was some pinching in the flex drain but the bathroom sink drains just fine so I dismissed that. On the kitchen sink the P-trap is up against the bottom of the sink and by design holds water. I tried to convince my wife it was just the P-trap holding water. After using the sink for some time I came to realize that the sink just drained very slow. One night with the sink half full of water I reached inside the cabinet and unscrewed the vacuum breaker and the water rushed out of the sink like crazy. Armed with that information I went to Lowe's and purchased a high quality Studor Vent and screwed that in place. I was certain that would solve the problem but it did not. The sink still drained slow. For the time being we have removed the vacuum breaker altogether and since we have not been experiencing any odor plan to leave it off. I am assuming the drain system is not producing adequate force to open the vacuum breaker. I doubt that Thor cares because they dropped the JM31 floorplan.

[Zenith]

We don't have a quantum, but our magnitude has a full wall slide with a kitchen sink and we don't have any slow drain issues. If you're having slow drain issues even with a high-quality vent like the studor in place I'd guess there's a pinched or clogged line somewhere along the way.



On the plus side - this is just grey water - it won't ever stink much if you drain your tanks regularly.



On the negative side, a slow drain means your sink is slow to that grey tank. Retrofit valves like the studor open easily from my experience - I'd guess there's a clog or a pinched flex pipe to fix.

[Bob Nodine]

Originally Posted by Zenith

We don't have a quantum, but our magnitude has a full wall slide with a kitchen sink and we don't have any slow drain issues. If you're having slow drain issues even with a high-quality vent like the studor in place I'd guess there's a pinched or clogged line somewhere along the way.



On the plus side - this is just grey water - it won't ever stink much if you drain your tanks regularly.



On the negative side, a slow drain means your sink is slow to that grey tank. Retrofit valves like the studor open easily from my experience - I'd guess there's a clog or a pinched flex pipe to fix.

Nope, both sinks have hard PVC drain pipe and are Teed together before the flex line. If you trace back from the Tee the PVC pipe to the vacuum breaker is a straight run with a little slope. The bathroom sink had no problem opening the vacuum breaker. If there is a clog in the section between the vacuum breaker and the Tee I would think it would also slow the bathroom sink. It might have something to do with the level drain from the sink to the vacuum breaker. See photo below.

[chunker21]

One problem is lack of slope in the drain lines. If you "level" in a right side low condition even a bit, now you are trying to drain uphill. You bought poorly designed drain system and there isn't much you can do with is short of rebuilding the whole thing which will require cabinetry work also. This is also an example of sloppy and or non existent QA on thor's part and why they'll use the common "it's normal" excuse. Their isn't going to acknowledge there's a problem because then the "town" the situation.

[Grumpy Grampa]

Not enough slope, unscrew wall bracket, you should be able to lower a little, just be careful, then reattach.

[Chateau_Nomad]

Agree with lack of slope. In addition to what Grumpy Grandpa said, you could gain maybe an inch by shortening the straight piece below the Tee. You'd have to replace the tee. Doesn't sound like much, but in that short run, you be surprised... IF that's the issue... ?

But if you're bathroom sink on the same run will "suck" the vent open, you likely have a flow issue caused by that screwy plumbing.

[chunker21]

Originally Posted by Grumpy Grampa

Not enough slope, unscrew wall bracket, you should be able to lower a little, just be careful, then reattach.

Might be worth a try if he can get to the area. Looking at the picture, over next to the outside wall just below that "T" and above the 2 45s there might be an inch or 2 that could be cut out. That would increase the slope a bit. That's where the cabinetry issue may come in though.

[chunker21]

Originally Posted by chunker21

. Their isn't going to acknowledge there's a problem because then the "town" the situation.

Correcting to say what I wrote before spell check fixed it. "Thor isn't going to acknowledge there's a problem because then they "own" the situation.

[Bob Nodine]

I agree guys that there is not only not enough slope than is no slope at all on the kitchen sink drain from the sink to the Tee. I have been eyeing that ever since purchase but my main problem is access. May be able to take out the stove and two drawers under the stove and get to the back wall.

[Galobo]

Originally Posted by Bob Nodine

Nope, both sinks have hard PVC drain pipe and are Teed together before the flex line. If you trace back from the Tee the PVC pipe to the vacuum breaker is a straight run with a little slope. The bathroom sink had no problem opening the vacuum breaker. If there is a clog in the section between the vacuum breaker and the Tee I would think it would also slow the bathroom sink. It might have something to do with the level drain from the sink to the vacuum breaker. See photo below.

Your picture looks like you do not have enough fall to support the drain. If you could lower the drain and raise the vent I feel like your sink would drain faster., easier said then done.

[Bob Nodine]

Originally Posted by Galobo

Your picture looks like you do not have enough fall to support the drain. If you could lower the drain and raise the vent I feel like your sink would drain faster., easier said then done.

Agree 100% and that has been my thought since we took delivery in May. The main obstacle is getting to the plumbing to make the change.

[chunker21]

Originally Posted by Bob Nodine

Agree 100% and that has been my thought since we took delivery in May. The main obstacle is getting to the plumbing to make the change.

It was an expensive method but this is how I changed it.

https://www.thorforums.com/forums/f4...xes-29412.html

[CHS]

Originally Posted by Bob Nodine

Nope, both sinks have hard PVC drain pipe and are Teed together before the flex line. If you trace back from the Tee the PVC pipe to the vacuum breaker is a straight run with a little slope. The bathroom sink had no problem opening the vacuum breaker. If there is a clog in the section between the vacuum breaker and the Tee I would think it would also slow the bathroom sink. It might have something to do with the level drain from the sink to the vacuum breaker. See photo below.

I came across this. It states (for unknown reasons) It must be installed at least 6 inches above the trap arm (horizontal pipe after the trap).
By your photo, I cannot make out if it is or not.

[chunker21]

Originally Posted by CHS

I came across this. It states (for unknown reasons) It must be installed at least 6 inches above the trap arm (horizontal pipe after the trap).
By your photo, I cannot make out if it is or not.

Drain pipe is probably 1.5" and the measurement of the vent drawing you supplied shows 6" minimum from the top of the horizontal pipe. Meaning maybe 3" that thor put the vent. Not surprising thor couldn't install anything correctly or to spec. An example also is the slide toppers or awnings. On the omni the manufacturers specifications for mounting the awning rail was 3-4", as I recall above, the awning roller but they were flat. Meaning no draining for the awnings either.

[Bob Nodine]

Originally Posted by CHS

I came across this. It states (for unknown reasons) It must be installed at least 6 inches above the trap arm (horizontal pipe after the trap).
By your photo, I cannot make out if it is or not.

Looks like you may have discovered the problem because the vacuum breaker is only about 3 inches above the horizontal pipe from the P-trap. See post #3. In that photo the vacuum breaker is not present but it screws into the vertical pipe near the back wall. As you can see definitely under 6 inches.

[chunker21]

Originally Posted by Bob Nodine

Looks like you may have discovered the problem because the vacuum breaker is only about 3 inches above the horizontal pipe from the P-trap. See post #3. In that photo the vacuum breaker is not present but it screws into the vertical pipe near the back wall. As you can see definitely under 6 inches.

Bob I was assuming that the vacuum breaker was the top piece of that pipe but I understand you are saying that's just a connector and probably open with nothing on it??

[Bob Nodine]

Originally Posted by chunker21

Bob I was assuming that the vacuum breaker was the top piece of that pipe but I understand you are saying that's just a connector and probably open with nothing on it??

Correct because I removed the vacuum breaker for the time being so the sink will drain properly. We are not having any odor issues and as long as we don't I may not worry about it and just leave it off. Time will tell. It is a new camper and there has not been much in the way of food particles in the gray tank to cause odor.

[chunker21]

Originally Posted by Bob Nodine

Correct because I removed the vacuum breaker for the time being so the sink will drain properly. We are not having any odor issues and as long as we don't I may not worry about it and just leave it off. Time will tell. It is a new camper and there has not been much in the way of food particles in the gray tank to cause odor.

That likely will come regardless how careful you are. I live in the country on a septic tank and as such don't feed the sink drain food. In the RV we wipe plates with the paper towels into the garbage before they go into the sink.

Couple suggestions for the drain/vent. Go to your faviorite hardware and get a good quality vacuum break and add an extension to get it higher. RV manufacturers use the cheapest component available, thor especially, and maybe a better one will help the issue. When you took the OEM piece off did that help the draining any?

[Rybie]

I don't have any pictures but when our quantum began draining slowly, I ended up taking the drainpipes out.

what I found was the design of the connection from the two sinks had very little opening. The pipe coming in had half the downtube for each sink, minus the material wall thickness. Also, some plastic from the manufacturing process was reducing it further. When I cleaned out that and the food that had accumulated it drained well.

I'm probably not describing it very well but hopefully you can figure it out, or ask me more questions.

[Bob Nodine]

Originally Posted by chunker21

That likely will come regardless how careful you are. I live in the country on a septic tank and as such don't feed the sink drain food. In the RV we wipe plates with the paper towels into the garbage before they go into the sink.

Couple suggestions for the drain/vent. Go to your faviorite hardware and get a good quality vacuum break and add an extension to get it higher. RV manufacturers use the cheapest component available, thor especially, and maybe a better one will help the issue. When you took the OEM piece off did that help the draining any?

If you look back at post #1 you will see that the first thing I did was go to Lowe's and buy a high quality Studor Vent to replace the cheap one Thor installed. It did not solve the problem. At the time I was not aware of he minimum height above the P-trap requirement so have not yet tried an extension to raise the vacuum breaker. Will look into that but there is not much head room between the pipe and the bottom of the countertop.