Installation of Dometic 320 Toilet

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Installation of Dometic 320 Toilet

May 23, 2015, 06:00:13 pm

Working on installing a new Dometic 320 toilet. The biggest problem has been the longer bowl interferes with the clothes hamper door behind the toilet. However, I have now discovered a bigger problem, the toilet flange.

I removed the old Thedford Toilet, Bravura I think. It was sitting on a Thedford Toilet Riser, which raised the height of the toilet about 2.5". When I test fitted the new toilet, it did not appear to go down to the floor (even without the foam seal donut). The PO had tile installed as a factory option at purchase time.

The first and second photos show what remains when the brass flange is removed. The ABS closet flange appears to be one piece of ABS that narrows to 3" and drops straight down into the top of the black tank. The brass flange holds the T-bolts that come through the base of the toilet and are used to tighten the toilet in position. My problem was that the height of the ABS/brass flange sat too high for the toilet to fit to the floor.

The third photo shows the bottom of the new toilet. It looks like it is designed to be supported primarily by the reinforced areas on each side, and the edges of the toilet base only come in contact with the floor to help stabilize the toilet. When the T-bolts are inserted, you can push the front down, but then the back is about 1/2" above the tile.

The fourth photo shows a closeup of the toilet flange assembly. It reveals that there is a ring of plywood (about 1/2" thick) between the original floor and the ABS flange. It is free to spin now, but when the screws are inserted through the flanges, it would be solid. This might have been to raise the height of the flange above the tile, but it looks like that it is what is preventing the new toilet from being installed properly. (It also might have been to repair a problem with the floor, but since it was an original factory option, I doubt that was the case.)

I tried prying on the edge of the ABS flange, but it would only move a little bit. It was also willing to go back down. At this point, I was thinking that it was just a one-piece unit with about an 18" tailpiece. If I could remove it, I could just remove the wood ring and put a new flange/tailpiece into the top of the black tank. In looking at ABS flanges, I found what appears to be the identical item on Amazon. The one I now have has Sealand Technology Inc and a 6-digit number, 345892, embossed on it. I found a Dometic 3" Bolt Closet Flange socket, with the part number 307345892. See the last photo.

Amazon.com: Dometic 307345892 3" Bolt Closet Flange Socket: Automotive

Unfortunately, it looks like it is designed to have a tailpiece attached. That means it could be attached to something at the black tank end, and not just a force-fit or insertion-fit. So now I need some help from all you experienced guys and dolls.

Have any of you removed this ABS toilet flange? What is involved?

Although not trivial, I could probably drill/cut/chisel enough of the wood ring to remove it. My hope is that the existing assembly might be flexible enough to let me then screw it onto the original floor. This would let me install the new toilet at the proper level (I think).

Is there a better way of removing the tailpiece from the black tank?

Is there any way of accessing the top of the black tank?

If I can remove the existing flange, I would like to try installing an offset flange if possible. This would possibly let me solve both the installation problem, and the original too-close-to-the-hamper problem that I first confronted. Has anyone tried that as a solution?

I would appreciate any advice, suggestions, or comments from any members of this august brain trust.

Thanks,

Trent

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Re: Installation of Dometic 320 Toilet

Reply #1 – May 23, 2015, 06:56:10 pm

Your problem is probably best resolved by returning the toilet and buying a different brand & model. I have a concern about ABS gluing to old ABS and long term issues.

Re: Installation of Dometic 320 Toilet

Reply #2 – May 23, 2015, 07:12:30 pm

We got into the same, as I read what you have written and thinking what we began to see. So we back off. Mr. Risch said that while they could modify the cabinet for me if we wanted, it would be a considerable undertaking.....I am not sure yours is the same as ours, but sounds like it, I can post a photo if you wish.....

Instead he recommended that we replace a critical piece and most likely to fail in the toilet we have a critical piece and that by having it, he thought we would be good for many more miles. I do not recall what he called it, but it was plastic or teflon type and functioned to move the flushing parts. I can get details if you would like, advise.

The problem was that our toilet was built into the cabinet, a compartment behind it that is hinged outward from the bottom, and that would have been very significant. Plus in the building of this at the factory, it offset the toilet drain such that we were going to have a major issue fitting an alternate design.

Note though we had no problem. I began simply from the idea of copying the replacement that John S. did, but apparently his cabinets were built differently. We each have 2001 coaches but his is a 42 ft so may have been differently configured than ours.

I ended up doing what Barry wrote, I went the direction Risch suggested. But you sound less easily discouraged than I so good luck, it should be helpful to others if you make the change.

Re: Installation of Dometic 320 Toilet

Reply #3 – May 23, 2015, 07:56:15 pm

Well my opinion (and it comes with many years of doing this exact same job in both S&B and coach's) the way they did the tile install was wrong, wrong wrong. The tile has to go under the flange in all cases and so what they did was lift the flange and put that ply ring there to lift it up the way it should be done. My remedy is either use a Dremel or other tool to cut the tile slightly away from that flange about 3/8th circular OR take the tile off the top and fit it under the flange. I would opt now for the former as it actually should not be hard to do, this way the trim ring under base of toilet will slide down into this groove and allow it to sit properly on the main larger rim of toilet. Do a few measuremeonts first to double check this but am sure it will fix the "rocking" of toilet. Also measure the inside diameter of the plastic toilet flange to make sure that it goes over the circular ring of plywood. No need to change the toilet to another as I am sure you will find the same problem. I did not disect your comment as soon as I saw the pics I knew what the problem is.
This is not a big deal if you follow my suggestions.
on edit--- you can also grind down that inner flange a bit to allow toilet to sit on outer rim, but I woulf first cut the tile diameter as stated.
JohnH

Re: Installation of Dometic 320 Toilet

Reply #4 – May 23, 2015, 09:27:53 pm

Quote from: John Haygarth – May 23, 2015, 07:56:15 pm

The tile has to go under the flange in all cases and so what they did was lift the flange and put that ply ring there to lift it up the way it should be done.

John,

Instead of cutting the tile to fit the tailpiece, they cut it to fit the flange. When they realized their mistake, they tried to fix it by putting the plywood ring in to replace the removed tile. The problem was the plywood was too thick. Now it causes the ABS flange to sit above the level of the tile. I think I can fix this by removing the too-thick plywood ring with something that is the same thickness as the tile. The something can probably installed as two half-rings. If I am understanding you, then all should be right with the world, as far as the height of the flange.

I understand that in our 2-D world pictures it is not obvious, but the tile is already cut all the way around the flange. I don't think any more has to be done with the tile, except to replace what should not have been removed with the ring of the right thickness. I have included another photo that may make this a little more obvious. What you can see on the foreground of the picture is the same for all 360 degrees.

Thank you for sharing your expertise. My wife and I are looking forward to using our toilet that is built for normal-sized people.

Trent

Re: Installation of Dometic 320 Toilet

Reply #5 – May 23, 2015, 11:06:57 pm

Barry,

Returning it at this time is not a very viable option. Even if the dealer were willing, I paid $60 for shipping here and would lose another $60 sending it back.

Trent

Re: Installation of Dometic 320 Toilet

Reply #6 – May 23, 2015, 11:24:27 pm

Trent, just having john ideas and your perserverance i am betting on you. Hope your documenting helps others!

Mike

Re: Installation of Dometic 320 Toilet

Reply #7 – May 23, 2015, 11:45:00 pm

Trent,
I have no experience removing the flange from the floor.
However, I have recently removed my black tank and have only a tidbit of information that may help.
As you might already know the holding tanks sits on stands. To remove the tanks you first remove the stands so the tank can drop low enough so the vent and drain pipes will clear the top of the tank. There is a rubber boot that seals the pipes to the tank and it had a very good grip on the pipe. I had to spray silicone lube around it and also use a small screw driver to break the seal and allow the silicone to get between the pipe and boot. I had the advantage of gravity pull on the tank too - it was still difficult.
In addition, I also noticed copious amounts of silicone sealer on the ceiling of the bay around the pipe as it passed through the floor. I think that is what you are up against. Certainly not impossible to remove but it will take some work and gaining access to the tank boot might be required. It's also not impossible that you could just push it down farther. The rubber boots usually have a flange to act as a stop so the pipe can go in only so far. On mine that flange was cut off and the pipe went well past it.
Hope this helps.

Re: Installation of Dometic 320 Toilet

Reply #8 – May 24, 2015, 12:25:50 am

Trent, measure the tile diameter at its smallest place as they did not cut it very even. Then measure the outside diameter of the flange on toilet that would fit inside this tile "hole' and see if indeed the flange "can" go inside the tile "hole". My betting is it will not and or the plywood ring diameter maybe too big to allow flange to sit around it. If my description is not too clear then just imagine what is supposed to happen when fitting together and I am sure you will understand. A toilet flange should allways fit on top of the flooring covering.
JohnH
on edit--- put a straight edge across the larger outside rim and measure how much more the centre "horn" sticks past this rim. Then put a straight edge across tile floor and measure down to were tis horn fits. You may find that there is not the room for it to fit free of touching the flnge then removing the amout needed will allow the toilet outer rim to sit on the tile. Looking again at the pictures it may what is actually happening. If the underside of flange IS higher than the surface of tile then replacing the plywood with the correct thickness will help some.As I said previously just take a bunch of measurements and it will become obvious I am sure.
John

Re: Installation of Dometic 320 Toilet

Reply #9 – May 24, 2015, 01:19:31 am

John,

I think I understood you to say that the ABS flange should sit on top of the tile. The installers made a hole to sit the flange on the floor, below the tile. To correct this mistake, they put a plywood ring under the ABS flange to bring it back up as if it were still sitting on top of the tile. Unfortunately, they made the plywood ring too thick, so it is now sitting proud of the tile, which is too high for my Dometic 320 to sit flat on the floor. I think that is where we are currently.

My idea is too remove the too-thick plywood ring and replace it with one that is the thickness of the installed tile (probably too half-rings for installation).

My understanding of the leakless mating of the two occurs because a beveled foam looking donut fits around the (short) tailpipe of the toilet. This assembly then fits into the horn of the ABS flange. As the nuts are tightened onto the T-bolts, the donut is compressed tighter into the horn. At the same time, the compression of the donut allows the outside edge of the toilet base to make contact with the tile surface, effecting a very stable installation.

I will contact Dometic on Tuesday to confirm that their design allows for installation of their toilet onto a surface with an ABS flange on top of the surface, plus a brass flange on top of the ABS flange. If all of that is true, then I think all I have to do is remove the too-thick plywood ring, and replace it with one the thickness of the tile.

If that is not the way their toilet is designed to be installed, then we should be able to make whatever adjustments are necessary when we find that out.

Is my understanding of what you have tried to explain to me accurate?

With hopeful thanks,

Trent

Re: Installation of Dometic 320 Toilet

Reply #10 – May 24, 2015, 01:26:37 am

JohnFitz,

Thank you very much for the details concerning removal of the black tank.

I had expected a rubber boot, but did not expect silicon sealant around the floor opening, too.

I am confident that the people at Dometic will be able to explain how their toilet is designed to be installed. I am hopeful that if my installation is not standard, they will be willing to help explain to me what has to be done to allow me to smile while using their product.

Trent

Re: Installation of Dometic 320 Toilet

Reply #11 – May 24, 2015, 12:49:20 pm

Trent, this should not be "rocket science" as all you want is an unimpeded flow thru to tank of solids and liquids.
measuring it all as described will tell you what is wrong. There should be no need for the metal flange unless they used it to gain height. One thing you do not want is that horn to not sit inside the flange opening or you will have leakage from joint. Measure it all as I said and you will surely figure out what needs to be done! The foam ring is really only a 'smell " seal but I have seen it also actually in contact with the solids etc.
JohnH
edit-- They could have put the metal ring on to fasten toilet bolt pattern on if the flange was installed out of alignment or the holes in it are not positioned right for the hold down bolts in toilet.

Re: Installation of Dometic 320 Toilet

Reply #12 – May 24, 2015, 05:14:06 pm

Quote from: John Haygarth – May 24, 2015, 12:49:20 pm

They could have put the metal ring on to fasten toilet bolt pattern on if the flange was installed out of alignment or the holes in it are not positioned right for the hold down bolts in toilet.

John,

Okay, that explains the brass flange. The slots in the ABS flange do not even come close to being 9:00 and 3:00.

But, that adds another layer of height which I have to fight to get the toilet to mount onto the bolts AND rest solidly on the tile. So my "wood" ring will be less than the thickness of the tile, to allow for the thickness of the brass ring, correct?

I will ask Dometic about that on Tuesday.

BTW, the design of the toilet tailpipe prevents the donut from getting into the flow of things. The tailpiece is below the donut when it is compressed into the horn of the flange. It is close to, but out of the flow of the stuff.

Thank you for your patient explanations.

Trent

Re: Installation of Dometic 320 Toilet

Reply #13 – May 24, 2015, 06:43:42 pm

Trent, just a question here, does the toilet fit correctly if the ring is left off ie- sits on tile surface?
If so then why not just sit the toilet onto the plastic flange and use screws thru the holes to go into the plastic face? They do make a bolt that one end has machine threads on it and the other end regular screw thread.. You would firstly make sure the ply and flange if screwed down to box frame securely.
JohnH

Re: Installation of Dometic 320 Toilet

Reply #14 – May 24, 2015, 09:10:02 pm

Trent, don't know if your toilet is directly over your holding tan, but I recently watched, during a new toilet installation, their ABS flange and down pipe, just pulled straight up out from the holding tank rubber grommet. And later just pushed right back in.
Our toilet is not over our tank so it requires a short toilet, mounted to a wood box and our ABS pipe angles from toilet to over our holding tank. So we can't pull our pipe up.

Re: Installation of Dometic 320 Toilet

Reply #15 – May 25, 2015, 02:45:57 am

Quote from: John Haygarth – May 24, 2015, 06:43:42 pm

They do make a bolt that one end has machine threads on it and the other end regular screw thread.

John,

That is a great idea! I have not tried it without the metal flange, because I assumed it was needed. I will try that tomorrow (and take a picture of my clothes hamper problem).

BTW, in searching through Youtube, I came across two videos that addressed the RV ABS flange.

One was how to remove it; he simply unscrewed it, since it was threaded in. I had assumed that ours was cemented into a long tailpipe. Anybody know for sure?

The other one involved removing the metal flange, and rotating the ABS flange around so the slots lined up properly. That might work even without threads by tapping the ABS Flange near the edge to rotate the whole assembly. Any thoughts on that possibility?

Thanks for continuing to ruminate on my problem,

Trent

Re: Installation of Dometic 320 Toilet

Reply #16 – May 25, 2015, 02:57:18 am

Barry,

My toilet sits smack dab over the holding tank. It is the high profile version, installed at floor level.

BTW, looking down into the tank makes me want to go out and buy a truckload of ice cubes. Or is that just an urban legend. The tanks are still dry from winterizing. I did not expect it to be pristine, but was surprised at how much dried stuff was stuck to the floor. Fortunately, there is no mountain under the toilet pipe.

I had considered an offset flange to gain a couple of inches from the wall, but I think the simplicity of a direct drop is probably worthwhile. The center of the hole is 11" from the cabinet, which is what the spec calls for. Since it is an elongated bowl, it does stick out further in the front and back than a round bowl would.

Trent

Re: Installation of Dometic 320 Toilet

Reply #17 – May 25, 2015, 07:28:56 am

Quote from: TulsaTrent – May 23, 2015, 09:27:53 pm

My wife and I are looking forward to using our toilet that is built for normal-sized people.
Trent

I'm not sure what "normal sized people" are? Maybe you went the wrong way.

5 Problems with Sitting on Your Toilet

good luck,

Re: Installation of Dometic 320 Toilet

Reply #18 – May 25, 2015, 09:23:51 am

Rick,

Thanks for the link.

Now I know where to store the step stool!

Trent

Re: Installation of Dometic 320 Toilet

Reply #19 – May 25, 2015, 11:43:17 am

Trent, my thought is since you have a need to work between the ABS flange and the floor, you could work (twist, etc) the ABS pipe out from the top of the tank, prepare the floor and put the pipe back into the tank.
For your tank inside bottom, you could now soak the bottom of the tank crud and use a strong hose stream directed at it to bust it loose. We dump tanks every week and bring a 50' 1/2" hose with the brass end cut off (to keep from scratching things) through the kitchen window, and use it to flush out the black tank and shower/sink traps. Maybe this type of flushing would lessen the inside of the tanks from having crud. Sidewalls probably have crud too.

Re: Installation of Dometic 320 Toilet

Reply #20 – May 27, 2015, 01:18:11 am

Quote from: John Haygarth – May 24, 2015, 06:43:42 pm

Trent, just a question here, does the toilet fit correctly if the ring is left off ie- sits on tile surface?

John,

Experimented today, and it does.

Talked to Dometic Tech Support. They said the flange should be on top of the tile. The simplest "fix" is if I can rotate the ABS flange so the slots are at the 9:00 and 3:00 position. Will try my Big Daddy screwdriver in the slot and see if I can coax it to rotate; looks like it only has to rotate about 15-20 degrees.

In spite of all the rain we have been having, things look better for this installation hiccup now.

Thanks,

Trent

Re: Installation of Dometic 320 Toilet

Reply #21 – May 27, 2015, 09:29:00 pm

Trent, if you cannot rotate that flange then just fasten the flange down with a few screws then use 2 #10 or #12 screws with a washer under head to hold toilet in place once you put seal etc on. It will not move and the thing will work.
Johnh

Re: Installation of Dometic 320 Toilet

Reply #22 – May 28, 2015, 12:42:25 am

John,

The flange rotated like a trooper. Bolted it in place, inserted the two T-bolts, and dry-fitted the toilet. All A-OK!

Went to Lowe's earlier to get a stainless 12" hose. Asked for one with two 1/2" ends. He sold me one with a 7/8" end because ("All toilets use a 7/8" fitting"). Will take it back tomorrow and get the one I tried to buy originally.

Had one slight hitch. I had purchased four new 2" #12 screws to hold the adapter down (instructions had said at least four, up to eight). When I tried to drill the pilot hole for the one closest to the wall, I hit metal; same thing in the one adjacent to it. Assumed it was probably a square framing tube and decided not to mess with it. Used the four new and two of the old ones to give me six holding it down. It is very solid.

Just have to cut the PEX and insert the 1/2" male plug to provide my input. I thought it would be neater if I installed the plug behind the wall so just the short hose shows. Since it is only a plug attached with a screw-on clamp - no PEX crimpers - it should be fairly straight forward, but it might be better to keep the adapters outside of the wall in case of problems. Any thoughts?

After this, I will install my third valve while the tanks are dry. Then we add some water, cross our fingers, and turn the water pump on. Will be checking the new bathroom faucet, the toilet, and the new third valve.

Thanks for all of the advice,

Trent

Re: Installation of Dometic 320 Toilet

Reply #23 – May 28, 2015, 01:10:28 am

Well glad that is over and hope it all works or we will all be in the s--t especially you

You did say you were a Sanitory Engineer did you not???
JohnH

Re: Installation of Dometic 320 Toilet

Reply #24 – November 27, 2015, 06:46:00 pm

I just removed the original toilet and installed a new Thetford Aqua Magic STYLE PLUS.

Additionally............. I had the same problem as Trent in that after removing the 8 screws the flange wouldn't budge to allow the bolt holes to be relocated at 9 and 3 o'clock. What I did was put the toilet back on the flange, tighten up the 4 nuts on the bolts and then twist the entire toilet and the flange along with it.

I had no problem with the height of the tile or the flange itself and the foam Johnny Ring compressed nicely to form a
water tight seal. I also had the plywood ring which appears to be a spacer that provides a firm surface at the right height
for the flange to sit on when it's screwed down.

Thank y'all for a great thread.

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