TMC Electric toilet water level

[srt]

I recently installed a TMC 99902 basic electric toilet complete with the TMC timed control panel. It is installed as per all the recommendations with vented loops on inlet and outlet.

The problem is the water level in the bowl is too high. It is only about about 90mm down from the rim of the bowl. it flushes OK but the water level remains uncomfortably close to the top.

I consulted the local vendor who was no help. I emailed TMC at sales1@tmcint.com which is the address on the user documentation and they have just ignored me.

Can anyone please advise?

[GordMay]

Greetings and welcome aboard the CF, srt.

[peghall]

I just spent 20 minutes going through the installation instructions without finding any solution to your problem there. So my only suggestions are: Find out if you can adjust the timer on the flush panel to bring in less water. If not, consider replacing the flush panel with one that is adjustable. It doesn't have to be a TMC flush panel...you shoud be able to wire any mfr's panel to your toilet.

[srt]

Thanks Peggie for taking the trouble to read those instructions. The timer has 2 different settings, a short flush and a longer flush, and the result is the same for both. So the duration of the flush does not effect the level, it seems after the flush stops it keeps filling. I am wondering if it is the water draining back from the vented loops after the flush stops. But this must be a pretty standard sort of installation in a pretty common boat (Oceanis 370), it should not be a problem. If it is caused by water draining back from vented loops, then the height of the vented loop would cause different water levels in every different installation. I have installed the vented loops just below gunnel level, trying to keep them above outside water level when heeled, which is as per instructions.

I guess it would not be difficult to temporarily attach a manual on/off switch and disconnect the auto panel, so I could try that to see if it makes a difference.

However researching now more online now it seems that the toilets with adjustable water level have separate inlet and outlet pumps. The TMC has the macerator pump doing both jobs simultaneously so it is difficult to see how the water level could be controlled electronically.

I am left thinking there is no adjustment, but then wonder why no one else is having this problem,

Thanks Stuart

[HopCar]

Stuart, your idea that it is flow from the vented loop sounds plausible to me. Hopefully it is only from the intake hose. What ever water is in the down hill side of the loop will end up in the bowl after you stop flushing.

The trick then is to reduce the volume of water the intake pump brings in while flushing.
You don't want to restrict the intake or discharge as that is hard on rubber impellers. You could just buy a better toilet that allows you to set the run time of the intake pump.

I wonder what would happen if you cut one or more vanes from the intake impeller? That should reduce the intake volume and not hurt the pump. It would cost you an impeller to try it.

I hate this type of work around but it's all I can come up with.
Keep trying to contact TMC. They've got a website.

[peghall]

I am wondering if it is the water draining back from the vented loops after the flush stops. But this must be a pretty standard sort of installation in a pretty common boat (Oceanis 370), it should not be a problem. If it is caused by water draining back from vented loops, then the height of the vented loop would cause different water levels in every different installation. I have installed the vented loops just below gunnel level, trying to keep them above outside water level when heeled, which is as per instructions.

Aha! You've misjudged how high vented loops need to be to keep them above waterline when heeled... They need to be at least 6-8" above waterline AT ANY ANGLE OF HEEL...which on most sailboats would put them 2-3 FEET above the bowl.

Check the water level in the toilet against the boat's waterline...if I'm right, the water in the bowl is rising to the waterline. When the inlet vented loop is where it belongs, ONLY the water left in the line between the top of the loop and the bowl will run into the bowl.

If you compounded your error by putting a vent line on the loop where an air valve/vacuum breaker belongs instead, that would interfere with the toilet's ability to prime, which would reduce flush water, not increase it...but ONLY until salt and sea water minerals clog the vent line, turning the vented loop into an UNVENTED loop that no longer has any ability to break a siphon or prevent water from rising to the waterline. Remove the vent line and install an air valve...see the loop mfrs' site to order.

If you also made the classic mistake of installing the inlet loop in the line from the thru-hull to the pump, instead of in the line between the pump and the bowl (see the illustration on p.2 of the installation instructions) you should correct that too.

Btw...you'll also need to move the loop in the discharge line and correct any of these errors in it too...water can flood the bowl when the seacock is open.

[srt]

Hi Peggie, after your post I have checked everything. I believe the vented loops are at the correct height, they are about 3" below the side deck/gunnel. (maybe not even high enough if the boat was really being heeled over.) This also puts them about 30" above the top of the bowl which does fit with your suggestion of the correct height above the bowl. The thruhull is correctly connected direct to the pump and the inlet vented loop is between the pump and the bowl.

I did not understand your comment of the error of "putting a vent line where a valve/vacuum breaker belongs". Is a valve/vacuum breaker different to a vented loop? I did try on line to find information online re your meaning but was not successful. To my understanding I have installed to exactly what the manufacturer has requested.

The installation is pretty new and there is no salt etc clogging anywhere, and it seems that the flushing is all working very well.

Very hard to measure accurately sea level and level of water in bowl, but they are very similar and could be the same. If they are the same I do not understand how the outside water level can influence the level in the bowl with the vented loop in the middle, unless it is traveling from the inlet direct through the pump into the bowl, and surely that should not happen. Looking at an exploded view of the pump it would appear that the inlet water is sealed from traveling that way.

I did not understand your suggestion of moving the vented loop in the discharge line? I believe I have followed TMC instructions. My installation also has a Y valve and discharge possible into a separately plumbed holding tank. The water level is the same whether discharging over the side or into the holding tank.

Stuart

[srt]

Originally Posted by HopCar

Stuart, your idea that it is flow from the vented loop sounds plausible to me. Hopefully it is only from the intake hose. What ever water is in the down hill side of the loop will end up in the bowl after you stop flushing.

The trick then is to reduce the volume of water the intake pump brings in while flushing.
You don't want to restrict the intake or discharge as that is hard on rubber impellers. You could just buy a better toilet that allows you to set the run time of the intake pump.

I wonder what would happen if you cut one or more vanes from the intake impeller? That should reduce the intake volume and not hurt the pump. It would cost you an impeller to try it.

I hate this type of work around but it's all I can come up with.
Keep trying to contact TMC. They've got a website.

Hi HopCar, I experimented a bit more with the inlet line, I took it down and laid it nearly level with the bowl, then after flushing lifted it, the amount of water in the line which then went into the bowl resulted in only about 1" of water level increase. Also took valve off vented loop and blocked the vent hole, then opened it after flushing, similar result, so my problem is not caused by water in the inlet line.

Following on Peggie's suggestion, there does seem to be a possibility that the outside water level is the level in the bowl, but should not be possible unless leaking through the pump.

Stuart

[peghall]

I did not understand your comment of the error of "putting a vent line where a valve/vacuum breaker belongs". Is a valve/vacuum breaker different to a vented loop?

If your vented loop is PVC, there is a nipple on the top of the loop...the inside of that nipple is threaded. That is where an air valve (aka "vacuum breaker") belongs. It closes when liquid is PULLED through a line--as in bringing in flush water, opens to release the vacuum, and therefore break any siphon when pumping ceases.

Because air valves are replaceable and sold separately from the loop, many people--you included, apparently--aren't aware that air valves exist and are needed in vented loops. So to solve the problem of squirting out the hole in the top, they put a vent line on it that may tap into another line or go to a vent thru-hull. Because that line is so small--only 1/4"--it very quickly--within weeks, even days--becomes clogged with salt and/or sea water minerals. When that happens, the loop ceases to be a VENTED loop. Because attaching a hose has solved the squirting problem, it never occurs to anyone that it needs cleaning...the loop becomes "out of sight, out of mind." So IF you've attached a hose to the nipple on top of a vented loop, it should be removed and replaced with an air valve. You can see a good example of an air valve here (the red thing on the top of the loop):
Vented Loop, with air valve

I did not understand your suggestion of moving the vented loop in the discharge line?

Wouldn't it stand to reason that IF your inlet vented loop is too low, your discharge vented loop is also likely to be?

I've given you everything I can think of...hopefully TMC will be able to solve your problem.

[benji 2]

I have the same problem. With intake gate valve closed no problem. I have a sink draining into the same hull fitting so with gate valve close I filled the sink and water drained from the sink into toilet bowl. The only seal between the intake water of the pump and waste water side seems to be Part no 17 Sleeve Kit and Part no 34 O-ring. I pulled the pump apart today and found that there was no o-ring inside the Sleeve kit. Thought I had solved the problem got new o-ring installed with plenty of silicone grease. Still the same problem not sure how the o-ring was supposed to work as it didn't seem to have any housing other than the sleeve kit. Back to square one minus a bit of skin.
Only thing for sure the pump is leaking

[srt]

Hi Benji 2, what is happening with these TMC electric toilets is very confusing. Peggie's suggestion that in my installation the water level in the bowl is the same as outside water level seemed to bear out in the pen. I tested that by going for a sail and flushing when toilet was on windward side, and discovered that water level is much lower and no doubt reflecting the outside water level when the toilet is elevated by being on the high side. So back in the pen, and thinking there is direct connection to outside water level through the pump I tested by filling the bowl with water by manually pouring in it till the bowl was full, thinking that it would then slowly drain out through the pump. Did not happen, bowl remained full.

So that leaves me speculating that when the pump is operating and valves are open then the bowl is "seeing" the outside level (whatever it happens to be) until the pump stops and the valves close. If that is the case it is hardly satisfactory. Now I need to test further by going for a sail and flushing when on the leeward (low) side and see what happens. If I was smarter I would have done that last time.

I also intend to write a letter to TMC, as they did not respond to my email, maybe something on paper will get a response.

[GordMay]

Greetings and welcome aboard the CF, Benji.

[Rubikoop]

I installed pvc ball valves on the intake and waste line very close to the toilet. When sitting still the water level is fine. When underway it splashes out and gets too high. My departure procedure is to close the intake valve, flush head until bowl is empty and finally close waste valve. Yes all this can be done with seacocks in the bilge but the convenience of locating another set of easily accessible valves has worked well for us. I'm sure the intake impeller doesn't like being run dry, which is why I have a spare, but so far in draining the bowl hundreds of times it's been ok.


Sent from my iPhone using Cruisers Sailing Forum

[benji 2]

Hi Stuart,
I think I have the answer to our problems. I emailed TMC and got this reply

"the water comes into the toilet from the flexible impeller, part 29. and waste water is checked by the flapper valve part 23.
If water is getting into the toilet bowl when off, the impeller is deformed or burned as can happen if the pump runs dry. Or the water pressure is on the intake side is greater than the flex impeller can contain.
The intake pump is isolated from the waste side by the wear plate and seal between them which you talked about in your memo. However any leak from the seal would be measured in drops and if failed completely would leak all the time.
Look at the flex impeller or high intake pressure as the cause.


Regards,



Tim Richardson

TMCIN,INC

tim@tmcin.com "

Trust this may help

[divezonescuba]

We have a Jabsco compact on our dive boat. It does the same thing.

What exactly happens depends on the inlet, pump, vent loop arrangement. Originally, on ours, the system had a inlet line, the pump, and a direct hose with no loop or vent directly into the top of the bowl. We had a fresh water tank above the toilet teed into the salt water inlet line. When the raw water seacock was closed, the fresh water was pumped.

Few flexible impeller based pumps are completely water tight. Water flows around the sides of the vane between the cover place and/or the back of the pump housing. Next time you take off your engine or generator raw water pump, try this. Blow through one end and most likely some air is going to go out the other end. The more the cover or back housing is scored, the more air or water will go through. This doesn't cause a problem with generators or propulsion motors because the leak is small and the system is sealed.

But with the toilet, the freshwater leaked from that tank into the bowl around the sides of the impeller until it reached equilibrium. It would take a while, but you could see the steady stream of water going into the bowl.

We changed this with a loop with a vent between the outlet on the fresh water pump fitting and the inlet to the bowl. Still, you have to contend with the amount of water in the toilet side of the vent loop. So, even when you stop pumping what is left will eventually drain into the toilet.

If you don't have a vent loop and the toilet is below the waterline, if you use salt water, it will slowly leak water past the sides of the impeller into the bowl until it reaches the waterline.

If you keep the vent loop as short as possible, but keep it above the waterline, only that amount of water will drain into the bowl. Another alternative would be to put a spring loaded ball check valve into the system. But that introduces other potential problems as well.