Sealand Dometic T-24 pump

[greatpapabear]

Hi All,

Another hoilding tank question. In 15 years, I've had to replace the T24 pump three times, each time caused by split bellows.

I take great care not to leave the pump running unnecessarily not the least that split bellows means spilt poo into the bilge under the main cabin.

Does anyone else suffer these piump failures?

 

[DavidM]

I only had about five years of experience with one until I sold the boat, but it worked perfectly during that period, but that is about the interval you are getting with yours.


I have had centrifugal macerator pumps that didn't last that long though.


David

 

[OldDan1943]

Replacing the entire pump is unnecessary. You could have rebuilt it, replacing the bellows and 'duck' valves in less than an hour, assuming the pump is not "buried".
I have but one head so I carry a spare bellows and a set of 'duck' valves. In 5 years time, I replace the bellows once and the 'duck' valves twice. I do not consider that unusual.

 

[Tator]

In over 25 years of boating I've only had to replace a Vacuflush pump once and that was for split bellows. Granted that was four different pumps on three boats, but the one that did go south had been in constant use for 5-6 months of the year with multiple passengers for 11 years. It had also been used with saltwater for about half of that time. It was being used as the toilet pump rather than the holding tank pump, but as I understand it, It's the same pump with reversed fittings. I rebuilt it with new bellows. It does leave a mess if not caught right away. Your having to replace it that often seems excessive. Perhaps a restriction that is making it have to work harder?

Tator

 

[greatpapabear]

Now I have 2 spare pumps, I've instigated a 3-yearly rebuild regime. Mind you, looking at the quality of these Chinese built pumps, I'm not really surprised the bellows are not built to last long.

 

[HeadMistress]

The Dometic/SeaLand T-Pump (overboard discharge pump) isn't a VacuFlush pump, it's a discharge pump used to dump the holding tank. I'm guessing that the boat has 24v DC power...hence the T-24 designation instead of the typical T-12. The T-Pump is among the most durable trouble free overboard discharge pumps, if not THE most durable...I had one on one of my own boats that was 11 years old and still working fine with all original parts except for duckbills when I sold the boat.

You said you "take great care not to leave the pump running unnecessarily." It should never run except to dump the tank, which means only when the thru-hull is open...and then not just left running for any length of time after the tank is empty. If it's run against a closed thru-hull the waste it's pulling out of the tank has no place to go...it's backing up into the pump. Based on your previous problem with sludge buildup in the tank it would not be at all surprising if the sludge clogged the bellows in the pump to the point of bursting it. If the sludge is/was even an inch or two deep, it's highly possible that it could clog the pump even if it's only run when the thru-hull IS open.


So I have a strong suspicion that this is another problem that a little preventive system maintenance could have prevented.

Marine toilets also require preventive maintenance...What's the make/model/age of the toilet(s) on the boat?

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[greatpapabear]

Hi Peggie,

Thank for the interest in our holding tank! OK, I always leave the thru-hull open so there's never a time when it would be pumping and backing up.

As part of the annual check, I blow back through the two vents to check they are clear.

When pumping out, I keep a good watch on the outflow and when it seems it's finished, the pump is turned off. At most, that's 10 minutes.

Then I pump in salt water for 2 minutes before starting another pump out. I usually do this twice per emptying.

The boat is a Fleming 55, built in late 2002 and which I bought new in early 2003.

Should I be doing anything else?

 

[HeadMistress]

When you say "pumping out" you actually mean that you're dumping the tank...not at a pumpout?


As part of the annual check, I blow back through the two vents to check they are clear.

Only annually?? Insects, waste etc are an ongoing occurance that can block tank vents any time. Holding tank vent lines should be back flushed with clean fresh water (put a hose nozzle against the thru-hull) every time you wash the boat and/or pump out. If your vent thru-hulls aren't designed to allow you to do this, replace 'em with open "bulkhead" thru-hulls that are. (Unfortunately a filter in the vent line won't allow you to back flush the vent line because filters can't get wet).


If you never flushed out the tank or the pump with clean FRESH water, it's possible that sea water mineral buildup may be clogging your T-Pump. What has the bellows in the pumps that have failed looked like?



If crusted, I suggest you clean out the system with about a 15% solution of muriatic (hydrochloric) acid available from any decent hardware store...sometimes known as "brick cleaner" in the UK. Put a few gallons into the tank via the deck pumpout fitting, run the T-Pump--against a closed thru-hull this time, but ONLY long enough to get the solution into the discharge line and pump!--then let it be for 45-60 minutes. Open the thru-hull and flush the solution out of the tank and lines with plenty of clean fresh water via the deck pumpout fitting. And from then on, run some fresh water through the pump after each use.


I think you might profit from the information in my book (see link in my signature, just click on the title). The title (my publisher's idea) is a bit misleading because although it does deal with every source of odor on a boat and how to eliminate--better yet, prevent--'em, it's actually a comprehensive "marine toilets, holding tanks and sanitation systems 101" manual that helps people learn how to prevent 90% of problems instead of having to cure 'em. 'cuz preventive maintenance can be done your YOUR terms when it's convenient...which is NEVER true of cures!


--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[greatpapabear]

This is really helpful. Thank you. In answer to some questions:

1) No, I've never used a pump-out facility, only ever pumping out directly overboard.

2) The vents have carbon filters in line, so I'll fabricate a hose which can replace the filters and then wash through, followed by blowing through them to make sure they are clear before reacing the filters.

3) When I next change the bellows, I'll check to see what build up there is in case it's from the sea-water.

4) Sadly, the plumbing doesn't allow for fresh water to be used to flush the pump. But, if I'm able to pump fresh water into the tank for a few flushes, might this help flush the pump?

5) I'll see if I can obtain your book in the UK. Sounds a really ensible reference to have - thanks for the tip.

 

[greatpapabear]

Hi Peggie,

Book ordered. Thanks so much for all the help.

 

[HeadMistress]

The vents have carbon filters in line, so I'll fabricate a hose which can replace the filters and then wash through, followed by blowing through them to make sure they are clear before reacing the filters.

If No-Flex works as it should, you shouldn't need filters.

4) Sadly, the plumbing doesn't allow for fresh water to be used to flush the pump. But, if I'm able to pump fresh water into the tank for a few flushes, might this help flush the pump?

There is no fresh water washdown hose connection on your boat? That would be surprising on a boat that size. If not, I suggest that you use pumpout facilities occasionally. If you time the acid cleaning right, you can rinse out the tank with a hose provided there. In fact, it would be a good idea to use a pumpout facility and rinse out the tank with fresh water at least every couple of months anyway.

Btw...what make/model/age are your toilets?





Thanks for buying my book...I hope you'll find it useful! And I'm always glad to answer any questions it doesn't.


--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[greatpapabear]

4) Sadly, the plumbing doesn't allow for fresh water to be used to flush the pump. But, if I'm able to pump fresh water into the tank for a few flushes, might this help flush the pump?

There is no fresh water washdown hose connection on your boat? That would be surprising on a boat that size. If not, I suggest that you use pumpout facilities occasionally. If you time the acid cleaning right, you can rinse out the tank with a hose provided there. In fact, it would be a good idea to use a pumpout facility and rinse out the tank with fresh water at least every couple of months anyway.

There's fresh water wasdown, but nothing near the tank. However, I suspect I could plumb something in so I'll see what can be done.

BTW, having never used a shore pump out (!) I know where the access point is on the boat, but how does it work?

 

[sunchaser]

There's fresh water wasdown, but nothing near the tank. However, I suspect I could plumb something in so I'll see what can be done.

BTW, having never used a shore pump out (!) I know where the access point is on the boat, but how does it work?

Fill your holding tank from the dock or deck hose with fresh water through the deck fitting waste pump out. Then pump out to rinse tank. Insure the line is connected to the holding tank first though.

 

[HeadMistress]

BTW, having never used a shore pump out (!) I know where the access point is on the boat, but how does it work?

Remove the threaded cap....CAREFULLY! Unlike the caps on fuel and water fills, there is no chain on the cap, so make sure to set it down where it can't fall into the water!

The pumpout hose from the dock should have a piece on the end of it that attaches to the deck pumpout fitting tightly enough to create a sealed connection. There should be a dock hand who may handle the operation entirely or he may hand the pumpout hose to you and should be able to tell you how to connect it to your boat. No need for the hose to go any further than the deck fitting...the suction will pull the waste out and down the hose to wherever the marina sends it.

--Peggie

 

[twistedtree]

Replacing the entire pump is unnecessary. You could have rebuilt it, replacing the bellows and 'duck' valves in less than an hour, assuming the pump is not "buried".
I have but one head so I carry a spare bellows and a set of 'duck' valves. In 5 years time, I replace the bellows once and the 'duck' valves twice. I do not consider that unusual.

I carried the same spares. After one duck bill valve replacement, the pump worked well for maybe 6 mo, then struggled to draw up the goo. This was gray water, by the way, aimless gooy than you might imagine.

I replace the duck bills again to no avail, then replaced the bellows. It still wouldn’t suck worth a darn. Sick of wasting time, I replaced the whole pump.

I think those pumps are fine for an intermittent use boat, but for heavy use something more robust is required.

 

[Larry M]

I carried the same spares. After one duck bill valve replacement, the pump worked well for maybe 6 mo, then struggled to draw up the goo. This was gray water, by the way, aimless gooy than you might imagine.

I replace the duck bills again to no avail, then replaced the bellows. It still wouldn’t suck worth a darn. Sick of wasting time, I replaced the whole pump.

I think those pumps are fine for an intermittent use boat, but for heavy use something more robust is required.

We used ours full time for 5 years when we were outside the US and never had a failure or repair on our black water tank. Is there a better pump out there for over the side waste?

I did have to replace the duck valves after year 7. We were back in the States and closed/locked out the discharge thru hull. Once off shore, I went to dump the tank and the duck bills inverted instantly.

 

[OldDan1943]

Hmmm, sort of a question. My overboard macerator pump is key controlled. Is it still necessary to close the overboard valve?
My broker said 'no'.
I had the USCG Aux inspect my boat. She did not check the over board valve after I showed her the key control for the pump. She said, she had not seen a key control on the pump and went on with the inspection.

 

[greatpapabear]

I think those pumps are fine for an intermittent use boat, but for heavy use something more robust is required.

What pump would you use to replace the T-series?

 

[BDofMSP]

Old Dan,
I added one on my panel because we kept brushing past the switch getting out of the berth. CG inspector said it qualified for him.
Sorry about the rotation ...

 

[HeadMistress]

My overboard macerator pump is key controlled. Is it still necessary to close the overboard valve?

According to the letter of the law (33 CFR 159.7), it not only has to be closed, it has to be "secured" (wire tied). However, keyed macerators didn't exist when the law was written in the late '70s and the USCG and most state and local water cops accept it as an alternative to actually wiring the seacock closed (the thru-hull should be kept closed except when actually dumping the tank anyway, unless you want to risk filling the tank with sea water). But the law's never been amended, so there's nothing in writing that says a keyed pump is ok...leaving the possibility open that you could run into a "local yokel" with an advanced case of Barny Fife syndrome. So local knowledge from other boat owners when you cruise is worth seeking out.


--Peggie

 

[twistedtree]

What pump would you use to replace the T-series?

This is where it gets complicated. And keep in mind that my pump did last 4 years, and as a gray water pump, it operates WAY more than black water. I can only guess how much more, but I expect it’s 5 to 10 times as much. So it’s life pumping poo should be a lot longer, and I had no issues with the identical pop pump.

With that preamble, headhunter makes their “tortuga” pump which is much heavier duty. And the Edson ELB pumps are monsters and often used in shore side pumpout stations. Nordhavn uses both in their bigger boats, and I have seen them in other brand large boats. Cost is probably 10x to 20x, and they are significantly larger, especially the Edson.

I think looking back on it, my experience only says the T may not last real long in high duty service like gray water, but given their cost it’s still a pretty economical solution.

And perhaps the more significant point is that a bellows replacement still fix the pump, only whole replacement. I dont know why, but in the future I would just plan a whole unit replacement and not a bellows repair.

 

[HeadMistress]

I think those pumps are fine for an intermittent use boat, but for heavy use something more robust is required.

Then you'd have to say the same thing about a VacuFlush toilet, 'cuz the T-Series pump is identical to the VacuFlush S-pump with only two exceptions: it has only two duckbill valves costs about half the price. If a V/F pump is robust enough to last for years on a live-aboard boat, the T-Pump is certainly robust enough to last for decades doing nothing but dumping a tank every week or so.



--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[BDofMSP]

But the law's never been amended, so there's nothing in writing that says a keyed pump is ok...leaving the possibility open that you could run into a "local yokel" with an advanced case of Barny Fife syndrome. So local knowledge from other boat owners when you cruise is worth seeking out.


--Peggie

I agree. I boat on inland waters where discharge is NEVER allowed, so I've removed the handle (which is also compliant). But it seems to save me from having to clear the cockpit and open the hatch just to demonstrate compliance. It wasn't why I installed in the first place but it's had a nice side benefit.

 

[sunchaser]

Grey water applications may be more difficult that black water. Why? Grease buildup. For those that use a garbage disposal into a grey water tank it adds another dimension of very hard to pump stuff. Poo is easy in comparison.

Thus the grey water search for a capable but well priced centrifugal pump designed for pumping solids. I've used many of these types of slurry pumps in industry, lots to choose from. Unless the builder makes accommodations for the proper install of the right pump, it can get tricky for grey water applications.

 

[DDW]

The law is fairly specific about what is clearly acceptable:

"...the operator must secure each Type III device in a manner which prevents discharge of sewage. Acceptable methods of securing the device include -

(1) Closing each valve leading to an overboard discharge and removing the handle;

(2) Padlocking each valve leading to an overboard discharge in the closed position; or

(3) Using a non-releasable wire-tie to hold each valve leading to an overboard discharge in the closed position."

But the wording does not preclude other methods. It would be hard for them to convince a judge that a key lock on the valve or a plastic wire tie is more secure than a key lock on the pump required to use the valve.

I for one am certainly happy that my 40 gallons is not allowed to be added to the millions of gallons per day dumped into the same waters by the nearby cities.

 

[greatpapabear]

May I ask another question? When I serviced the last pump (replacing the bellows etc) I found it really, really hard to get the bellows clamps in place.

Any ideas how to make this easier?

 

[jglabrown]

Peggy, how could the holding tank fill with sea water (if the thru-hull is left open) since there should be two duck bills in the way?

 

[HeadMistress]

The operative phrase in your question is "should be." The T-Pump, unlike the S-Pump in a VacuFlush isn't troubled by air leaks...it could do just as good a job of dumping a holding tank without any duckbills (not recommending that!!) as it does with a pair of brand new ones. So replacing 'em is even easier to neglect than joker valves in toilets (How often do you change yours?). And like joker valves, duckbills in a T-Pump don't stay closed tightly very long...water being forced up a line through an open thru-hull would have little trouble seeping through the pump into the tank.



--Peggie

"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[Waywego]

According to the letter of the law (33 CFR 159.7), it not only has to be closed, it has to be "secured" (wire tied). However, keyed macerators didn't exist when the law was written in the late '70s and the USCG and most state and local water cops accept it as an alternative to actually wiring the seacock closed (the thru-hull should be kept closed except when actually dumping the tank anyway, unless you want to risk filling the tank with sea water). But the law's never been amended, so there's nothing in writing that says a keyed pump is ok...leaving the possibility open that you could run into a "local yokel" with an advanced case of Barny Fife syndrome. So local knowledge from other boat owners when you cruise is worth seeking out.


--Peggie

Where does this leave the Hold N'Treat system that Raritan advertises as legal in all US waters. Doesn't it lock out by key only?

 

[HeadMistress]

It doesn't "lock out" because there's nothing to lock out. The Hold 'n' Treat Raritan Hold N'Treat Bundle is a holding tank combined with an ElectroScan or PuraSan (Type I treatment devices). All flushes go into the tank which can either be pumped out or emptied via the treatment device. Not dumped, but metered out of the tank and into the treatment device a gallon at a time to be put through 2.5 minute treatment cycles until the tank is empty.

If you read 33 CFR 159.7 33 CFR 159.7 you'll see that closing and locking the door to the head is one of the acceptable means of "securing" a system that includes a Type I or Type II treatment device.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein