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Old 07-05-2012, 16:37   #1
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Electric head height of holding tank problem

Hi Guys - I have an electric head that goes to a tank in a cupboard that is standing up. Height from the bottom of the bowl to the top of the tank is 1500mm. Problem is that the bowl does not clear well and as a result a lot of water is used and the tank 110L fills quickly. The Jabsco head is rated to 1200 lift, so this is my problem really.

I am thinking of installing a new pump in series with the discharge line. What sort of pump though?? ie comes on with the toilet to help discharge line into the tank.

2 problems - limited by physical space and current draw. I have purchased a maceration type pump but it is large and draws 12 amps, together with 16 amps from the toilet could overload the circuit so have not installed.

I am wondering if an impeller type pump might work as a booster. Because the toilet macerates prior to the booster pump I am hoping it would not block??? What are your thoughts?? Thanks for taking the time to read this.

What I have done so far;

1. Replaced all hoses - 1"
2. Checked vent is working well - ok
3. checked for voltage drop - all good
4. Replaced the head with a new Jabsco - same result.
5. Tested with a discharge height of 900mm - works great.
6. Checked intake line - all good.

What I have not tried;

1. Someone suggested going to 3/4" hose on the discharge line as this may increase the pressure and then the lift. My worry is this could block up?

2. A booster pump.


Tanks again - Matt
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Old 07-05-2012, 19:08   #2
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Re: Electric head height of holding tank problem

Whose idea was it to install a tank with the inlet 5 FEET above the toilet discharge???? Didn't it occur to anyone to check the toilet installation instructions to find out whether it can lift that high? If they had, they'd found out that the maximum your toilet can lift is 4'--and that's optimistic. So nothing you've tried had a prayer of working and the solutions you're considering not only won't work, they'll only replace one problem with new ones.

There are only two viable solutions:

1. Relocate the tank (which may require replacing it) to a location that will keep the lift well below 4'.

2. Replace the toilet with one that has a much more powerful motor/discharge pump...Jabsco doesn't make one. There are two that are affordable: the Tecma EasyFit
Tecma EasyFit Eco
and the Raritan Elegance Raritan Elegance toilet

Both are around $600 USD. I'd go with the Elegance...Practical Sailor rated it "best in show" in their comparison of all the major electric macerating toilets in Feb of last year. Be sure to check out the flush button options for both toilets...they let you use less flush water.
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Old 07-05-2012, 19:11   #3
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Re: Electric head height of holding tank problem

ah, Interesting problem. The smaller hose will not make it better. The high lift already has the pump back up on its flow curve. so no improvement. You might try the 1-1/2" hose as the internal friction loss would be lower. But then it has more holding volume and that's a problem too.

Really your looking at a second pump in series as your only real option to get the higher head and reduce water usage. The 1500mm lift is the killer. The impeller design on the electric pump in the jabsco head is just a low efficiency type. Yes you'll have high amps for the flush but its only for a few seconds.
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Old 07-05-2012, 22:37   #4
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Re: Electric head height of holding tank problem

I vote with Peggy on this one. Move the tank.
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Old 08-05-2012, 00:06   #5
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Re: Electric head height of holding tank problem

Thanks - I just purchased this boat along with the head height problem. Had a fairly new TMC installed was hoping Jabsco may fix the problem but no better than the TMC. Very difficult to change the tank so I will look into the heads - thanks again, only problem maybe finding them in Australia. Also have a new Jabsco and fairly new TMC?
Matt
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Old 08-05-2012, 00:08   #6
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Re: Electric head height of holding tank problem

Thanks - really hard work to move the tank. Think I may try the pump in series to see if this works. Hoping an impeller type pump may work but clogging could be a problem? Thanks again.. Matt
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Old 08-05-2012, 07:50   #7
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Re: Electric head height of holding tank problem

If the tanks are above the head wouldn't that mean that the hoses are full of sewage all of the time? Seems that would make the hoses smell bad in a short time. It seems like with that setup removing a hose from the toilet would lead to the hose draining its contents into the boat.
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Old 08-05-2012, 15:15   #8
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Re: Electric head height of holding tank problem

Ben,

I don't know how the Jabsco pump is built. But, it might be possible to re-assemble the pump so that the discharge side is (mostly) unrestricted. You could then try to use a more powerful external pump as the discharge pump instead of the Jabsco internal pump.

Just a thought,

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Old 09-05-2012, 01:58   #9
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Re: Electric head height of holding tank problem

Thanks again Peggy. I have been getting prices here and they are very expensive. Local agent thinks that the Raritan Part # 4181452 Sea Era complete toilet, w/remote pump, 12vdc. $730.00 + GST and the Part # 4720106 Smartswitch Deluxe Toilet Controller. $225.00 + GST would work. It can lift upto 2 metres he says? They say that with the smart controller my problems will be solved. Cannot use some of the others as there is no room under the toilet for an input pump. The Raritan has a remote pump I can hide somewhere? Matt
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Old 09-05-2012, 08:00   #10
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Re: Electric head height of holding tank problem

The Raritan SeaEra is a fine toilet--FAR more durable and reliable than any Jabsco--and according to the specs on page 6 in the owners manual at

http://www.raritaneng.com/pdf_files/...eaerav0103.pdf

the discharge pump can lift 1.8 m (6 feet), which is BARELY adequate to solve your problem...and there is a much more affordable way to buy it: the "conversion" is everything but the bowl...your Jabsco bowl WILL fit (any bowl that has the standard 4-bolt mounting pattern will)...and, without the bowl, it weighs a lot less, making shipping costs low enough to order from a US source (Hopkins Carter--"hopcar" here--will be glad to quote). You MUST also add the 3-way "Momentary" flush option to go with it because that gives you the "dry bowl" option that will minimize backflow. However, that option ONLY works with the pressurized fresh water version (and can be added to any fresh water electric toilet, btw)...but since the fresh water version only draws 10a (vs 16 for the sea water version) and can cut your flush water use by up to 50%...PLUS eliminating sea water odor and mineral buildup problems, and it costs less to buy too...I don't think that should be a deal breaker.

Forget check valves or booster pumps etc in the head discharge line...that would be just trading one set of problems for a bunch more. So if you don't like this solution, relocating the tank--which wouldn't be nearly as hard as you think--is the only other viable solution.
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Old 12-05-2012, 13:23   #11
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Re: Electric head height of holding tank problem

Thanks again Peggy. I am chasing up a quote now from hopcar. How much water would you estimate for each flush with fresh water? My holding tank is 110L.
I have since found out that a numbers of boats (Ben Jean) were converted to holding tanks in Queensland a few years agon and they were all installed in the cupboard standing up and have had the same lift problem. They have installed Raritan or they say the Tecma was even better to get around problem.
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Old 12-05-2012, 19:10   #12
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Re: Electric head height of holding tank problem

How much water would you estimate for each flush with fresh water?

Approx. 1/2 liter. Again, I strongly recommend that you add the optional 3 way flush to help you conserve even more.

A shame the folks in Queensland who installed all those tanks didn't do a little research first about how to do it right. You'd think that they'd have at checked into how high most toilets can lift bowl contents! Tecma was one of the toilets I recommended to you...a shame none of the Tecma models fit your space (however, I suggest you check that again...'cuz the Easy Flush is about the same size as your current toilet), 'cuz it has a pump and motor that can lift 10 METERS!
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