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Ejector pump tank size?

John Kogel

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First you have to determine the needed GPM of the pump, based on fixture units plus the total head. Then, refer to the pump manufacturer's chart for the correct size basin for proper pump frequency.

Since I forgot my snorkel and face mask, [:-party] I'm am going to try and determine from the pic if that is a 1/3 Hp or 1/2 Hp pump there between the floaters.

A typical 1/3 hp grinder pump can blow 45 gpm for a head of 5 feet. The sewer line is maybe 20 feet up, maybe 25 depending where they buried the line.

If it is a 1/2 hp it can pump 67 gallons/min for 5 foot head, xx gpm up to 30 feet.

If the tank is 22" diam X 30" in height, how many gallons?

Vol = Pie R square x Ht = (11 x 11 )x 3.14 x 30 = ? cubic " = ? gallons?

Too slow, I got it - 47 US gallons. 39 Canadian.

Less than a minute to empty that sump, because the float trips it at the half-full point, so maybe 30 gallons between cycles.

I wish now I had found a piece of wire and pulled up on the float. But we had structure to look at, so now I'm trying to confirm if 4 toilets and four tub/showers, one DW and one clothes washer will fill that tub how fast.

I see for a head of 20 feet, Gal/min drops to 10 gals for a 1/2 hp.

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..........I'd point out that during a power failure, it wouldn't take much time to overwhelm the holding capacity of the tank. But on second thought, without any tank seal, the excess would just slop out into the basement[:-yuck]........Greg

Yes, thanks. I said the tub was too small without really knowing for sure. It just looks too small for a 4 bathroom house. And the lid needs to be repaired, so I said have a plumber repair the lid and check the capacity of the system.

With the lid properly sealed, I suppose crap would just wait in the pipe for the power to come back on?

It's not the fixtures, its the people.
Agreed. The couple that live there are probably good with what they've got. The guest suite is for occasional visitors.

My clients, older couple, would probably be OK, but maybe they'll rent the house out to a big family, or have kids and grandkids over for two months in the summer.

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Does it really matter? I'm aware of a fair number of commercial installations with a standard 30 gallon sump. They work fine.

How bad is it if the pump cycles a couple times? Not bad. Not even a little bad. This is presupposing a real pump, Zoeller, Hydramatic, or similar.

Pump frequency would be a consideration in industrial applications, but we're talking residential. Have people evolved to shit continually around the clock? O'Handley maybe, but normal humans aren't going to stress that rig at all.

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Kurt, I don't deny the small tanks work.

However, the pits are customarily much larger, holding tanks if you will? I have pics to illustrate my point.

Also a pump that cycles frequently will expire sooner than one that kicks in only a couple of times a day. I am of the opinion that an undersized unit will be trouble down the road, so that is how I wrote it.

Here is a larger tank, residential use.

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These lads have extracted the pump from an outdoor tank. It has a head of less than 10 feet to the sewer pipe, single family dwelling.

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Big outdoor sump....I don't know. The only one's I "see" are giant municipal lift stations handling the accumulated excrescence of entire neighborhoods of thousands of people. I've always assumed the tank is so big because it's gotta handle a lot of shit.

By pump, if you mean a real pump, cast iron housing, machined steel impeller, tapered roller bearings, double gasketed, drop it on the floor and it makes a hole kick ass pump....well, I think the Zoeller has something like a 500,000 hour mean time run average. Cycling a lot means it's only going to last 12 years as opposed to 13 or 14...(?)...

Chicago is the land of pumps. Every house has a couple. Cheap one's crap out. Good one's don't. They're all in little 22x28 sumps, have zero maintenance, run all the time, and the good one's last a decade. My best friend has a gallery down in the district; single ejector, two bathrooms, located in a lower level basement meaning 15' of head. On a big opening night, there's maybe 200 people taking a leak; the pump runs nonstop. His first one lasted about a decade. The 2nd one had a stuck switch and it ran nonstop for about 3 weeks until someone figured out what that humming sound was. I repaired it, it's still there 5 years later.

If it makes anyone feel good, recommend a new system with a big sump. Everyone gets to recommend whatever they want.

Personally, I think it would be a waste of money.

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Sounds good to me. Everyone does what's right for them. Folks want to calculate, calculate away.

The single factor that we've found matters is the pump. Put in the one you think is best. Everyone has an opinion what best is.

I think we do the Zoeller M57's. Max head is about 20', gpm at 5' is around 30+. I've got a couple that we put in 20 years ago in my friends business...still there pumping.

Of course a pump that cycles a lot will not last as long. If it's your basic cheap plastic pump, they die quick. Put in an M57 or similar quality, they run forever.

I tend to think that folks are overthinking this one. If one wants to overthink, that's their prerogative.

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I tend to think that folks are overthinking this one. If one wants to overthink, that's their prerogative.

Nah, I just was fishing for some background. Already reported it too small for 4 bathrooms.

I didn't know the volume of the jug so I calculated it from its approx size.

Those guys in my pic are working on a sewage pump where there were septic fields originally. A sewer line was put in, and everybody below the road now pumps up to it.

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