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Two Sump pump installation - Fine Homebuilding

Two Sump pump installation

I need to de-water a 1,000 square foot sunken concrete patio and drain tile around a large house. We have an existing 36†diameter sump pit about 5’ deep to install sump pumps.

There are two 4†pipes going into the sump pit, one from the patio drains and one from the drain tile.

I am thinking about installing two Zoeller sump pumps with a control panel that will alternate the operation from pump one to pump two and then back to pump one.

One pump will be a 2†pump and the second pump will be a Zoeller 1 ½â€ pump.

Has any body had any experience with alternating pumps, and what is your opinion of Zoeller pumps.

Thanks for your input.

Replies

We installed 4 floor drains that feed into one of the 4" PVC pipes that go into the sump pit.

If you are alternating them why 2 different sizes? Have you figured the capacity of the pumps and the amount of water that you will get?

And does the control panel offer lead/lag operations? That is a 2nd start point higher than the first to turn on both pumps.

The two different pump sizes are just to save money,but you are right, it probably makes sense to use the same size pumps.

No I have not calculated the amount of flow that will enter the pit, do you know were I can get information on drain tile (thru gravel) flow and patio drainage?

The sump pump controller that we are looking at is at: it does offer lag/lead operation, but both pumps are at the same elevation.

Thanks.

"ith one pump operating to handle normal flow, a second pump becomes operational in the event the water level continues to rise. The built-in alarm system, a standard feature, can be connected to sound when the second pump becomes operational (3 float switch system) or independently (4 float switch system)."

No, it does a lead/lag with different setpoints.

I did not bother with downloading the full specs/manual, but the controller looks full featured and is well suited for this application.

My controllers are sometimes this simple, but often they might have 3 small pumps, and 2 large pumps. They alternate within each size and then stage them, maybe 1 small, 2 large, 1 small and 1 large, then 2 large.

And that is if all of the available pumps are in auto and have not failed. These are used on water distribution systems where you have a large range of flows.

The basement drainage should not be that much of a problem. But the outside patio is. If you go the FHB main page and then look at the articles they had one on gutters and it had charts of maximum rain falls.

I would like to see the outside drainage separated from the inside, because if you had a failure then it would just be a way to dump water inside the basement.

But I am not sure how much you would gain. Because if the outside did fail and flooded then water would pond up. At least some would get through the doors. But that would help.

Also with the patio you will get trash (leaves, branches, etc). Can the pumps handle that?

Bill, thanks for the information.

The problem with the original wood deck is that the area below the deck was always wet. The deck was rotten, and any furniture placed on the deck would get moldy. So we decided to replace the wood deck with stamped concrete.

The existing rainwater filtered thru the wood deck and seeped through a gravel base, and eventually seeped into the sump pit. There are two 1 1/2" sump pumps in the pit, but only the lower pump currently works. The system is set up so that the upper pump only runs when the lower pump can't handle the water flow, or if the pump fails. We tried to run the upper pump manually but it does not work. One 1 1/2" pump has been adequate in the past to keep water out of the finished basement.

I'm thinking that if we run two pumps run alternately that they will last longer, do you agree? Just leaving the upper pump to sit for several years waiting for that one big storm does not seem like a good idea.

Unfortunately both the patio and drain tile flows into this one big sump pit.

As far as leaves go, we have grates on each of the 4 floor drains, so leaves should not clog the pumps. The homeowner is, and will have to be dillegent about keeping this lower patio free of leaves.

One concern I have is if we get a substantial rain after the snow builds up on the patio the rain water will not be able to drain away. This is a rare case in Illinois, but can happen. We can run an electric heat cord as a last resort.

So far the patio calculations are:

During a 1" rainfall = .104 gallons per minute (gpm) per square foot. This is 10.4 gpm for our 1,000 sf patio.This assumes that a 1" rainfall is the most we will have, and does not take into account the drain tile flow. A Zoeller model 53 standard 1 1/2" pump is rated at 34 gpm with a 10' head.

I'll get the calculations from my plumber on Monday, and post them when I can.

Still wondering what experience people have had with Zoeller pumps?

Bill, Thanks for lead on the rainfall totals:

based on the below chart here's the adjusted calculations. In my area according to the chart,the most intense five-minute burst of rain, measured in inches per hour, that's likely to occur in a ten-year period is 6" per hour.

So for the 1,000 sf deck. 6" x.0104 x 1000sf is 62.4 gpm for the patio alone. Under this rare sinario, two 1 1/2" pumps would be needed.

The calculation still does not add for the draintile flow.

Unisaw,

I use two pumps in the same pit, not quite the same situation as yours but may in part answer your question.

The only time I have a water problem is during the spring snow melt, water starts out slow for a week then runs like a river for two weeks then peters off to a trickle for a week or so. I have a small pump, about 1/8 hp set on the bottom with a cutoff switch set to the lowest point. A larger 1/2 hp pump sits directly above the small pump with a shut off just above the pump. The small pump kicks on as soon as the water starts entering the sump pit, constant runs, draws very little power and keeps up in the initial stages. The larger pump kicks on as the water flow increases, the smaller pump also extends the cycling time of the larger unit. Nothing kills a pump motor faster than excessive cycling. My first year I only had the one larger pump, it developed into a real problem since the pump cycled on and off so much during the early stages of snow melt that the switch burned out right when I needed it the most, not to mention the power bill. I have used the 2 pump system for two seasons now, works real well.

Armin, below is the elevation of the sump pit we are proposing:

Both sump pumps are at the same level at the bottom of the sump pit. Both pumps will be of the non-automatic type, so they will not have a float attached to them. The pumps will be controlled by separate floats, I like separate floats because they can be located in the center and are less likely to get stuck. 1 float controls the current pump, the second float is used when both pumps will be running, and the 3rd float is for the alarm bell/light. I agree that pumps that cycle too much will burn out quicker, so using by separate float switches the cord be shorter or longer depending on how long we want the current pump to cycle. This sump pit is 36" in diameter and over 5' deep so the pumps will not over cycle.

I like the alternating pump system better because when you use the second pump as a backup only it rarely gets used. In this case I don't think both pumps will ever run at the same time, so one pump will just sit and rust up. I think its best to run all mechanical equipment on a regular basis. It's like leaving your car sit outside for 3 years and then expecting it to run.

Unisaw,

I worked with Zoeller pumps in a commercial setting and they were absolutely kickass pumps.The building was a large medical office building with 16 suites,with the lower floor halfway below grade.Outside the footers and downspouts drained into a sump basin with dual (I forget the size)Zoeller pumps.And inside,all the drains and wastes flowed into a 6' diameter, 12' deep sewage ejector sump crock.I think the engineer spec'ed twin 10 HP 480v pumps.Bigger than what you need but controlled similar to the way you're thinking.The panel alternated them for even wear and had a full set of alarms.

The only problem we had was about a month after we started using them,sure enough the sewage high level alarm went off and we had to open up the crock.Full of feces and urine.I told the plumber I could bypass the controller to pump out the crock,so he gave the OK and called the supplier's representative out.The rep looked over the system and since it COULDN'T have been his equipment he blamed the way I had ty-rapped the floats to the standpipe at their specified heights.He said I should have cut the cords to the right length and let the floats dangle.The plumber and I had discussed this when we installed them, and thought in no way did we want them floating loose and tangling up with each other,then WE'D have to go in there to straighten them out.The plumber had to work with this supplier again so he said OK,he'd get a ladder and go down in the pit and cut the floats loose.I told him that first,that wasn't the problem,that there had to be a glitch in the controller,and that secondly,"....that's HUMAN S--- and P--- in there!" He said that yeah, but that's his bread and butter and sent the apprentice to find the worst ladder on the job.I asked him if there was a special Turd Acceptance School for plumbers.Finally as the apprentice showed up with the ladder I came up with one of my infrequent bright ideas and taped a hacksaw blade to a 10' length of 3/4 EMT conduit,and was able to slip the blade between the float cords and the standpipe and cut the tyraps.He shook my hand and to this day whenever he sees me he smiles and holds his nose.

And of course the problem was a printed circuit board in the control box.

You can't blame Zoeller though,anything with a PC board is going to fail at some time,and usually at the worst time.I spent $1200 on a GE refrigerator this summer,and 6 weeks later the PC board in it croaked.

I wouldn't have a clue about how to size the pumps you need,but the Zoeller pumps that I worked with really did work well.

Unisaw,

Zoeller pumps, by and large, are good products. If I remember correctly, though, the 53 uses a float integral with the pump. They have a tendency to hang up after they've been in use a while and/or the switch goes bad. If you decide to go with this model use the BN53 with a separate piggy back float.

You might check the availability of Myers pumps. Their model ME40MC-11. It's a 1 1/2" discharge also, but will pass 3/4" solids compared to the 1/2" with the Zoeller and will pump 70 gpm at a 10' head - even at 20 feet, where the Zoeller poops out, it will still deliver about 45 gpm. Again, use a piggy back float.

Allaround,

Thanks for the information.We will definately go with non-automatic pumps, and control them with separate float switches.

I will check into the Meyer pumps. I'm not sure what size we will end up with, but 70gpm at 10' x 2 pumps has to be enough. I will also use a pump that will handle 3/4" solids.

Barry, thanks for the info on Zoeller pumps. I appreciate my plumber every time he does work for me. Most of the time his working conditions are ok, but it can get pretty ugly sometimes.

This system is for storm water only. The only solids will be anything that can get through the floor drain covers. The control box does have printed circuits in it, and I agree, circuit boards can be a weak link, especially in damp locations around sump pits.

I am still working on flow calculations and what size pumps we will use. I'll talk get more information from my plumber on Monday.

Some thing else to ask your self. Did the developer and city build a large enough storm drain in the road. To make sure you don’t get over land flooding backing up into your sunken patio if the city gets a heavy rain. If not did the developer landscape your lot so it will protect you from over land flooding.

How did you decide that the 4" drain tile would be enough to drain the patio. With out real local rain down burst amounts that 4" drain could be 4 or 6 inch to small to drain the patio with out you having standing water backing into your home for a time.

Have you figure on back up power encase of power failure during heavy T storm or a tornado.

Fredsmart,

You bring up some good points. As far as overland flooding, the grade pitches away from the upper walls of the patio, so the only storm water I have to deal with is water that falls directly onto the patio.

The 4" pipe size was supplied by my plumber, I will get his calculations on Monday, but from past experience this size should be enough. Remember, the sump pumps are only 1-1/2" to 2" pipes to get the water back out. More of a concern is if the floor drains freeze up and then it rains - the water will have no where to go.

The house has a back up generator powered by natural gas with an automatic transfer switch. The pumps will be on this generator. I do use the battery back up pumps often on other houses, but they are high maintenance.

I have two two-pump sumps on my property. One word of advice - judging from all the leaves in your photo, you might want to add a screen just below the grate on your sump. Your homeowner will appreciate not having to muck out the pumps that will get clogged after every rain. And tell your homeowner to clean the screen after every rain.

After a harrowing experience where a pump got clogged with leaves, I added a screen. Makes it much easier and neater to clean.

Here's the stamped concrete lower patio so far. We finished stamping the concrete on Friday, and sawcut the expansion joint today.We will powerwash the area next.

The rainfall design calculations for the patio are as follows:

I contacted the design department at Zoeller and they confirm the following: 144 c.i. of water per sf per 1" rainfall x 750 square foot patio / 231ci per gallon = 467 gallons per hour for a 1" rainfall. A 6" rainfall is 2,800 gallons. This is 47 gallon per minute in a major rain. Currently I'm looking at two 1 1/2" pumps rated at 60gpm each. Run alternately with an alarm per above posts. (Note: I re-calculated the patio size as 750 square feet.)

Thanks for the info on leaves getting thru the grates and clogging the pumps, I realize that the grates are a weak point of this system. Sunken patios by design are high maintenance.

Here's the detail of the floor drain / grate:

They are forcasting heavy rain tonight, so we'll see how the drains work, wish me luck!

KAORISDAD,

Thanks for the info on the floor drain grates. I have had leaves clog drains before, but never clog the pumps. Could you tell me what size area are you draining, and what sump pump arrangement you have?

Unisaw,

The area is fairly large - it's my driveway between my house and garage - I'm guessing around 800 SF or so, including rain from several roof downspouts. At the time, I had a single sump pump, and it sucked debris up through the bottom of the pump and clogged. It was raining cats and dogs and the water rose (about 4-5 inches) until it was almost ready to enter my garage and house. There was a break in the rain which gave me a chance to yank up the pump and clear the leaves out of the intake vent. After that, I cleaned the sump out after each rainfall, as my driveway accumulates alot of leaves from my neighbors bushes (not even my own plants!).

I just viewed your latest photo - maybe your arrangement does not need any screens. My driveway drains directly to my sump so any debris is washed into the sump.

Since then, I've enlarged the sump and added a backup pump that is elevated - different from your arrangement which sounds pretty impressive. At the suggestion of my landscaper, he installed a metal screen just under the grate. Some smaller debris can still get to the pumps, but most of the larger (>3/8-inch) stuff sticks to the screen. Now, I just look at the screen after rainfalls, and determine when I need to clean it. I tend to think that the pumps are really built to be in a corrosive environment - they are not really complicated devices, so leaving a backup that only goes on if the primary pump fails, doesn't really bother me.

Hope this helps.

KAORISDAD,

I like the idea of two pumps in one sump pit. Just not sure which installation is better.

If both pumps are run alternately they both get run on a regular basis. The downside is that you are adding additional controls/maintenance to do this.

I don't like the idea of a pump just sitting idle for several years rusting up while waiting for that 1 day it is needed.

Just a quick up date. We sealed the stamped concrete lower patio area, and it looks great! It rained over 1" last Tuesday, and the drainage system worked well, there are a total of 4 floor drains. The rain was over a 10 hour period, so the gallons per minute of water was low.

We will install the new sump pumps and controller this next week. I'll post the final pictures and calculations when the work is done.

Here's the finished sump pump work. We changed from 1.5' to 2" PVC pipe with 2" check valves. The grey box to the right is the new Zoeller controller that alternates the pumps. The controller will also run both pumps if needed, with alarm. Total pumping with both pumps is 94 GPM.

This system works well so far. It is designed for a 6" rainfall in a 5 minute period.

Unisaw,

That is one impressive setup. Kudos for your attention and research for the owner. Not many contractors I know would have taken the time to do the homework you did.

How much does a controller like that typically cost installed?

KAORISDAD,

Thanks for your kind words and comments. Sorry it's taken me several days to respond. We are framing a master bedroom addition and they are calling for 3-6" of snow on Friday, so we are getting as much done as possible. We've got the tar paper on the roof, but I don't think we will get the shingles on before the snow. Here's where we're at this afternoon.

The Zoeller controller was from Dean Bennett supply. I had it mailed to me, since my local supplier did not have them in stock. I got their name by doing a Google search. The controller was $579.00, and I would figure another $200.00 to get it installed.

The sump pit is part of a larger project. The budget for the sump pit work was$2,000 for the pumps, controller, plumbing labor, electric labor, misc supplies and profit/overhead.

This system is different than my standard battery backup sump pump system. I normally install a 'Trusty Warns' 2" 83 GPM pump that runs on AC or battery, and will pump for 5 hours with a good charge.In comparison an "ace in the hole" pumps at 12 GPM for only 3 hours. The Trusty Warns system is provided by a local company and costs about $1,500, plus a yearly maintenance cost.

Although some people may feel this protection is costly, it beats the cost and headache of cleaning up a flooded basement.

Here in New Jersey, we have a lot of old trees and power lines. One good windy storm, and you're without power for days. Therefore, I always recommend a two pump system. The primary pump is a regular sump pump, usually a Zoeller, with integral float. For the back-up pump, I use a non-electric, water-driven pump. It gets piped with a one inch cold water feed line, and works by a venturi principle. They cost about $650.00, and install in a couple of hours. GPM depends upon water pressure, so lower pressure needs more volumn. The only maintainance necessary is to open up the seat valve manually, annually is fine. Never had one fail yet.When all else fails, use duct tape!

Daddoo,

I have not tried a water driven pump, but they do sound interesting. No battery or generator to worry about. What happens to the 1" supplly water? Is is recirculated, or does it go down the drain?

It goes down the drain with the waste water, the only drawback to the unit. Make sure you have an adequate outlet. And, it isn't the fastest pump around. But with no plug or battery to worry about, it is more than worth the trade. It has saved many a basement for my clients when the power goes out, and others are bailing........When all else fails, use duct tape!