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Thread: Sump pump/pit conundrum....

  1. #1
    DIY Junior Member
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    Default Sump pump/pit conundrum....

    Good day everyone....

    I am having some problems with my current sump pump and sump pit situation. I live in a Tri-level home (built in the late 1960's) with the lower level approximately four feet below grade. Over the last few years, I have had water in my finished basement on several occassions. The first couple of times, I didn't realize that my primary pump had failed. The HomeGuard water back up system was acting as my primary pump (the alarm was disconnected - go figure) which of course added an inordinate amount of water to the already saturated ground and it wasn't able to keep up. I discovered the problem and replaced my primary pump. Since our water table is incredibly high due to over developement "upstream" from us dumping all of their rain water into an unimproved storm sewer system, water has become a real problem in my neighborhood.

    Two days ago my two year old Little Giant sump pump failed and we once again had water. This time, I replaced my primary pump with a Zoeller M-53 pump. I will be switching to a battery back up system (I'm thinking of their 507 back up system) to get rid of all of the extra water from the Home Guard. My concern however, is my sump pit configuration (drawing below). I'm limited by a 1-1/4" discharge line that goes under the slab and up into the back yard where all of the excess water now tends to pool. The pit itself (well, the pit walls anyway) are also starting to show cracks. I'm assuming that's because of all of the pressure from the "extra" water from the Home Guard being in use so much over the last few years. I'm also a bit concerned that going from the standard 1-1/2" discharge into the 1-1/4" discharge may be putting too much pressure on my primary pump and what possibly caused my new pump to fail prematurely.

    When I switch out the Home Guard for the battery back up, I could very easily run 1-1/2" PVC up out of the pit and over and through a different outside wall and encase the pipe in a soffit to hide it. My worries about that however, is that assuming an approximate 10' verticle rise, I will have three 90 degree elbows (and a fourth outside the wall and even possibly a fifth to turn the water toward the yard) as well as an additional 20' of 1-1/2" PVC piping to get to the outside wall. Which will give me a total of approximately 30' of PVC with four or five 90 degree elbows. I'm thinking that might be way to far to try and pump the water with my M-53 or any type of back up pump.

    Any thoughts and suggestions would be GREATLY appreciated....

    My current configuration....
    Last edited by quadman Indy; 03-31-2010 at 10:15 AM. Reason: Can't seem to spell today.... LOL

  2. #2

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    Ok, lets see,

    Reducing the pipe size by 1/4 inch didn't kill your pump. What kills pumps is frequent cycling or severe flow restriction. Ideally you want your off time between cycles to be as long as possible. 5 minutes is great. 1.5 minutes is tolerable as long as it doesn't run this way all the time. Anything below that isn't good for the pump. Also, most pumps are water cooled so you need some flow. If your 50 year old cast iron pipe is corroded inside to the size of 1/4 inch pipe that could be a problem.

    Five 1.5 inch 90s and 30 feet of pipe is probably not a deal breaker, but I'm not familiar with battery backup pumps so I don't know for sure. Usually its the height that the pump has to move the water that causes the most drop in flow for sump pumps. If your worried about the number of 1.5 inch 90s just enlarge the pipe to 2 inches and you'll have less resistance to flow at the 90's and over the length of the pipe - problem solved.

    Also I'd be concerned about the condition of the iron pipe. It could be corroded to the point that much water is getting through it. If you need to replace it I would run 4 inch PVC under the lawn - assuming you can pitch it so that it will drain by gravity and 2 inch pvc in the house. This will minimize any resistance to flow cause by the pipe.

    -rick

  3. #3
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    Quote Originally Posted by drick View Post
    Ok, lets see,

    Reducing the pipe size by 1/4 inch didn't kill your pump. What kills pumps is frequent cycling or severe flow restriction. Ideally you want your off time between cycles to be as long as possible. 5 minutes is great. 1.5 minutes is tolerable as long as it doesn't run this way all the time. Anything below that isn't good for the pump. Also, most pumps are water cooled so you need some flow. If your 50 year old cast iron pipe is corroded inside to the size of 1/4 inch pipe that could be a problem.

    Five 1.5 inch 90s and 30 feet of pipe is probably not a deal breaker, but I'm not familiar with battery backup pumps so I don't know for sure. Usually its the height that the pump has to move the water that causes the most drop in flow for sump pumps. If your worried about the number of 1.5 inch 90s just enlarge the pipe to 2 inches and you'll have less resistance to flow at the 90's and over the length of the pipe - problem solved.

    Also I'd be concerned about the condition of the iron pipe. It could be corroded to the point that much water is getting through it. If you need to replace it I would run 4 inch PVC under the lawn - assuming you can pitch it so that it will drain by gravity and 2 inch pvc in the house. This will minimize any resistance to flow cause by the pipe.

    -rick
    Thanks Rick.... The original discharge pipe is 1-1/4" cast iron (I'm assuming that it's cast iron) that runs from the side of the pit, under the basement slab for 5' and then approximately 5' up to grade. There is no way I could replace that discharge pipe without jackhammering up my basement floor and then digging down five or six feet outside my house. That's one of the reasons I'm thinking of replacing it by taking it straight up out of the pit with PVC, then over to a different outside wall where I will get better drainage. I can't bury my discharge once it has left the house. I would dearly love to, but I can't.... I checked.

    I had a builder friend of mine confirm that he uses dual pumps with a generator back up with no type of battery or water based pump back ups, on his high end custom homes. It was suggested that I go this way on another forum and have a generator handy rather than mess with battery's or pumps that may or may not be as good as the primary pumps. I have room in the pit to add a second pump once I remove and cap off the existing discharge piping. I would mount the float switch higher than the main pump so that it would only come on in the event of failure or an inordinate amount of water entering the pit. They also recommended going to 2" PVC pipe which is easy enough for me to do.

    It would be some type of configuration like this.... (and I know I probably don't have my check valves in the right place and stuff).... but this is just food for thought and an alternative I am considering to my current situation.


  4. #4
    Test, Don't Guess! cacher_chick's Avatar
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    It's a fine idea. A lot of homes don't have a big enough pit to run 2 pumps; 2 pumps with float switches is even more of a challenge. Sizing is important for the life of the pump. To make the pump motor last it should never run for less than a minute. This is accomplished through proper sizing of the pit and pump.

    A generator is also a great idea, but it is not of great functionality unless it is set up with an automatic transfer switch to handle the function when nobody is home.

  5. #5
    Mechanical Engineer loafer's Avatar
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    Do you intend for both pumps to run at the same time? I don’t think it will work well if both pumps are plumbed into a common pipe, regardless of what you do with check valves and pipe diameters. The battery backup systems work with both pumps connected to the same pipe because both pumps will never run at the same time.

    At the Y where the pumps are joined the pressures have to be perfectly matched, otherwise the pump with the higher pressure will prevent the other pump from producing any flow. It will be impossible to balance the pressures of each pump so, if both pumps are run together they need their own pipe.

  6. #6
    Test, Don't Guess! cacher_chick's Avatar
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    Quote Originally Posted by loafer View Post
    Do you intend for both pumps to run at the same time?
    Dual pumps are connected to an alternator which causes the pumps to run alternately, reducing the wear of each pump by half. The alternator also allows one to run if the other fails.

    A generator or battery backup system is still needed to make the system exceptional.

  7. #7
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    Quote Originally Posted by loafer View Post
    Do you intend for both pumps to run at the same time? I don’t think it will work well if both pumps are plumbed into a common pipe, regardless of what you do with check valves and pipe diameters. The battery backup systems work with both pumps connected to the same pipe because both pumps will never run at the same time.

    At the Y where the pumps are joined the pressures have to be perfectly matched, otherwise the pump with the higher pressure will prevent the other pump from producing any flow. It will be impossible to balance the pressures of each pump so, if both pumps are run together they need their own pipe.
    Yeah, I suppose they would be technically running at the same time since the second pump would be there as a back up to the primary when we have one of our "water events." I didn't even think about the pressure and flow at the "Y" causing a restriction in flow from the primary pump. Ok.... so I need to scrap that idea and go back to a battery back up system I guess. Or, look into running dual discharges.

    I still think I'm going to redo my main discharge in PVC straight up out of the pit and over to a different outside wall which would give me much better drainage away from the house. I think I'm fine with my current Zoeller M-53 at 10' of head so I just need to focus then on a decent battery back up system. Any thoughts on Zoeller's 507 battery back up system?
    Last edited by quadman Indy; 04-06-2010 at 06:18 AM.

  8. #8

    Default Dual Pump, Primary and Backup

    In the above configuration both pumps will never run at the same time unless the first pump just can't keep up or it fails. The backup pump is raised up say 3 to 4" higher so the water level will never rise high enough for the second pump to come on. Now if float switch fails in lower pump, only then will the water level rise high enough to trigger the second pump. You should also install a Zoeller Aquanot alarm (about $20) with its sensor attach to the pipe about 2" above the turn on level of first pump. This way when first pump fails or gets overwhelmed, the alarm will go off to notify you that the first pump has failed. Alarm has an on/off switch. You could even use a second alarm mounted above the second pump turn on level to let you know when you're in really big trouble such as dual failure or really high inflow....
    No special electronics are needed and this is not the same as the Zoeller control unit that alternates between pumps to extend their life.
    Also, Zoeller makes a nice pump stand (10-2421) that accepts 2" PVC pipe as legs instead of bricks. Use one stand for the first pump to keep it about 2" above gravel and then add 3" PVC legs to second stand to create backup pump 5" above gravel.

    Now, if you get enough inflow on a regular basis such that one M53 can't keep up then I would still mount the pumps as shown but simply supply two 1.5" discharge lines, one per pump. The first pump will work the most with the second as backup and high water periods.
    Last edited by wraujr; 04-07-2010 at 04:15 PM. Reason: typos

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