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-   -   Sump depth and tethered float question (http://www.diychatroom.com/f7/sump-depth-tethered-float-question-177748/)

zipmsp 04-21-2013 01:11 PM

Sump depth and tethered float question
 
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We have a drain tile system in our basement with a sump well and pump. The pump has a tethered float that turns the pump on and off. Two questions.

1. The sump pump is brand new (just bought the house following a major renovation) and there is a bag on the float. Is this something I should remove? It seems like it's leftover packaging from shipping, but I might be wrong.

2. When I manually turn the pump on and drain the sump well, water flows out of the corrugated pipe for 1-2 minutes and then stops. Does this mean the water level is too high? If I need to lower the water level, do I unscrew the float wire from the pump and slide the wire in the attachment?

I attached a photo showing the pump.

joecaption 04-21-2013 01:36 PM

Hard to tell what style pump you have from that picture.
Is the float floating free on what looks like a piece of black wiring, or does it trip a lever to turn it on?

zipmsp 04-21-2013 01:59 PM

1 Attachment(s)
It is floating free, there is no lever. There is a piggyback plug attached to the float. The pump plugs into the float, and the float plugs in to the wall.

Daniel Holzman 04-21-2013 02:51 PM

I have a very similar setup. The "bag" is likely left over packaging as you thought. As to setting the level of the float, that topic has been debated endlessly on this forum with a wide range of opinions. You may want to do a search on the thread "set sump pump float" if you care to read the numerous opinions and theories.

My opinion is that the purpose of the sump pump is to keep the groundwater level below basement floor level. I like to try to keep the water about 4-6 inches lower than the floor, so I set my float to turn the pump on when the water level in the sump rises to about 4 inches below floor level. I set the float to turn the pump off when there is about 6 inches of water left in the sump pit.

There are numerous theories about the need to keep the drain tile less than full, there are theories about the need to keep the footers dry, and there are various theories about keeping air out of the tile etc. Based ons 22 years living with a sump pump in my house, and numerous designs of commercial sump pump installations, my opinion is that keeping the footers dry is irrelevant (concrete does not mind being wet), and keeping the drain tile less than full is also irrelevant (water will flow towards your sump pit as long as the water level in the pit is lower than the water level outside the pit, which will always be the case if your pump is working). So my conclusion is pretty simple, set the pump to turn on about 4 inches below your slab elevation, this makes the pump work the least amount, saving electricity and wear on the pump.

AllanJ 04-22-2013 07:05 PM

A perimeter drain system works best when there is an air space maintained going all the way around the perimeter. In most cases, if the drain pipes as seen in the pit are partly covered before the pump starts, the air space has not yet been filled up. Meanwhile there may be a critical level where turning on the pump before the water reaches that level results in much more frequent pump running and cycling.

The critical level varies with the weather (rainfall).

If you set the pump float too high (and the perimeter drain pipe fills up completely at any point along is length) then it is possible to get water up onto the basement floor at the far side of the basement while the pit is not quite full.

When you adjust the float, let the pump run for about a week before drawing conclusions that you changed things for the better. It takes that long for the soil all around the basement perimeter to react to the change in water level.

The pit should be nearly empty before the pump shuts off. The float should not actually hit the bottom otherwise it may occasionally fail to shut off the pump when it gets there. There are two adjustments for a tethered float, the fastening point of the tether, and the length of the tether.

Bpolijr 04-22-2013 10:46 PM

I respectfully disagree with Daniel completely.

The purpose of your tiles are to move water, not store water. If you allow the tiles to fill up, then allow the basin to fill up, where does any extra water under your basement slab have to go? No where, thus creating hydrostatic pressure, which can and will cause your basement floor to crack, allowing a easy access point for water to enter your basement. There are numerous videos on youtube showing set-ups where the homeowner has allowed the tiles to fill up completely with water, and while doing so, they also show that water begins to creep up between the basement slab and the wall.

Also, if you have a high water table, you are not lowering the water table any by storing the water - your mission is to GET RID of the water and evacuate it as quickly as possible.

Now, setting the float to kick on below tile height is definately harder on the switch and the pump - but myself, I'd rather have to replace a switch or a pump than have any adverse effects on my slab or walls.

Just make sure you have a decent backup system in place, should your primary pump/switch fail. Also, water alarms are cheap and effective.

Zip, like you I have battled with this issue. I've done HOURS and HOURS on research, and have spoken to more than a few professional contractors - all agree, keep your basin water BELOW tile height.

AllanJ 04-23-2013 05:59 AM

By maintaining the air pocket in the drain pipes and/or the gravel filled trench all around the basement perimeter, you lower the water table to that level artificially. The benefit of the lower water table extends a few feet to each side, how far depends on the water table outside.

(With the water table at the perimeter lowered to the level of the drain pipes, the water table in the middle of the basement floor usually goes down after a few days and stays down.)

(technical jargon) In a few cases the difference in artificial water table between being at the bottom of the drain pipe versus being 3/4 of the way to the top of the drain pipe can make the difference between having water come up onto the baseent floor (the slope between the water table directly above the drain pipe and the water table one foot outside the foundation crosses through the basement interior). If you started with the drain pipes full and some basement flooding, it takes several days for the water table contour to re-establish a new level after you adjust the pump float.

jomama45 04-23-2013 11:28 AM

I've stated it a number of times already, but maybe it's appropriate again. The actual height of the draintile as they enter the crock is usually not the same elevation of the draintile around the perimeter of the basement. The pipes usually dive down relatively quick for the last few feet as they enter the crock........

fetzer85 04-23-2013 01:23 PM

Yes, the drains in my dad's pit drop off about 6" in the last foot or two - meaning they could be covered with water in the pit but just a couple feet over they're empty.

Bpolijr 04-23-2013 06:22 PM

True, they do drop off.

However, when the basin fills up past the tiles, there is a LONG delay before the water in the basin begins to rise again. So during this long delay, the tiles are filling up. When the tiles are full, then the water in the basin begins to rise and the pump then kicks on. Therefor, your tiles are full - not a good idea.

jomama45 04-23-2013 06:36 PM

Most people get hung up on the tile itself, when most of the water doesn't even travel through the tile, but the stone it's bedded in. Corrugated tile like in the OP's picture obviously have slots around the whole diameter. The water would just as soon drop out of the lower slots than travel through the corrugated pipe. The most important part of the tile that enters the crock is the hole they enter through............


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