Separate and idependent drains needed for two pumps?

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,053
Pleasanton, CA
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Plaster
Chlorine
Salt Water Generator
That probably wasn't the best example but all I am saying is that you do not need a plastic sump. It can be made out of gunite as shown in section 2 of this manual:

The picture I showed is all gunite with no plastic sump. In this particular case, the pipe traverses well below the rebar (i.e. buried in substrate) so there is no reduction in the gunite surface (other than the penetration).
 
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JamesW

TFP Expert
Mar 2, 2011
24,208
The pipe has to be 1.5 x the pipe diameter below the grate.

I don't see how they are going to be able to have the pipe 3.75" (2.5 x 1.5) below the grate.

The sump has to be 2.5" deep at the diameter of the grate before sloping to the pipe.

Field fabricated sumps usually need to be designed and certified by a qualified professional to make sure that they are properly designed.

The picture of the field fabricated sump in the reference shows a fully formed sump.

I don't see how they are going to get the fully formed sump without cutting the concrete.
 
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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,053
Pleasanton, CA
Pool Size
20000
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Plaster
Chlorine
Salt Water Generator
I don't see how they are going to be able to have the pipe 3.75" (2.5 x 1.5) below the grate.

The sump has to be 2.5" deep at the diameter of the grate before sloping to the pipe.

I think those are the only important requirements. I don't believe it needs to be fully formed as shown at the top of page 3. It only needs to meet the dimension requirements at the bottom half of page 3.

Here is what APSP-7 says about sumps:

4.5.1 Field built sumps. Field built sumps shall be built so that the opening of the suction pipe will be no closer than 1.5 times its inside diameter from the bottom of the listed suction outlet cover/grate.
 
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JamesW

TFP Expert
Mar 2, 2011
24,208
The pipe has to be cut about 3/8" above the gunite so that the plaster can come up on the pipe and waterproof up to the pipe.

Then, the bottom of the grate has to be 3.75" above the pipe.

How are they going to do that?

The top of the grate will have to be more than 4.5" above the gunite.
 
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JamesW

TFP Expert
Mar 2, 2011
24,208
Field fabricated sumps usually need to be designed and certified by a qualified professional.

Maybe the local inspector doesn't inspect these things very carefully.

Most likely, the contractor gets away with just cutting the pipe and sticking a grate over it due to lax inspections.

In any case, it's probably not being done correctly.
 
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GrandLSU

Member
May 14, 2020
22
Baton Rouge, LA
In the above case, each pump would have its own line to the main drain.

So I understand why two separate pumps cannot pull from the same common drain, but I have a very different but slightly related question. Assuming two pumps do each have their own separate dedicated drains, can the two pumps both output water to the same water feature? For example, could the output of two pumps be teed together into a single pipe, that then supplied the water from both pumps to a single high flow requirement water feature (e.g. a water slide)?
 

JamesW

TFP Expert
Mar 2, 2011
24,208
could the output of two pumps be teed together into a single pipe, that then supplied the water from both pumps to a single high flow requirement water feature (e.g. a water slide)?
I would not do that.

Why would you want to do that instead of a single properly sized pump?