Return pump pressure head and friction loss

[Potatohead]

I would be really susprised if a mag drive 18 didn't flow a lot more with your setup than the Vectras do. Mind you the thing uses 145w also.

An Iwaki would be a great choice if you are able to go external.

 

[jda]

All of those options will still pump pretty well all the way up to that 21 feet. What is your head feet, exactly? If you are approaching 20, then order a bulkhead and plumb in a PanWorld, BlueLine or Iwaki since they are the only real tool for this job under $1000.

Laguna 4260 will move some serious water from my basement to the main floor. So will a Mag 2400 or 3600 - 1800 does an OK job. Fluval SP6 is not quite as powerful, but still really good. These pumps will also not slow down nearly as much with pipe sizes. The are a bit more wattage, but that is what it takes to do the job... plus they will heat the water just a bit which will save one some heater costs which is beneficial unless you live in Miami or the Mojave or Sahara.

Post up your head number if feet and we can review it. My sincere apologies if you already did this and I missed it.

 

[92Miata]

Well they said that it won’t have much impact because it still has to get reduce to 3/4” at the tank. I can’t decided between 1.25 or 1.5.

Head loss in these sort of situations is about friction loss - the higher speed the water is moving through the pipe, the higher friction loss. Larger pipe means lower velocity means less friction loss.

Friction loss is proportional to the length of the pipe that the water is traveling along at the specific velocity. 10 feet of 3" pipe followed by a choke down to 1/2" will move decidedly more water than 10 feet of 1/2" pipe because the velocity (and hence friction losses) are only high in a very short part of the pipe in the first scenario vs the whole pipe in the second.

The 10 feet of 3" pipe followed by a 1/2" chokedown will movemore water than a 10' piece of 1" pipe after you get past a certain velocity.

Run the biggest pipe you can fit, and that won't flood your sump when you turn the pump off.

 

[jda]

Lastly (sorry for the multiple posts) sizing down the pipe will increase head on some of these. Going from 1" to 3/4 will get you up another number of feet... like 8 or 10 feet in some cases. I am talking about the output size of the pump, not the pipe size.

Also, going too large straight out of the pump can slow stuff down with losses near the outlet... I learned this the hard way plumbing a 3/4 outlet directly into a 1.5" pipe once.

 

[DCR]

You will certainly gain some flow by upgrading the main line even if you have to reduce it at the tank. Piping friction losses are cumulative - i.e the flow is determined by the sum total of all the piping and not by the most restrictive component. I would second the idea of replacing the line first. For 300 gph, a 1" line should be sufficient. 1-1/4" if you want some extra insurance, but 1-1/2" is overkill for 300 gph.

Both the M2 and the L2 state a maximum head of 21.5 ft, so I can see why you did not see any improvement with running them so far back on the curve with the piping choked down so much. I hear the observations that DC pumps do not handle backpressure well, but effectively what that means is that the supplied pump data is not valid. Maybe the suppliers are providing false data, but if their data is correct, you should be able to achieve 300 gph with 1" and especially 1-1/4" piping with either pump. I would certainly increase the flow meter size. You could also go over the top to get around the 3/4" restriction. Are there one or two 3/4' returns, because two 3/4" returns should easily handle 300 gph.

 

[Jackooze]

All of those options will still pump pretty well all the way up to that 21 feet. What is your head feet, exactly? If you are approaching 20, then order a bulkhead and plumb in a PanWorld, BlueLine or Iwaki since they are the only real tool for this job under $1000.

Laguna 4260 will move some serious water from my basement to the main floor. So will a Mag 2400 or 3600 - 1800 does an OK job. Fluval SP6 is not quite as powerful, but still really good. These pumps will also not slow down nearly as much with pipe sizes. The are a bit more wattage, but that is what it takes to do the job... plus they will heat the water just a bit which will save one some heater costs which is beneficial unless you live in Miami or the Mojave or Sahara.

Post up your head number if feet and we can review it. My sincere apologies if you already did this and I missed it.

From the sump 4ft to the ceiling , 11 ft across the basement ceiling and then 4 ft up to the tank.
My issue with all the pumps you are recommending is I will have drill the sump to add an external pump which I don’t want to do. I only have room for a pump that’s 5” width x 8” length.

 

[Jackooze]

You will certainly gain some flow by upgrading the main line even if you have to reduce it at the tank. Piping friction losses are cumulative - i.e the flow is determined by the sum total of all the piping and not by the most restrictive component. I would second the idea of replacing the line first. For 300 gph, a 1" line should be sufficient. 1-1/4" if you want some extra insurance, but 1-1/2" is overkill for 300 gph.

Both the M2 and the L2 state a maximum head of 21.5 ft, so I can see why you did not see any improvement with running them so far back on the curve with the piping choked down so much. I hear the observations that DC pumps do not handle backpressure well, but effectively what that means is that the supplied pump data is not valid. Maybe the suppliers are providing false data, but if their data is correct, you should be able to achieve 300 gph with 1" and especially 1-1/4" piping with either pump. I would certainly increase the flow meter size. You could also go over the top to get around the 3/4" restriction. Are there one or two 3/4' returns, because two 3/4" returns should easily handle 300 gph.

One 3/4” return that goes into a Y nozzles. I don’t think that will be an option. I was hoping to make this adjustment as simple as possible.

 

[jda]

4 up, 11 over and 4 up is like 10 or 12 feet to me. Get a large Laguna or Mag Drive and you should be OK. Keep it all 3/4 with flex line (if you can) and it will hum - if not 3/4, then the outlet size of the pump... do not neck it down or size it up if at all possible. The soft line will eliminate elbows and stuff and can really help too.

 

[Jackooze]

After hearing from everyone I think I will change diameter of pipe to 1.25 from 3/4” and reduce the amount of elbows. Changing the pump to recommended brands everyone suggested will not fit inside my chamber and drilling is not an option. So I hope that increasing the pipe with the Vectra L2 will do the trick. Is there anyway to figure out if my sump can handle 1.25 return line ?

 

[jda]

I do not know honestly... flow pumps are hard to judge and especially when the manufacturer does not give you good data to look at. A pressure pump could handle that with no problem, but the Vectra is not that. Probably no way to know until you give it a go.

 

[BZOFIQ]

You need your return size to be properly sized for your pump. If the pump has 1.25 or 1.5" out, don't connect it to anything less. If you have to split it, run is as far as you can before split using the "native" pipe size.

DC pumps with few exceptions are absolutely terrible with head, throw in a small pipe diameter and you quickly get fraction of its rating.

 

[BZOFIQ]

I see an abyzz in your future; unless you want to stick to AC for short term cost reduction.

 

[Jackooze]

Not sure if this is a stupid question but does an external pump have to have the inlet plumbing drilled through the sump or can you run the pvc directly into the sump?

 

[kyleinpdx]

I also think that increasing the diameter of your plumbing will help you out a good bit.

Yes, you will still run into the issue at the tank itself, but that should be much less than you were experiencing across the whole run. Its not a perfect analog, but think of (or try this and take) a 25ft garden hose, put a little water in it and blow on the end, feel how much force it takes to push that water/make some bubbles. Now take a 50ft garden hose and do the same thing. The longer run should require more force to move the water. You can also think of it like the barrel of a gun, the longer the barrel (typically) the higher the velocity of the bullet will be when it leaves the barrel. Now in that example, we're demonstrating the inverse of what you want, but its a decent way to show how it works. The velocity increases because the force pushing that bullet has longer to go before it equalizes with the atmosphere. I hope that makes sense.

Think of friction as "stick" with the smaller diameter pipe you have 10+ feet of pipe for the water the "stick" to, with the larger diameter piping more water will pass through without "sticking" if that makes sense.

 

[ca1ore]

I’m surprised everyone recommends Fluval Sea when it’s max head pressure is 12.1 feet.

Fluval pumps appear to be configured for pressure rather than flow …. you will still lose flow, just not as much as with a pump configured for flow.

 

[Potatohead]

Not sure if this is a stupid question but does an external pump have to have the inlet plumbing drilled through the sump or can you run the pvc directly into the sump?

The level of the water it is pulling from must be above the pump, in other words it must be gravity fed, you cannot run a pipe over the edge of the sump to feed one.

 

[DCR]

The level of the water it is pulling from must be above the pump, in other words it must be gravity fed, you cannot run a pipe over the edge of the sump to feed one.

This is not strictly true, although I would agree it is probably not advisable. A pump can lift the liquid over the edge of the sump and it can even be above the liquid level. It will probably be a pain to get the suction line liquid full and get the pump started. Industrial pumps will sometimes install a foot valve on the end of the suction line which is basically a check valve to help keep the pump primed. If you get air into the pump and lose suction for an extended period, you will likely damage or destroy the pump. You might be able to create a dry running protection based on low amperage on an Apex, but it is risky.

 

[sarcophytonIndy]

I would reconsider the decision of putting the sump in the basement. But if you must, then you might do yourself a favor by putting the sump on a table or stand, say four feet off the floor. This would reduce head pressure by four feet, which might be just enough to make your existing pump adequate.

 

[LC8Sumi]

Not sure if it has been pointed out before, but the main problem is the 90 degree elbow in the overflow box in the return section. That’s only like 16mm’s dia. So no matter if you use bigger pipe downstream, that bend kills the flow, especially with a dc pump. What you could do is avoid using the stock return pipe (the one in the overflow box), and do a 1” return pipe all the way into the tank (outside of the overflow box). It’s ugly, but at least you’ll get flow. Unfortunatelly there is no other reasonable way around.

this is the problem:

 

[Potatohead]

This is not strictly true, although I would agree it is probably not advisable. A pump can lift the liquid over the edge of the sump and it can even be above the liquid level. It will probably be a pain to get the suction line liquid full and get the pump started. Industrial pumps will sometimes install a foot valve on the end of the suction line which is basically a check valve to help keep the pump primed. If you get air into the pump and lose suction for an extended period, you will likely damage or destroy the pump. You might be able to create a dry running protection based on low amperage on an Apex, but it is risky.

I thought about that but even if you got it started, it would all fall apart during a power outage and/or every time you turned the pump off.

I'm sure there is some convoluted way to make it work with check valves... But, why?