Two return pumps into single return line... Possible?
- Thread starter Potatohead
- Start date
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NeonRabbit221B
2500 Club Member
If pump 1 fails then pump 2 fill follow the path of least resistance (down).
This is possible,
You will need check valves and unions so they wont fight one another.
This happens a lot in my world.
I am an electrician that work on fueling sites.
Often high volume gas stations will have two tanks and two turbines on one line.
Without check valves one tank will fill up as the other turbine is stronger.
90% of the time they just put a larger turbine in tank 1 and create tank 2 into a slave syphoned tank, and the second turbine still in place is just a backup for the big boy.
Do you need massive flow or just trying to keep costs down with two smaller pumps.
Might be better able to answer knowing your needs wants.
You will need check valves and unions so they wont fight one another.
This happens a lot in my world.
I am an electrician that work on fueling sites.
Often high volume gas stations will have two tanks and two turbines on one line.
Without check valves one tank will fill up as the other turbine is stronger.
90% of the time they just put a larger turbine in tank 1 and create tank 2 into a slave syphoned tank, and the second turbine still in place is just a backup for the big boy.
Do you need massive flow or just trying to keep costs down with two smaller pumps.
Might be better able to answer knowing your needs wants.
NanoDJS
Valuable Member
piping can only supply x amount of water at y pressure , so adding two pumps to the same line with check valves to prevent reclaiming to pump if one goes out. This is the best way to do it , you rate both pumps output to your flow rate, then if one falls out youll still be around 1/2 -2/3 your total flow with both. Its basically going to increase the head pressure and improve the pump curve. You need those check valves though 
like k7bmg said , having 2 returns and 2 pumps, can cause other issues , dead section of tank flow, or worse back siphoning ( extra drain ) below the water line thats still being actively filled ............ think about that for a min.......... you must keep positive pressure on ALL return feeds at all times while tank is running.
like k7bmg said , having 2 returns and 2 pumps, can cause other issues , dead section of tank flow, or worse back siphoning ( extra drain ) below the water line thats still being actively filled ............ think about that for a min.......... you must keep positive pressure on ALL return feeds at all times while tank is running.
OP
OP
Potatohead
Valuable Member
Nothing to do with flow really, just redundancy. I do not have a controller, don't really want one, but return pump failure is pretty much as bad as a power outage and probably my main achilles heel with my tank.
OP
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Potatohead
Valuable Member
It's a Tunze. I'm sure it's fine, been going three years, but the one weak spot. I check my wifi cam a couple times a day and have spares on the shelf. I travel a few weeks a year too.
NanoDJS
Valuable Member
Yeah if you have the spares , then do it !!! Equidistant piping of the pumps to the tee will pressure balance the whole deal, also add a multi turn gate valve to the feed after its twined , this will give the ability to dial in the flow if the pumps are not dc .
Rubblereefer
Active Member
Honestly I would just go with 2 return pumps and 2 return lines. Check valves can and do fail.
NanoDJS
Valuable Member
a swing check in after the pumps in vertical orientation would'nt fail in any lifetime of any system Ive seen . Now a spring check ... total garbage and not for this application. Those are unicorn parts for people who piped incorrect , got knocked down and have to add a check with no correct placement, or a boiler potable supply line , neither of which this application would be ......just a swing check. And what happens when your non checked supply a stops and supply b is running , supply A becomes a drain at whatever level your supply nozzle was , so youre screwed in that case. Get the Vacuum unless your sump is HUGE ...
Greybeard
2500 Club Member
Bonus: they act as a heater, as well as a pump
My 20+ year old Danner Mag18 will heat a 60g drum of water overnight, exceeding my tank's temp by a dozen or more degrees. I've dedicated that one to pumping water up the slide in the swimming pool
It would be possible from a technical viewpoint, but a maintenance nightmare. You would need check valves (swings) but since return lines don't tend to get cleaned a lot, you will find sponges, vermitid snails, feather dusters, and who knows what else colonizing return pipes. Now what is going to comee loose at some point to prevent that check valve from working properly when you need it unless you keep them realy clean?
Two seperate return lines with siphon breaks will give all the redundancy you need with far less maintenance.
Two seperate return lines with siphon breaks will give all the redundancy you need with far less maintenance.
OP
OP
Potatohead
Valuable Member
The only way I can see to run two new return lines is if I actually ran soft tubing through the existing hard return line, since the new pumps would flow less and have smaller outputs. I don't know if they would even fit through, I doubt it.
I think I will just leave it be for now, not much other choice without major work.
I think I will just leave it be for now, not much other choice without major work.
Rubblereefer
Active Member
you could just run them with soft tubing and retuns that rest on the back rim of the tank. Or just run a small one like that in addition to your main return pump. Thats what I do
OP
OP
Potatohead
Valuable Member
Don't want to do the over the back thing
Rubblereefer
Active Member
Thats what she said
LobsterOfJustice
Valuable Member
You can combine them, but there is a fair bit of efficiency loss - for example if you are running two 700 GPH pumps combined you might see around 1000 GPH. I have a remote sump ~70 feet from my display so running a second entire return line wasn’t a good option for me. I have two pumps which combine at a wye and the pipe diameter up sizes when they combine. I also have check valves as noted on the outlet of each individual pump. Never cleaned them or done any other maintenance on those valves but after 3 years maybe I should.
