Float Switch turning OFF Return Pump?
- Thread starter Stidd
- Start date
cstires
New member
Even if you cut the power to the pump, your sump could still overflow, since water will be siphoning back through the pump.
I've been able to prevent this by simply drilling a small hole in the return line, just below the water line, as well as making sure my returns are positioned at the top of the water level to make sure there won't be too much water draining back into the sump before the suction is broken...
I've been able to prevent this by simply drilling a small hole in the return line, just below the water line, as well as making sure my returns are positioned at the top of the water level to make sure there won't be too much water draining back into the sump before the suction is broken...
BeanAnimal
Premium Member
You can use a flot switch to cut the power, but the problem becomes on of oscillation.
1) siphon breaks
2) tank water level rises
3) float switch rises and breaks contact
4) becaseu pump is off the water siphons back through pump into sump
5) float switch in display drops and restarts pump
6) overflow siphon is still broken so water level rises in tank again
7) float switch cuts power to pump...
8) the whole process repeates until you stop it, the pump burns up, or enough water evaporates to break the cycle.
SO...
You will need some sort of logic (latching relay, time deley relay or circuit) etc.
I hope this makes sense.
What size display tank? How long has it been setup and is there any chance of drilling it?
1) siphon breaks
2) tank water level rises
3) float switch rises and breaks contact
4) becaseu pump is off the water siphons back through pump into sump
5) float switch in display drops and restarts pump
6) overflow siphon is still broken so water level rises in tank again
7) float switch cuts power to pump...
8) the whole process repeates until you stop it, the pump burns up, or enough water evaporates to break the cycle.
SO...
You will need some sort of logic (latching relay, time deley relay or circuit) etc.
I hope this makes sense.
What size display tank? How long has it been setup and is there any chance of drilling it?
Pbrown3701
New member
or you coulp put a check valve in line with your return... This is not fail proof, but it would give you a little extra insurance.
javajaws
Premium Member
I don't think a hole in the return line would prevent the oscillation...just think about it. As soon as the water rises the float kills the pump, but the water will still return to its normal water level before reaching the hole in the return line (which I presume would be slightly beneath the normal water line).
You definitely need a latching relay of some sort that you can manually restart. If you're not the DIY type, the Reef Fanatic level controller in mode "B" may be able to do this. Just use one of the float switches so the relay never gets unlatched (restart the controller to reset power to the pump).
You definitely need a latching relay of some sort that you can manually restart. If you're not the DIY type, the Reef Fanatic level controller in mode "B" may be able to do this. Just use one of the float switches so the relay never gets unlatched (restart the controller to reset power to the pump).
Driftwood
New member
In order for a float valve to cut the power until human intervention you need a relay. If not, the water level will just fall and the float switch with turn the power back on automatically.
I would just have a small return section in your sump(2 gallons), the worst that would happen is the pump runs dry and fills the tank with bubbles and maybe burn out the pump.
You could get one of those black snakelike return nozzles that bend and put it mostly under the water except for just a little and point it down diagonally. That way if the pump is cut off it starts sucking air immediately before the water level drops.
Does your overflow have an airline tube on it? If so you can get a lifter or attach the airline to a powerhead venturi, that syphon will not break... If it is a u-tube I think I've seen plans to add an airline tube to one. This way no air bubbles can build up.
Good luck!
I would just have a small return section in your sump(2 gallons), the worst that would happen is the pump runs dry and fills the tank with bubbles and maybe burn out the pump.
You could get one of those black snakelike return nozzles that bend and put it mostly under the water except for just a little and point it down diagonally. That way if the pump is cut off it starts sucking air immediately before the water level drops.
Does your overflow have an airline tube on it? If so you can get a lifter or attach the airline to a powerhead venturi, that syphon will not break... If it is a u-tube I think I've seen plans to add an airline tube to one. This way no air bubbles can build up.
Good luck!
oldsaltman
New member
I use an aqualifter pupm to pull a vacume on my overflow tube 24/7. It has a small oneway valve just in case the aqualifter cuts off. My main pump is on a small computer battery pack so it never goes off.
BeanAnimal
Premium Member
FWIW you can not run a motor on a non sine wave "UPS" which is what I imagine your "small computer battery pack" is. The setup will either damage the pump or backup... or worse cause a fire.
BeanAnimal
Premium Member
Two points:
Driftwood, it is a HUGE deal. The ups output bus in simply not designed to handle the load signature of a motor. The "modified sine wave" radically changes the way the motor operates and this in turn puts a tremendous stress on the output devices (transistors) in the UPS. This can EASILY result in damge to the unit and/or fire.
I am the guy who sells specifies and services the UPS systems your company uses... you know the BIG 1000kVa UPS systems that go into your sever rooms and the little 3kVa systems that back up your servers. There is a big difference between a desktop UPS and a true sine wave UPS.
Second point:
dpstrand: The oscillation is very likely to burn out the return pump in short order. Figure on it happening at the worst time (10 mintus after you leave for work). That is 8 hours of oscillation at maybe 30-100 times a minutes. Lets just say 50 for ease of the math. That is 300 times an hours or... 2400 power cyles to the pump in 8 hours. Most pumps just can't handle that kind of stress. When the pump goes, will it burn up or just shear the impeller?. Who knows. Take the chance of the flood or the burned up pump... or a more robust failsafe setup. That is up to you
Bean
Driftwood, it is a HUGE deal. The ups output bus in simply not designed to handle the load signature of a motor. The "modified sine wave" radically changes the way the motor operates and this in turn puts a tremendous stress on the output devices (transistors) in the UPS. This can EASILY result in damge to the unit and/or fire.
I am the guy who sells specifies and services the UPS systems your company uses... you know the BIG 1000kVa UPS systems that go into your sever rooms and the little 3kVa systems that back up your servers. There is a big difference between a desktop UPS and a true sine wave UPS.
Second point:
dpstrand: The oscillation is very likely to burn out the return pump in short order. Figure on it happening at the worst time (10 mintus after you leave for work). That is 8 hours of oscillation at maybe 30-100 times a minutes. Lets just say 50 for ease of the math. That is 300 times an hours or... 2400 power cyles to the pump in 8 hours. Most pumps just can't handle that kind of stress. When the pump goes, will it burn up or just shear the impeller?. Who knows. Take the chance of the flood or the burned up pump... or a more robust failsafe setup. That is up to you
Bean
CoolUsername
New member
I agree with dpstrand. This would actually make a nice alarm. The siphon break on my return makes an eery sucking sound. I would notice if my tank made it every 2 minutes repeatedly. It would be a nice built in alarm. Assuming someone is there to hear it.
BeanAnimal
Premium Member
cooluser.... you must have never hear of Murphy... as in the guy with all the laws. When it happens, nobody will be around to hear it.
CoolUsername
New member
<a href=showthread.php?s=&postid=7960980#post7960980 target=_blank>Originally posted</a> by BeanAnimal
Second point:
dpstrand: The oscillation is very likely to burn out the return pump in short order. Figure on it happening at the worst time (10 mintus after you leave for work). That is 8 hours of oscillation at maybe 30-100 times a minutes. Lets just say 50 for ease of the math. That is 300 times an hours or... 2400 power cyles to the pump in 8 hours. Most pumps just can't handle that kind of stress. When the pump goes, will it burn up or just shear the impeller?. Who knows. Take the chance of the flood or the burned up pump... or a more robust failsafe setup. That is up to you
Bean
Oops you are probably right. I was thinking that It might take around 30 seconds to fill up to the overflow point and then maybe 30 seconds to drain. Which would put the oscillation rate at once per minute. Not a big deal considering wave makers switch powerheads faster then this. But I was wrong in thinking 30 seconds+ 30 seconds. As soon as a little water is drained the switch will close again. If this happens quickly after the switch opens, then the oscillation rate might be quick. Maybe put in a switch with a large hysterisis as a safety factor?
Or yeah I would probably go with a latching relay. It would be cheap to hook up a small piezo for an alarm condition using the relay.
schristi69
Master of Space and Time
buy an Oceanus ATO system
itZme
New member
Could be done pretty easily with a CHEAPO LATCHING RELAY but I would still use that one to power another heavy duty relay since that one is only rated at 2A load.
This type would shut things down and leave it off until you pressed a "reset" switch reversing the current and making the relay switch back to the "pumping" position. You could use a DPDT relay to operate a buzzer or light or both to alert you of the problem if it occurs.
It still seems like a bunch of work for something that is not very common. I would rather have dual U-tubes or even dual overflows to be safe and have total redundancy.
HTH
-- Kevin
This type would shut things down and leave it off until you pressed a "reset" switch reversing the current and making the relay switch back to the "pumping" position. You could use a DPDT relay to operate a buzzer or light or both to alert you of the problem if it occurs.
It still seems like a bunch of work for something that is not very common. I would rather have dual U-tubes or even dual overflows to be safe and have total redundancy.
HTH
-- Kevin
CoolUsername
New member
I agree with the redundancy comment in general, but on u-tubes you want them running at close to capacity. The main problem with u-tubes is losing siphon. This happens when large bubbles accumulate in the top of the U. If the flow is slow through the tube is the bubbles are more likely to accumulate. If they accumulate to a certain point, you loose siphon. If the flow is fast however the bubbles get pushed though the tube and don't accumulate. Having two tubes would half the rate and put you more at risk.
You have to do something else like egg crate to keep the critters out.
