Outdoor sump pump - freezing?

[bonedoc22]

Hi-
Question from an amateur/DIY - we had a sump pump installed at the bottom of a stairwell, to prevent rare basement flooding with torrential rain. What is the best way to deal with winter/freezing temperatures? The sump pit itself is probably 6-7' below ground level, and the pipe outflow is open/exposed, ultimately connecting with a patio drainage system (see attached pics). My two concerns were water in the pit freezing and water in the pipe freezing. A simple solution might be a temperature regulated outlet, turning the pump off below 35 (?) degrees? But that might be a problem if temperatures quickly rises, before the ice could melt? Another possibility I thought of was some sort of warming cable for the pit (bird bath etc?) and a heat wrap for the pipe?

Is any of that even necessary, or is there a better solution someone can suggest?

Thank you!

 

[Geofd]

You may have to heat trace from were the pipe connect to pump to the end we're it goesi to the ground,, you may have to cycle some rv anti freeze thru the pit and pump and pipe, with snow, and melting and refreezing you will have to keep on it, the check valve is always gonna hold water in the pipe

 

[bonedoc22]

You may have to heat trace from were the pipe connect to pump to the end we're it goesi to the ground,, you may have to cycle some rv anti freeze thru the pit and pump and pipe, with snow, and melting and refreezing you will have to keep on it, the check valve is always gonna hold water in the pipe

thanks very much for the reply-
as an alternative, i could keep the pump unplugged all winter (i only need it for summer downpours).
do you think freezing in the sump pit would damage the actual pump if it were powered off/unplugged?
do you think the water standing in the pipe from the check valve will crack the pvc pipe during a freeze? is there any practical way to flush the pvc piping entirely, prior to turning off the pump for the winter?

 

[RS]

I don't think a discharge pipe like that should have a check valve, it should have a vacuum breaker at the high point, I just installed a system like that at our cabin.

 

[Geofd]

Check valve is there so what's in the vertical pipe doesn't drain back into the pit after cycling causing short cycling

 

[RS]

But in below freezing weather I certainly don't want an exposed pipe full of water! If you put a vacuum breaker at the high point the water drains both ways, and the pipe is empty.

 

[bonedoc22]

would a heater in the sump pit (bird bath type, etc) and a heat wrap on the vertical section of exposed pipe be a reasonable fix here?

 

[GymBag]

thanks very much for the reply-
as an alternative, i could keep the pump unplugged all winter (i only need it for summer downpours).
do you think freezing in the sump pit would damage the actual pump if it were powered off/unplugged?
do you think the water standing in the pipe from the check valve will crack the pvc pipe during a freeze? is there any practical way to flush the pvc piping entirely, prior to turning off the pump for the winter?

If water in the pipe/pump/pit freezes, it doesn't matter if the pump is unplugged, it will still be damaged. Water is one of, if not the only substance, that expands when it freezes and thaws. Ask anyone whose boat's engine cracked because it wasn't Winterized properly. Freezing/thawing water can crack a cast iron engine block and it happens every year in cold climate areas.

If you want to prevent freezing, you can pour RV antifreeze into the pit- get the stuff that's rated for -75°F and make sure to fill any low parts of the pipe and make sure you see that it's coming out of the discharge end- it's pink or purple, so it will be easy enough to tell if it was enough. If the pit doesn't hold a lot of water when the pump shuts off, I would use a shop vac to remove as much as possible before pouring the antifreeze in. It's environmentally safe.

 

[bonedoc22]

If water in the pipe/pump/pit freezes, it doesn't matter if the pump is unplugged, it will still be damaged. Water is one of, if not the only substance, that expands when it freezes and thaws. Ask anyone whose boat's engine cracked because it wasn't Winterized properly. Freezing/thawing water can crack a cast iron engine block and it happens every year in cold climate areas.

If you want to prevent freezing, you can pour RV antifreeze into the pit- get the stuff that's rated for -75°F and make sure to fill any low parts of the pipe and make sure you see that it's coming out of the discharge end- it's pink or purple, so it will be easy enough to tell if it was enough. If the pit doesn't hold a lot of water when the pump shuts off, I would use a shop vac to remove as much as possible before pouring the antifreeze in. It's environmentally safe.

Thanks very much!
So just to make sure I understand correctly- drain the pit as fully as possible, pour all the antifreeze into the pit, cycle the pump once to eject some of the antifreeze into the piping, and then turn off the pump for the winter?
Do I need to periodically add more antifreeze into the pit throughout the winter, as rain and snow dilute it?
And the antifreeze doesn’t damage the mechanicals of the pump itself?

Thank you

 

[GymBag]

Thanks very much!
So just to make sure I understand correctly- drain the pit as fully as possible, pour all the antifreeze into the pit, cycle the pump once to eject some of the antifreeze into the piping, and then turn off the pump for the winter?
Do I need to periodically add more antifreeze into the pit throughout the winter, as rain and snow dilute it?
And the antifreeze doesn’t damage the mechanicals of the pump itself?

Thank you

I don't know what material was used for the pump's impeller, but boats are Winterized with this stuff all over (if the people doing the service decide to use it)- if the impeller is a hard material, it's using brute force to move the liquid but boats usually have rubber impellers that like to be lubricated for startup. Anything in the pump is that doesn't freeze is better than water. If you can cover the pit, it would be a good idea but it would be good to know how deep the pit is- if you're in the North, your frost line is about 4' down but that assumes no exposure to ambient temperature. If you can come up with a way to block water entering the pit, it would be a good idea. The problem is, Murphy's Law always enters the picture and when you need it to remove water, it won't be able to.

 

[bonedoc22]

I don't know what material was used for the pump's impeller, but boats are Winterized with this stuff all over (if the people doing the service decide to use it)- if the impeller is a hard material, it's using brute force to move the liquid but boats usually have rubber impellers that like to be lubricated for startup. Anything in the pump is that doesn't freeze is better than water. If you can cover the pit, it would be a good idea but it would be good to know how deep the pit is- if you're in the North, your frost line is about 4' down but that assumes no exposure to ambient temperature. If you can come up with a way to block water entering the pit, it would be a good idea. The problem is, Murphy's Law always enters the picture and when you need it to remove water, it won't be able to.

for whatever it's worth, zoeller support is advising against antifreeze, stating the chemicals will damage the pump mechanicals

 

[GymBag]

That's surprising- did they state exactly which chemicals or types of antifreeze cause the damage? The environmentally friendly/animal safe stuff is used in all kinds of applications- will have to look.

Haven't seen any mention of this in the literature, but it's definitely a good idea to contact the manufacturer and ask about using RV/Marine antifreeze.

 

[Twowaxhack]

If you don’t need it in the winter then I’d remove it and drain the piping. That’s the only fool proof method of protecting the pipe.

Ideally the pit would be large enough so that it wouldn’t require a check valve so that a little backflow from the line wouldn’t matter and the pit would be far enough below ground that it wouldn’t freeze.