Sump pump questiion - Canadian TV, Computing and Home Theatre Forums
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post #1 of 8 (permalink) Old 2019-06-13, 04:41 PM Thread Starter
Join Date: Oct 2008
Location: S.W. Ontario
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Sump pump questiion

I've had this Simer 1/2 HP submersible cast iron sump for about 7 years and it's always worked perfectly. Today after a heavy deluge I heard my high water alarm because the water level was up around 8" below the floor. The pump was humming, but couldn't hear water going up the pipe. I unplugged it for a while in case it had overheated or something, but when I plugged it in again, same thing. So I started unscrewing the upper check valve connection, about 2' above the floor and water came out. When that was drained, I tightened it back up. I then plugged the pump back in and lo and behold it pumped out the sump in short order and has been working fine ever since. So what happened? Had the sump filled up so quickly during the deluge that the pump could not pump against about 10' head? Or had it sat dry so long before that the rotor was air locked? I found the pump manual and there's something about drilling a 1/8" in the discharge pipe just above where it screws into the pump and I can't remember if I did that when I installed it. But a couple of months ago when we had a long period of constant rain I thought the pump was cycling too frequently and noticed a lot of water squirting out around the threaded connection and recirculating, so I wrapped it with silicone tape and it cycled less frequently. So maybe I covered that hole? I'll probably have to replace that connection this summer when we're out of the rainy season.
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post #2 of 8 (permalink) Old 2019-06-13, 05:56 PM
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It sounds like an air lock. It was probably caused by pulling the pump and covering the hole. Unscrewing the check valve would have let the air escape. Another possibility is that a piece of debris was preventing the pump motor from turning and that was loosened when the check valve was unscrewed. Sump pumps will still make a humming noise if they are jammed or air locked. Another issue I've seen is a seized motor due to a damaged rotor. The rotor can often be replaced.
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post #3 of 8 (permalink) Old 2019-06-13, 06:22 PM Thread Starter
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It did not sound like a stalled pump, but just spinning and trying to pump air. It most likely was an air lock, which I now know how to fix. I probably sealed the vent hole when fixing the loose or cracked threaded connection at the discharge. I'll do a proper job later this summer. Meanwhile, I googled "sump pump air lock" and came up with a whole load of useful results.
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post #4 of 8 (permalink) Old 2019-07-20, 04:22 PM Thread Starter
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Just a follow-up. I got a high water alarm again at 8 am the other morning after another flash storm. The water was within 6" of the top of the pit and I could not hear the pump running. The thermal cutout must have shut it down when it overheats continuously pumping air. Anyway, this time just wiggling the pipe broke the air lock and it started and pumped out. So today, while it wasn't raining and filling the sump, I pulled it out for a better look and removed the silicone tape I'd wrapped around what I thought was a loose or cracked threaded joint. Turns out there was no crack or looseness. The water must have been coming in and getting pumped out at the same rate, causing frequent cycling and the squirting I was seeing was from the vent hole, which I ended up covering, having forgotten all about it. With the flash floods we've been having lately, I feel a lot safer knowing I won't get an air lock.
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post #5 of 8 (permalink) Old 2019-07-22, 01:21 PM
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One thing I noticed with some one way valves, if it dries and creates an air pocket, the best of pumps can't do their job pushing air. One way to correct this was to rub some dielectric silicone.

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post #6 of 8 (permalink) Old 2019-07-22, 02:56 PM Thread Starter
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My check valve is about were the original one was when I bought the house 35 years ago, about 2 feet above floor level with about 6 feet of water column above it before the pipe goes horizontal in the kitchen overhang, then down to the tile. I've never thought about it sticking, but that should present less resistance than than working against probably 9' of head.
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post #7 of 8 (permalink) Old 2019-07-25, 11:13 PM
Join Date: Jun 2019
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The check valve may have a spring that has broken and stopped the water from flowing. By taking the pump out you may have changed the position of the broken spring and it is working again. My guess.
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post #8 of 8 (permalink) Old 2019-12-08, 04:24 PM Thread Starter
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Just to close this thread, I had noticed a lot of what I thought was water spurting from the joint at the pump and discharge pipe, which I thought may be cracked or loose. This seemed to be making the pump cycle too frequently. So I wrapped the joint with silicone tape until I could get around to fixing it. Turns out it was normal and I had ended up covering the vent hole, which caused the pump to not start a couple of times because it was air locked. Going over the installation instructions again, it says "Drill a 1/16" - 1/8" (1.6mm - 3.2mm) dia. hole between pump discharge & check valve (1-2” above where the discharge pipe screws into the pump discharge and below the
waterline)." That is what I had done when I installed the pump years ago. Unwrapping the silicone tape and clearing out the hole fixed it. Without the hole, if tere is a long dry spell, then a flood, the pump impeller would be spinning in air and not pump. A smaller hole would mean less recycling water instead of ejecting, bur it's probably also more prone to clogging and defeating its purpose.
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