I have a laundry tube in the basement that has a pump attached to its drain to pump water up to the main pipe. The pump comes on automatically whenever the water gets to a certain level. The pump pipe is 1 1/4 PVC. The problem I have is whenever the pump stops pumping, the pipe and pump begin hammering very hard, load and fast like a machine gun for about 20 seconds then it stops. It hammers the system so hard the fittings around the drain begin to leak after about a month of this and I keep having to re-tighten them. Whenever the water softener recharges in the middle of the night, it drains into this tub and usually wakes the entire family up because of this hammering.
Any of you heard of this or have any ideas?
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Maybe the hammering is the pump going on and off rapidly. The switch that senses the fluid level is supposed to have some hysteresis. That is, it turns the switch on at one level, and turns it off at some other level. If those levels are too close together, it could cause the effect you're seeing.
TUB not tube...nice spelling by me is probably confusing some people.
Thanks Jamie, but I don't think it's any kind of level switch because 1) it happens at any water level 2) the hammering decreases with every pulse...it starts real loud and hard, then keeps getting a little quieter until it can't be heard any more. My best guess is that it is some kind of pulsating diaphragm inside, but I wish I knew a way to stop it or at least isolate it.
I think this might be what is happening. It does not have a check valve or the check valve is jammed.
The unit starts up and runs until the water goes down put that leave the discharge pipe full of water. The missing/bad check valve allows tha water to flow back into the tank.
Raising the level enough for the switch to trigger again.
If you monitor it while it is doing that you can probably tell if the motor is starting up each time.
Bill,
You may be onto something. I monitored it as you said and the motor isn't coming on (I unplugged it right after it drained) but there is water coming back because I see it come out of the drain a little. I think it may be that check valve going bad and slamming open and shut as the water is forced back through. I'm going to tear it apart this weekend and check it out. But it sure is loud!!
Thanks.
Had the same damn problem!! Waked everyone up in the middle of the night. It's the check valve flapper slamming as the water rushes down the pipe back into the tub drain. Had to replace the pump OR ad a second inline check valve! Much cheaper! Worked great.