How do I fix this?

Luna Great And as always very informative post!

 

Its my understanding that a 1" drain has a flow of 600gph and a 1 1/4" has a 700 gph flow



luna

 

I gated the valve back about 1/8turn and so far so good, I'll keep you posted!

 

ok, update, I have gated about 1/4 down now and still getting the same result. I will try a little further I guess.

 

I repeat my question.



luna

 

sorry luna, its sch 40 and 1.5 inch I have it gated between 1/4 and 1/2 off of full open and haven't had a toilet sound in a couple hours. But that seems like a lot to gate down on that pump

 

Here's my scenario, I have a Magdrive 18 which pushes 1800gph. Take into consideration that I have roughly 7' of head, that leaves me with 1060gph(according to Danner's charts). I posted 3 pics of my stand pipe which is only 1" drain. That 1" drain is "sucking" roughly 1000gph. My question to you is, why is your 1.5" drain having trouble with 1100gph?
Is 1100 gph a true estimate or is it a guess-timate? Did you take into consideration all of your head pressure?



luna

 

I googled your pump, Iwaki MD-40RXT – 1,344 per hour (advertised at 22.4 GPM on the iwaki web site) so I assume you have calculated your head loss and told us 1,100.

Try this, remove that filter sock and open up the gate valve – I suspect that sock is filling and foaming and releasing air up into the tube and creating your flushing effect.

If it flushes hit the valve again and see how much you need to cut it back this time, hopefully not as much as 1/2 - which is crazy

 

Also keep in mind while testing that it can take a long time before the tank stabilizes at a certain flow rate. I've got a creative version of a durso and if I crank the pump up it flushes about every 5 minutes. When I crank it down to about 75% the 5 minute flush interval slowly increases to about a half hour which I can live with but it may take 4 or 5 hours to slow down that much.

Basically what I'm saying it make a change and wait a while to see the effect.

 

This I agree with, I just saw the sock on there. Cutting to 1/2 is not the solution as that is too much (why have the bigger pump then?). A third hole in the top of the cap may be in order also. Try a good size hole, you can always close it up or reduce it if need be. Some have drilled a large hole and screwed in a valve to have precise regulatory options for air intake.