Is this a design that is acceptable?

Basically I am building a small box that will collect water pumped up by the condense drain. I will put this up in the ceiling in the furnace room just between the joists. The pump will pump the water in the box. If the 1/2" does not have a proper slope this will compensate for the lack of it; as the water level increases in the basin it will force the water to drain through the pipe.

This is intended to reduce the stress on the water pump which is currently having to push twice to push the water surplus through the existing setup. This is partially because I went all the way to main drain with a 3/8" PVC tubing and I think that is bad. When the pump stops the water trapped on the vertical segment between ceiling and joists level has nowhere to go and it drains back in the pump collector box.

That in turn makes the pump start again and the cycle repeats till sufficient amount of water is finally pushed through to stop this even when the water is coming back.

enter image description here

The alternative, in case I manage to give it a mild slope is to use this setup enter image description here Update: NOt sure what is causing the water backflow that I am seeing at the bathroom end where the drain will be (for now I am using a bucket to test this) The pump seems to have a backflow preventer as there is water in the vertical segment enter image description here

Update2: I think what is happening here is this. When the pump stops there is a hump at point ❶ in the last picture. That water will flow back and it creates negative pressure and that is causing the water movement that I am seeing in the tub despite the pump having a backflow valve

enter image description here

  • 1
    You're making a fairly simple problem complex. Just put in a backflow preventer. – isherwood Sep 14 '20 at 13:20
  • that sounds like an easy win... will it sit on the 1/2" pipe or on the 3/8" one or at the junction? – MiniMe Sep 14 '20 at 13:44
  • Usually right above the pump. – isherwood Sep 14 '20 at 13:49
  • Hmm it seems I need to add a supplementary one as the pump seem to have one already... I need to check that, it is true that I did not check to see it the water level in the pump is bouncing, l looked only at the clear pvc tube. Now that this came up I remember that the I could see that the vertical still had water in the tube ... I could see the water moving back and forth at the other end i.imgur.com/swDAXfW.png – MiniMe Sep 14 '20 at 14:29
  • I update my post. I am wondering if these work in a horizontal position. – MiniMe Sep 14 '20 at 14:32

no you can't do that. if it connects to the sewer it needs need to either be sealed or have a trap.

Use a fatter pipe eg: (inch and a half) , support it properly and fit a proper trap on the end. the flow rate is low enough that your run can self-vent but you will need 1:100 slope

maybe find somewhere else to discharge the condensate. it's basically pure water, it doesn't need to go into the sanitary sewer.

  • no this is going to connect to a dry vent which will discharge in an already trapped drain ...posted a lot about my pluming lately ..you can go back and see if you are curious – MiniMe Sep 14 '20 at 13:43

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