Eshopps PF-1200 HOB overflow is "burping".

[Dom]

I have an Eshopps PF-1200 HOB overflow installed. It has (2) 1 inch drain lines. It is plumed using straight PVC down to the sump, only using two 45s to make turns.

One drain lines flows fine, but, the second drain line seems to build up air and eventually, pushes it through to the sump and expels a big air bubble.

I'm uncertain as to the cause. Can someone help?

 

[PotatoPig]

How much flow is going through it?

I have an HOB overflow (single tube) but have a spare. It’s weird, but although the two tubes are nominally identical one of them seems to have a much higher tendency to build up these bubbles.

I suspect there’s either higher surface roughness in one, or the bend is very slightly different and the curvature puts some weird turbulence effects on the water that cause it to be more prone to bubbles collecting.

One other option - check the water going into the overflow and look for little bubbles caused by the falling water landing in the interior reservoir. Algae, and possibly very slightly different differences in water level from one side to the other, can make one side more prone to bubbles, so one of your tubes could just be sucking up more bubbles than the other.

 

[Dom]

One other option - check the water going into the overflow and look for little bubbles caused by the falling water landing in the interior reservoir.

Are you speaking of the Weir? Isn't that the portion of the overflow that sits inside the tank?

 

[PotatoPig]

Are you speaking of the Weir? Isn't that the portion of the overflow that sits inside the tank?

Right. In mine the falling water from the DT to the container inside the tank can cause little bubbles, and if the flows not high enough these can collect.

 

[PlayDoh]

Right. In mine the falling water from the DT to the container inside the tank can cause little bubbles, and if the flows not high enough these can collect.

This is also happening to me currently. I start out with a perfect suction with no bubbles and by the time i come down in the morning, there is lots of air in the tube.

 

[exnisstech]

Sounds like you need increase the flow from the return to raise the level in the box .

 

[vlangel]

Yes, I agree with @exnisstech that you need more flow. With a variable speed DC return pump you can dial in the flow so that no air bubbles build up but not so much flow as to create a siphon that makes a toilet flush sound.