Tankless water heater condensate drainage problem

We had rinnai ruc90in tankless water heater installed and plumber did not account for condensate drainage. We got an error code and noticed it was leaking out the black cap. So we call and they say they don't handle condensate that's the HVAC guys. But they will do it for an extra fee. So they come out and do this. Problem is the condensate drip is so slow it does not push the water through the p trap. Does this application look correct? The water just sits in the p trap and leaks out It's not strong enough pressure to push it through to drain. What is typical installation? I feel like the plumber that installed this is not very familiar with tankless heaters. Thank you

To make that p trap functional, you must add an additional pipe so the height is higher than where the line drains to. Looks like an easy fix. Call 'em back out and explain how gravity works, and that water will flow out the lowest point of the pipe.

Is there any grade to the 2inch pipe? And yes extend the stand pipe. Don't know if the plumber you called out knows how a trap works....

Are you suppose to put a check valve in the condensate line where you live???

Good catch, doubt it has enough force to open said check valve. Not quite sure about the plumbing job as a whole.

I was thinking the same thing Justin, can that water open up that flapper.

He's supposed to come back out Monday to fix it so hopefully it will work. I'll ask about the valve. He told me we needed that to prevent the septic from ever backing up into the house?

You should have a lower point in the house that the sewer would back up in.

All that check valve is going to do is stop any thing from coming back up that pipe only and not the rest of the house.