First-time poster, so please be gentle 🙂Â
I recently purchased a new home and had a washer and dryer installed. Below is how the "installer" left the water trap (I added the clamps). I foolishly ran a trial run, and the open hole became a fountain!Â
Three questions:
(1) Is that the expected outcome (I assume so but should confirm)?Â
(2) If so, can I just cap/seal the open hole?
(3) Wild card, alternatively, could I use that smaller hole to connect my heat pump dryer drain hose - though I'm worried about the fountain issue?

Thanks in advance to anyone willing to help!Â