How to stop water coming out of laundry water trap?

[Etilop1]

First-time poster, so please be gentle  

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! 

Three questions:

(1) Is that the expected outcome (I assume so but should confirm)? 

(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! 

[MitchellMc]

Welcome to the Bunnings Workshop community @Etilop1. It's brilliant to have you join us, and many thanks for your question about connecting appliances to an S trap.

No, that's not the expected outcome. The installer has overlooked the fact that a barb had been drilled out where they are normally sealed. That might not have been on their radar, as their job might have been to install the appliances rather than check the functionality; it would have been nice, though.

The industry standard for sealing an open barb is to silicone on a rubber chair leg tip. You might find a product to do this on the market, but I am unaware of one.

I would be concerned about you running another appliance off the lower barb. You'd need to test to see if the water is pushed back up the hose from the pressure.

Please let me know if you have any questions.

Mitchell
 

[Etilop1]

Thanks so much, Mitchell. I deeply appreciate your helpful reply.

Based on this, I'll likely replace the trap and get an adaptor/connection kit to make it all work (including the heat pump dryer hose). The joys of home ownership!