Two questions on BB accessories

sunlight33

1. I have a 14 ft BB run in one room, can I add this coupling in the middle for thermal expansion: https://www.supplyhouse.com/Raven-R1644-3-4-x-6-Coupling-x-Coupling-Baseboard-Connector#reviews-content

2. What's a good accessory for purging air in BB? I found this but not looking heavy duty, wonder if it will develop any leak in the future: https://www.pexuniverse.com/3-4-c-x-1-8-mpt-x-3-4-c-cast-brass-baseboard-tee-with-vent-cap
My LLH has an air bleeder valve but it's located about 4 feet below BB on the second floor of the house, not sure if this is enough to do the job or I need to add one to the BB. Thanks!

STEVEusaPA

1. It may work, but sometimes the noise is from the baseboard rubbing the bracket, or a pipe rubbing at a penetration, in which case this wont help.
2. Proper piping (pumping away) with well placed valve(s) and drain(s) will allow you to purge almost all the air in the basement, and a proper air eliminator (if you have a bladder tank and not a steel expansion tank) will take care of the rest.
If you use that elbow, you'll end up putting on one of the cheapest devices around, a hy vent. You can't use it with a steel expansion tank. It will eventually leak/fail and become useless, and you'll be draining down the system to replace it (unless you have the room to put a small shut off on it.

NY_Rob

You could use a baseboard Tee with a 1/8" FPT and a Coin Vent. It would be easier to control vs. that brass cap.

https://www.pexuniverse.com/3-4-c-x-1-8-fpt-x-3-4-c-cast-brass-baseboard-tee

https://www.supplyhouse.com/Taco-417-3-Coin-Vent-11389000-p

sunlight33

Thanks, never seen that before, guess I am very new to hydronics.
This can be placed on either the supply side or the return side right? Because I can't figure out which end of the BB is which, lol!
Also if all BB are connected in series, I just need to place one on any of them, right?