New Pool Install - Blower problem

[MCF50]

New in ground install. 8 x 7 h5ot tub. 6 jets around perimeter and 2 in the floor. Designed to be used with a single 1.5hp silencer blower. Since day one the bottom jets have not worked. The layout is such that almost immediately out of blower two lines are run to hot tub - one for 6 perimeter jets and one for 2 floor jets. We installed a manual valve in the line for the 6 jets and closed it and the lower bubbles work just fine. Slowly open it and get bubbles out of all 8 jets. Set it and forget it and come back 45 minutes later and no bubbles out of lower jets again. Have to close valve, force air to lower jets, and then slowly open again. We tried a 2hp Silencer blower and no change. The pool company has never seen this before....the plumbing company showed up - saw that we already installed a valve and said, "you need two blowers". Absolutely not. I have pics of the plumbing and there is some 'questionable' elbows in a line to the hot tub - cannot tell what the line is to though. My though is obviously excessive back pressure in the one line. Thoughts / ideas?

 

[cowboycasey]

Just read about this on an earlier thread... Because the 2 loops are at different heights the air goes to the least resistant pipe, the upper pipes and will not go to the lower ones until you block the upper pipes like you do... just like you found out it will slowly go back up to the upper pipes until none will come out the lower..

The pool company is correct if you want air out both you will need 2 blowers...

 

[MCF50]

The pool company has done this on every single job they have done and have never encountered this before. The owner was out today and is investing in a pressure test kit and a plumbing camera to figure out what is going on in the plumbing.

 

[MCF50]

Once you get air coming out of all jets, it will stay that way indefinitely until you turn off the blower for 30-40 minutes.

 

[cowboycasey]

Interesting, hopefully they get it working