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I'm not sure if they use gate or globe valves?.?I've taken the valve retainer nut off only once,and never looked down to see what was what. Are we talking about the diverter valve or the valve next to the pump/s?
Sounds like it's air locked. You should be able to loosen the connection at the pump. Tighten it back when water flows out instead of air.
I agree with everyone that it could be an air lock however, air locks typically have no pressure at all. If the spa has more than one filter you might try switching then and see how that changes the dynamics. I've seen filters with problems like that right off the shelf.
I beg to differ Stuart as I played tech just last night and bled off a pump on a first fill. The air pressure was at the pump and when it escaped the water followed. It took me longer to figure out my drill then to take care of the airlocked pump. My boss let me get some tools and now I'm quite dangerous.Spahappy
Short Norwegian woman loose with power tools! SAY IT ISN'T SO! Listen, you've given birth and raised children. That makes you a genius! (It will take a couple of more years in the Navy for your son to figure that out though! )
I stopped by a new customer's house last night that had just filled his spa and pump #2 "wouldn't work". It took me longer to remove the doors than it took me to loosen the nut at the pump to let the air out. I knew the guy thought he had a "real" problem. Boy did his atttitude change real quick when he realized his problem wasn't a manufactured problem and should have been his to deal with. He admitted after all was well that he initaially thought I was full of it when I told him upon investigation that it was an air lock and all would be fine in a minute or two.