BillGeddes

Thanks everyone for your advice! Went to Tahoe Pool Service / Tahoe Pool and Spa and got a new pressure switch. Problem solved. We've used them in the past, and will again: If you're in the Lake Tahoe/Carson area, I highly recommend them.

I can see water movement (tiny bubbles) in the clear vinyl hoses on either end of the heater manifold, and can hear/ the water movement as well. When I swapped out the pressure switch, got a good 3' stream coming out of the fitting hole, and no bubbles were noted on either end of the manifold. I replaced the assumed original(?) flat, square, switch with an adjustable Tecmark 3902 unit recommended by a tech friend out of the area. Sending that back assuming/hoping it's defective and hoping to source an "OEM" one from a local shop this AM. (The control panel cover won't fit over the Tecmark unit anyway, so best to spend the $ to get OEM style) Finally figured out how to attach, so removed switch, installed Tecmark replacement, and video below of behaviour https://www.youtube.com/watch?v=pUEvIiLtc5M

@RDspaguy? (you seemed to be a huge help with a "recent" solana post, so figured I'd bother you 😁)

2011 Hot Spot TX Turn it on and run low speed circ pump or big pump and within 60 seconds throws open pressure switch error and will not heat. Just assumed the flow switch was bad, so replaced it with a new Tecmark 3902: same behavior. If I run just the circ pump, I can hear and feel flow through the heater manifold. The switch is not closing-testing with an ohmmeter, it is staying open. If I pull the leads off the switch and short the circuit, the heater will come on. So: bad replacement switch, or...?