Hi! My pool/spa has an older, gas Raypak RP2100 millivolt heater that was here when I bought the house. It's at least 10 years old, I believe. It has worked fine for the 2 years I've been here. I can't read the words on the panel with indicator lights, except the lowest of the four lights seems to be POWER and the one above that is "CALL FOR HEAT" or something similar. Usually those two are yellow when I'm heating the spa. The last few nights, there is a red light lit above those. I think it's the top light of four. The heater seems to work fine, though. I can't read the label and Raypak's link to old manuals doesn't work. This is not a digital display.
I had a heater tech come out when I first bought the place to show me why it wasn't fully heating the spa. He turned a jandy valve, laughed at me, charged me $100 and left. So I'd rather not call a tech again just yet.
Anyone know what the red light is for? Thanks!