Hotsprings thermister replacement - drain or not?

[wschwisow]

Hello,

I have a hotsprings sovereign from about 2000. It hasn't been used in about 4-5 years, but I cleaned it up, replaced the filters and filled it. Pumps ran fine but I got a flashing green "ready" light. Everything I've read about it suggests replacing the high limit thermister and control thermister. I bought new parts, but when I went to unscrew the old ones water came out. Is this just water from the heater coming out and will only be a small amount? Or do I need to drain the tub to do this procedure? I panicked and quickly screwed the old one back in, just in case! Thanks for any help.

[Dr. Spa™ Ret.]

Too bad you didn't quickly screw the new one in...you'd be done. Too slow, and all the water will drain out.

[Nessuno]

Whenever I work on my tub, I have found that a shotgun shell makes a great plug for the hoses (I think they are 3/4"). I also learned the hard way to disconnect my heater from the control box and run the pumps first to make sure all the air is out and to verify water is flowing through the heater housing. I  had a dry fire and my heater housing melted to a goo. Smoke and smelled pretty bad too. At any cost, you will be okay to just bleed the air out of the motors before resuming operation. You shouldn't have to drain the tub and fill it again.