I've got a coleman 455 running off a 240V main. It has a Balboa 51140-07 board (also marked as model 400 CA-9), and is ozone-ready (actually had an old, UV-type ozonator but the bulb had died).

I purchased a 240V SpaEclipse CD ozonator as a replacement, and ran into a couple of issues when I installed it....

1) At first I couldn't get the ozonator to work at all...thought the unit was DOA, but then I finally noticed that the AMP plugs were wired slightly differently so that there was an open circuit. Easy fix.

2) After that problem was solved, I checked the voltage at the ozonator terminals. This is where things get weird....the voltage varies from 0V (when the spa is in standby and nothing is running) to ~90V when a pump or pumps are running, to the required 240V when the spa is in filter mode.

I was worried about how the SpaEclipse would react to seeing an undervoltage situation anytime the spa was running, so I wired it to the low-speed pump instead. According to the manual, this is acceptable, and it appears to work.

I am curious about the varying voltage on the dedicated ozonator circuit, though. Is anyone familiar with how the ozonator circuit is wired? I would think that since it's 240 V it would be a simple relay...but that trickle voltage makes me think a triac or other semiconductor voltage regulator is in the circuit and is on the fritz....or am I over analyzing the situation?

Thanks,
Bob

It probably uses a 120vcommon leg (always hot) and a 120v switched leg for 240v power. It wouldn't be unusual for the switched leg to make for a poor neutral when not energized, thus giving you some wacky readings between the common and "switched off" leg. If that's the case, not harfull at all, while it gives you "undervoltage" when not plugged in, it isn't harmful to the ozone generator. The circuit isn't truly complete under load, and the ozone unit would remain off.