How to prevent Pentair SWG with EasyTouch from running with no flow?

[patterrr]

Our pool was installed in 2016; it has an IC20 SWG, Intelliflow pump, EasyTouch8 controller, and in-pool spa. This is how the pool installer plumbed it:
Pool Suction -> Pump -> Sand Filter -> Heater -> motorized valve that splits to: 1) SWG -> pool return, or 2) spa return.
They did properly wire the SWG transformer to only run with the pump... but the pump runs in spa mode.

Yesterday I was randomly reading this page: Pentair Intellichlor ICXX SWG - Further Reading
Which then led me to read several posts about SWG explosions due to gas build-up.

This has gotten me concerned because the end of the post linked above states that the flow switch is a secondary safety mechanism, and reading the explosion threads it looks like the root cause was the flow switch being used as the only safety mechanism, and it failing. The reason for my concern is that when we are using the spa, the motorized valve is set such that there is no flow through the SWG, but yet it is still powered and trying to operate and the flow sensor is the only reason it isn't operating.

Is there a way with the EasyTouch 8 to program it to not run the SWG when in spa mode?

I read that gas bubbles move up the pipes if they form, and our pool equipment is a story below the pool so it's a pretty vertical shot up to the pool from the SWG so chances are that gas bubbles would make their way up to a pool return, but I'm still concerned about our setup.

 

[Jimrahbe]

Pat,

The Cell should be installed so that it feeds the pool or the spa.

If it is installed in only the pool return line, that is wrong.

It means that the flow switch is all that is keeping the cell from working when there is no flow.

Show us some pics of your equipment pad.

There is no way to program the ET around your problem.

Cell do blow up, but it is not very often.

You could use a separate DPDT relay, to power the SWCG transformer, when the system was in the pool mode and not when the system was in the Spa mode. The relays that come the ET are SPDT, but you could use a Pentair 2-speed relay or any DPDT with a 24 VDC coil.

Thanks,

Jim R.

 

[patterrr]

Thank you for the reply Jim. I questioned this during install, but didn't push it as I didn't realize that it is a dangerous setup. It's unfortunately since it was done by the most reputable pool builder in my state...

Here are a couple pictures (SWG is behind filter in the most inconvenient place possible):





It wouldn't have been hard to put the SWG in the correct place, and would have been much more accessible. But now it would be a real pain to change. For instance, the motorized valve has five elbows butted so close together that there's no pipe to cut and put in a new fitting, so the entire valve assembly would have to be replaced.

Given my EE background, installing a relay to turn off the transformer when in spa mode would not be very difficult, so I'd rather do that than replumb. I was just really hoping for the easiest solution, which would be to program the EasyTouch to command zero SWG current during spa mode.

Thanks!

 

[ajw22]

Do you have an unused AUX relay in your ET?

If you do then run wires from the filter/pump relay LOAD screws to the LINE screws of the relay.

Move the SWG power to the LOAD screws of the relay.

Schedule that SWG AUX for the same time as the filter/pump.

When you change to SPA mode you can now turn off the SWG relay and will need to remember to turn it on when you go back to POOL mode.

 

[Jimrahbe]

Pat,

Or... Just use a DPDT relay and wire it to the 'spa' relay output on the main card. This connection is not used often so it should be empty. So, anytime the system is in the Spa mode the relay would open the NC contacts controlling the AC power to the SWCG transformer. This will work whether you schedule the spa, or manually turn it on.

With your background it should be a piece of cake.

Thanks,

Jim R.

 

[Mechanicman]

You should be able to set the SWG output in the easy touch to 0% for spa mode. That will turn it off and then the flow switch is your secondary safety again.

 

[patterrr]

You should be able to set the SWG output in the easy touch to 0% for spa mode. That will turn it off and then the flow switch is your secondary safety again.

This is definitely the easiest option! Good idea... The only trouble with this problem is anytime I change the % of the SWG for pool mode, it automatically sets the spa to a non-zero value so then I have to be sure to set it back to zero. But this will definitely be the route I take for the next month or two until installing a relay to interlock it to SPA mode bubbles to the top of my todo list.

@Jimrahbe Long-term solution will be exactly what you suggested of having the SPA mode turn on a relay that will disconnect the transformer that's connected to the relay's NC contacts.