Got my automation online - but slight problem with valve speeds

[stimpsonjcat]

I got the majority of the automation working for my pool/spa this weekend.

I can now control the pump, heater, and the supply and return valves from a PLC in a panel in the pool room using a panel-mounted touch-screen.

However, I ran into a problem. Initially I set the program up to delay turning on the pump any time the valves need to change position for the 40 seconds it takes for them to move (Intermatic).

The problem is that during the return valve movement, the spa drains into the pool. It loses a good 3-4 inches in those 40 seconds.

Since I have a 'freeze protection mode' programmed to switch back and forth between circulating the pool and circulating the spa, this is a problem.

I took the delay out for the pump and this reduced the loss per transfer to about an inch. So the current plan is to add some code to count the number of cycles that occur in freeze protection mode and after 5 switch into 'refill spa mode' where water is pulled from pool and put into the spa.

Overall I am very happy with the automation, and more importantly it has de-mystified the operation of the pool/spa for the wife and daughter.

Want to get in the spa? Push the 'spa mode' button and wait for heat.
Want to get in the pool? Push the 'pool mode' button and dial up the pool temp you want.
Done in the spa? Press the 'refill spa' button and walk away.
Done in the pool? Press 'standby mode' and walk away.

I still need to install the thermocouples for the outside air temp and pool water temp.

I'll get some pics posted if anyone is interested.

 

[isriam]

you dont have a spa overflow into the pool? freeze protection should run for pool, and the spa will fill slowly via fountain/returns to keep those lines clear also.

 

[stimpsonjcat]

I do have a spillover from spa to pool.
'spa refill mode' takes advantage of this, but the freeze protection needs to work both pool returns and both spa supply paths, not just leave it in pool>spa mode.

 

[xyz]

Can a check valve solve your issue? Does the SPA overflow into the pool?

 

[stimpsonjcat]

Can a check valve solve your issue?

It could, although I think check valves in returns is generally frowned upon.

The problem is I would need two, as there is not enough room in the piping as installed to add just one between the skimmer/main-drain valve and the 3-way return valve. There is only an elbow between them!

Does the SPA overflow into the pool?

Yes.