kemperflow

Swimming Pool PLC

8 posts in this topic

Swimming pool controllers are pretty awful. They are very expensive, not very expandable and most just don't have the ability to use basic logic. Pool equipment seems to be designed so that the equipment (ie, pumps, chlorinators, etc) become the "fuses" of the system, so that you have to spend $500 to $600 everytime something goes wrong. As an example: 1) One of the pool return valves got closed, pump dead headed while we were gone, cycled on and off as pump went to thermal shutdown. By the time we returned, the pump's bearings were gone. The system has a flow switch for the salt cell, but the "pool brain" doesn't use the flow switch to see whether or not the pump should remain on. 2) The salt cell outputs chlorination and salt levels, but the pool brain doesn't use the values. So even if chlorine is good, pump runs for an 8 hour cycle (only needs to run for a couple hours if chlorine levels are good) 3) Wanted to add a second control panel in the house, they want $750 for a single control panel that is just a dummy panel to the main unit, a remote control unit (to just switch modes, etc) is almost $1000 4) If flow is slow from the skimmer return basket (ie, it is getting full), adjust the electronic gate valve to pull more water from the bottom of the pool so the pump doesn't strain 5) To computer control the pool, or simply monitor the pool, you have to buy a proprietary RS422 converter box and serial adapter, and upgrade the firmware (total cost about $1000) I used to program Mitsubishi Melsecs and some AB PLC's back in the day (I worked for a water pressure booster pump station manufacturer) and I'm trying to see what is out there on the market today that would be "somewhat" cost reasonable. 1) PLC that can be programmed without a lot of overhead (specialty programmers, special cables, software cost, etc). Looking for possibly free software and an RS-232 or Ethernet connection 2) PLC that can be controlled or monitored via RS-232 or Ethernet (I'd write a small web interface or use a home automation package) 3) Maybe 14 inputs, 10 out. 10 analog inputs, maybe 4 digital (pressure, temperature) 4) Are there any kind of remote panel/monitoring type solutions (I think I used to use a Maple panel back in the day?) -- Anyhow, I'm not looking for automated chemical control, just the basic equipment operations with some failsafes, and the ability to put it on the network.. Any help is appreciated! Thanks!

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Any PLC should be able to do what you ask. The question will be cost vs. the dedicated controllers. I could easily build a Mitsubishi system with FX3G-24MR/ES and FX2N-8AD module(s), but would it compete with the dedicated one? You could potentially get a small HMi on that too. But then you need programming software, cables, and programming time. Dedicated controls tend to be lower cost, but as you indicated, lower functionality or lower quality.

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Just found the Blue Series line from Maple: http://www.maplesystems.com/products/blu300m_blu.htm At $179 a pop, this would be a perfect wall mounted interface for the pool. Found a handful of Mitsubishi FX PLC's on ebay, will most likely head that route. Looks like they all support basic ASCII messaging out of the box for register control. Hardware-wise should be good for less than $500 including the sensors I need. That is less expensive than 'one' dumb-wall mounted pool control panel. Minus the time to program the unit, it looks like a PLC is actually a less expensive way to go that offers way more functionality. (I'm not discounting the time to program it, but at least I can, vs the dedicated which you can't do anything with).

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For a home project where budget is an issue you might want to check out the offerings at www.automationdirect.com

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My 'bread and butter' business is filtration plants for commercial pools. I use Omron CP1L or CJ1M - just done one with a CJ2M with Ethernet IP for 3 colour touch screens, web server, SMS messaging etc - bit flash - stainless steel panel cost me heaps. be careful of flow switches - they do jam. Also I often see plant rooms where 2 pumps pump into the same flow line, there is not enough room above the pumps for separate flow switches, they put 1 flow switch in the common line, one pump is running OK - the other is dry but the common flow switch cannot pick up the problem - hot pump - melted 200mm plastic piep - not pretty. Plumbers do not understand anythin about control system design, and do not ask, until a pump dies, pipe melts and it costs them money. They then try to blame the PLC programmer because the flow switch in the common line did not turn off the pump!!!!

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Reminds me of when one of our techs rewired a huge pump motor, but didn't follow the guidelines for making the power connections. Fired the thing up and it single phased and shot flame out the back and toasted off his ankle hair. They tried to blame the PLC tech because they swore that somehow the phase detector should've triggered the PLC to not start the pump. The location of the switch suffers from the problem that you mention, but the good thing is that the EGV's on the supply and return are common for the pumps, so the flow switch can't be triggered in a situation that would be bad for either pump. I do have a fallback in using pressure on the filter housing (which can either signal a dirty filter or closed valve). I checked out AutomationDirect (thanks for the link Alaric), and I think I will be going with: 2 C-More 6" panels (one for outside in the pool control enclosure, and another mounted in the house) Existing flow switch Pressure transducer on filter housing (pressure rises when filter is dirty or when any valves are shut) AquaRite salt cell (outputs salt measurement and chlorine levels) 3 Temperature transducer's - one showing water intake, another showing water output from heater, third showing ambient outside temperature & maybe the CLICK series PLC's 8 digital in, 8 analog-in expansion, 6-8 relay out (I'd like to add PH monitoring, but the more I read, it sounds like they have to be calibrated often and the readings are never as reliable as a hand-held hanna meter, etc) My ELK Automation unit for the house will also allow me to control the pool anywhere by web interface or from any alarm control panel because it can receive and send from anything using RS-232. I'll do a write up here when done in case people find it helpful.

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I have just bought a  new house and there is a swimming pool inside. I think there is need to re-innovate  it. Is it necessary to change the pool pump and pool heater?

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If the pump doesn't pump water or the heater doesn't turn on and heat, then you need to determine whether the pump or heater is faulty or whether the control circuit that tells the pump to run or the heater to turn on can be the reason those things do not turn on and do what they're supposed to.

 

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