My DIY HomeBrew Pool Automation Controller


Gold Supporter
May 2, 2018
Cherry Hill, NJ
Has anyone tried connecting via a serial connector to a Hayward Pool heater. I would rather just send a signal to the heater on what temperature I would like it rather then power cycling the heater off an on.
I just looked up the manual on your Hayward H400FDP. It operates the same as my RayPak 406A. The Hayward outputs a 24VAC signal and you can use a dry relay to switch between pool, SPA or Off. Because there are three states, you'll need two relays. One to enable the heater mode, and one to select between Heat/Pool temp. The temperature has to be hardset out of band and can't be controlled via remote.


Bronze Supporter
Jun 1, 2016
Gilbert, AZ
See what happens when a EE retires!.

I am travelling and haven't been working on this project (actually I am home for just a few days). But I have this update for those considering the Milone eTape, especially for an acid tank. My ACID Milone eTape has failed for a 2nd time. Once again I am sending it back to Milone Industries for their analysis. The owner will be looking at it again to see if the strong acid fumes are something that their current packaging solution "might" have an issue with (or it could be that I received a 2nd bad unit). He will let me know.

My chlorine tank Milone eTape monitor has been flawless. I double-checked it (measuring the resistances) and there has been no degradation in its performance. I am getting readings for the Chlorine tank level that I believe are within a few ounces of actual (I have a 16 gallon tank).

As I said in my last post, all 1st stage "sensors" are installed except for my additional pump watts meter (I am currently reading the one that is built into the pump itself, but it is not accurate at very low RPMs). All that sensor data is being recorded in a google spreadsheet. So when I start working on this again, I will have plenty of data to decide what sort of alarms/notices that I want to implement.

For those that haven't seen this...Segalion is making a bunch of progress/updates on his RaspberryPi pool controller solution...very impressive.


Rattus Suffocatus

Silver Supporter
Jun 5, 2019
Corona de Tucson, AZ
Has anyone hacked specifically the Hayward Tristar VS RS-485 protocol? I am so tempted to play with it... But it also has relay inputs for four speeds and I know that would be easier and probably more reliable. I still am not sure if the LED pool light is hackable as well.. But in my simple setup that is all I have so I never will buy a thousand dollar controller...
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Silver Supporter
Aug 22, 2017
West Palm Beach/Florida
Yes, both the Pentair and the Hayward pump protocols for RS-485 are available. Here is a link for the Hayward pump. But as you said it might be easier if you use 3 relays that can control up to 8 settings. The Hayward pump requires a command being sent every 1 second via RS-485.


Rattus Suffocatus

Silver Supporter
Jun 5, 2019
Corona de Tucson, AZ
Okay, so the EcoStar are the same commands as the Tristar? I suppose I can eventually find out. Sending them every second could be handled easily by an Arduino... Even the ESP8266s I have (in a box somewhere) could be made to work for that but it still might be better to use the relay inputs for that to be robust... Can't leave stuff like this alone...
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