Jandy LT heater not reaching set point - any chance this could be due to aqualinkd?

[bmwhd123]

Since I've started using this awesome software, I've had an issue with my older Jandy LT heater. If I set the spa temp set point to 101F and then enable spa mode and spa heater, the heater will start and work fine, raising the water temp in the spa up to 94F. At that point the heater shuts off and starts short cycling. However, the short cycling is not due to failure to ignite, nor are any errors displayed, either in the aqualinkd logs or on the heater itself. No high limit, flow, pressure, errors at all. So my question - is there any chance aqualinkd or MQTT (via mosquitto broker) could be getting confused due to the F to C conversion? Maybe some sort of timeout that's not obvious? Something else? I doubt it but I'm at a loss where to go next without any error coming from the heater. One other thought - I upgraded my RS panel to a Rev 8157 JJ as part of getting aqualinkd to work, could that be an issue for this old heater?

[ballle98]

Look at the manual for your heater. I know on mine there is a manual setting. If you switch it over to manual and you set the heat below the maximum 104 it will limit how hot the heater will go.

[bmwhd123]

The heater thermostat controls are locked at the highest setting since the RS is controlling it.

[sfeakes]

AqualinkD simply sets the temperature on the control panel. If the heater is being controlled over RS485 then it does read some heater RS485 messages that are sent from heater to the control panel, but it has no direct connection to the heater itself.

You could use your keypad (or AqualinkD in simulator mode) to check that it's setting the correct temperature at the control panel.

When you replaced the control panel did you setup the heater correctly?
Heater can be setup in one of two ways.

1. RS485 control (I'm not sure panel rev JJ completely supports that, you'll have to check). In this mode, the panel simply sends the temp settings to the heater, and the heater will do everything else. (Like turn on/off).
2. Hardwired. The Panel will physically turn the heater on and off. In this mode, you set the heater to the max temp settings on the heater itself. Then the Jandy panel will read the water temp and physically turn the heater on and off as needed.

You have to physically set both the panel and the heater to either mode #1 or #2, and also wire appropriately. The panel and heater both have a different set of wires to use for these modes. If you have a miss-match, then you get unexplainable results.

Also all heaters support mode #2(hardwired) and only some mode #1. So the majority or heaters are wired for #2 even though they may support #1.

Other than that, I thought some heaters had a MAX temp difference as a fail safe. As an example if this was 40deg, then you can only increase the water temp 40deg, (ie from 50 to 90). maybe in the current cold weather you are hitting some limit like this.

[bmwhd123]

Thank you for all this. Historically the heater would heat the water in the spa to any set point up to 104F regardless of air or pool water temp since in spa mode, it's a closed circuit. The heater has always been wired as per #2 above so perhaps the new panel is expecting to communicate via RS485 (note that your serial logger reported that capability). I'm not seeing how to configure the RS panel to be #2 other than it being hard wired to the heater. I didn't change any of the wiring when I replaced my old PDA-only panel with this one.

[sfeakes]

I seem to remember a dip switch sets the heater mode on the control panel. But it's been years since I've configured a heater so I may have that wrong.

If the serial logger picked up the heater then that means the control panel is communicating with the heater over RS485. So maybe disconnecting the heater RS485 wires would help.

[bmwhd123]

I'm going to close this as the heater is doing this even with aqualinkd out of the picture. Something is glitching in the heater itself. Thanks for you help.