ARS & Proportional Thermostats?

Hi All. Got a minor issue here that is stumping me. I have an ARS 7030 rack here with 10 levels. Been trouble free for years. I had it plugged into a single zone Ranco but recently I had trouble regulating temps on all levels. I reached out to ARS and they suggested a dual-zone thermostat with one probe on the bottom and one in the middle of the upper seven levels.

I hooked up the thermostat this way and it seems to hold temps perfect. However, I’ve noticed that once the thermostat gets to a point where its only delivering a little bit of power to keep the heat at the setpoint, one of the heat panels somewhere in the upper seven will make a faint buzzing sound. I’ve tried moving the probe, re-seating the heat panels, shifting tubs around. No matter what, one of the heat panels will make a little buzz when its getting power.

I never had this happen with the Ranco. Nothing appears to be wrong and there is definitely no burning smell. I reached out to Spyder and haven’t received a response yet. Anyone have any idea what is causing this? I have a second 10-level ARS with the same probe arrangement and I’m not having this problem. TIA!

Well I guess I should have consulted the User Manual first, duh.

Sorry guys. I figured it out. :open_mouth:


I’m curious what the solution was? Sounds like a grounding or wiring issue.

Not totally sure. But the Herpstat 2 manual says to change the output mode from “dimming” to “pulse” if you are using metal racks. Whatever the reason was, it worked.

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Go to know I gotta file that away for future reference :stuck_out_tongue:

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