With three connections you will have N.O./Common/N.C. as your ports. Make sure you use the Normally Open and Common positions, otherwise your heater will be on all the time.

-C

Thanks to the extremely well-informed advice of the above, I'm now officially PID'd. Pulled my first shot this morning and the results were impressive... now I have one less variable to worry about and can focus on my technique / grind. Just need to dial in the temperature settings... I'm amazed at how well this thing keeps the temperature stable. Before the PID was fully hooked up, I was watching temps that would surpass 125° C, then fall back to under 100, then slingshot back up again. Now I have it set to 105 and it hovers within 1 degree after letting the PID autotune itself.

Great news, Dennis. Congrats on finishing the project

A final bit of cautious advice would be to use as long a cycle time as you can get by with and still have decent temperature control. The life expectancy of the relay contacts in your PID will be directly related to the number of times they open and close. Minimizing the number of open/close cycles means maximizing the control period, or cycle time.

The doc's that came with your PID may tell you how many closures the relay should be able to tolerate. From this you can get a rough idea of an appropriate cycle time. The fact that you are switching a low voltage and low current DC signal will help.

Jim

Also, an oft overlooked parameter is the MINIMUM contact load. Unless enough power flows to keep the contacts clean, they can foul and be destroyed as effectively as with too much power.

Good info! Will have to play around with the settings some more. Right now it seems like there is a decent balance between temperature and cycle time- generally, from warmup to extraction, I only hear see the PID opening 4-5 times, including blank "warmup" shot and my manual "preinfusion"... a few more if i let the machine fully heat-soak, but for a $26 part, I won't be too disappointed if it only lasts a year or two, hopefully by then I'll have a decent machine


(this is about minute and a half after extraction... i was pretty excited at how much thicker the crema was so i forgot to get out my camera in time)