What type of external relay do I need to control a March 809 pump?

**flananuts** · 10-07-2009, 04:49 PM

I plan to use the alarm relay output on my PID to control a relay handling the off/on of my march pump. I'm not sure what I should be looking for. Any help would be appreciated.

Flananuts

DrKarma · 10-07-2009, 06:30 PM

A SSR (Solid State Relay) - get one from e-bay.
http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=Solid+Stat e+Relay&_sacat=See-All-Categories

JKoravos · 10-08-2009, 07:34 PM

What's the rating of the alarm relay on the controller?

**flananuts** · 10-08-2009, 09:20 PM

the relay is 3A 24v 3A 120v and 2A 240. I bought on eBay an SSR that can handle 24v-240 control and 12-240 output. Auber Instruments got back to me and said the alarm relay is rated for 100,000 cycles and I would essentially speed up the deterioration by running 110 through it. I'm going to program the alarm to be on unless the temp goes above the high process setting. So when the temp goes above 156 at the RTD the HLT pump to my HERMS will shut off. Does this make sense or am I missing something huge here?

JKoravos · 10-09-2009, 01:25 AM

If it were we, I'd just use the alarm relay...unless you're planning on brewing thousands of batches on this rig.

Otherwise, everything you're planning sounds fine.