I had a hiatus from the brewing (and drinking) for a year, but have been driven back to it by current circumstances
and now have an issue with my Topsflo TD5 (stainless head) pump that I use in my HERMS rig. The issue, simply, is that it has started to cut out. This is bad, usually, as when the pump stops running the HERMS reservoir overheats as the temp sensor for the PID is on the outflow pipe, thus the PID keeps driving the element in the HERMS vessel, heating the water within but not affecting the outflow temp sensor. This happened a couple of times a year or so ago, and I stopped using the pump (just when back to an old school simple mash). I have recently rebuilt my control panel, checked all connections to the pump and installed a new 12V power supply. All seemed well for a couple of brews, but it again cut out on me today - so it seems the pump itself is at fault. I have had the pump apart as far as possible (not very), impeller seems fine etc and I do not believe this is a blockage issue, as the pump has generally just started working again at some point after the cut out. There are some electronic smarts in these pumps to cut out on over current/voltage and, I think, heat, so I suspect something might be going on here. Does anyone have any ideas on how to test/fix this?Second question relates to the first; since getting this issue, I have installed an extra PID that measures temp within the HERMS reservoir and triggers an alarm if it goes above 90C. This works well, although one only has about 30 seconds to reach the setup before the HERMS starts boiling, so it is not a perfect solution. What I would like to add to this is a way of cutting off the kettle element when the alarm is triggered. The alarm is triggered by a relay within the PID, which is set up to switch the 240v live. What I need is something like a normally open relay, that can take kettle element current and be driven by 240v as well. Even better would be something that stays off once triggered, and has an easy reset (like, e.g. an RCD switch). I know that latching relays exist but not sure how I would switch it back to closed after triggering it? Unless its just power down/up? DIN rail mounted would be good, too, and hopefully not too expensive. If I could set up my rig to continue to sound the alarm whilst cutting off the HERMS element, I would have somewhat more confidence in using the pump again - otherwise, I fear, it is new pump time.
thanks for reading!