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Brews & Views Bulletin Board Service * Brews and Views Archive 2006 * Archive through August 31, 2006 * Float Switch Question < Previous Next >

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dhacker
Intermediate Member
Username: Dhacker

Post Number: 368
Registered: 11-2002
Posted From: 72.4.22.214
Posted on Wednesday, August 16, 2006 - 04:58 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I need to add float switches to both my new HLT and HERMS tank. I've looked on McMaster Carr's site and see several options. For those using float switches to prevent DES (dry element syndrome) Are you using switches with Normally Open contacts that close when the water level exceeds the switch level, then opens when it falls below the switch?

I'm thinking this is the proper approach.

TIA
 

JD
Junior Member
Username: Tasbrewer

Post Number: 49
Registered: 12-2004
Posted From: 131.217.6.8
Posted on Thursday, August 17, 2006 - 01:25 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

So you trying to stop frying the elements in your HLT while your sparging? If so, then I suspect you have the right idea in switch configuration

ie. You want it to keep power to the elements when the vessel is full (so the switch has to be closed in the full vessel) then the switch opens when the level falls below your switch (hence cutting power to the elements when the water is low).

I have a funny feeling that if I remember correctly, a lot of the available float switches can be rotated to accommodate your desired purpose and placement. If you follow?

Here is one example of the type I'm talking about. If you install this switch so the float goes up, and it's covered with water it's open, rotate it 180 degrees and the float always tries to go up when covered, thus keeping it always closed.

http://www.rsaustralia.com/cgi-bin/bv/rswww/searchBrowseAction.do?D=float%20swit ch&Ntt=float%20switch&Nr=avl%3aau&Ntk=I18NAll&N=0&Nty=1&name=SiteStandard&forwar dingPage=line&R=0845976&callingPage=/jsp/search/search.jsp&BV_SessionID=@@@@0974220386.1155775408@@@@&BV_EngineID=cccdaddiijidhkfcefeceefdffhdgmk.0&cach eID=auie

As far as what you want to do with your separate HERMS tank, why do you run the risk of exposing your elements in there? Unless your boiling it dry, which I doubt, I'm not sure I understand the risk of exposing elements here?

Cheers.
 

dhacker
Intermediate Member
Username: Dhacker

Post Number: 370
Registered: 11-2002
Posted From: 74.226.106.18
Posted on Thursday, August 17, 2006 - 02:04 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Thanks JD,

Couldn't get the link you listed to work.

Anyway, my intent is to "insure" that neither the HLT nor the HERMS tank will receive power from the PID if for some reason I forget to fill them with water or the PID's energize the heating elements when first powered up. It's a fail safe kinda thing. Obviously, the HLT is used not only for sparging but also for mashing. The HERMS tank probably won't be evaporated dry during a brew session, but again, I don't want the element to energize unless a sufficient amount of water is in the vessel.
 

Ned Buntline
Member
Username: Ned_buntline

Post Number: 224
Registered: 12-2005
Posted From: 71.248.243.103
Posted on Thursday, August 17, 2006 - 02:54 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

dhacker, here you go:

http://www.dwyer-inst.com/htdocs/LEVEL/qsLevelTOC.cfm

Scroll down to the level switch section. You'll find switches from $15.00 to $700.00+.
 

Flobey
Junior Member
Username: Flobey

Post Number: 52
Registered: 06-2004
Posted From: 204.124.198.29
Posted on Thursday, August 17, 2006 - 02:20 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Not sure where I first saw this; apologies if it was here. Pretty trick:

http://essersnet.com/php/content.php?viewPage&ID=160
 

Dan Listermann
Senior Member
Username: Listermann

Post Number: 3243
Registered: 03-2004
Posted From: 216.23.59.245
Posted on Thursday, August 17, 2006 - 02:33 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I have a similar system that uses low voltage float switches instead of probes. I bought a fan thermostat to provide the 24 volts and control the 110V.

Dan

--This space is STILL being left intentionally blank.-


 

don price
Advanced Member
Username: Donzoid

Post Number: 888
Registered: 02-2003
Posted From: 65.32.230.81
Posted on Thursday, August 17, 2006 - 10:11 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

The conductivity based level control relays rock! If you don't want to drill holes or deal with grommets you can use good ol' copper tube or wire and just run it up and over the edge of the vessel and down to whatever level you want. Keep the probes covered with vinyl tubing except for the bottom 1/4" or so to keep them from grounding out against each other or the tank. Lots more info here...

http://www.gemssensors.com/TOCProducts.asp?nContentsID=28

My favorite application is the "pump up" configuration where I use the level probe to close a solenoid valve ($10 irrigation valve actually) on my HLT tank fill water line. When I need water I just turn the switch from "off" to "auto" and don't have to watch the tank level. Very handy when filling at <1 gpm through a carbon filter.

You can also use them for auto control of your mash tun sparge water supply pump.

Don
 

JD
Junior Member
Username: Tasbrewer

Post Number: 50
Registered: 12-2004
Posted From: 131.217.6.8
Posted on Friday, August 18, 2006 - 12:11 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I'll just add one more thing that Dan alludes to above.

I'd set up a separate power supply to run through the float switch (eg. 12V from a plug in power pack) and use this voltage to switch your main relay. That way you don't have a 110V or 240V sitting submerged in you HLT/HERMS tank that if it leaked could possibly go live.

Best to keep that 110/240 volts out of the tun and just run a lower voltage through the switch.

P.S. To get my link above to work you will need to cut and paste the whole link into your browser (include the last bit that isn't highlighted blue). I don't know how to make tinyurls.

Cheers, JD
 

dhacker
Intermediate Member
Username: Dhacker

Post Number: 372
Registered: 11-2002
Posted From: 70.146.180.94
Posted on Friday, August 18, 2006 - 12:43 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

My original plan was to control the 12vdc from the SSR output of the PID so as NOT to have dangerous voltages circulating in the tuns. Now that I've seen the probe method Flobey and Don showed I think that is the way to go . . cool as heck! I should be able to design and build that circuit at little to no cost with salvaged parts laying around the radio station. And Don's idea of "Over the Top and Down" with the probe makes great sense.
 

don price
Advanced Member
Username: Donzoid

Post Number: 889
Registered: 02-2003
Posted From: 65.32.230.81
Posted on Friday, August 18, 2006 - 01:24 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Yes, of course, I should have mentioned the Warrick conductivity based relays are intrinsicly safe and do not involve actually running 110/220 V through the level switch. The ones I salvaged also happen to be rated for use in explosion-proof circuits. Overkill, but really cool.

Don
 

dhacker
Intermediate Member
Username: Dhacker

Post Number: 374
Registered: 11-2002
Posted From: 72.155.216.64
Posted on Friday, August 18, 2006 - 12:52 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Whilst poking around I came across this doc from National Semiconductor. Might be just the ticket.

http://www.national.com/an/AB/AB-10.pdf