Need a sanity check on my schematic..

Hi all - my engineering classes were many years and many thousands of beers ago, so I want to be sure I don't kill myself, or worse, ruin my first batch on my HERMS setup.

The panel schematic has 2 switches - a master for all power feeds and a pump override for when I want to just recirculate. When the master is closed it should power the temp controller, which when tripped will power the heating element and the pump.




Look workable? Any suggestions for improvement are welcomed!

I see several problems with that setup.

One, you have a lot of items in series with each other. The heater and pump won't work if you have them in series with a light bulb. The bulb should be wired in parallel.

Also, you shouldn't have the pump in series with the heater element, neither will work properly, and if you flip the pump switch on, the pump will work fine, but the heater won't work at all (it would be hot on both sides, so no current flow)

Since it appears that you are doing a RIMS (heating element) instead of HERMS (Heat exchanger) I wouldn't have the pump tied to the heating element at all, just have it on it's own switch and run the pump throughout the mash, that'll keep wort moving over the element and temp sensor, and should help prevent scortching

Whew - i'm so glad I asked!

The bulb should be wired in parallel.

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This I can fix no problem (can you tell I learned on DC circuits, and poorly at that?)

if you flip the pump switch on, the pump will work fine, but the heater won't work at all (it would be hot on both sides, so no current flow)

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In this case it's actually the intended behavior - the pump switch would circulate the wort but not kick on the heater (for vorlauf). That said, your statement about neither working properly in series means my temp controller won't do the intended job of turning both on. I need to wire them in parallel and still get the pump override switch to work.

Since it appears that you are doing a RIMS (heating element) instead of HERMS (Heat exchanger) I wouldn't have the pump tied to the heating element at all, just have it on it's own switch and run the pump throughout the mash, that'll keep wort moving over the element and temp sensor, and should help prevent scortching

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It is in fact supposed to be a HERMS system - what's missing from the schematic is the fact that the heating element is inside a water-filled 3-gallon cooler. The wort is circulated through a 50' copper coil inside the cooler, so no direct contact with the heating element.

Thanks a ton for the input - it's greatly appreciated!

skifast1 said:

In this case it's actually the intended behavior - the pump switch would circulate the wort but not kick on the heater (for vorlauf). That said, your statement about neither working properly in series means my temp controller won't do the intended job of turning both on. I need to wire them in parallel and still get the pump override switch to work.

Click to expand...

In that case, use a SPDT (single pole, double throw) switch, run the common to the pump, tie one side to the hot wire of the heater, and the other side to hot, then you have choice of on, or automatic control

skifast1 said:

It is in fact supposed to be a HERMS system - what's missing from the schematic is the fact that the heating element is inside a water-filled 3-gallon cooler. The wort is circulated through a 50' copper coil inside the cooler, so no direct contact with the heating element.

Click to expand...

where's your temp probe going to be? With how you've described it, I'd be concerned about being able accuratly and quickly maintain temp control. As is, you have two vessels that you'll be using to maintain temp control of one. If you place the probe in the mash, it will cycle when the mash gets low, but since the heating cooler could be at any number of temps (due to different cooling rates, etc) you will probably get greater temp swings than you should with such a system, since you have no direct way of keeping the herms coil from getting too hot or too cold. If you place the probe anywhere else, with the pump off, it won't be indicative of the mash temp.


What I would suggest, to keep with a single controller, is to run the pump continuously, and place the temp probe at the outlet of the herms coil. This will provide several advantages, one, the temp control will be much more stable, as the heater will cycle to keep the herms coil at the right temp, and since you're running constantly, the mash should maintain a consistent temp. It'll also give you a very clear wort (one of the goals of many rims/herms builders), disadvantage, is it will be a bit sluggish in raising the temp of the wort, since you'll also have to heat the extra water in the tank.

If you don't want to run the pump continuously, you should probably look at a second controller, one to control the heater to maintain the temp for the herms coil tank, and a second to cycle the pump for the mash. This will let you maintain both at a proper temp without wild swings in either, and will allow a quicker response for raising the temp.

One other suggestion, you might consider an agitator in the herms tank to boost the heat transfer efficiency, but this could be a later addition if you'd like.

Maybe this will help. I used SPDT switches on everything to bypass the controllers.
Edit: I just noticed this is the drawing without the lights. You can see how the lights are wired in in the pic below...




This is what it looks like all hooked up without the 220 side. I just finished that last night and haven't taken pics yet.



and the front...

Wow - you guys rock. These are fantastic suggestions and definitely have me rethinking how I want to build this (fortunately nothing's done yet beyond a simple cart to hold the MLT & HERMS tank).

I'm not averse to using 2 TC's, in fact I have two sitting idle as we speak. So let's assume the following setup per Shock's suggestion:

TC1 monitors the HERMS tank temp (not the coil) and controls the heater (w/ SPDT override)

TC2 monitors the mash temp and controls the pump, again w/ override.

The mash temp is obviously the target temp, and I'd think you'd want the other controller to be set pretty close to the same temp (say just a few degrees more) to minimize the temp swings. Sounds a bit like a mass-damper system, eh? Set the temps too far apart and it's underdamped, swinging wide and slow. Set them too close (i.e. as if using just one controller) and it's overdamped, always overshooting the target. I'm sure there's a way to set this up on a constant (but adjustable) temp differential, but it's way beyond me.

One other suggestion, you might consider an agitator in the herms tank to boost the heat transfer efficiency, but this could be a later addition if you'd like

Click to expand...

Sounds like a good use for that underpowered aquarium pump I have laying around!


Monster Mash - (killer setup, btw) - I think I'm definitely going to need a bigger junction box. 2-gang + wirenuts just isn't going to cut it :cross: I just saw your pics on the freezer collar - (i'll be building one of those in the next week or two). Very sharp!

I put a stir motor in the HLT and the controller switches both the Heating element and the stir motor.

This is the motor I am using.
Stir Motor <----Click

Okay, n00b question on terminology: I'll have several hot wires to the various components and I want to bring the hot lead into a single junction and hook in the various other hot wires to the 'hub'. What's that thing called? It's like a grounding block, but with an insulating housing. Terminal blocks look to be for just connecting 1-to-1, but I want to connect 1-to-many.

Thanks again for the patience - I have what I think is a workable schematic and I'll try to have it posted tomorrow night.

bus bar?

if you are using terminals, you can just put more than one lead on the same screw

You can use a terminal block with jumpers. If you look at the pic I posted above you can see how I hooked up multiple connections to a short terminal block. One side has jumpers across the terminals.

Ah - the jumpers are what I'm missing. I was thinking I'd have to build a bunch of my own 1" jumpers with spades on each end, but that's much better.

They are just metal tabs that are bent to go over the seperators and connect 2 terminals together. You could make wire jumpers also but it these are easier.

Remember, you can easily fit 3 wires per screw so it saves a bunch of space. I also hooked a bunch of stuff together in-line to save space on the terminal blocks.

wow..............

MonsterMash: I checked the spec sheet on the Ranco last night and I think it said the normally open contact rating was only like 6 amps; if so I think I should be running a relay between the Ranco and the heater (a la your schematic). Besides bridging the 110 to 220 lines, is this why you went with relays across the board?

The Love controllers I am using are rated 220v 16A but Im switching my pump and stir motor at the same time which are 110v. I could have used the relays for the 220v side only and used the controller contacts for the pump and motor but I had a bunch of SSR's laying around so I went with 4 SSR's.

eBay has some good deals on Solid State Relays so keep an eye out there. You will need a DC power supply to switch them but they will work fine with the Ranco controller.

So here's an updated schematic, borrowing heavily from MonsterMash's setup:

After getting everything hooked up I learned a valuable lesson. Do not use SSR's for switching plugs, they require a load in order to switch so when the heating elements are unplugged there is 220v going to the plugs even when the SSR's are not activated. When you plug in the elements the relay opens and does not close again until the SSR is powered. If you are going to have the elements hard wired into the SSR's then you will be okay.

I don't like the idea of having constant power when unplugged so Im pulling the SSR's for the elements and putting in contacts. I will also be able to switch both legs of the 220v with the contacts were the SSR's are only capable of switching one leg which is dangerous in itself.

Good to know! I'm keeping it simple and hard-wiring everything through terminal blocks. I'll post a box wiring layout later tonight (gotta squeeze in the relay somewhere in the spiderweb)

Just remember that Solid state relays will show power if nothing is connected to them. It took me a while to figure that out because I was only testing with a volt meter, when I hooked up a motor it worked fine.

I just finished swapping out the SSR's on the high volage side with mechanical relays. I'll post pics when I take them.

Here's the box layout, warts and all:

Edit: Revised to show switching on the hot wires instead of the neutral wires. The schematic above just needs the SPDT switches moved to the hot lines to be correct.

Looks pretty good and should work well for ya.

Just a couple comments: I'd consider making the stir motor on all the time (or on it's own switch), you'd want it on both when the wort pump is on, or the heater is on to be most effective at heat transfer from the water to the wort.

also it's usually good practice to switch the hot leg instead of the neutral leg for safety reasons. It won't effect the operation at all, but does reduce the chance for shock. The reason is, by switching the neutral, the items are still hot, but they aren't running which can mislead someone into thinking the power is off. If you switch the hot lead, then the item doesn't have AC power when it's not running.

Like I said, it's not going to affect the operation, but it's a good design habit to have.

Most excellent suggestions - many thanks! I'm about 80% through the box wiring, but it's all modular so it shouldn't be too difficult to re-route to switch the hots.

BTW, I noticed a couple of errors in the original box wiring diagram:
> The heater bulb should not go to the hot junction, rather it should be in parallel with the stir motor & heater.
> The neutral of the stir motor & heater needs to go to the neutral junction
> The temp controller neutrals should go to the NO terminal, not the NC.

Edit - corrected version now on previous page

Here is the finished schematic before switching out the SSR's. I don't know if Im going to bother redrawing it since everything is working properly.



Here is the finished panel with the monster relays....

I think I can speak for the forum at large when I say, "Holy CRAP!!"

:rockin:

Well, the box is all wired up and on the mashing cart. It sure looks prettier on the schematic

Heh - if this is MonsterMash's setup:



...then this is mine :cross:

hehehe.... as long as it does what you want it to do who cares what it looks like!!

Just make sure you kick the rat out of that nest before you plug it in....

Believe me, the first time I power it up i'll be standing 10 feet away using a stick to flip the switch! I put a GFI outlet on the cart for the box to plug into just to be sure...if my plumbing skills are as rusty as my wiring skills i'll have mash spraying everywhere.

Success! I rigged some spare lightbulb sockets in place of the pump/heater and (after failing to realize that I had to pull the little chain on the #&@! socket) it worked!

A HUGE thank you to Shockerengr and MonsterMash for their shared wisdom, which most certainly kept me out of the emergency room

skifast1 said:

Success! I rigged some spare lightbulb sockets in place of the pump/heater and (after failing to realize that I had to pull the little chain on the #&@! socket) it worked!

Click to expand...

hehe, i hate it when that happens

A HUGE thank you to Shockerengr and MonsterMash for their shared wisdom, which most certainly kept me out of the emergency room

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Glad to hear it's working for ya...now I just gotta go get mine built

My brain hurts, but the avatar kept me coming back for more!

knipknup said:

My brain hurts, but the avatar kept me coming back for more!

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If you look closely, you'll see there's actually a beer in there

Reviving this thead to try and understand something...

According to Ranco's spec sheet for the ETC-111000, it can handle the following amps:

full load amps: 16 (5.8) A @ 120V / 8 (2.9) A @ 240V
locked rotor amps: 96 (34.8) A @ 120V / 48 (17.4) A @ 240V
resistive amps: 15 (5.8) A @ 120V / 8 (2.9) A @ 240V

Is this not enough amperage to run a heating element without using relays?

A resistive heating element of 1800W would draw 15amps (120v * 15A), so my 1500W element should be fine. I put in the relay as much to play around with the setup as anything, but if it results in less 'stress' on the controller components, all the better. (at this point i'm officially talking out of my ass) :cross:

Thanks for the reply...

I am in the process of designing my controller and had not even considered tripping it through relays. It looks like 1800~2000W is the max end for a Ranco... which might be plenty for my needs.

I am going to us propane to initially heat my HLT, then switch to electric to maintain its temp. I am in hopes that a 1500w / 120v element will be strong enough to maintain the temperature of 10 gallons.

John Beere said:

I am in hopes that a 1500w / 120v element will be strong enough to maintain the temperature of 10 gallons.

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I'll defer to the practicing mechanical engineers on the board for this one. My 1500W element is submerged in a 2-gal cooler to transfer heat via coiled copper, and I'm hoping it's not so strong that it melts out the bottom of the cooler!