[Pawtucket Patriot]

I've been researching RIMS systems for the past few weeks and I've realized that my 15A outlet in the garage may not be able to handle the RIMS setup I'm envisioning building next spring/summer.  I'm planning on building a RIMS tube that I will outfit with a 1500w low-density element and a liquid-tight RTD sensor.  I plan on incorporating a PID (Auber SYL-2352) and a 25A SSR.  I plan to house the PID and SSR in a custom electrical enclosure that will also control both of my March pumps.  I will only be using the RIMS setup to recirculate my mash.

The pumps only draw 1.4A max each, so I'm not worried about those.  But the element draws 12.5A max, and when you add the PID draw (probably pretty minimal, but I'm not sure), the total max draw exceeds 15A.  I don't want to burn down the house by not using a proper 20A outlet connected to a 20A breaker.

For those of you who have RIMS setups similar to the one I'm describing, what amperage are you using to power your setup?  Could I get away with using a 15A outlet?

[tschmidlin]

For those of you who have RIMS setups similar to the one I'm describing, what amperage are you using to power your setup?  Could I get away with using a 15A outlet?

For what it's worth, I would not try to "get away" with anything when it comes to electricity.  Although you are more likely to trip the breaker than burn down your house.  I would run an extension cord from another circuit to power the low amperage stuff.

[mabrungard]

I ran a similar system for years on a 15a circuit.  The thing that makes it OK is that the heating circuit is not typically working full time and the pump amperage is not that great in the first place. 

The most important thing is that you won't burn down the house as long as the wiring in that circuit uses 14g or larger copper wiring and the circuit breaker is rated at 15a.  The circuit will always blow before the wiring is in danger of overheating.  You will know if the circuit is overloaded if the thing keeps tripping.  You may need to try another circuit if that is the case since there may be other loads that you don't know about on the circuit you are using.

[dak0415]

If you use a 4500W/240V low density element then you will only draw 9.4 amps (1125 watts).  That is still plenty for a RIMS plenum.

[Pawtucket Patriot]

You may need to try another circuit if that is the case since there may be other loads that you don't know about on the circuit you are using.

This is another consideration I meant to mention in my original post.  I'm not sure if there are additional loads on the circuit that goes to the garage.  It's certainly possible.  Could I use my multimeter to determine whether there are additional loads?

I was planning on using 14g copper wire, so I guess that minimizes the possibility that the wire will overheat.  I think you're right that the element will not always be on.  I expect that in the warmer months it would not be on much at all, but I could see it being on a lot more in colder months.

I definitely don't want to play around with electricity, but I guess there is pretty minimal danger since the breaker will trip if the circuit becomes overloaded.  I know a little about circuits and electricity, and I'm planning on learning a lot more before I even start this RIMS project.

[mabrungard]

A multimeter won't work.  You need an amp meter to check how much load a circuit has.  Some multimeters have an amp meter, but they are typically for teeny loads.  The easiest way to check the loads on a circuit is to turn it off and see what was connected to it by looking for inoperative stuff. 

Another thing, you said you are going to use a 1500w element?  That rating is based on 240v operation, so the current loading at 120v is much lower.  As pointed out above, a 4500w element operated at 120v has a much lower draw.  I think my old RIMS used a 4500w low density element and I never had a problem with over-current.  My new RIMS is run at 240v and all the circuitry was designed for a 50a max load.  That handles 5500w and 4500w elements operating together.   

[Pawtucket Patriot]

I'll have to look at my multimeter to see if it even measures amps.

So would the wattage difference between running a 1500w element at 120v be proportional to the voltage difference?  In other words, would running the element at 120v use a maximum 750w?  If so, then I think I should be fine with using a standard 15A outlet.

[mabrungard]

First, find element resistance:

Resistance = (Voltage x Voltage) / Wattage 

In the case of most water heater elements, the voltage at which their power is rated is 220 to 240 volts (its usually 240v).  For a 1500w element, its resistance is therefore between 32 and 38 ohms.

Second, find the current draw at the new voltage:

Current (in amps) = Voltage / Resistance

In the case of a 1500w element operating with 120v, the current is: 3.75 to 3.15 amps. 

You should now see that a 1500w element is no problem for a 15a circuit.  I would upsize to at least 4500w (9.4a @ 120v) and you could also go with a 5500w (11.4a @ 120v) element.  They should be low or ultra-low density elements to reduce any chance at wort scorching, although scorching is unlikely if a PID is used and setup properly.

Enjoy!   
 

[Pawtucket Patriot]

Thanks a lot, Martin.  This is very helpful!!

[dak0415]

I would check the specs on the 1500W element.  1500W is PROBABLY a 120v element.

[Pawtucket Patriot]

I would check the specs on the 1500W element.  1500W is PROBABLY a 120v element.

I think you're right.  But based on the formulas Martin posted, a 4500w element rated for 240v would draw less current at 120v than a 1500w element rated for 120v.  So, I think I will go with the 4500w element, which I will run at 120v.

[rob_f]

A 240V/4500W element driven at 120V will give you 1125W of heating.  You won't be happy with this if you want to step up the mash temperature.  I know from experience with that exact setup.  I'm going to either upgrade to 240V (need new 240 GFI outlet) or go with a direct-fire mash tun.

[weithman5]

i run a 1500 watt element for my boil (4gallon pot)  it is a 120 watt element.  which is 12.5 amp (1500/120).  i had two 20 amp circuits run to my garage - one for refrigerators, and one for tools.  my air compressor always would trip my garage circuit.  that said. i can boil anywhere. i use a power strip with a separate gfi that i plug my kettle in too. 

[Pawtucket Patriot]

A 240V/4500W element driven at 120V will give you 1125W of heating.  You won't be happy with this if you want to step up the mash temperature.  I know from experience with that exact setup.  I'm going to either upgrade to 240V (need new 240 GFI outlet) or go with a direct-fire mash tun.

Generally, I don't do step mashes.  But when I build my RIMS, I will also install a new burner under the MLT.  So, I will be able to direct fire the MLT if I want to move between steps.  The RIMS element will only serve to maintain each step temp.

[DaveR]

I'll have to look at my multimeter to see if it even measures amps.

I find it difficult to get enough info on mains current draw with a multimeter. I prefer this:



http://p3international.com/products/special/P4400/P4400-CE.html

I have several Kill-O-Watts. I picked up my first at Walmart for $20. I hacked that one so I can monitor electrical usage over the internet. But that's overkill.

You can use one to monitor electrical consumption of an appliance --such as how much it costs to run a keezer.  I useful for simple stuff, like telling me when my 5 cu ft fermentation cooler is running (cheap model, no LED when it's on). The Kill-O-Watt is also capable of a lot more.

It's an inexpensive solution if you're using ~115v. You can probably find something that does the same for  220v, but the cost of the device would probably be greater.