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Comment by yish | Hacker News Reader

I have made a modified sous-vide setup based on the following excellent instructions which I have not seen mentioned here. Total cost was under $75 for me since I simplified the setup a bit. Temperature accuracy is excellent.

http://seattlefoodgeek.com/2010/02/diy-sous-vide-heating-imm...

Quick overview of my modifications. I used a 6" deep full size hotel pan I got in chinatown as my water bath and a standard $9 1500 watt water heater element instead of the set of immersion heaters.

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That is awesome. How hard was it to make? When you switched to the 1500 watt heater, did you have to tinker much with the PID controller?

Pretty easy once I got all the parts together. Assembled it all over the course of one night. Hardest part was drilling the hole into the side of the hotel pan for the water heater. Luckily my neighbor is an electrician and had a step bit that worked perfectly, took about 45 minutes.

Oh, and the Radio Shack relay mentioned didn't work for me when hooked up to my PID's solid state relay (different PID then used in the link). The switching voltage wasn't enough but eventually got a relay that only needed 5V to switch. Short term I used the internal relay which worked fine, but was noisy and I wasn't comfortable driving that amount of amperage through it.

By using beer cooler, you can reduce the heat output required to maintain a constant temperature. I also wonder if one could substitute a mixer or model boat propeller on the end of a rod and a small motor for the pump?

Thanks for the link! I've been looking for plans to build a mash heater for home-brewing, and that looks like it will fit the bill nicely.

Actually, what gave me the confidence to use the 1500 watt heating element was when I searched for the PID I was buying on google, I found a lot of links to home-brewers who used these heating elements drilled into the side of big aluminum/stainless steel pots. They were using even higher wattage units to get quicker boil times.

It's great that we can so easily share information between different hobbies, isn't it? :-)

Oh, I also ought to mention one thing regarding the heating element for those who might not be familiar. If I remember correctly the National Electric Code indicates that a constant load (such as a heating element) cannot be more than 80% of the peak load rating for the circuit - which (I think) ends up being 1440 watts on a 15 amp branch.

It's almost certainly safe to operate on a 15-amp circuit, but if one is particularly worried about the letter of the law or insurance coverage if anything unfortunate happens, be sure to run on a 20-amp circuit.

In general, if it has a plug on it, it's considered a "demand load" not a "continuous load" as far as the NEC is concerned.

Hair dryer, slow cooker, electric space heater, etc are all demand loads and can use 100% of the rated ampacity.

Edit: Source: Article 100 of NEC

Interesting, I wonder if this is a new development (can't find that in my 2005 NEC codebook). I did run across something else, though, 200.21B2 states that the total load on a single 15-amp receptacle cannot exceed 12 amps, which might also apply.

I guess I'm going to have to go back and re-read the whole section. This concludes the thread-jack. We now return you to the regular discussion.

Wouldn't a propane burner be several times faster? Do you need it to work indoors?

The mash temperature needs to be pretty exact, and I (personally) find it hard to do fine temperature control with a burner. Even a few degrees variation during mash can favor different enzymes and result in inconsistent starch conversion or an alteration in flavor. I've never had much success trying to keep the temperature that steady for a full hour using a propane burner. That's not to say no-one else has success that way.

Besides that, I use a big 100 quart cooler as a mash tun to help keep the temp consistent which precludes using external heat.

A little background info on mashing for those interested: http://www.byo.com/stories/techniques/article/indices/45-mas...

My roommate was just using a burner and a pot to heat the water to the desired temp, and then he placed the hot water in a big insulated cooler, which keeps the temperature extremely stable for the hour or so while the warm water flows down into the sparging system in a second cooler holding the mash, unless I'm just completely confused about the process...

Yeah, if you have a cooler that consistent and adjust your temp for the measured thermal mass of the cooler it would work fine. Mine loses about ten degrees per hour at mash temp, however, so I need to adjust the temp pretty continuously during mash.

Of course, another part of it is just my desire to hack together nifty gadgets. :-)

I'm thinking of building something similar but instead of connecting the heating elements directly install a normal wall outlet and use a longer cable for the temp probe.

This way it would be possible to use a rice cooker as some have used in different projects or you can always plug in the same heating elements you used in your setup.

Do you think this would be feasible?

You pretty much describe exactly what I built. It's all installed in a wooden box I created that sits on my counter, the top has the PID display, on either side is a wall outlet, one controlled by the PID and one direct 120V current for the water pump. The temperature controller is on a long wire that just comes out of a whole I drilled on the front, though you can build the fancy headphone attachment as detailed in the link. All the other wiring is in the box too, including the relay which is nice since it muffles the sound of the relay switching on/off.

I tried using it with the rice cooker I had and the results weren't great. I found the temperature fluctuations too erratic but didn't really investigate too much since my rice cooker was gonna be too small for anything but eggs.

Nice! I'd love to hear about what you used for heating elements ( are you the same person who wrote that article? ) and as cooking vessel?

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