turn an old coffee maker into an on-demand water heater

 by foobear
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Hey guys, this was a fun and novel idea I had but on retrospect, I don't think it's really something safe enough to recommend for people to try for realz, so I am deleting it...

Thank you for reading!
 
 
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Step 1: Are you forgetting something?

Did you read all the safety warnings and follow them?

Are you sure you want to do this?

Did you feed the cat? 


 

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desertdog says: Nov 28, 2010. 6:22 AM
Interesting approach. Reminds me of a guy I know that used the heating element from an electric hot water heater heater to achieve the same thing.

As far as I know he is still alive.
Rayvillian913 says: Nov 28, 2010. 12:03 PM
Used this years back to heat a hot soaking tub for my wife. You don't need a pump just put the coffeemaker at the water level of the tub and add a siphon hose to put the water back in the coffeemaker tank, that will make the two water level stay equal. Works great except the pot would calcium up after about 2 months of continual use and have to be replaced. I've since gone to a 5 gal bucket heater and a waterbed thermostat teaked a bit to raise the temp to 110 degrees.


foobear (author) in reply to Rayvillian913Nov 28, 2010. 2:30 PM
Awesome!
cnathan says: Jan 17, 2013. 11:53 PM
I actually made a homemade water heater using a coffee maker and some other supplies. I travel in a motor home and do not like using LP gas so I ripped out the gas heater and built a rather cheap but efficient water heater. All in all, I spent maybe $60 to build and took a day to construct. I made a supply list and step-by-step instructions but it's not letting me add photos. I made a 20 gallon tank and it takes about 6 to 8 hours to get around 110-130 degrees. The only problem I have had with it so far is if I use well water, I have to clean the water lines once a month as lime and calcium build up. I use vinegar to clean lines.
foobear (author) in reply to cnathanJan 18, 2013. 5:48 PM
Awesome, good to hear that this idea can actually work. I got so much flack for this one that I deleted most of the article. Maybe you will post an instructable that people will appreciate.
mikesnyd says: Jan 23, 2011. 1:44 PM
What is the aproxima GPM output of hot water? Thanks. I was just wondering how long i am going to have to wait for a tub to be filled. I have a small 100L tub i want to fill for my camping expiditions. due to the girlfriend not wanting to camp unless she has hot showers/baths everyday. Thanks
tinstructable says: Dec 31, 2010. 4:54 AM
Can someone say sketchy? Haha, don't kill yourself with a coffee maker next to a bathtub.
Cartuner55 says: Nov 28, 2010. 8:23 AM
Damn, forgot to feed the cat.
KadenP in reply to Cartuner55Dec 5, 2010. 7:38 PM
So did I. Anyone want to loan me a cat so I can feed it and get past step 3?
fly_boy_bc says: Nov 29, 2010. 1:22 PM
Why not READ the instructable before submitting a critical comment?

"Not sure it wouldn't be easier just to turn on the hot water to re-heat the bath"

The FIRST PARAGRAPH tells you why he does not do this.

I have EXACTLY the same problem AND I have a spare (and gutted) coffemaker I was using as a distillery. I will be lounging in warm water all night!

siwasher in reply to fly_boy_bcNov 30, 2010. 4:22 PM
Sorry for overlooking that point, but I wasn't being critical. I love the idea.
espdp2 says: Nov 29, 2010. 3:09 PM
That's what the cat is for!
fly_boy_bc in reply to espdp2Nov 30, 2010. 2:31 PM
Of course! That's why we had to feed the cat! He's our TEST BATHER!
Ultra-Indigo says: Nov 29, 2010. 11:14 PM
You don't need to start a siphon the coffee maker already does that normally when you use it to make a pot of coffee. That is why the water in the tank in the back of the pot doesn't get hot and all the hot water ends up in the pot. The key is there is a ball valve inside the heating element so when the water heats up it expands and creates lower pressure on the hot side drawing in the cold water past the ball valve which in turn gets heated up. That is why you don't have a pump on the coffee maker in the first place.
The ball valve is also the part that gets kludged up with lime and you have to clean it with vinegar or it gets too hot and you burn out that little heat fuse. I like the bike tire (cheap and easy) but it might be better with silicone tubing to withstand the heat hate to have the tube leak in the middle of a nice bath.
Oroka says: Nov 28, 2010. 10:49 AM
Interesting project, but how big is your water heater? Unless it is teeny tiny, you should be getting a lot more hot water out of it. Perhaps a element is burned out or something.
foobear (author) in reply to OrokaNov 29, 2010. 5:22 PM
It has just enough capacity to fill the tub once only. It requires a 30-40 minute wait to heat up all its water again.
Oroka in reply to foobearNov 29, 2010. 8:15 PM
wow, that is quite small.

Used hot water heaters really are not that expensive. As long as the tank is solid, the rest of the tank is pretty simple.
foobear (author) says: Nov 29, 2010. 5:25 PM
I assume you mean the hot water outlet of the coffee maker and not the tub.
foobear (author) says: Nov 29, 2010. 5:24 PM
Certainly, don't try this at home.
DeusXMachina says: Nov 28, 2010. 1:29 PM
http://www.amazon.com/Marshalltown-742G-Bucket-Water-Heater/dp/B000BDB4UG/ref=pd_cp_hi_2

Using something like that, I think you could come up with a slightly more elegant and less dangerous kludge.
foobear (author) in reply to DeusXMachinaNov 29, 2010. 5:21 PM
interesting. I didn't know about this device. thanks
computurwizard says: Nov 29, 2010. 6:40 AM
If you are gonna play around with this, then you need to replace the electrical outlet in your bathroom with a GFCI outlet and make sure the coffeemaker is properly grounded. PLEASE do this, it could save your life!
foobear (author) in reply to computurwizardNov 29, 2010. 5:18 PM
I thought GFCI outlets were required by code in all bathrooms. I don't know. Maybe not in every state.
foobear (author) says: Nov 29, 2010. 5:17 PM
Definitely don't try it if you feel like that. Stay safe.
jptrsn says: Nov 28, 2010. 7:39 AM
Check out http://www.youtube.com/watch?v=4j4Q_YBRJEI

It explains how the coffee maker works without a pump. That means that if you take the heater assembly, hack both hoses into the tub, and keep the whole thing lower than the water level in the tub, it should work without a pump.

Use really long hoses, and you won't have the safety hazards that this project entails.

Let us know if you work on it more! 

foobear (author) in reply to jptrsnNov 28, 2010. 8:58 AM
I like this idea. It's very simple. I'm not sure how to easily get the siphon started to get the water flowing from the tub to the element though.
espdp2 in reply to foobearNov 29, 2010. 3:04 PM
How about one of those squeeze bulbs for a marine outboard motor's fuel tank? A few squeezes will push water up and over the edge of the tub, and the bulb will let it keep flowing in that direction.
foobear (author) in reply to espdp2Nov 29, 2010. 5:16 PM
The problem is you'd have to somehow squeeze it from the device side to get the cold water flowing into it. Just having trouble visualizing how to hook that up.
jptrsn in reply to foobearNov 29, 2010. 6:15 AM
If you've got enough of a length of tubing, getting the siphon started is pretty simple. I use the following method for cleaning my fish tank and draining the swimming pool:

1) Submerge as much of the tube as you can in the water.
2) Cap the open end of the tube (a thumb comes in handy here).
3) Pull the tube out so that the water in the tube goes up over the edge and comes down to a level lower than the surface of the water.
4) Remove thumb.

As long as the water in the tube is lower than the surface, the pressure differential will push water through the tube. Get the water going, then raise the open end of the tube and put it back in the tub. As long as it's primed to the heater element, it'll draw cold(er) water from the tub.
foobear (author) in reply to jptrsnNov 29, 2010. 5:23 PM
I see what you're saying. I'd like to find an easier way though.
sheilamommy says: Nov 28, 2010. 6:43 AM
Room's ambient temp 51 degrees. And I thought I kept my house on the cool side. I will show your instructable to my kids to let them know how goodthey've got it at 65 degrees.
foobear (author) in reply to sheilamommyNov 28, 2010. 8:38 AM
Yes, I bought an old fixer upper and it has no insulation anywhere! So, even with all the heaters on and the fireplace, we couldn't keep it warm enough. Outside was 20 degrees or so.
espdp2 in reply to foobearNov 29, 2010. 3:09 PM
Hire a teenager to put in some fiberglass and spray-can insulation. It will save you lots of money over running the heaters and fireplace. Anything is better than a drafty box.

Also, you should look into a pellet stove. They are just about the greenest heating solution out there, not TOO terribly expensive, and easier than a fireplace to keep going.
foobear (author) in reply to espdp2Nov 29, 2010. 5:13 PM
certainly good advice
foobear (author) says: Nov 29, 2010. 3:17 PM
Thanks, that was constructive feedback.
fly_boy_bc says: Nov 29, 2010. 1:30 PM
This is exactly the way to do it and I assumed it was the way this instructable worked before I read it. Really easy to imement and no syphoning difficulties.

I think it will be easy to make sure it is safe too. Just make sure there is no way for the coffemaker element to get wet. (on he outside) NO danger.

WingDings says: Nov 29, 2010. 5:52 AM
:D Lethal!
Rayvillian913 says: Nov 29, 2010. 5:34 AM
I use an old water bed heater for the heatpad for seed starting. Put the heater in the bottom of a wood box with 1x4 sides. put a plastic sheet to keep water from the heat element than 1 1/2" wet sand on top to spread the heat out. Thermostat bulb buried in the sand controls it. You have to add water occasionally.
abfarrer says: Nov 28, 2010. 4:18 PM
Ok, I can see you hesitance to have gas installed to make for more hot water, but do yourself a favor, and look into electric on-demand water heaters. you can get small "point of use" models that mount under a sink, I'm sure you can find something that would fit your needs far more safely than this contraption.

Of course, it will cost you more than $10.
Spokehedz says: Nov 28, 2010. 9:30 AM
Nice... Like the sous vide heater in the kitchen. :P
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