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Uses for an old hot water heater?

29K views 72 replies 58 participants last post by  cook  
#1 ·
Our home has gas service but the previous owners never converted any of the appliances over when they converted the furnace (previous furnace may have been oil). Once tax refund time rolls around, I'm hoping to change our electric water heater to gas, leaving me with an unused water heater. It is old enough that it won't be worth much to sell but but it is still good; no leaks, heats water fine, probably needs a good flush and new anode rod.

I've have been looking for ideas on what to do with it and wanted to ask here as well. A couple ideas that have been interesting so far:

- Temper tank/emergency water storage - The idea here is to have water come into the old tank where it sits and comes up to room temp. before going to the new tank to be heated. The theory is that the amount of energy required and recovery time of the new tank is reduced. You also end up with 80-100 gal. of available clean water in the event of a power outage, well pump failure, etc. If you stuck to the 1 gal. per person per day rule, that is nearly a month of water for a family of 3. The water stays fresh since it is always being circulated through.

- Solar water tank - Many flavors of how people do this.

I will continue to research but are there any other clever uses for an old water heater? I plan to explore the temper tank idea more.

Thanks!
 
#8 ·
If its a regular home heating tank --- strip everything offa it down to the tank itself -- cold water in - heated water out - overheat pop off valve plumbed to outside ----- build it into a 6" thick insulated box with a double thick glass / plastic cover ( old sliding patio door ) paint interior flat black -- heat tape pipes going into and leaving -- triple wrap --- either pre-heat boiler water or use as is --

99 % of the time the heated water in the tank wont freeze at night :thumb:

And --

Interweb --
Image
 
#31 ·
Yep, a stove. Got an old copy of a Mother Earth News specialty magazine that covered a series of Energy Topics and lots of DIY projects for each back in the late 70's, and a woodstove made from old water heater tanks was the one that caught my eye.
Came into possesion of an Oxy/Acetyl. set last year, and am going to save at least one of the tanks that I'll end up scrapping this coming spring clean-up in the local neighborhoods.
Always get at least a half dozen or more to scrap during the year, and I will be looking to save one of the larger ones from the scrap heap for a DIY wood stove project for myself.

Won't be installing it as a main source heating device, but instead setting it aside for SHTF with my other long-term preps. Just a matter of buying one of the barrel stove kits that used a 55 gal drum. It has the legs, door assembly, and flue collar. All you need to add after that is a flue damper assembly, all the needed flue pipe, and a cap. Oh sure, I could just go and buy a small box stove from Lowe's, and all the flue pipe and accessories I needed to do the job, but I still like the DIY factor of making one from an old water heater tank. :thumb:
 
#4 ·
First of all, used water heaters have almost no resale value.

Sometimes, just because you have something, doesn't mean you have to find another way (re-purpose) it.

There are a number things you 'could' do with it, Would be easy, using a small pump and a long coll of tubing (plastic) and use it to heat your floors.


Me, I'd just junk it.
 
#51 ·
I'm not too sure I agree with you on the no resale value thing. While it may not have value for its original use, a LOT of DIY / homestead / prepper types would love to get their hands on a used tank because there are so many things you can do with it. I'd say post it on Craigs List for $50-ish, depending on where you live. Betcha somebody will take it off your hands!

Also, one cool use I saw for an old hot water heater was as a culvert or underpass for a chicken moat. Cut both ends off so it's a tube, trench it in and then put dirt back over top of it to allow water / critters to pass under an otherwise-fenced-in area. Don't know about having heavy vehicles parked on it for any length of time, but for just coming and going it might be OK.
 
#5 ·
The ones that I have taken out have a layer of sprayed foam that sticks to both the tank and the exterior. I heard they make nice fish fryers, but I've never seen anyone tear one down and build anything with it. Looks like quite a job to me.
 
#68 ·
I made a smoker out of one for a friend...salvaged the burner and fittings/gas valve for otheruses, used a $2 electric hot plate for the smoke heat.

it's a pain to weld with the coating, but the foam can be scraped off fairly easily.

it's crude and ugly but it works quite well and it was a favor so I didn't make it too pretty...
 

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#6 ·
Pre heater to room temp is a good idea, gives you storage too. If you have room keep it as water storage. I've had one on the garden hose supply for years, every time I use the hose, the water runs through the old heater. Storage is constantly refreshed, if I need it I can drain it out through the drain valve. Change that little drain valve, and clean out the sediment before you set it all up. Easier when empty. Works for me...
 
#9 ·
If you have the space, leave it plumb in with breakers off as a settling/storage tank on the supply side to the new gas unit. If you have a big temporary demand for hot water you could turn it on.

With a set of bypass valves around the new unit, you could still have hot water if you had electricity (commercial or generator) and not gas.
 
#12 ·
I made still's out of a couple of smaller water heaters. Was easy to find fittings for condenser coil, thermometer on top and worked well. One was gas and the other had internal heating element which burnt the mash and somehow imparted a tequila flavor lol. Coil was directed downward through a 5 gallon bucket of flowing water. Not sure it could get hot enough to distill water only but was easily controlled otherwise.
 
#13 ·
Does anyone know if all tanks are made of the same metal and what metal that is?

I heard it was stainless a long time ago. No idea if it still is, ever was, or if it's universal.
 
#15 ·
We collected a few dead water-heaters. We flushed the sand out of them, and used them to form a Thermal-Bank.

Our woodstove heats water; that heated water circulates in a loop with the Thermal-Bank. A second loop circulates the heated water from the Thermal-Bank and through our radiant heated floor.

Water heaters plumbed in series work great for thermal storage. :)

Now that we are on Solar-Power, we have way too much electricity during day-light. I have thought about replacing the electric heating elements in the water-heaters and putting them on timers. So during day-light 40amps of my surplus power can be used to heat the water in our Thermal-Bank.
 
#20 ·
I'm curious as to what you think of your tankless system? Is it electric? How did your bill change?

My wife has wanted tankless and I've been dragging my feet. We have a 40 gallon natural gas water heater that is pretty much free to operate. It never runs more than the gas minimum while the central heat is not being used.

I know or am assured that I will have hot water as long as we have water, as I have never lost natural gas service since 1975. I see no need in changing.
 
#27 ·
since it's not a leaker make a solar preheater out of it black pain in the box outside. and plumb into your gas heater. or as JohnAmmo said use as a fresh water storage prep area. be sure you research any check valves you may need also if you are using it for solar and you live in a really hot place you might get water is hotter than expected be sure you are plumbed correctly with a T&P valve. We have had a few barbque made out of them but they were leakers so no value as a water storage.
 
#28 ·
Strip the tank down to just the bare essentials, and plumb it inline BEFORE the Hot water tank. It gives you a constantly freshened source of 40 extra gallons of water. It also warms the water to room temperature before going into the actual water heater, thus lowering the heating bill slightly.
 
#30 ·
It would depend on how old the tank is. In the 1980's the previous tanks were all metal, then they started to line them with glass. Look for a manufacture date, if it is before 80 then you can cut them up for a lot if projects, if it is after 80 then call the manufacturer, then it could only be used for liquids.
 
#32 ·
Uses for a used hot water heater......


Umm...why do you need to heat hot water??

Just playin..I'd run with the "leave it plumbed" scenario. With a twist.. put it after new heater with bypass set up. You could have double amount of heated water for daily use (think storage). Or turn on breaker for heavy usage. Bypass (but full) for emergency water supply.