Can 55 gallon metal drums be used in hot water production

Hello Good Premies People,

I have access to food grade metal and plastic 55 gallon drums.  I am trying to heat a 16 x 18 foot greenhouse, that will be going to running all winter.

Here is the grand idea:

-16x18 foot wooden frame, vinyl windows
-I have a RMHeater already built
-adding a cast iron wood stove for overnight burns
-primary objective is to run an aquaponic system all winters long

-A Jean Pain mound is going to be built outside the greenhouse
-I know I can use the metal drums to circulate the hot water produced from the wood chip compost heater, without major temperature/pressure issues.

I am planning on retrofitting my cast iron stove with a copper coil on top to produce hot water for a radiant system
-This is where the metal drum idea comes in.  Can I use them to store hot water in them, with the proper pressure valves?  These are metal drums that have a removable metal lid with two bung holes.
They have a ring with a large bolt to fasten the lid.  
I have used these drums for the rocket mass heater.

So instead of a hot water tank can I use metal 55 gallon drums to store hot water generated from the wood stove and Jean Pain wood chip pile, with the proper pressure valves?

I will circulate the hot water with a dc pump solar system .

All advice and suggestions are warmly welcomed.

There is no reason that I'm aware of that would prevent you from using the drums as you describe. But I do have a couple of questions: 1) Is it your intention for the drums to radiate some of their heat into the greenhouse? 2) If not, how do you intend to insulate them. The advantage of using water heater tanks is that they are already insulated. 3) How hot is the water you are expecting to contain? 4) other than pressure relief valves, what safety measures are you planning (e.g. For power failure of the pump, a major leak in the system that drains the water and leaves empty pipes being heated) ? Just my first take on your question.

I've seen what happens when a fellow worker at a place where I was employed decided to "leak-test" a drum by plugging one bung and attaching
a fitting with a Chicago fitting to the other bung.  From there he ran an air hose to a 90-psi connection....

Within seconds there were two loud pops...and both barrel ends had arched out into a convex shape.

Hot water tank temperature/pressure safety valves are set at 150-psi and a temperature of 212 F

Here is an interesting article on hot water tanks:

http://www.combustionsafety.com/hot-water-heater-explosion-elementary-school/

It is your choice, of course, if you want to use 55-gal drums in a closed system.  The other thing is that, when letting them cool off, if you don't vent them
then the condensation inside will cause a pressure difference. You get to watch your drums fold into a pretzel.

R Jay wrote:I've seen what happens when a fellow worker at a place where I was employed decided to "leak-test" a drum by plugging one bung and attaching
a fitting with a Chicago fitting to the other bung.  From there he ran an air hose to a 90-psi connection....

Within seconds there were two loud pops...and both barrel ends had arched out into a convex shape.

Hot water tank temperature/pressure safety valves are set at 150-psi and a temperature of 212 F

Here is an interesting article on hot water tanks:

http://www.combustionsafety.com/hot-water-heater-explosion-elementary-school/

It is your choice, of course, if you want to use 55-gal drums in a closed system.  The other thing is that, when letting them cool off, if you don't vent them
then the condensation inside will cause a pressure difference. You get to watch your drums fold into a pretzel.

He should NOT be using relief valves off a hot water heater, he should be using relief valves off a boiler which release at 12 PSI. Since sealed steel 55 gallon drums are rated at 22 PSI this is a very safe and recommended. Boiler relief valves can be had at any hardware store including Home Depot. He had asked in another post about using barrels and I said it was not needed, but I thought he was using a Jean Pain type compost system as heat, but since he plans to use a wood stove to heat the water, then a relief valve is REQUIRED.

If for some reason you decide to go with a bigger 275 gallon home heating oil tank though, keep in mind they are rated for only 7 PSI.

As for testing, when I used to weld up pressure vessels, for hydrotesting we would fill them with water and then pump them up to 2500 PSI, but if the same tank was to be filled with air, it might only be tested at 10 PSI. With tanks that big, if there was an blowout at 2500 psi it would kill everyone inside the building. When using compressed air on anything not specifically rated for a PSI, I will NOT go above 10 PSI. I know your friend did not know what he was getting into, but 90 PSI was insane for flat bottomed tanks!

BTW: Useless information here, but did you know for safety sake a soda bottle is designed to take 200 PSI, but if you look at them there is not a flat spot on them.

[quote=Travis Johnson

He should NOT be using relief valves off a hot water heater, he should be using relief valves off a boiler which release at 12 PSI. Since sealed steel 55 gallon drums are rated at 22 PSI this is a very safe and recommended. Boiler relief valves can be had at any hardware store including Home Depot. He had asked in another post about using barrels and I said it was not needed, but I thought he was using a Jean Pain type compost system as heat, but since he plans to use a wood stove to heat the water, then a relief valve is REQUIRED.


When I read the original post, it stated that the water was going to be heated by a copper coil on top of the stove.  It also stated that the hot water was going to be circulated by a pump run by solar power.

The supply of makeup water is coming from where?  Well water systems use a pressure tank to maintain water pressure up to 60-psi--a bit more than a 12-psi boiler relief valve attached to the barrel can handle.  So the water system will have to be isolated using a gravity-fed system to keep the water pressure down below 12-psi.  And where is the solar-powered recirc pump going to be installed...and at what pressure will it be running?

I didn't see any mention of a tempering valve, or any mention of regulating the wood stove dampers once temperature is reached.  A stove top can reach 500 degrees F...enough to bubble the water in the copper coil and generate steam in the case of a circulation failure.  

The system is not unusable, just not very convenient. The person can only fire it up every 2nd or 3rd day, run a very low fire to keep the temperature down, and use really dry wood to prevent creosote build-up.  It would not be a system that a person would want to run unsupervised.  If it was...and the person was lucky....any system failure could turn the 16 x 18 greenhouse into a really hot sauna...

Seems safer to use a regular hot water tank or just the Jean Pain system....just my opinion... after spending over 30 years as a power engineer running high-pressure boilers and turbines for a couple of pulp mills, then at the Alberta oil sands, I developed a healthy respect for steam and vacuum.

Here are some I-net sources on wood stove hot water heating from a post 2 years ago:

http://sustainablepreparedness.com/index.php/blog/hot-water-for-free-from-the-wood-cook-stove

https://www.survivalmonkey.com/threads/domestic-hot-water-from-a-woodstove.32038/

There was also greentrust.org...but at present it has been hijacked and you get redirected to a software download site. Fortunetaly there is the Internet "wayback machine"...a reference to Professor Peabody and Sherman for those old enough to remember Rocky and Bullwinkle cartoons....

https://web.archive.org/web/20150201145756/www.green-trust.org/2003/fireandwater.htm

BTW--bit of useless into--the steam-driven car--the Stanley Steamer--unlike the steamboats and steam-driven tractors--only had a couple of explosions.  One happened because the owner decided to remove the reinforcing bands that enclosed the flash boiler.  The other was because the owner, like the steamboat captains, decided to circumvent the safety systems in order to over-pressurize and make the car "go faster."  And maybe if Detroit hadn't developed an ignition system that let a person drive off right away, instead of waiting for pressure to build, we might be still driving steam-driven cars today--made out of "weed"-based plastic and powered by "weed" oil....

I guess I am confused because the whole purpose of using the boiler relief valve is so the make-up water is reduced in pressure from 60 PSI down to the 12 PSI boiler operating pressure. It comes as a kit usually, acting as a vent, and tying into an expansion tank as well.

I personally would just stick with the Jean Pain compost heat and not bother with trying to incorporate another form of heat to the system. Just go with the low temperature heat, using a circulating pump with an on-off relay. Start small and only build what is needed instead of getting too complex right out of the gate.

R jay is right because things do get sticky with water and hand fed boilers. If I was to stoke my New Yorker WC-90 boiler full of wood, and then the power goes out, that wood is going to burn! Granted the power draft will not be coming on so the fire won't be roaring, but the wood is still burning and producing heat, and that heat is warming the water jacket which has no pump moving it so it could flash to steam, hence the last resort...the boiler relief valve. I plumbed mine to outside just in case that scenario occurred. Another scenario I had to anticipate for is a dump zone in case of an over-fire situation. In that case at 200 degrees my dump zone opens up and dissipates my heat through a fan driven modine, but a cast iron radiator from an old house works better. The latter is used a lot, but is kind of tricky because it should be located in a spot that won't freeze, yet will get the occasional influx of heat. (Due to inefficiency and cost, I do not use antifreeze in my heating systems).

Travis Johnson wrote:I guess I am confused because the whole purpose of using the boiler relief valve is so the make-up water is reduced in pressure from 60 PSI down to the 12 PSI boiler operating pressure. It comes as a kit usually, acting as a vent, and tying into an expansion tank as well.

When I first read your reply I went....Huh?...a relief valve does what?....then I realized that possibly there is some confusipn here....

A pressure-reducing valve would be installed on the cold-water side to reduce the make-up water from 60-psi to 12-psi.  It reduces pressure from a higher pressure to a lower {and safer} working pressure for the system.  It is not a relief valve.  It does not vent....only reduces.

A pressure-relief valve would be installed on the hot-water side and would just sit there in the closed position until the internal pressure exceeded the rated relief valve pressure and the valve would open to vent to atmosphere...thus safely reducing the internal pressure in the system.

Two different valves....  

Yeah you have to have both, one to knock down the pressure and then one to protect the system once it is reduced.

On my system, which is essentially an add on wood boiler to a propane boiler, I used the make up water for the propane boiler, then added on a loop for the add on wood boiler so that they operate as one without having redundant systems, but I still had to add a relief valve and hi temperature dump zone for my add on wood boiler. But as you mentioned in another post, a tempering valve should be installed as well. I use a mixing valve (really just a computer driven circulator) to do the same thing.

I am 100% with you, a person can really do some amazing things with hydronic heat, but it can get really complicated and expensive too. I got over 10 grand in my heating system, but it has more then paid back these past 11 years.

I have been meaning to add Jean Pain compost heating to my radiant heating system, but never got there, but have never really thought about scaling it back to just do my domestic hot water. That would be really doable as I have plenty of sheep manure and wood chips to cook up.

Hi Trevor

Sounds like you have quite the heating system.  If I was going to spend that much money, I would look at either:

http://www.builditsolar.com/Experimental/PEXColDHW/Overview.htm

or:

http://www.builditsolar.com/Projects/SpaceHeating/DHWplusSpace/Main.htm

And since my place is in an area that allows outdoor wood furnaces:

http://www.heatmasterss.com/

All three systems use hot water and can be set up for under-the-floor radiant piping or above-floor radiators.  Putting the hot water tank into the loop is not that difficult,either.

I think a combination of a solar-type system with an outdoor furnace would be almost ideal....no creosote buildup from the outdoor furnace....no hi temp/hi pressure problems
from the solar system....outdoor furnace has auto damper control to control temperature....only problem would be possible freezing of system components during winter....

No I don't think so. I originally thought that too when I was thinking about putting my wood boiler in a non-heated space, but as long as everything is hooked up together, the wood boiler will back-heat the plumbing going to the solar array. etc so no gycol needed. The only thing you would have to be concerned about is backup electricity in that case. A small generator would work as long as you or the spouse was there to fire it up should the power go out, but if not an automatic back up generator would be ideal.

I am not a huge fan of outdoor wood boilers, my father had one but he was a slave to it. It seemed he was either getting wood for it, cutting up wood for it, or actually burning it. I think he burned some 20 cord of wood a year for the thing. But that was a few years ago. After the darn thing burned his house down he went to a wood pellet boiler instead. I am not advocating for them either though.

I went with an add-on inside wood boiler. The problem was, my propane boiler is almost too efficient. It heats my 2500 square foot home here in Maine for $1800 a year with propane which is amazing, so spending $7000 on a new indoor wood boiler did not make sense. By the time I reached the savings for $7000 for burning wood over propane, the indoor wood boiler would be worn out and time to buy another one. So I went with a used add-on boiler for $700 which makes my return on investment a lot better.

I briefly looked at your links and they looked nice. A guy in Canada used soda cans to heat his home via solar hot air. It was a very unique way to heat a home for cheap and I will see if I can find the link. I agree 100% with you that solar and wood is great for northern homes. My house is ideally situated for solar, but also compost heat because of my flock of sheep. Incidentally it is ideally suited for wind, but electricity is not a huge concern for me right now, heating water seems to be my biggest cost because of a big household (all girls) and hydronic heat.

I see in the thread starter where you mention valves and such, but don't quite get the need for any pressure at all on your system.  I use a small 12v transfer pump on my system and only heat water without pressure. Since I use an old hot water heater there is no problem turning the supply valve and having fully pressurized water when I'm ready for it



a small thermostat  turns the pump on when water in the coil is hot enough

and one time when power failed and the coil was dry   some solder melted out of the joints of my copper tubing coil.

I now keep a bucket of sand or clay nearby to put out the fire in my j tube rocket firebox--just in case--an airtight stove would have the same effect.

I have also added some safety features, backups on the backups--an led light to indicate power to the system, a jumper wire with alligator clips to bypass the thermostat and turn the pump on manually, plus a combination of valves that can supply water to the coil and send the hot water output safely from the system-  if the primary pump  fails.

Hot water improvisation can easily go very wrong, very fast, as has been mentioned numerous times on Permies (and in this thread),  During my first years running my system I can't count the number of times steam has come out of the open relief because a pump failed, or a thermostat failed, or I forgot to open a valve.

If you can position the water storage close to the heat supply a thermosiphon might be possible in which water naturally moves from the heat source to the storage and back, no pumps or thermostats, just keep the system full of water, when this is possible it is my preferred alternative

Yeah..I remember the sodapop heater.....

Saved a few youtube vids.....

Only link I have is:

http://www.alternativesjournal.ca/sustainable-living/web-exclusive-diy-pop-can-solar-heater

Some how-to videos and some how-to texts

bob day wrote:I see in the thread starter where you mention valves and such, but don't quite get the need for any pressure at all on your system.  I use a small 12v transfer pump on my system and only heat water without pressure. Since I use an old hot water heater there is no problem turning the supply valve and having fully pressurized water when I'm ready for it

You heat water without pressure using a 12v transfer pump and you have fully pressurized water when you are ready to use it......

I have an old motor home on my property that I use as a cabin.  It uses a 12-volt pump to transfer water from the fresh water tank....pump runs around 3 gallons a minute....pressure is controlled by an internal adjustable pressure switch to try and maintain around 55-psi and there is definitely a relief valve on the propane heating unit. I suppose I could run it without any of that safety stuff...just not too sure I'd want to......

If you can position the water storage close to the heat supply a thermosiphon might be possible in which water naturally moves from the heat source to the storage and back, no pumps or thermostats, just keep the system full of water, when this is possible it is my preferred alternative

Thermosiphon systems are pretty simple on a solar system....just a collector and a storage tank...and maybe depending on a design there is a check valve to prevent reverse flow at night.  With a gravity-fed system, any make-up water can just flow into the top of the storage tank and level could be controlled with modifications to a toilet tank float/inlet valve.  Once it gets more complicated.....wood stove for back-up....a pressurized cold water supply for makeup and tempering....safety devices seem like a good idea.....

Back in the day when farm tractors were huge steam-driven beasts, all the operator had was a glass tube attached to the boiler to show water level.  Problem was that he had to drive the machine also.  If he  forgot to occasionally glance to check the level in the tube....well....when water in liquid form flashes and becomes a gas--steam--it needs a volume almost 600 times greater than it had as a liquid.  The basics of a boiler explosion....and why an ordinary hot water tank was able to kill 7 and injured 36 more as written in one of my previous post on this thread......

http://www.combustionsafety.com/hot-water-heater-explosion-elementary-school/

I use an RV pump to provide my main pressure in the system, the hot coil and storage can be isolated during heating from the main system so it is free to expand or blow off steam --the circulating pump is centrifugal, so it does not interfere with the water flow when the main pressurized  system is engaged, although that is only used as a backup to supply water to the coil.

The main thing here is that even 45 lbs of pressure could create a mess hooked to one of those metal barrels according to some of the previous information in this thread, even if it didn't blow sky high and kill you.

I documented some of the development  here  if you are interested in more information on my system.

Hi Bob

I looked at your website and wondered:  Why do you have to lift the barrel?  It is maybe a dumb question, but I only started to do any reading on rocket stoves.  I had been wondering,also, whether having a rocket stove was just a "funky" thing that you had to do to claim that you are a follower of permaculture...being a member of the "Woodstock" generation {or a my kids would say:  Alive when dinosaurs still roamed the earth} I seen my share of "funkiness" during the '60's and '70's

However...

...then I found this excerpt from an article written in greenenergyexperimenter.com that seems to explain it all about rocket stoves:

"If you want to heat your indoor air, regardless of the type of stove, you are going to have to burn a lot of wood. So where do people get the idea that rocket stoves are miserly on wood consumption? The answer is in the rocket mass heater. Instead of heating air, they focus on heating your personal space. People who use them dress warmer and maintain a much lower temperature differential. With a blanket over you, sitting on a bench that doubles as the thermal battery, it doesn’t take much energy to keep warm at all. Kind of how a heating blanket can keep you warmer with 130 watts than a 1500 watt space heater can."

According to a post on richsoil.com, you don't have to be wrapped in a blanket, either.  You just have to pull up a desk near the "thermal battery" bench.  For upper-body warmth you create a Paul Wheaton heat bubble using a 40-watt incandescent bulb inside a chicken brooder fixture, a heated computer mouse, and a heated keyboard...an easy load even for a strictly solar system.

Save on petroleum...save on coal...save the planet.  Maybe it is the Woodstock thing with "free association", but I can't help thinking: Save a tree....and give everybody in the household a bucket and a rag.  

Anyway...what I noticed that you use the barrel to transfer heat to your hot water system by wrapping a length of copper tubing around it.

Doesn't that detract from the "heat bubble" effect, by diverting heat meant for your personal space and instead heating water with it.  If your rocket stove can burn and produce...say...1800 degrees F...then if it is 80% efficient...then you would get an exhaust temperature of around 360 deg F after the barrel and bench.

I don't know...but wouldn't it make more sense to put the coil somewhere on the exhaust to heat the water and use the barrel temperature to create a better "heat bubble"?

As I wrote previously, I am not totally familiar with rocket stove...other than using an internal riser inside the drum instead of an external stack{chimney} to produce draft...just wondering...the result of transferring big industry's use of "pinch analysis" to a permaculture environment...

I had planned a "facelift" on the stove, including cleaning out the ash, and more insulation on the riser- the current barrel has been in place about three years now so it's about due.

Yes, the coil does take heat from the system, and the bench stays remarkably cool, The exhaust is also relatively cool but that heat is going into the radiant floor and my hot showers, so the trade off works in my situation.

Of course this is a retrofit of an existing structure, if I were doing it over I might have just buried the exhaust in the floor and eliminated the water transfer middle man