strange idea to use water filled barrels

[Wood Duck]

I think it is fairly common to use barrels of water in greenhouses to collect heat during the day and give it back during the night. I have heard of this idea enough times that it must work at least to a degree. i don't see why a similar idea wouldn't work for wood stoves, except that it seems pretty awkward to have barrels of water in the room with the stove. Also, although I am sure it would help, I don't know how much it would help - maybe not enough to be worth it. If I was designing a setup like this, I'd want an oversized stove so I could get extra heat out of it when I needed to warm both the barrels and the rest of the house after a cold night.

 

[KeepItNatural]

You know what, I've actually wondered the same thing before about using water to store heat.
The idea I had was to fill metal buckets with medium sized round stones and water and heat them on a stove until the water came to a slight boil, and then move them to different areas of the house to release the heat- but... That's alot of running around and my mom and girlfriend would probably think I'm nuts (for good reason).
The idea of the barrels full of water is and interesting idea... I say, what the heck, go ahead and give it a shot- it might look a little funky- but you can always put a table cloth or something on it- I'm not really sure what you could do, but if it works, it works and you can get creative later.

I might add that on this site in the gassifier forums some of the people talk about hot water storage tanks... might be worth it to jump over there and see what them guys have to say. MAYBE there's some wacky set up none of us have thought about that those guys use on a regular basis which could help.

 

[Sleepy]

The application probably won't work well, but the idea is sound. This is the idea behind modern wood-fired boiler systems.

The challenge with the drum idea is figuring out how to get them to absorb enough heat energy to heat the area they are in with a simple wood stove. The rate of heat given off will be dependent on the temperature difference between the drum and the surrounding air.

It takes one BTU to raise one pound of water one degree. A gallon weighs slightly over 8 pounds. 55 gallons needs to absorb 440 BTUs for each degree of rise and gives off 440 BTUs for each degree of fall. A small sunroom will have a heatloss of around 15,000 BTUs per hour on a cold day (there are variables here). Let's say you had four drums or 220 gallons. Each degree of temperature fall will produce 1760 BTUs. This means you need to drop 8-9 degrees per hour to heat the room. This may be possible if you could get the water very hot to start with.

This is the idea behind gasifier boilers and large water storage. You fire your boiler once a day as hot as it will run, and heat 1000 gallons or more 80+ degrees. The boiler runs very clean. You need some sort of convector to get the heat into the indoor air like baseboard fin tube or a fan, water coil, and duct system.
Heating 1000 gallons (8350 lbs) from 100 to 180 degrees takes 668,000 BTUs. Cooling that water back to 100 degrees will heat an average house in my area for 10-12 hours in very cold weather. If that is not enough, you add water storage. Very clean and efficient way to heat with wood.

 

[ttamoneypit]

woodstove is in the lower level of my bi level or raised ranch (not sure what to call it) so barrels would not be an eye sore and they would sit on cement floor

my house is small about 1600 sq ft and having a fire going for about 3-4 hrs when its 15deg outside has my house at about 74 degrees

last electric bill was $122 thats with using mainly electric heat and randomly using the wood stove--maybe 3-4 days a week

but I'm sure those electric rates are going up up up soon

 

[tickbitty]

I knew some folks who had large, clear plexi tubes (held perhaps 50 gallons or more) standing in the corners of their screened-in porch. They had a little food coloring in the water, like blue or something. These held heat from the day and heated the porch a bit on cool evenings. Or that was the idea, anyway. I suppose it worked.

 

[Cire3]

Ok, can't say I haven't thought of this idea as well.... Just a twist.

I have the Regency F2400, I posted about using different material for the top baffle "this is OE firebrick". I want to use stainless steel above the pipes. Reason being I want that extra 3/4 inch to run copper tube in the area just before the stack. I already have a centrifugal pump and heater core. Plastic high temp line and foam to insulate the pipe outside the box.

Have I fully though about this ? I think so and I don't see why it wouldn't work. First off it's a open system, I'm not looking to make a bomb When you add pressure temps and boiling point drop "worked on cars in a dealer for 13 years" So why not try to pump some heat to another point of the house ? I'm going to start small and work my way out. And yes for safety I'm going to install blow off's just in case for some reason the pump stopped or some how the pipe plugged.

This is taking the heat just before it takes off outside anyway, and some off the baffle. What will I have to look for ? I'm sure more black crap in my pipe, but how much and will it pay off ? EPA stove shouldn't produce that much running well.

This would be followed by a temp switch to turn the pump on only when I have temp in the pipe. Electronics class will pay off yet lol


I have issues and can't leave stuff alone, I will tinker with my new heat . Also running a line for DHW by the stove. I never did understand pumping 32 F well water in a hot water tank to warm. Seems a bit cold before it enters. This will not enter the inside of the stove as I feel it's too cold to place in it and it would sure sweat moisture "something I don't want"

If it doesn't work we can laugh and I will have occupied time not getting myself in real trouble


My2Cents.... All it's worth.

 

['bert]

all i'm reading is a lot of blah, blah, blah......just do it already and take pictures.

OK hold on, let me just check with the wife..................................................


Great now I have to go and pick my stuff up from in front of the house - and I am pretty sure there was a `no F******G way in the somewhere. Maybe some one else should try it, someone who is already single perhaps.

 

[DavidV]

You would probly be better off spending the time and resources on insulation and blockage of airflow.

 

[DanCorcoran]

Grateful,

You said in Tucson, daytime high of 100, nighttime low of 40...that's a swing of 60 degrees. The average of 100 and 40 is 70, the temperature of the water. It was just damping the lows and highs, which is what we expect.

 

[cycloxer]

+1 Just Do It. Report back w/ results.

 

[LLigetfa]

It takes one BTU to raise one pound of water one degree. A gallon weighs slightly over 8 pounds. 55 gallons needs to absorb 440 BTUs for each degree of rise and gives off 440 BTUs for each degree of fall. A small sunroom will have a heatloss of around 15,000 BTUs per hour on a cold day (there are variables here). Let's say you had four drums or 220 gallons. Each degree of temperature fall will produce 1760 BTUs. This means you need to drop 8-9 degrees per hour to heat the room. This may be possible if you could get the water very hot to start with.

Ja, this is the needed math to show how a passive system won't work with such a small quantity of water, but don't let facts get in the way of a good argument.

 

[Battenkiller]

Way, way back in my hippie days, I bought a book called "Low Cost Energy Efficient Housing". Still have it after all these years. It began my quest for the dream home - off the grid, passive solar heat, high insulation factor, etc. About that time, I began to think of welding monolithic water-filled metal "sculptures" that would sit in south facing windows in order to capture solar energy and then release it into the house at night.

Two 1'D x 3'W x 5'H water-filled steel storage tanks would contain 30 cu.ft. of water (four 55-gallon drums worth) weighing about 1870 pounds. It would take 187,000 BTU to raise the temp of the water in them from 70ºF to 170º. Placed one on each side of a stove whose average output was 30,000 BTU, let's assume that 40% of the radiant heat would be striking the two steel faces, and that 100% of the heat was captured and stored in the water (we would use a pump to circulate the water in the tank instead of relying on convection). Each hour of burn time would them raise the temperature of the water by about 6.4ºF. If we ran the stove for 16 hours, the temp of the water would be raised by 100ºF. Sleepy's sun room would then be able to be retain its heat for about 12 hours without any additional heat from the stove.

This is where those massively oversized stoves might come in handy.


Sleepy..... please check my math.


With some sort of decorative top plate (maybe a 500-pound granite slab), this could be made to look very attractive to the wife. It might even make a splendid VD gift instead of the same old candy and flowers. ;-)

 

[LLigetfa]

I think you guys are overly optimistic about how much heat you can trasfer to a barrel of water simply sitting beside a stove. I encourage anyone with enough curiosity to take a metal 5 gallon pail filled with water and set it beside the stove to see how hot you can make it. Also, take your largest pot filled with water and put it on top of your stove and see if you can make it boil.

 

[midwestcoast]

I agree that any thermal mass would even out the heat delivery some & the math on the performance has been provided already; The problem, as I see it, is that you currently run the stove for a few hours a day. I don't doubt you could heat the water drums with the stove, but my guess is it'd take longer than 2-4 hours to get them very warm, so you'd be getting fairly low temp changes & not a whole lot of heat after the stove cools.
If you want to run the stove for the same amount of time & assuming your stove can provide more heat than required to counteract heat-loss from the house, I suggest you'd need a system that transfers the heat more quickly to the thermal mass. A radiator or coil near the stove & a pump would do that, but you'd really have to know what you're doing or risk a massive steam explosion. Another (safer) method used in solar heating is blowing hot air through an pit of stones in a basement or crawlspace. The much greater surface area of the stones would pick up heat faster (also release it faster). So how 'bout a few barrels full of rocks, small ducts connectinng theminn series & a fan to pull hot air from the stove & push it through them. Once the stove cools the fan keeps blowing, & the rocks warm the air on the way through.
Hey if 55 gal drums don't bother you, what's wrong with 55 gal drums with a bunch of 4' ducts hanging off'em?

 

[pybyr]

Storing heat in water will work, at least in a greenhouse but to heat a home would probably take a full basement of it.

Come over to the Hearth.com boiler room where lots of people use water in insulated tanks as heat storage; 500-1000 gallons can store a LOT of heat if you get it up near 200F.

 

[gibson]

Do you mean the hot water bottle in the sleeping bag trick?

 

[Birdman1]

You might want to build an Ark in the living room if you use plastic drums and they get a little too hot.
Just sayn'

 

[Cire3]

I don't see me pulling that off with my EPA stove.... Now the dragon I just sold would have been a completely different story. Although it would kill some wood. I think you can do better storing the heat rather than the loss into the air. Any way to capture it in a usable form of stored heat with slow release I would assume would work. Yes the word "assume" is in there on purpose.

Now I'm upset I sold my Kodiak so fast. I would have tried this in a heart beat. I do have one weapon on my side.... FREE WOOD

 

[Backwoods Savage]

Storing heat in water will work, at least in a greenhouse but to heat a home would probably take a full basement of it.

Come over to the Hearth.com boiler room where lots of people use water in insulated tanks as heat storage; 500-1000 gallons can store a LOT of heat if you get it up near 200F.

Thank you for the invitation, but even that amount of water at only 200 degrees is minimal. Sure, it will help but there is only so much space a 200 degree tank would heat. In addition to that, how many btu's does it take to raise water temperature from 50-60 degrees to 200 degrees. Might those same btu's simply heat the air space to begin with?

With the talk about water being used in a greenhouse, most that I've talked to only want to keep the temperature above the freezing point at night. So even if they keep the temperature at 50 degrees, that would make for a very cold home.

I recall seeing plans for a new house with the entire basement holding this huge water tank with several thousand gallons of water and the theory was to help warm in winter and cool in summer. It looked like a nightmare to me but I do suppose it would help; not do the job entirely, but assist which is worth something.

 

[Battenkiller]

Thank you for the invitation, but even that amount of water at only 200 degrees is minimal. Sure, it will help but there is only so much space a 200 degree tank would heat. In addition to that, how many btu's does it take to raise water temperature from 50-60 degrees to 200 degrees. Might those same btu's simply heat the air space to begin with?

1000 gallons of water at 200ºF, by dropping to 70º, will release 1,085,500 BTU into the surrounding space anywhere in the universe. That's not minimal at all. In fact, it's the same amount of energy produced by burning wood at a constant output of 80,000 BTU for 13.5 hours. I keep reading about all these feast or famine stories, where folks are hitting 86º in the day and then waking up cold. If your stove can barely keep up at the coldest times, sure... you won't get any net gain at all. You'll actual be colder because some of the energy from the stove will be warming the water instead of your surroundings. But if you have a huge stove that produces an excess of heat at certain times of the day, why not capture a portion of it and use it later on?

The only problem I see is with the method proposed here, using barrels of water placed in the room. Expecting them to be warmed up by room air - which has virtually no heat energy compared to the water it is attempting to warm- will be a pretty frustrating experience. They would need to be right next to the stove in order to gain any significant rise in temperature. Radiant heat is really just high amplitude light being emitted from the stove at a frequency that we can't see. Light energy falls off four times for every doubling of the distance. The barrels, being round, will reflect a lot of the radiant IR energy striking the surface instead of absorbing it. That's why my idea of large flat metal tanks placed right next to the sides of the stove (and the back as well if you wanted to) would be more effective by a huge margin. Of course, all those Jotul owners will then have to load from the front door.

I recall seeing plans for a new house with the entire basement holding this huge water tank with several thousand gallons of water and the theory was to help warm in and cool in summer. It looked like a nightmare to me but I do suppose it would help; not do the job entirely, but assist which is worth something.

I fail to see how that would work without having a heat pump to move the heat in and out of the water as needed. I used to swim in a good sized indoor pool on at a rich guy's horse farm I worked on. The water temp was kept at a constant 70 something degrees, but there was still a need for gas-fired hot air in the pool room. You'd get in there when it was 20 below outside, and you'd have to wait half an hour for the room to get warm enough to disrobe.

Without adding heat to it, a gigantic underwater reservoir beneath a home would eventually reach the same temperature as the surrounding ground, probably in the neighborhood of 55ºF on the average. Cave temps. But even though it would be a bit chilly temperature wise, it would contain a massive amount of heat energy that could be exchanged with a heat pump rather efficiently. Same principle as using ground water for the purpose.

 

[SteveKG]

There was much speculation about using water for heat storage and temp. moderation back in the 70s and early 80s when I was both thinking about and building my cottage. The info' was everywhere, it seemed. Along with buried stores of stones, massive blocks of concrete, etc. Anything that gets heated will later provide heat back into the air around it. Eventually.

So, I knew a number of people who tried the water storage ideas, some of them. None still have the things set up, whatever they were. The results were disappointing, to be blunt. Barrels had stratification which seemed to decrease efficiency [according to those who used them, anyway]. Even painted flat black, they never heated up as much [or even near as much] as calculated. Plus, shorter daylight spells available when the heat is wanted [winter] kept the water from ever getting very warm, so there was never much heat to add back into the greenhouse or room. Plus, the space those barrels took, the physical presence, was unfortunate...lots of lost square footage for living in or growing plants.

One couple up here tried the gallon-milk-jug thing, hundreds of them stacked along a wall in the greenhouse, in full sun [filtered thru the glazing, of course] and filled with black-dyed water. It has been too long for me to remember specifics except to say they eventually got rid of all the jugs and considered it a failure.

I watched all these things and never tried them myself, plus my own place is small and I have limited space to sacrifice.

Reading magazine articles and etc. back then, some experimenters decided that the answer was to have a pump which would stir the water, eliminate stratification. More technology, plumbing, electricity, no longer a passive system. I don't recall those results. Heating the water in storage with wood or whatever fuel would help but the question is would the gain be increased; in other words, one would be hoping to get more BTUs or more usable BTUs from the same fire...begins to make no sense to me. If it requires more fuel to get more storage, is there a net gain.... Well, if one is hoping to spread out the heat available throughout the day and night, then maybe.

But experimenting is fine. My observations of the others around here trying these things is that the problem was getting the water heated up sufficiently to have the heat to put back in the first place. At least, doing so with "free" and hassle-free solar gain. If one must use propane or electricity or wood to heat up the water in storage, well.....

 

[LLigetfa]

...it would contain a massive amount of heat energy that could be exchanged with a heat pump rather efficiently...

A Stirling engine powered by the heat of the wood stove could drive the heat pump. When there is a surplus of heat, it could pump the heat into the store only to reverse and pump heat out of the store when demand increased. The heat pump could also help to redistribute the heat to all areas of the home.

One isssue with passive heat storage is to be able to have enough useful heat that can easily be extracted. Conventional passive radiators need to be large to get lower grade heat out. THe lower the grade of heat, the larger the radiator/store need be. Old homes that had very large central stone hearths gave up as much as a third of the available space to a heat store.

A heat pump can store lower grade heat and also extract lower grade heat than a hot water or steam boiler/radiator system. Heat pumps are always more than 100% efficient and the greater the difference between ambient air and store, the greater the efficiency.

Beside the use of water as a heat store are passive phase change stores. They can store much more heat in the same space but generally require even more complex infrastructure than basic heat pumps. Beyond that are materials that act like a battery to store and release heat through different reactions.

 

[firefighterjake]

from reading about soapstone and how it retains heat and gives it off after the fire dies and I read in a magazine about people using 1 gallon milk jugs painted black in their sunroom/greenhouse to absorb heat during the day and then gives the heat off at night


I think i could fit 3 or 4 water filled 55 gallon drums around my wood burner so is this a crazy idea or could it work out very well for my small house--i just need to figure out how to avoid leaks--maybe plastic barrels would be better but they might melt

I think what we're missing here is that if you are married, ask your wife what she thinks about the idea. In my small house, if my wife had to look over and around three or four 55 gallon drums to watch Wheel of Fortune, me and the barrels would be mighty cold by nightfall.

That was my thinking too Quads . . . whether this would work or not would not matter . . . my wife would quickly nix the idea of bringing in 3-4 water-filled 55 gallon drums in the living room.

 

[Lumber-Jack]

I was measuring the room where my wood stove is and was thinking about the kid's inflatable swimming pool we have stored away,,,, I think if I get rid of all the furniture it just might fit????
:cheese:

 

[ihookem]

I think I have an easier way. Don't use water. Don't take hot water bottles to bed. My dad, back in da 30's used to live in an old farm house with 2 wood stoves and no insulation. Before bed he would take his brick and put it on the stove. After a while he would wrap it in a towel and take it to bed. I have done the same up at our cabin with an old free standing earth stove, except mine is a cast iron frying pan. It gets hot and stays hot for a long time. Don't laugh, It gets down to 0 degrees in that cabin and sometimes I don't get in till 10 pm. I think a guy can just do that , wrap it in a towel, put it under the wifes cold feet and she will have warm feet for a long time. Then you don't have to raise the temp of the whole room. I hope this makes sense.