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[netwerx-r-us]

Anyone have any knowledge around  using a large storage tank tied into a outdoor boiler to store your heat for later ie all night ?been reading a few sites and they claim that the boiler will only work 6-7 hours and then store that heat ? anyone have any experience in this , here is one site http://slatevalleyboilers.com/index_files/Heat_Storage_Tanks.htm

[LittleJohn]

I personally do not use/have a large storage/buffer tank, in my system.  So please take everything I say with a grain of salt. 

Assuming that your stove is correctly sized (BTU rating) you should be able to keep a fire/warm water all night.  When fired correctly evern on COLDEST day (recently -20's, with windchill -60) I was only firing 3 times a day:
 1) Once at night before bed, loader up good
 2) Morning, probably 1/4 to 1/3 full, just to keep bed of coals and to help restart fire
 3) Lunch time, probably 1/3 to 1/2 full, enought to get me to night

Also, how much heat loss in that large storage tank have and since it does store energy (say 200k btu like that article stated) that mean that the first 200k Btu the boiler makes during a burn will go straight toward warming the storage tank back up and not heating the house.  So yes it may be great to have a storage/backup plan you should also think about how it will affect burn/recovery time on boiler.

[slimjim]

Storage tanks on OWB's or any stove for that matter do not create BTU's, they only store them, you can certainly extend the burn times at night but you first must create the BTU's during the day. A good application for storage would be a greenhouse that uses very little heat during the day so more heat can be dumped into the tank, this keeps the boiler running hot in daytime and then those BTU's can be used to supplement at night when there is a huge demand on the system

[fryedaddy]

I haven't tried this because my setup has plenty of storage but I did read an interesting article in Mother Earth News about it.
They were setting their system up based on solar power an built a storage tank on the cheap.

You can source all parts from your local building supply company and build it yourself.

If you're interested I can copy the post tomorrow and post it.

[Scott7m]

Slim is tellin ya where the only advantage is. 

More water does not equal more efficiency.

[ITO]

 I can see this working in a greenhouse like Slim said or maybe if you have the tank in a basement under your living area, for me in a slab home I don't think there would be a good place to put it and outside in winter would seem like you're wasting any advantage.

[hoardac]

Some of those super efficient indoor boilers use a large storage tank, One big burn and then it is done for a few days. My friend has one but they are really expensive he paid 30g installed. So disagreeing with some thoughts there is a benefit to one long burn verses a lot of firings your temps are at maximum efficiency for gassification. You also get the freedom of being able to go away for a few days and your house wont freeze. So initially you will have to shovel the wood in to get the tank up to temp once you are there it will not be as bad next time it cycles. I am in the process of building one and it should be done by middle of march. I do not have a gassifier so I may not have any great efficiency gains but the ability to leave for 3-4 days without worry or bothering someone is worth the cost to me.

[Scott7m]

Batch burn units arent compared to owb though.  A long burn can be most efficient.  I know folks with garns who have spent 25k or more and still fire everyday and sometimes twice in cold weather with 2000 gallons.  One bad thing is if you let it get to cool before you refire then one batch wont bring it back up to temp, so instead of throwing wood in and going on about there day, they have to stick around to throw in another batch. 

With 2000 gallons and 50 degrees worth of drop

16,600 pounds of water.  200 degree down to 150 is 830,000 btu. 

Conventional stove may get 50 percent of btu available, thats being generous

So.  Wood is 8600 btu per pound.  Moisture content pets say is .25. 6450 available btu, a conventional stove may claim half those, so 3225 btu per pound of wood.

It would take 257 pounds of wood to acheive that 830k available btu

With 830k btu your heat loads would look like this.    If your heat load was 69kbtu per hour youd last 12 hour
if it was 34,500 youd go 24 hours.  48 hours on 830k would only be 17000 btu per hour

Soo...  Youve either gotta have far more than 2000 gallons pf storage or this 3-4 days stuff aint gonna happen. 

At 2000 gallons with 50 degree drop, 96 hours would only provide you with 8500 btu per hour

I know there is more heat available than simply 200 down to 150

But once you go below 150 your ability to heat watrr through an exchanger drops significantly as well as performance

[fryedaddy]

I've noticed with my setup once it gets below 150 degrees it takes alot longer to get from say 120-150
than from 150-180.

I'm not sure but I believe when water gets this cold the stove condensates up to 145-150.
Once I reach 150 it takes off.

700 gallons lasts me 12hrs in most cases. If it's below 25 degrees I have to load my box (2) times
per day. My firebox is alot smaller (15cuft) than most, if burns up completely if I allow it to go down to
120 then get it to temp 180.

I should use alot less wood next year because I'm insulating my shop (where it's located).

[Scott7m]

Fryedaddy, where you located?! 

[victor6deep]

All I know is my stove has been recovering way faster at 165-180 vs 150-165.

[netwerx-r-us]

thanks all , very good info to think on , I do heat 2 large greenhouses and I,m leaning towards a solar water heating ( thermosyphon or pump) , but a storage tank in ground to store whats collected during the day and run off at night , i was inquiring about feasibility to tie in to boiler but i think Someone said it , i still have to heat that water to begin with so i don't think there's much advantage there , But a solar system with no moving parts might be a wise investment ,home made on builditsolar,  thanks again

[slimjim]

Netwerx, that is one of those places that it works very well, are you in Dairy country, old milk tanks make great storage tanks, I'd like to talk more about it.

[fryedaddy]

Scott,

I'm in N.C. "Foothills", doesn't get as cold as most of you guy's

 

[fryedaddy]

Netwurx,

FYI, I can gain heat with my solar panels on a 36 degree day, my stove was around 150 degrees with full sun.
I have (6) panels but you would need alot more for greenhouses, plus storage.

If you look around you can find the panels fairly cheap. I'd also look into old cast iron heaters as well. They would
allow you to realize the heat better, depending on the setup, just my belief.