Economical thermal storage tank

[bmblank]

If you're fine with unpressurized, you could go with something like a heavy duty 55 gal. drum. You just need to make up some copper coils to drop into them. You will need circulators, but Tarm has some pretty good schematics for a three way valve system for unpressurized storage.

 

[woodsmaster]

If you're fine with unpressurized, you could go with something like a heavy duty 55 gal. drum. You just need to make up some copper coils to drop into them. You will need circulators, but Tarm has some pretty good schematics for a three way valve system for unpressurized storage.

55 gallons wouldn't be worth messing with in my opinion. 250 gallon would be the minimum I'd install, and that would be pushing it.

 

[bmblank]

Multiple drums can increase capacity.

 

[woodsmaster]

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Multiple drums can increase capacity.

that makes for a lot of tanks, fittings, exchangers, and harder to insulate. I'd just build a tank if i were going unpressurized.

 

[Carl Webber]

From talking with "NE Wood Burner" i think i have found a place where i can buy tanks, i have called the guy and given him the dimensions i can work with. Hopefully he can find me 2 tanks that will work for me that are at least 200 gallons each. I'm hoping for 250.

Now for my next big question. With pressurized storage do you need an expansion tank other than the one that normally hangs above the boiler? If so, how large of an expansion tank would i need with 500 gallons of pressurized storage? Can anyone possibly explain to me how to calculate this so i will know for the future.

 

[hobbyheater]

I don't know if you considered building your own soft tank? These are the plans from the Jetstream manual . It has been recommended to use stainless steel fasteners , pressure treated lumber ,and buy your liner from Tom http://www.americansolartechnics.com/.
Big cost of this setup , copper coils and the liner .

 

[Carl Webber]

I looked at building my own unpressurized storage tank and it really seems to me like it is more cost effective to go with the pressurized storage and use old propane tanks. If i use old propane tanks. it seems like i can get them for the cost of about 50 cents per gallon. For 500 gallons of storage it will cost me $250. The rest is just labor. The welding of fittings on the tank i can do for free, no copper coils needed, from what i can tell they are really efficient. It seems to me like the old propane tank idea is the most economical for me and right now every cent counts.

 

[woodsmaster]

Yes you will need a bigger expansion tank for pressurized storage. You can make one, but a bladder tank seems to be better if you can afford it. If I remember right you need a tank about 11% of total volume if you make your own,so if you have 550 gallon, you need a 60 gallon tank. A bladder tank is the biggest expense of pressurized storage when using propane tanks for the storage.

 

[NE WOOD BURNER]

A bladder tank is the biggest expense of pressurized storage when using propane tanks for the storage

you can find these used easy enough. Or just use another smaller tank, much discussion here about that.
Eventually you will be replacing the older boiler with a newer gasser and the correct tank set up will pay dividends when that happens.
I would run it this year with out storage and save your pennies for more storage and a new gasser.

 

[velvetfoot]

I was going to use these thermal tank plans to build a pellet storage bin; still might, but am leaning towards bulk bag delivery since I already bought the stuff.
Anyway, I digress. Here's the link: http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Construction.htm I think the fellow who runs the site is also a contributor here.

 

[woodsmaster]

A pic of my homemade exp. tank made from a 125 propane tank. These have a built in float gauge that makes it easy to monitor the amount of water in the tank. Sorry pic is sideways, I rotated it and it still loaded sideways... ?

 

[ElkRiverFJ]

A pic of my homemade exp. tank

LOL, I see you refuse to let go of the factory supplied Biomass fire stoker...mines not quite that bent yet.

 

[Bob Rohr]

View attachment 138892 A pic of my homemade exp. tank made from a 125 propane tank. These have a built in float gauge that makes it easy to monitor the amount of water in the tank. Sorry pic is sideways, I rotated it and it still loaded sideways... ?

Nice re-purpose of that tank for expansion. Keep an eye on your pressure when you fire it up and run to 180- 190° or so. I think you may be a tad small on that expansion size.

Using the Wessel online calc sheet, www.wessel.com, click on expansion sizer. I plugged in 1100 gallons, water, 60- 190° temperature 12-28 psi pressure. It shows 170 gallons for a tank like that.

Not sure what your entire system volume is?

The relief valve will start to seep as you approach discharge pressure, be sure it's discharge is piped down to the floor. If you ever over-heat and flash to steam, the discharge from a relief valve will be quite an eye opener

 

[Carl Webber]

ok, since someone suggested it i have to ask the question. With an old boiler like mine that is not a gasser (Tarm-OT50), can you successfully run them without storage? Its a little late in the season, but i wasn't able to find the boiler i wanted and could afford until now. So, i'm using as much dry wood as i can, but i think i'm going to have some semi seasoned wood in the back of my pile. I have a fan and a dehumidifier running so i think it will dry quite a bit by the time i use it, but all the same it will not be perfectly dry wood. If i have storage i can run the boiler wide open and all the extra heat will go to storage. If I don't have storage, it will make the buildup of creosote much more likely. Can i really run this boiler successfully for a year or two without storage? It does have oil backup so i could always run it during the day as long as i can tend it and then throw in a few sticks before i go to bed and then let the oil kick in when that runs out and start it all over again when i get up in the morning. I'm a little new to the wood boiler thing. I only have experience with a wood stove or a fireplace, and both of those need frequent tending. My main worry is overheating the boiler or having a chimney fire from creosote. If it is possible to run this without storage, can someone give me a few pointers.

 

[maple1]

That's the way it was built to run, so yes. It's just that it would run much better if storage were added.

Just make sure it is installed right (overheat protection, adequate expansion, pressure relief, etc.) - standard boiler install stuff.

Get a thorough understanding of maintenance requirements and stay on top of them. Watch your chimney closely.

If you re-split as much wood as you have space for, and loosely stack it in the area of the boiler, and maybe also set up a box fan on low speed blowing into the bottom of the pile during teh daytime, you can dry the wood a lot more before you burn it. A small electric splitter is handy for that operation. You can rotate that wood during the winter as burning & space permits.

There are quite a few on here who have gone that route - burned without storage until they could add it later.

 

[Bob Rohr]

ok, since someone suggested it i have to ask the question. With an old boiler like mine that is not a gasser (Tarm-OT50), can you successfully run them without storage? Its a little late in the season, but i wasn't able to find the boiler i wanted and could afford until now. So, i'm using as much dry wood as i can, but i think i'm going to have some semi seasoned wood in the back of my pile. I have a fan and a dehumidifier running so i think it will dry quite a bit by the time i use it, but all the same it will not be perfectly dry wood. If i have storage i can run the boiler wide open and all the extra heat will go to storage. If I don't have storage, it will make the buildup of creosote much more likely. Can i really run this boiler successfully for a year or two without storage? It does have oil backup so i could always run it during the day as long as i can tend it and then throw in a few sticks before i go to bed and then let the oil kick in when that runs out and start it all over again when i get up in the morning. I'm a little new to the wood boiler thing. I only have experience with a wood stove or a fireplace, and both of those need frequent tending. My main worry is overheating the boiler or having a chimney fire from creosote. If it is possible to run this without storage, can someone give me a few pointers.

Sure, storage just makes the boiler more operator friendly. It give you some non-burn energy storage, and some over-flow parking space should you over-fire.

Owner get the hang of adjusting the burn and loading to match the weather conditions and building load. It comes down to how much time you have to "tend" the system.

I ran my EKO 40 with just an 80 gallon buffer last year, until I get my 500 gallon better insulated. I used less wood with just the 80, compared to previous years with poorly insulated 500 gallons. It just took more trips to the boiler room to feed the fire at the correct rate.

 

[maple1]

I'll add a bit of my 'pre-storage' experience.

That involved using a very inefficient wood/oil boiler, which compounded the issues. But when it was any kind of cold out at all, I had to tend the fire every 2 hours in the day time, stay up way later at night than I wanted to to get that last load of wood in it, get up earlier than I wanted to to get the fire going again, chase periodic coal buildup that I had to empty out to get my firebox space back (which meant dumping unburned coals that still had BTU value to them), and clean my chimney and stove pipe of creosote at least 4 times per winter (the stove pipe more frequently but easier to do).

All of that is now history. Plus I plan to never have to go up on my two storey slippery steel roof again.

I did keep us (mostly) warm during all those years, but I was seriously wearing myself down doing it.

 

[hobbyheater]

I have run two none gasification boilers without storage . The biggest challenge or concern is creosote in the chimney , because the firebox walls of the boiler are surrounded by water this makes for a lower temperature burn and more creosote when compared to a conventional stove with firebrick lined sides which give a little hotter and cleaner burn. So when your boiler goes into standby mode when there is no demand for hot water this creosote issue gets even worse . The second convention boiler when I added storage the creosote problem became a nightmare , the return water could be as low as 90 degrees .With storage boiler return water protection is needed .
If your wood is not under 20% moisture content you will have creosote issues with or without storage .Buy a cheap moisture meter its the only way to know the moisture content of what your burning.

 

[NE WOOD BURNER]

If your wood is not under 20% moisture content you will have creosote issues with or without storage .Buy a cheap moisture meter its the only way to know the moisture content of what your burnin

This has been the much of the problem with many unhappy wood burners I have met and helped over the years! Admitting the issue is the first step for many.

 

[woodsmaster]

I've run my system for 3 years now with no problems. I have around 1100 gallons. I wouldn't go with any smaller tank than what I have though.

Edit: I usually gain 10 psi when I fire, mabey 13 if i let the temp get real low like 110 F then bring it all the way to 190 / 195. My water never gets lower than 100 F. on average. I burn year around for DHW

 

[woodsmaster]

LOL, I see you refuse to let go of the factory supplied Biomass fire stoker...mines not quite that bent yet.

LOL, I'm over due for a better one...

 

[Carl Webber]

Ok, thanks guys. This has helped me a lot. I really want some storage, but money doesn't really allow for it now unless i want to do it really cheap and maybe have problems later. I think i would rather just install the boiler the way it is and run it without storage for a couple years until i save enough to buy the right storage and install it properly.

I know you guys said it takes a lot of tending and staying up late and getting up early to keep things going properly. Because my boiler is a wood/oil combo, does anybody see any problem with me staying up late as i can, or getting up early as i can and taking care of the fire as much as possible, but if it happens that that is not enough, letting the oil kick in overnight sometimes? I don't mind burning a little oil just to make things more convenient for now until i get storage.

 

[maple1]

Nothing wrong with that, just that you'll have to pay for the oil.

Mine did that once in a while too - I was just too stubborn to not do all I could to avoid it. The sound of the burner kicking in was like nails on a chalk board to me. Actually, sometimes when it was real cold out, the oil and wood were burning at the same time if my wood wouldn't catch up on its own.

 

[Bob Rohr]

Ok, thanks guys. This has helped me a lot. I really want some storage, but money doesn't really allow for it now unless i want to do it really cheap and maybe have problems later. I think i would rather just install the boiler the way it is and run it without storage for a couple years until i save enough to buy the right storage and install it properly.

I know you guys said it takes a lot of tending and staying up late and getting up early to keep things going properly. Because my boiler is a wood/oil combo, does anybody see any problem with me staying up late as i can, or getting up early as i can and taking care of the fire as much as possible, but if it happens that that is not enough, letting the oil kick in overnight sometimes? I don't mind burning a little oil just to make things more convenient for now until i get storage.

It's really all weather dependent, no two systems heat, or need the same amount of tending. As long as you are aware of the problems with idle mode of over-firing, give it a try. I ran mine several seasons until the right tank came along. No doubt it used some LP, but I agree wait until you have the $$ to do the storage properly.

 

[NE WOOD BURNER]

Is your wood supply dry for this year?