Storage will . . . and Storage will not . . .

ISeeDeadBTUs said:

I think sometimes newbies think storage will help them save wood. The only way that will happen is if you are using up a bunch of wood while on idle. And then I would want to know where the heat from the idle-burning is going.

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In all fairness, it's not always the newbie's fault. Some dealers oversell the benefits of storage. As to where the heat goes, the answer is up the chimney as unburned wood gas. You'd have to be doing a lot of idling to lose enough heat that way to make a big difference. However, some folks get a boiler that's WAY too big and run it 24/7, idling 75% of the time. That could do it.

When I was brand new to this boiler/storage concept I never really considered the "saving wood" part as it relates to storage. My sole purpose for storage was to run 16 hours per day with no wood burning. That's it....and without storage I certainly could not have accomplished this goal. One benefit may be slightly increased efficiency but overall I did it only for the burn scheduling...

I did storage on my system, was thinking more for convenience, typically gone 12 hrs. during the day. I am fairly new to this stuff, I figured if I didn't install the boiler and storage all at once I would never get the storage in. I am glad I did it but the thing I didn't consider is I have Baseboard for heat delivery. It is standard Baseboard sized for Oil and 180* water, as storage temp goes down it is less efficient for heating the house, when it is cold 0* and below or Windy I need to keep the boiler running more. So this summer I will be swapping the baseboard with the high efficiency so I can run 140-150* water. It will be an easy job. I wish it was something I considered at the get go, my dealer didn't mention it either.

nofossil said:

ISeeDeadBTUs said:

I think sometimes newbies think storage will help them save wood. The only way that will happen is if you are using up a bunch of wood while on idle. And then I would want to know where the heat from the idle-burning is going.

Click to expand...

In all fairness, it's not always the newbie's fault. Some dealers oversell the benefits of storage. As to where the heat goes, the answer is up the chimney as unburned wood gas. You'd have to be doing a lot of idling to lose enough heat that way to make a big difference. However, some folks get a boiler that's WAY too big and run it 24/7, idling 75% of the time. That could do it.

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I certainly don't want to dispute this or any subject that you have stated your opinion on, Nofossil, since you have proven your intelligence is far superior to mine. BUT! When my boiler is idling there is always a small amount of smoke coming out of the chimney indicating a small, smokey fire in the boiler. There is a period when the combustion fan stops and the fire is cooling down and another period of time that the fan starts and for a period of time produces heat at a temperature that is not usable. Last heating season before I had storage on line, my boiler idled alot and I was basically burning 24/7. I am now only having one fire per day (short and hot). The temperature in my basement was a constant 70 degrees last season and this year it is staying at a constant 60 degrees. I feel I was loosing alot of heat up the chimney as well as to the room and I believe I am seeing it in my wood consumption, but as you say, the greatest benefit is being able to light a fire at my convenience.
If only we had a way to use low grade heat. Look at the cooling towers at the power plant and the amount of water that it takes from the Connecticut River to cool Vermont Yankee.

Fred61 said:

I certainly don't want to dispute this or any subject that you have stated your opinion on, Nofossil, since you have proven your intelligence is far superior to mine. BUT! When my boiler is idling there is always a small amount of smoke coming out of the chimney indicating a small, smokey fire in the boiler. There is a period when the combustion fan stops and the fire is cooling down and another period of time that the fan starts and for a period of time produces heat at a temperature that is not usable. Last heating season before I had storage on line, my boiler idled alot and I was basically burning 24/7. I am now only having one fire per day (short and hot). The temperature in my basement was a constant 70 degrees last season and this year it is staying at a constant 60 degrees. I feel I was loosing alot of heat up the chimney as well as to the room and I believe I am seeing it in my wood consumption, but as you say, the greatest benefit is being able to light a fire at my convenience.
If only we had a way to use low grade heat. Look at the cooling towers at the power plant and the amount of water that it takes from the Connecticut River to cool Vermont Yankee.

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There seems to be a commonly held misconception that I know what I'm talking about. Don't believe it. I make this stuff up on the fly.

That having been said, I think we've come to the same conclusion. I don't think in most cases that storage makes a big difference in wood consumption. To the extent that it does, the loss is unburned fuel (smoke) up the chimney. When I added storage, my wood consumption actually went up. Of course, the average temperature in my house went up as well. I burned as efficiently as possible (small, short, hot fires) when I didn't have storage rather than idling a lot.

nofossil said:

Fred61 said:

I certainly don't want to dispute this or any subject that you have stated your opinion on, Nofossil, since you have proven your intelligence is far superior to mine. BUT! When my boiler is idling there is always a small amount of smoke coming out of the chimney indicating a small, smokey fire in the boiler. There is a period when the combustion fan stops and the fire is cooling down and another period of time that the fan starts and for a period of time produces heat at a temperature that is not usable. Last heating season before I had storage on line, my boiler idled alot and I was basically burning 24/7. I am now only having one fire per day (short and hot). The temperature in my basement was a constant 70 degrees last season and this year it is staying at a constant 60 degrees. I feel I was loosing alot of heat up the chimney as well as to the room and I believe I am seeing it in my wood consumption, but as you say, the greatest benefit is being able to light a fire at my convenience.
If only we had a way to use low grade heat. Look at the cooling towers at the power plant and the amount of water that it takes from the Connecticut River to cool Vermont Yankee.

Click to expand...

There seems to be a commonly held misconception that I know what I'm talking about. Don't believe it. I make this stuff up on the fly.

That having been said, I think we've come to the same conclusion. I don't think in most cases that storage makes a big difference in wood consumption. To the extent that it does, the loss is unburned fuel (smoke) up the chimney. When I added storage, my wood consumption actually went up. Of course, the average temperature in my house went up as well. I burned as efficiently as possible (small, short, hot fires) when I didn't have storage rather than idling a lot.

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Yea, I definately was doing it wrong to the extent that I had to attach a drip pan to the outlet in order to stop that black perfume from dripping on my return pipe.
Although it is amazing how much loss there is coming from the smoke pipe, boiler and associated short runs of plumbing between the boiler and storage.

For me,storage gives me flexibility in when and how often/long I burn. Load the GARN in the AM, set the timer for 2 hours and go to work. Have heat for the whole day. Repeat at 6:30PM. Total time spent in GARN shed is under 10 minutes for the day. Or, I can burn two loads in the evening and none in the AM. How storage helps, or doesn't, depends a lot on how your system is designed, the water temps you can use, etc. Wood use is a secondary consideration. If we are just talking about 2-stage furnaces, that is.

Storage may be a wash or a loss unless your boiler's heat exchanger is improved by a different type of fire. To know this some system level measurements would need to be made 1) the sustained peak combustion temperature, 2) the associated flue gas temperature, and 3) the heat transferred to the water. It is that delta T that matters when determining boiler heat transfer efficiency.

Storage as has many benefits such as allowing a hot fire which better for the equipment. In my area the best one is being able to burn during the "shoulder season". Shoulder season is practically all we have; a manually fed wood boiler is useful but not too feasible without the addition of storage. Today's high 50F.

Ok I have a long list of what storage will do, let me burn when I want, let me rest when I want, let me burn cleaner as I can eliminate idling etc, etc all of which I see as being to my advantage. Makes me

So lets start a list of what storage will not do. Mow my grass, shovel the snow, load the boiler....anything else that would make me or have I about covered it all????

Thermal storage CAN do alot of things... whether it actually does it or not is a different story. As with everything else that is discussed on this forum, there are a multitude of variables that come into play. The three biggest that effect wood usage are transmission losses, standby losses, and thermal and combustion efficiency of the boiler during a burn.

Transmission and standby losses are pretty straight forward... losing heat through the tanks and piping either outdoors, in the ground, or even into an area of the home that is warmer than it needs to be, and you will net an increase in wood consumption.

The efficiency of the wood boiler under various operating conditions is not always the easiest to wrap your head around, and can have alot to do with how the controls are set up. There is no doubt that thermal storage will increase the overal combustion efficiency of a downdraft gasifier over the entire course of a burn. By keeping the coals and refractory hot until the fuel load is completely consumed we can prevent wood gas from escaping the burn chamber unburned. This, however, can come at the expense of pushing a tremendous number of CFM through the boiler and out the stack at high fan speeds, which can ultimately reduce thermal efficiency. On some boilers, what you gain in combustion efficiency will be lost in thermal efficiency. By turning the primary air down, you can increase the thermal efficiency of the unit, but perhaps at the cost of some combustion efficiency and of course diminished output. This can be a difficult balance to find unless you are using lambda sensors and stack temp sensors to constantly monitor and adjust air flows during a burn... these types of wood boilers are where you will see a definite decrease in wood usage compared to a standard downdraft gasifier when applying thermal storage. That having been said, most of the gasifiers out there do a fairly decent job with static air settings.

Thermal storage can be your best friend... extending cycle times between fires, keeping your boiler and chimney clean, and even reduce wood consumption depending on the boiler. Generally, I would say that thermal storage will net you a small decrease in wood usage on most wood gasifiers providing standby and transmission losses are kept inside the structure, though this decrease could be so small as to be held inside the margin of error given all the variables we deal with in heating with wood.

cheers

System Dynamics! Thermal Storage Can net fairly large gains. Not so much with the realy cold weather, but.. in the spring and fall. There are many advantages to having thermal storage as is being discussed. I think the most important advantage is clean exhaust values at times of lower heat demand. In the spring and fall, one realizes why a properly set up thermal storage system is so awesome! Rather than maintaining a smoldering fire 24-7 to keep the house comfortable a fire once in 2-3 days does the trick. This is where the addition of a solar thermal array is the iceing on the cake!

Yep, Jimbo you are correct, storage is not likely going to help him.

As far as any reply to his message, I did not see anyone who encourage that idea. I told him to look at his load, to see why he is burning what he thought was too much.

I would think you could help him with your experience with the boiler design and living fairly close to his area. You might have scared him off with that comment about his wife.

didnt scare me off on the wife comment More affected by the guy taking my WOOD!
Thermal loss from boiler to house and back to boiler is 2.5 to 3 degrees with no load,Its 150 ft each way so a total of 300 ft.. Jim has been willing to stop and take a look at the set up just havent been able to make schedules meet sorta say... I do understand that keeping the house a few degrees warmer does cost me in wood,but I dont think 73 is way outa line,when others are heating multiple buildings,and DHW on less wood. Just keeps me scratching my head more than anything else.

How many gallons per minute at 2.5 to 3 degrees delta t? use this to calculate total heatloss in the ground. 10 gallons per minute at 3 degrees is about 15,000 Btu's per hour. Then compare that to the heat loss of your structure as a percentage to see how much wood it's costing you. You could be losing 1/3 of your heat into the ground, though it doesn't sound like you're outside the normal parameters of acceptable underground heat loss on a decent outdoor install 150 ft from the house.


cheers

Deere10 said:

didnt scare me off on the wife comment More affected by the guy taking my WOOD!
Thermal loss from boiler to house and back to boiler is 2.5 to 3 degrees with no load,Its 150 ft each way so a total of 300 ft.. Jim has been willing to stop and take a look at the set up just havent been able to make schedules meet sorta say... I do understand that keeping the house a few degrees warmer does cost me in wood,but I dont think 73 is way outa line,when others are heating multiple buildings,and DHW on less wood. Just keeps me scratching my head more than anything else.

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That is alot of btu's going into the ground. With that said depending on if your storage is in the house that will help. If you have the storage in the house you can run the boiler hard and then with the storage it will not be lost in the transmision back and forth to the boiler. If the storage is with the boiler you might be lossing alot pumping it back and forth. One way to help with the heat loss is to keep your water temp as low as you can and maintain your house temp. That will lesson the difference between the pipes and the ground.
Alot of people are having the same problem. The only solution I know of is to put in piping with sprayfoam properly. Expensive I know but been there done that. Spray foam is the best way I have seen or heard of to insulate your lines. Most other ways make good snow melt systems. There has been millions of dollars spent on plastic pipe with foil-bubble-foil wrap, dead air space, plastic foam, open cell foam, i/2 in filled foam and who knows what other stuff and i haven't seen anything that works better than spray foam over and under, between 3in thick.
leaddog

Frozen Canuck said:

Ok I have a long list of what storage will do, let me burn when I want, let me rest when I want, let me burn cleaner as I can eliminate idling etc, etc all of which I see as being to my advantage. Makes me

So lets start a list of what storage will not do. Mow my grass, shovel the snow, load the boiler....anything else that would make me or have I about covered it all????

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Looks like what your storage cant do, your wife can.

I bought the best insulated pex my supplier could find at 14.76 a ft. and 3 ft. down. I have 2 degree heat loss at 120 ft. from the house and my inside thermostat is another 20' inside the house. The only thing else I can do is put a foot of snow over it when I plow my driveway. I leave the snow above where the pex is in the ground. I didn't have snow melt above where the pex is but I swear it helped. What else can a guy do. I don't like loosing 15k btu's per hr. That's half my heat load most days. I love the idea of putting it in the basement but I must have seen 15 thousand Asian beetles on my wood this winter and would be everywhere.

Based on experience to date (building storage but... alas... not yet quite on-line) I'd say that not only will storage allow more efficiency through mimimization of idling, it'll also let you do a more concentrated/long-lasting intense burn with a big bed of coals.

Without storage, on cold days, I can run my unit in "full tilt boogie burn" for extended times- with a continuous big bed of coals and a big flame in the secondary chamber; on more moderate days, I feed it a more gradual diet of wood in order to avoid making the house _too warm_- but in the latter case, it's harder to keep a big bed of coals and a roaring flame, and I notice that the heat yield per unit wood is noticeably less.

Storage isn't going to be a panacea, but it will be a welcome improvement to the overall system.

I have zero snow melt where the pex is. Wish I would have found the site before I did my pex run and I would have used the spray foam( a buddy of mine does it as a side project).Went down over 4 ft used #1 stone first and then 8inches of sand,put the pex in then covered w another 8 in of sand to help w any water.The pex I used was what CB markets. I know people w OWB and I can see the snow melt right over their line. So I feel content w the underground install.Got some logs dropped off yesterday gonna try n post them to see what others think.

Being a slow learner, or to jump on the political boob of the moment, a fire retardant, it took 'til this 3rd burning season to "tune" my burn with storage and I'm now learning to "tune" stack temp with burn and storage. Although I have not yet collected data to verify the stack temp experience, I believe that 1) storage can make the burns more efficient, although for the same plus a little different reason than mentioned, and 2) adding a few temperature meters and data logging with charting has the potential to really improve on (1).

I think 3 temperature meters/gauges (preferably digital) will do the trick: one at a point about at the bottom 1/3 of the storage tank, a second at the bottom of the storage tank, and a third to measure stack temp. If you have less than 1000 gal of storage, might put one meter at the 1/2 point rather than bottom 1/3 point. These can be done with mechanical thermometers, but a bright digital display is barely more expensive and you can see everything in the same place and at a glance. More gauges might help and certainly make everything more interesting if they randomly blink in different colors, especially for the disinterested significant other who would rather do something mundane like read a book to increase one's intellectual prowess.

I use pressurized storage, and you may have to adjust the numbers a bit if you use an hx and experience somewhat lower temps. The two tank meters at a glance will tell you the status of tank charging and let you know whether you should add more wood or let the current load burn to finish in order to fully charge storage. When the meter at the bottom 1/3 starts to move up, say above 160F, the bottom meter likely will still read quite low, but you know it won't take too many more btu's to charge to near capacity. Probably should not add any more wood, or if you have a full load burning with little demand, you may have more btu's than your storage can accept. The bottom meter instantly reports total tank charge status, but as the bottom may cool quickly, the meter at the bottom 1/3 may give a more accurate tank charge status.

The digital stack temp meter really gives you a good picture of your burn. The benefit here is that you can easily tune down or accelerate your burn to meet demand or to instead focus on burn btu transfer to water efficiency. For example, I have learned that at about 465-480F stack temp the Tarm is putting out about 80-90% of rated capacity. At stack temp of about 515F I'm getting about 100% of rated capacity. At stack temp of about 400F, I'm still getting good gasification but output is much less, burn is longer. I use the chain turbulators, so these numbers likely will change if no or other turbulators. All of this on the Tarm is controlled mostly by draft fan speed. Oops! - need to also consider a speed control on the draft fan; I'm working on an automatic one but a manual one works pretty good also.

Based on demand/need, by slowing the burn down and still maintaining good gasification, I believe you will increase total burn efficiency and maximize btu transfer to water as a result of fewer btu's going up the chimney. At some point I may focus on trying to measure this, but there really are a lot of variables at work here.

Data logging and charting adds the ability to see performance over a time period without staring at the meters for hours on end, which really is quite entertaining because the brain is moved into numbed oblivion, an altered state that some use other means to achieve. The chart verifies observations and puts them into perspective.

There any many ways to accomplish this. Look at the Data Logger thread to get some ideas. For me, since I had a laptop PC with a program to format collected data, total cost, including a box in which to mount everything, was about $155.

Jim, i am not familiar with a tarm's internal hx/ transfer to water setup, when you mention flue temps/ to rated output, isn't the flue temp dependant in part on the to the water temp the hx tubes are seeing, for example given the same process gas temp entering the hx tubes, with cooler water the tubes wil shed more heat , resulting in a lower flue temp and a higher combustion effiency calc. If the entering water temp is higher the hx tubes shed less heat and show higher flue temp and a lower combustion effiency, even though the boiler is delivering the same process gas temp ,ie same fire size to the hx tubes the flue temp will differ, creating a different rated output. I am not sure flue temp alone is a indicator of rated output. My experience is with a garn, i can watch with the same secondary burn temp[process gastemp] that with starting water temp of 140 , my flue will be 265, high effiency calc, as the boiler water temp rises to 200, my flue temp will top off at 300. Basically for me a lower flue temp = higher effiency for the same output. i know you have some thoughts!

I use to use a lot more wood than I do now. It took me several seasons to learn how to run my boiler with out storage more efficiently. Loading times vrs boiler temp outdoor temp and wood species takes a while to get the hang of. i have no real data other than I know my house is warmer and I use less wood now because I am smarter than I used to be about how to load on a regular basis. i would add storage if I had the space,time and money, but I don't. I need the space for the beer storage fridge. There is another newbie thread going on here right now about what to buy and I am cheap. I suggested a good old used tarm was a good start, but if he has the dough, go for the caddilac.