Is there such a thing as to much storage?

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Get Wood

Get Wood

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Nov 23, 2012
83
Flinton Ontario
I am getting ready to build my wood shed which will be connected to the boiler room. I want to decide what storage size before I build the wood shed.

Planning on using the Bio Mass 60 boiler. Heating 6000 sq. ft. 1600 sq. ft. house breezeway garage shop and ice melt. All buildings will be well insulated.

Pressurized storage options are 1000 gal. 1800 gal. 2500 gal. 3600 gal. I have pretty well eliminated the 3600 gal. Because of cost unless it would really make things better.

What would be best for my situation? Room is not a issue.

Thanks
 
Minimum would normally be enough storage to take up as much heat as can be produced by a loaded boiler, which depends on the size of the load of wood and how much heat demand there is in the meantime.

Maximum depends on how long and often the boiler can be tended to have enough output to heat the tank. Also space and heat loss would make a larger tank impractical.

In your situation 500 gallons would definitely not be enough, 12,000 gallons would be too much.

([Edit:] See Noah's reply below for a less flip and more useful answer.)
 
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Hi Marvin,

A comprehensive heat load calculation is definitely the place to start. Once you have this, you can then figure out your lowest usable supply temps as well as flow rates and get a pretty good idea of how much storage you might want/need based on your priorities. IOW, do you want one fire a day at design temp? or one fire a day during avg temps? How fast do you want to be able to recharge storage?
You just cant know these things without knowing the heat load and guessing with expensive hydronics is not worth it for sure.

Is the house in the design phase or is it already built?

Noah
 
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Floydian said:
Hi Marvin,

A comprehensive heat load calculation is definitely the place to start. Once you have this, you can then figure out your lowest usable supply temps as well as flow rates and get a pretty good idea of how much storage you might want/need based on your priorities. IOW, do you want one fire a day at design temp? or one fire a day during avg temps? How fast do you want to be able to recharge storage?
You just cant know these things without knowing the heat load and guessing with expensive hydronics is not worth it for sure.

Is the house in the design phase or is it already built?

Noah
Click to expand...

Nothing is built yet just have plans I am working on. I understand it would be nice to have things figured out before I start this but not sure if I can figure that at this point. All the heat will be in floor heat.

As far as firing times, I am retired and won't have anything else to do but cut wood and take care of a few animals and chickens.

Plans are to get electric and well and wood shed done this year. Shop/barn and boiler room next year and house the next year.
 
Get Wood said:
Planning on using the Bio Mass 60 boiler. Heating 6000 sq. ft. 1600 sq. ft. house breezeway garage shop and ice melt. All buildings will be well insulated.
Click to expand...


Even if well insulated, seeing you are in Canada, that load would seem quite ambitious for a boiler of that size with storage. In order to realize the benefits of storage, ideally you need a boiler capable of outputting several times your heat load otherwise all the boiler output goes to the load and none to storage...
 
Get Wood said:
Nothing is built yet just have plans I am working on. I understand it would be nice to have things figured out before I start this but not sure if I can figure that at this point. All the heat will be in floor heat.
Click to expand...

In that case I would highly recommend that you get an energy consultant involved with your project. They should be able to run your plans through their modeling software and give you a pretty accurate heat load (btus/hr) as well as your annual heat load. With new construction you have the chance to basically pick how much energy you want to use. It sure would be nice knowing this before you build and would represent a tiny portion of your building budget.

How much wood do you want to process now or in the coming years?

I also have to recommend this site http://www.greenbuildingadvisor.com/ . The site is working on some technical issues and is down sometimes but it is worth exploring. This page in particular has links to many aspects of designing and building efficient, durable structures: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-do-everything

Noah
 
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I would suspect the ice melting would present a pretty big heat load. Curious though to read some numbers from anyone who has run them or is melting ice - not something I've read about on here.

EDIT: Also likely a fairly big install number? Glycol loops on their own pumps & HXs?
 
kuribo said:
In order to realize the benefits of storage, ideally you need a boiler capable of outputting several times your heat load otherwise all the boiler output goes to the load and none to storage...
Click to expand...

I don't agree. Given what a small percentage of the year is design temps, I think you can be fine with a boiler that's just big enough (or a tiny touch more) for design days, and lots of storage so that the boiler can store heat the 98% of the time that it's not design days. But sure, if you want to only need to load wood once/twice a day when it's a design day, I guess you could design that way - it just seems like you'll end up with a system that's oversized 98% of the year.

In-floor heat is a good design move. Doing some energy consulting/design/price trade-offs will help to make sure you buy/install enough insulation now (in the design phase) when it's cheapest and most effective, rather than fighting a house that could have been designed/built better, later. $1000 in well-placed insulation can save a lot more than $1000 in the heating system, without even getting into the running cost for 20-50 years...
 
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Boil&Toil said:
I don't agree. ...But sure, if you want to only need to load wood once/twice a day when it's a design day, I guess you could design that way - it just seems like you'll end up with a system that's oversized 98% of the year.
Click to expand...

The design day is the day I want to have storage so I don't have to be loading wood all day long when it's -20F outside....YMMV.
 
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Floydian said:
In that case I would highly recommend that you get an energy consultant involved with your project. They should be able to run your plans through their modeling software and give you a pretty accurate heat load (btus/hr) as well as your annual heat load. With new construction you have the chance to basically pick how much energy you want to use. It sure would be nice knowing this before you build and would represent a tiny portion of your building budget.

How much wood do you want to process now or in the coming years?

I also have to recommend this site http://www.greenbuildingadvisor.com/ . The site is working on some technical issues and is down sometimes but it is worth exploring. This page in particular has links to many aspects of designing and building efficient, durable structures: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-do-everything

Noah
Click to expand...

Thanks Noah,
That is what I was thinking I would have to do. Just wanted to get a rough idea. I can proudly be able to do that by spring before I build the shed. I am in Florida for the winter. We sold our house a year and a half ago and living full time in our RV.
I cut split and stacked over 11 cord last year and will do at least that much this year.
 
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maple1 said:
I would suspect the ice melting would present a pretty big heat load. Curious though to read some numbers from anyone who has run them or is melting ice - not something I've read about on here.

EDIT: Also likely a fairly big install number? Glycol loops on their own pumps & HXs?
Click to expand...


There is a couple threads on here about ice melt. I read every post on here, that is how I spent my winter last year.
In the boiler room and the wood shed ;em
 
I am sizing a system for a future renovation of an old house. One of the things I was surprised to find was that even a small boiler would output a lot of BTUs, way more than I had been considering for storage, if the firebox was filled with hardwoods. The smallest boiler (5 cubic foot firebox) outputs enough BTUs to increase 1000 gallons of storage by 80 or more degrees. If you are considering a big boiler, you should take this into consideration, and perhaps size your storage for one full re-charge from your boiler, from minimum temperature that you can use the heat at to maximum temperature the storage can accommodate.
 
DBoon said:
I am sizing a system for a future renovation of an old house. One of the things I was surprised to find was that even a small boiler would output a lot of BTUs, way more than I had been considering for storage, if the firebox was filled with hardwoods. The smallest boiler (5 cubic foot firebox) outputs enough BTUs to increase 1000 gallons of storage by 80 or more degrees. If you are considering a big boiler, you should take this into consideration, and perhaps size your storage for one full re-charge from your boiler, from minimum temperature that you can use the heat at to maximum temperature the storage can accommodate.
Click to expand...


Thanks
The one I am looking at holds 8 cubic ft.
 
DBoon said:
The smallest boiler (5 cubic foot firebox) outputs enough BTUs to increase 1000 gallons of storage by 80 or more degrees.
Click to expand...


You can't store btu's that are being used to heat the loads. If you insulate well enough, wait long enough, and have a long enough match, you can increase 1000 gallons of storage by 80 or more degrees with that match.....How much the boiler can output is but half of the equation. Storage = boiler output in - heat to loads out....
 
I know of an guy who built a "Garn" himself and made it around 3,000 gallons if I recall. When we were yapping about it he said if he had to do it over he would make the next one even BIGGER.!
He did a darn nice job on his home made Garn too.
 
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I sure wish my 1600 gal were bigger.
 
Since I gather you're not placing the storage in the living space, make sure you insulating it extremely well. Seems that's one of the biggest downfalls of oversized storage...losses as you go above ambient. I know, it's costing me now for a variety of reasons.

I read (elsewhere I think) where someone had done like heaterman mentioned, Super storage. However, they had built in an R value in the 100+ range, if I recall correctly.
 
I'm currently leaning toward some storage in the house and some outside. I want domestic hot water all year, but I don't want a large hot storage tank in the house during the summer. During winter some large, moderately insulated tanks in the basement would be welcome. I suppose a large, mind-bogglingly well-insulated storage tank in the house could work for DHW without cooking the house. Exterior storage would be in the very well insulated boiler barn, and be well insulated itself on top of that.
 
I have an Eko 40 with 1200 gal of storage and there are times when I wished I had a boiler with more output, then I would only have to light one fire a day instead if two. But having said that the 40 still does the job.

Huff
 
I suppose it then comes down to what your goals are for the storage for burn cycle times. How long do you want the storage to last and how long are you willing to spend firing to recharge it? As Noah said, once one has the load calculations it's just a matter of answering those other two questions.
 
heaterman said:
I know of an guy who built a "Garn" himself and made it around 3,000 gallons if I recall. When we were yapping about it he said if he had to do it over he would make the next one even BIGGER.! He did a darn nice job on his home made Garn too.
Click to expand...
So a Garn 3200 in a well insulated building and 2000 gallons of divorced storage is not really that silly!? bypass the divorced storage for the summer if it gets to warm. big btus for quick recovery!
Once upon a time I saw a DIY video on a boiler build looked similar to Garn. I cant seem to find it now.
 
Boil&Toil said:
I'm currently leaning toward some storage in the house and some outside. I want domestic hot water all year, but I don't want a large hot storage tank in the house during the summer. During winter some large, moderately insulated tanks in the basement would be welcome. I suppose a large, mind-bogglingly well-insulated storage tank in the house could work for DHW without cooking the house. Exterior storage would be in the very well insulated boiler barn, and be well insulated itself on top of that.
Click to expand...

My tanks are in my basement. I'm pretty sure I wouldn't have them anywhere else. I burned for all but the two hottest summer months last year. Excess heat in the basement wasn't from storage but rather the flue pipes when burning. Mine hold the heat in and it's nothing elaborate - just a box around them stuffed with insulation. I actually have to crack one end of the box open in the winter because my basement gets a little too cool - it was warmer back before I had storage & was feeding the smoker because, well, I was feeding the smoker all the time. I definitely wouldn't put storage outside for the reason of keeping the house cooler in the summer - you can keep all the heat in the tanks without doing anything mind-boggling.
 
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As mentioned earlier, you need to figure the heat load of your buildings. There are calculators on www.builditsolar.com.
It is an excellent exercise which does not take long.
The other factors are how low can you draw the tank down temperature-wise? And how long do you want to go in between firings during an average winter day.
All that being said, most spit in the wind and take an educated guess.
Yours is big enough that I would run some numbers. Could be an enlightening half hour!
 
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