EDPM Liner and stratification

[Duetech]

Hey Boiler room!
I am new to the storage tank end of boilers and have only had a boiler for two seasons and it sure beats propane dhw and fuel oil heat. Edpm sounds like the liner to have as I am restricted to an open storage tank that will be dyi. Estimated 5'h/5.5-6'dia. Due to height restrictions in my basement (old MI home) the tank will sit 2' deep on a poured slab so only 3' will extend up into the basement area. Any how, where does a person find this edpm liner that is being referred to?
Another question I have is about stratification. Since my tank is non pressurized "Is stratification important to me?" My single coil plan is heat the side arm dhw then my water/ air heatx. then pass on through to supply my storage tank unless I should heat my storage tank first(?). I will have ball valves and a by-pass to manually control water going to my storage tank if the tanks is first in the system to control initial start up but eventually it will be a straight shot into the tank. I have a circ-pump on manual that runs 24-7 and I figured if the tank is last in the system that it would charge whenever there is no call for heat if the tank is last in the circuit before going back to the boiler.
The coil I am building from hard copper so I can design coil flow to control how the water is moved through the tank. Theoretically water will flow in a "vertical up/horizontal out/vertical down/horizontal in" repeated circuit that resembles a large fan blade from the top. I know it's labor intensive but soft copper does not lend itself to "buy this part today and that part next week assembly." Since by design the "coil" will address both upper and lower limits of the tank I am inclined to believe there will be no stratification on any serious degree nor would it be desired. Are there any suggestions out there? Thanks...

 

[WoodNotOil]

Check out my site in my signature for design information and links to suppliers. Stratification is desirable with storage no matter the type. For stratification you will need the ability to move water in either direction through a coil. Hot to top for charging and hot from top for drawing.

 

[Duetech]

Thanks WoodNotOil,
I'm really not understanding the stratification thing.Until I do, changing water direction is foggy to me. Is there a site I can visit that explains the thermal dynamics of stratification? My description was vague but I was trying to say the coil system I would be using will not function as a standard coil. As an example in a 5' w tank the spread will be about 4.5' w in a 5' bath top to bottom the height of the coil will be about 4.5' reaching across and up and down with some element of the coil. Thermal induction would seem to eliminate stratification by mixing and thermal transfer, either in or out, would be a blended compromise of the extremes of the tank. Charging/discharging would be in constant flux as the one pump (secondary) will always be running. During the summer I use the stove to heat my dhw and the primary circ is the only pump controlled by temperature. The temperature of the stove, EKO40, is what controls the burn and the fire in theory would run out of fuel if it could not get the water up to temp. Conversely the stove would idle down to stand by if temp were reached and fuel remained. Stratification via flow reversal looks to do the same thing but requires more bells and whistles.
Thanks for the links you provided to help me get a better grasp of this storage tank and components business. Even if I go another winter with out an expansion tank I am way ahead of the old wood add on furnace I was using and light years ahead on oil and propane. Cave2k

 

[Nofossil]

Whether you have pressurized on non-pressurized storage, you want as much stratification as possible - hottest possible water at the top of the tank. If you can do it, you'd like to introduce heat (or hot water) from the top, so that there's a sharp dividing line between hot and cold that moves down the tank as heat is added. That's why you want top-to-bottom flow when charging the tank.

When discharging, you want the reverse situation - drawing heat from the top of the tank while introducing cold at the bottom.

Think of it this way: A non-stratified tank at 140 degrees has the same amount of energy as a tank that has a layer of 180 degree water in the top half sitting on a layer of 100 degree water in the bottom half. The stratified tank has a LOT of useful stored heat, while the non-stratified tank is close to useless.

 

[sdrobertson]

Whether you have pressurized on non-pressurized storage, you want as much stratification as possible - hottest possible water at the top of the tank. If you can do it, you'd like to introduce heat (or hot water) from the top, so that there's a sharp dividing line between hot and cold that moves down the tank as heat is added. That's why you want top-to-bottom flow when charging the tank.

When discharging, you want the reverse situation - drawing heat from the top of the tank while introducing cold at the bottom.

Think of it this way: A non-stratified tank at 140 degrees has the same amount of energy as a tank that has a layer of 180 degree water in the top half sitting on a layer of 100 degree water in the bottom half. The stratified tank has a LOT of useful stored heat, while the non-stratified tank is close to useless.

The advantage is that at 180 degrees you have to move allot less water to get the BTU's out of the water. Also, its easier to put btu's into 100 degree water as opposed to 140 degree water. It's allot more efficent and that's what your shooting for with storage.

 

[MarcM]

Whether you have pressurized on non-pressurized storage, you want as much stratification as possible - hottest possible water at the top of the tank. If you can do it, you'd like to introduce heat (or hot water) from the top, so that there's a sharp dividing line between hot and cold that moves down the tank as heat is added. That's why you want top-to-bottom flow when charging the tank.

When discharging, you want the reverse situation - drawing heat from the top of the tank while introducing cold at the bottom.

Think of it this way: A non-stratified tank at 140 degrees has the same amount of energy as a tank that has a layer of 180 degree water in the top half sitting on a layer of 100 degree water in the bottom half. The stratified tank has a LOT of useful stored heat, while the non-stratified tank is close to useless.

The advantage is that at 180 degrees you have to move allot less water to get the BTU's out of the water. Also, its easier to put btu's into 100 degree water as opposed to 140 degree water. It's allot more efficent and that's what your shooting for with storage.

Please keep us updated on your wood consumption going from the CB to the Eko.

 

[MrEd]

If its easier to transfer Btu's into cold water, why wouldn't it make sense to pipe the excess heat (after zones are satisfied) into the bottom of the tank, and allow time to stratify the tank?

 

[mysticfalcon]

Because then you are taking already hot water and heating it. By drawing from the bottom you are heating the coldest water and adding it to the already hot water at the top of the tank.