Froling Layered Tanks

[fowlerrudi]

(broken link removed to http://www.froeling.com/en/products/overview/tanks.html)

There is very little info on these tanks - but I assume they are a hit in Europe. Does anyone have any info on them? Sizes - advantages, etc? I'm not following this "layered storage" idea.

 

[Como]

Basically different heat sources produce different water temperatures

 

[Chris Hoskin]

we just had the gang from Austria here and got the skinny on these tanks. These tanks not only maximize stratification in the tank (good thing), they also allow for temperature equalization across multiple tanks.

Example: A desirable heat storage set up for a small-ish wood boiler would be two 800 liter tanks (pressurized storage). It would be nice if your heat storage also served as an indirect water heater and had the ability to allow for heat input from a solar collector. So, because this kind of 'combi-tank' is expensive, we only have one of these tanks and the other tank is a simple plain buffer tank of equal volume. The problem comes when you start reducing the temperature of the combi-tank by withdrawing heat for domestic hot water. Now you have one tank hotter than the other which is the opposite of good stratification and means you are not utilizing the energy stored in the second (buffer) tank. The first tank temp drops, there is a call for heat, all the water mixes and the useable temp in the tank drops. Now you have to refire the wood boiler because the tank temp is not high enough (even though there are still lots of BTUs in the tank, they are just at too low a temp). The Fröling tanks address this by having multiple large ports by which the tanks are connected. These large ports allow the two tanks to remain at the same temperature AND stay stratified simply via conduction from the warmer tank to the cooler tank via these ports. Very cool......and very expensive. We have our eye on them, but not sure if the market will bare the price.

Chris
BioHeatUSA Sales Guy

 

[chuck172]

"A desirable heat storage set up for a small-ish wood boiler would be two 800 liter tanks (pressurized storage). "
That's only about 420 gallons!

 

[Chris Hoskin]

"That's only about 420 gallons!". Yup. A small-ish boiler would be 100,000 BTU and for someone who is interested in using the wood boiler primarily during heating season, this set up seems to be a good compromise between ability to handle/move tanks, space requirements, budget and benefits of storage. Are you satisfied with 500 gallons and 140,000 BTU boiler, or do you find you would rather have more? We all agree here about the benefits of storage, but the 'correct' amount is a little more difficult to determine

 

[chuck172]

I'm trying to make myself satisfied with 500 gallons of storage. I realize that more storage doesn't mean more efficient wood usage. The only drawback to less storage is starting more fires.

 

[WoodNotOil]

We desperately need a domestic manufacturer of pressurized storage tanks. The advantages of utilizing a higher temp and smaller volume of water make it ideal. Seems to me it would be a cost effective venture and that there would be enough demand to make it worth while. I like all of these Euro designs, but it seems ridiculous to pay all that money to import something that could be easily made right here.