# horizontal vs, vertical storage.



## kjahnz (Nov 30, 2012)

my question is, if the tanks are the same dia. and the same length and have an equal amount of insulation (with-in-guestamation). Does it make a difference which way they are orientated (in vertical, or in horizontal)? For instance you take two 250 gallon or two 500 gallon propane tanks, plumb them to except hot water up high and draw cold water from down low, does either way have a benefit over the other? With my limited knowledge, I can only guess that having the most or largest dia. connections between the two tanks (equalization), will make the biggest difference. thanks for any suggestions.


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## JP11 (Nov 30, 2012)

Limited knowledge here too.  

I can tell you a few practical things.  My storage tanks are two vertical 500s.  I was surprised how much heat transfer occurred between the two tanks using 2 1.25 inch lines that I forgot to close.  I was messing around when the boiler was new.. and was attempting to charge just one tank.

I can tell you that during no load.... no stirring going on.. my top of tanks is 7 to 10 degrees hotter than the bottom.  Now... when I say top and bottom.. mine are plumbed and measured at the last vertical surface.  EG just above the dome on bottom.. and just below the dome on top.

Don't know if that tells you much or not.

JP


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## heaterman (Nov 30, 2012)

Height is what you want for best stratification. John Sigenthaler (Modern Hydronic Heating fame) built a tank that is on the order of 18' tall into his house when it was constructed. Now THAT will stratify.


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## kjahnz (Nov 30, 2012)

thanks jp11,
     Maybe there is some light reading I can do? Got some suggestions? I guess if the two tanks are plumbed correctly, when there is no mixing, two vert. tanks should have the same temp readings measured at the same height? Also, if your 7-10 degree diference means, for example : 170 at the top you would have about 160 at the bottem, when idle? (or after mixing).


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## kjahnz (Nov 30, 2012)

heaterman,
    O.K., height is a desired quality. Then, one vessel is better than two, given they are of equal volume? Also, two vessels have more surface area that will disapate more heat, compared to the single vessel with the same volume? Thanks.


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## Floydian (Nov 30, 2012)

heaterman said:


> John Sigenthaler (Modern Hydronic Heating fame) built a tank that is on the order of 18' tall into his house when it was constructed. Now THAT will stratify.


 
Very interesting. Do you know how many gallons? And what heat source(s)? Closed pressurized?

Noah


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## kjahnz (Nov 30, 2012)

Closed pressurized, the rest not so sure. I first thought of stacking two 250 gal. tanks horizontal, one on top of the other. I could inclose them and still stack wood on top. I have 10 feet of clearance (floor to ceiling). What ever room I use for water storage will take away from my wood storage. On average, a single 500 gal. tank is 10 ft. long, that leaves no wiggle room. Next to impossible to install.


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## JP11 (Dec 1, 2012)

kjahnz said:


> Closed pressurized, the rest not so sure. I first thought of stacking two 250 gal. tanks horizontal, one on top of the other. I could inclose them and still stack wood on top. I have 10 feet of clearance (floor to ceiling). What ever room I use for water storage will take away from my wood storage. On average, a single 500 gal. tank is 10 ft. long, that leaves no wiggle room. Next to impossible to install.


 
I have 10' 3 or so.  I had to use ALL of it.  I even had to use the height between the joists above.. as it swung into place.

Now, you might buy a few inches with your tank couplings.. Mine were fair sized... stuck out a few inches.  You could use low profile.  I did it the way I did because I wanted to use minimum floor space.  I think I used up a 4x8' section of floor for 1000 gal of storage.  The split I was talking about on temps is really at all times.  It doesn't really stir up during heat load use very much.  Split will be 6 degrees or so.  (I just looked at the temps now)  The tanks really stir up when I light the boiler.  Than 24gpm pump will stir them enough to be homogenous.

JP


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## woodsmaster (Dec 1, 2012)

Verticle will definitly stratify better, but you really arn't gaining a lot. if it's going to be a problem to put verticle I would't bother. If It's not a problem to put them verticle then that is the way to go.


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## maple1 (Dec 1, 2012)

Overall I don't think it will matter as much as practically fitting to the space you have for them will.

I have two 330 gallon tanks stacked horizontal. They seem to stratify good. Right now I have two temp probes taped to the middle of each of the two tanks. The split in temps will vary depending on what is going on. Generally, when the boiler is just heating storage, it's bigger, when I'm drawing from storage, it's smaller. Don't think it's ever less than 10°, when just heating storage it can be up to or over 30° if storage was drawn down considerably before starting. Although, when just heating storage & the storage gets higher to max charge, the split will narrow considerably - theoretically to zero. That was all likely somewhat contradictory - main point is it will vary.

Just plumb for even balanced flow as best you can - the lighter hot water & heavier cool water will more or less sort itself out..


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## Gasifier (Dec 1, 2012)

kjahnz said:


> Closed pressurized, the rest not so sure. I first thought of stacking two 250 gal. tanks horizontal, one on top of the other. I could inclose them and still stack wood on top. I have 10 feet of clearance (floor to ceiling). What ever room I use for water storage will take away from my wood storage. On average, a single 500 gal. tank is 10 ft. long, that leaves no wiggle room. Next to impossible to install.


 
kjahnz, I have a 400 gallon verticle tank. That height with the usual stand will work under a 10' ceiling. Of course you would always want to double check. I don't know your location, but there are some folks around who sell used propane tanks that they do the necessary welding of fittings and stand to, etc. Like smoklessheat - http://www.smokelessheat.com/categories/thermal-storage-tanks

I was getting ready to buy one from them but ended up finding a tank that saved me some money. If you are getting ready to add storage to your system or putting in a new system go with as much storage as you can. Depending on heat load needed, space, and boiler size, the more the better. Longer time between burns. But even if you can only put one tank in like I did, that is better than none. Good luck and keep us posted on your decisions.

The advantage of space savings is something to consider with vertical.


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## jebatty (Dec 1, 2012)

Stratification is desirable, but system operation to/from storage will greatly impact how effective stratification can be maintained. I think the ideal is to inject system return water into storage at the temperature point where return temp = storage temp, but this is not easy to achieve. Injection at any other point will result in mixing up or mixing down. Flow rate to/from storage will also greatly affect stratification. Sophisticated plumbing, valving, and multiple injection points can achieve great results, but for most of us simplicity is better, and good enough is good enough.


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## DaveBP (Dec 1, 2012)

I didn't have room to mount mine vertically and not even enough to mount them horizontally if there was any space between them. So, just for fun I welded the 2 500s tight up together and was able to clear the steel center beam in my basement by 1/2".







Water goes in and out horizontally at top and bottom each end. Not the easy way to do it but there is 6ft. between the top and bottom ports. It became the celebrity project in the shop where I work.


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## Gasifier (Dec 1, 2012)

Cool DaveBP. How did you insulate them and what do you use to heat them with?


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## tmudd (Dec 1, 2012)

All the members have stories and trials to contribute to this great site.
DaveBP gave me the incentive for stacking two 500 gallon propane tanks horizontally. Space was my issue.
Close placement to the boiler is also important in the scheme of loading tanks . Mark at Ahona re inforces the message that vertically of horizontally is not as important as just doing it! Mine were attatched similiar to DaveBP's but had 4-2500 lb wheels welded to it so it could be rolled into service. Pros and cons to all methods. One large tank is cetainly easier than two. I put four sensors for temp reading at the 1/4 tank interval horizontally. The Frohling can make the tanks the same temp all the way down. I got hung up on the stratification theory early and it caused analysis paralysis. My pet peeve was spreading out the flow going into the tanks so I built three 1 1/2 " ports on top and bottom and made a manifold. The mainifold pipes right to the storage and the load t"s off from there. It seems to move the BTU's to the tank from the furnace quickly wth the three speed loading un it. 1000 gallons of hot water is 1000 galoons of hot water, no matter how you stack it.

tmudd


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## mikefrommaine (Dec 1, 2012)

I'm adding two 500 gallon tanks. Both horizontal next to each other. Piped in a reverse return configuration. And I'm using a second danfoss valve with a 160 degree element installed "backwards" on the load returns to reduce tank mixing.

Hope it works!


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## Tennman (Dec 2, 2012)

Very cool Dave. Looks like one of those research submarines. Nice fab job.


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## maple1 (Dec 2, 2012)

mikefrommaine said:


> I'm adding two 500 gallon tanks. Both horizontal next to each other. Piped in a reverse return configuration. And I'm using a second danfoss valve with a 160 degree element installed "backwards" on the load returns to reduce tank mixing.
> 
> Hope it works!


 
Will the tanks be sitting on the floor, or will you be raising them up high?

I kind of went through those thoughts, figuring if the tanks were on the floor I could use the space over the tanks for other stuff (like maybe even another small horizontal tank for DHW heating use, or a buffer - if not just junk storage). But figured it would be better to get the tanks up as high as I could for good boiler-storage flow & forget about the other stuff. I ended up stacking anyway which made it not matter in the end for me.


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## mikefrommaine (Dec 2, 2012)

Tanks are sitting end to end on the floor. I put them along the foundation I what is going to be a media room. I'll build cabinets and put the a/v stuff above them. I could have stacked them but the space works just as well if not better without going through that expense.


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## stupe (Dec 3, 2012)

This is a timely discussion... I have a 500 gallon tank sitting vertically.  I feel insane for even saying this but I was getting 150F at the top of the tank and 95F 20" below the top of the tank (where my system draws hot water from).  This was when the wood boiler was off.  I would have never thought I'd get that much stratification in 20".  I can't even get my head wrapped around it.  I confirmed all of this with an infra-red temp gun and some temp sensors.  I had to abandon my temp wells at the top of the tank and move my sensors further down the tank to get more representative readings of usable water temp.  Everything works perfect now.  When the sensors were at the top of the tank, it was mistakenly locking out my propane boiler because it thought the tank was hotter than it really was.  When the wood boiler was charging the tank the problem was less pronounced (due to water moving around).  Anyone else experience this phenomenon?


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## heaterman (Dec 3, 2012)

Floydian said:


> Very interesting. Do you know how many gallons? And what heat source(s)? Closed pressurized?
> 
> Noah


 
I don't recall the gallons but do think it was pressurized.
He wrote about it in Plumbing and Mechanical magazine years ago and you may be able to find it searching the archives of that publication. That article was one of the first things that really got me thinking about the advantages of storage.

EDIT: Here you go. The heat source was solar and an oil fired boiler. It was pressurized but is no longer, at least at the time the article was written in 2004.


http://www.pmmag.com/Articles/Column/7df8232b040d7010VgnVCM100000f932a8c0____

And here is another one that Hot Rod wrote regarding Siggys set up.

http://www.pmmag.com/Articles/Feature_Article/fecae6286efc7010VgnVCM100000f932a8c0____


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## Floydian (Dec 3, 2012)

heaterman said:


> I don't recall the gallons but do think it was pressurized.
> He wrote about it in Plumbing and Mechanical magazine years ago and you may be able to find it searching the archives of that publication. That article was one of the first things that really got me thinking about the advantages of storage.
> 
> EDIT: Here you go. The heat source was solar and an oil fired boiler. It was pressurized but is no longer, at least at the time the article was written in 2004.
> ...


 
Thanks a lot, Heaterman!

I look forward to reading that tomorrow.

Good evening,
Noah


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## stee6043 (Dec 4, 2012)

As stated above I think the thermodynamics of these tanks will generally support vertical orientation as being the better tank position for stratification.  Assuming mixing is being managed equally.

I would personally feel that how much insulation you can get on top of the tanks is more important than how much stratification you can acheive.  As as result, most of us installing our tanks in the basement will likely find the horizontal position enables us to fill substantially more insulation over the tanks.

Here is what we strive for.  HA:




http://www.flickr.com/photos/cheapinebriant/8211353924/


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## maple1 (Dec 4, 2012)

My tanks are horizontal, but tipped up a little bit on one end. Not much, maybe an inch or so - no more than two. That 'narrows' the hot area at the top tapping that my zones draw from at the high end (the hottest water will gravitate to that spot), and the lowest point of my storage on the bottom opposite serves as a sort of a sediment bowl and I have a small drain there. Or at least those were my thoughts when I did it that way.


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