storage plumbing

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jason elmer

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Oct 4, 2009
28
west michigan
I need some help understanding storage piping. I have a 1000 gallon anhydrous tank I will be using for storage. The tank will be installed horizontal it is 16' long and about 42" in diameter. On the spherical end it has three 1-1/4" openings with two pipes going to the top of the tank and one pipe going to the bottom. In the middle of the tank is a baffle that will reduce or slow cross currents. In the half opposite the end with the 3 openings there are three 2" openings on the top of the tank. Each is spaced about two to three feet apart with the first one near the middle of the tank and the last one about a foot from where the tank begins the other half sphere. There is also an 1-1/4" drain on this far end.

With all these openings I was wondering if I could use the two 1-1/4" openings with tubes to top for heat input from boiler and use the far 1-1/4" bottom drain for return to boiler. For supply to zones I would like to use the far 2" top opening. Return from zones would use the 1-1/4" dip tube below the boiler inputs.

Does it make sense to do this? In essence I am running the water only in one direction. I don't understand how storage systems work with just two pipes going to storage. Do the systems reverse flow? Or do they send hot water from the boiler to the bottom of the tank? I guess I'm trying to keep the mixing to a minimum for better stratification.


Jason
 
A picture would be worth a 1000 words. I might consider something like this: 1) boiler supply to one of the 1-1/4 fittings at the top on one end; boiler return from the 1-1/4 drain on the opposite end. 2) system supply from one the top 2" fittings towards the end away from boiler supply; system return to the 1-1/4 fitting near boiler supply that goes to the bottom of the tank.

I also would want to know how many gpm's in the boiler circuit and how many in the system circuit.
 
...and how that baffle is configured in there could effect how it would best be plumbed, too. Is it vertical across the 42" width of the tank with openings at top and bottom? Is there more than one baffle? Is it solid or full of holes? It would help to know. Maybe you can see traces of the welds on the outside of the tank. Can you get a little inspection mirror (periscope style) into one of the ports and put a flashlight in one on the opposite end?

I think the "added feature" of the baffle(s) argues for Jim's suggestion to cross connect the supply and return from opposite ends. If you are going to use a high flow circulator you may end up short circuiting across one end of the tank if the baffle puts up too much resistance to flow across the length of the tank.
 
Here is an image of the baffle inside an anhydrous ammonia tank. I too have an anhydrous ammonia tank I will be using for storage although my configuration of fittings is a bit different than white pine's. I'm curious to hear what you guys think of a baffle like this in a storage tank.
 

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white pine said:
I need some help understanding storage piping. I have a 1000 gallon anhydrous tank I will be using for storage. The tank will be installed horizontal it is 16' long and about 42" in diameter. On the spherical end it has three 1-1/4" openings with two pipes going to the top of the tank and one pipe going to the bottom. In the middle of the tank is a baffle that will reduce or slow cross currents. In the half opposite the end with the 3 openings there are three 2" openings on the top of the tank. Each is spaced about two to three feet apart with the first one near the middle of the tank and the last one about a foot from where the tank begins the other half sphere. There is also an 1-1/4" drain on this far end.

With all these openings I was wondering if I could use the two 1-1/4" openings with tubes to top for heat input from boiler and use the far 1-1/4" bottom drain for return to boiler. For supply to zones I would like to use the far 2" top opening. Return from zones would use the 1-1/4" dip tube below the boiler inputs.

Does it make sense to do this? In essence I am running the water only in one direction. I don't understand how storage systems work with just two pipes going to storage. Do the systems reverse flow? Or do they send hot water from the boiler to the bottom of the tank? I guess I'm trying to keep the mixing to a minimum for better stratification.


Jason
Click to expand...

Can you show some pictures of your "ends" with all the openings? If your tank has a baffle like the one pictured above I would be inclined to plumb both "halves" of the tank in parallel as if they were separate tanks. Run supply and return lines to both halves (assuming the plumbing is symmetrical both in terms of size and location). Join the two halves with tee's going to the boiler supply and return.

This is assuming you aren't pulling water directly from the ends, of course. You'd short circuit your flow if you had supply and return on the "end" of the tank without some kind of dip tube or otherwise.

And to answer your question about flow - most systems do reverse flow. But you don't need fancy controls, just two pumps (or more). We charge the tanks with hot going in the top and cold coming out of the bottom. When we start pulling heat from the tanks we want to pull from the top and return to the bottom...
 
Thanks guys for the input so far. I know a picture would help a lot. I have pics, I'm just not up to speed on how to post them. My baffle is exactly like the pic posted by Floydian.

A little more about the system. The boiler is a BioMass 60 rated at 60K to 215K BTU/hr. The boiler will be located in a soon to be constructed pool/boiler house no more than 50 feet from my home. The storage tank will be near the boiler in the pool house. I am planning on using 1-1/2" steel for the boiler to storage loop. That's why I was planning on splitting the boiler supply to the tank, using both of the 1-1/4" taps to the top of tank. I want to slow the water down to reduce mixing. How jebatty described my setup is exactly what I was thinking except for the split.

I am planning on using 1-1/4" pex for the main zone loop which will travel underground from the pool house to the basement. I guess this loop will be around 250' or less for supply and return. Heat emitters include: a forced air heat exchanger for house, side arm on DHW, radiant slab in garage, and future baseboard in basement. Garage has 5 250' loops of 1/2" pex. Area of garage is 1100 sq ft. I did a heat calc a while back and I came up with 76,000 btu/hr at design for both garage and house. Not sure how good that number really is. The garage will most likely be kept in the low 60's and upper 50's during colder stretches.

In the summer I plan on heating the pool with the boiler and perhaps the hot tub year round. A small greenhouse is also in the works. These would be plumbed from the poolhouse as a separate loop.

I've been reading the primary secondary sticky and the simplest pressurized storage and I am still trying to figure out all this piping stuff.

Thanks again for your help this forum is incredible.
 
With the baffle in the middle of the tank I would plumb it on both ends with equal length piping to a manifold. Off this manifold I would run the lines to the boiler and also run lines to the supply for the heat load. Make one manifold for the top of the tank which would be for the "Hot" side which would be the supply for the heat loads and the supply from the "hot" pipe on the boiler. Off the bottom of the tank use equal piping again for the "Cold" side which would be the return from the heat load and the "In" side of the boiler. If every pipe to the manifolds is exactly the same size and length, then it should transfer the same amount of water into each end of the tank so the stratification line should be equal even though you have a baffle in the tank. For the lines running to the boiler and heat load I would place a "t" fitting (4 way) in the middle of the manifold so that everything balances out, with one going to the heat load, one going to the boiler, and the remaining two going to the tank.

Clear as mud huh.
 
I avoided a propane tank that had those end connections but I agree with everyone about parallel piping (like 2 separate 500 gal tanks). Make sure the supply and return on each end are as far apart as possible though. Will be tougher on the 1/2 of tank with the top conections. Don't water the supply and return to "short circuit" and not mix in the tank like they should.
 
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