How to convert a 500g propane tank to a Storage tank

[Bj1234]

Hi all -
I have searched through the topics about building/converting propane tanks into hot water storage tanks for wood boilers, I'll start reading ones comments and get lost cause topics sometimes go sidewyas.

So I was hoping a few of the experienced guys can post thier "directions" on converting( 1) 500g propane tank into storage, then how to add a second later. Including size pipe recommendations, do we put a heat exchanger coil inside, to their favorate websites to buy the parts from, and how does the water heat/move through such a big tank. Since this is for new "do it your selfers", simple and easy would be appreciated.
Now If i missed a topic on this then I'm sorry, and hope someone would post the link here.
Thanks!

 

[maple1]

It's a simple thing really. No coils. Just in & out fittings on top & bottom you can thread pipe into. Mine are 1-1/4", same as boiler tappings & near boiler piping. If you pump water in (or out) one fitting, it has to come out (or in) the other one. It's just a matter of putting the tank in a loop in series - broadly speaking. There are some intricacies in getting flows the way you'd want when also considering how your loads get piped in too - depending on the whole system layout. Check out the recent 'simplest pressurized storage revisited' thread - think all the basic bases are covered there, with diagrams & good broad discussion.

 

[Bj1234]

I was wondering about the coils. So it's a no on the coils... alright.. now it dosent seem as hard as I thought. I thought I had to run,coils in the tank.. thanks for the thread. I had a feeling I'd miss a thread, couldn't be the only one overthinking this....thanks

 

[huffdawg]

Here's a pic of my tank mods.

 

[JohnDolz]

Here's a pic of my tank mods. View attachment 172140

Here is 1000 gallons, horizontal. Low ceilings but if I had to do it over again I would spend more time researching how I moght do it with vertical tanks.

 

[JohnDolz]

Here is 1000 gallons, horizontal. Low ceilings but if I had to do it over again I would spend more time researching how I moght do it with vertical tanks.

View attachment 172142

Brain Crawford made these tanks for me. I should have mentioned his approach was to pipe from the top of the lower tank but there is a pipe inside the tank to pull from the bottom. If I had to guess I would say Brian read some threads here about water disturbance and went with this approach to minimize water disruption/stratification.

 

[Bj1234]

Nice set up guys... huffdawg , your pic easily show the pipes.. so the bottom is the (out )as In to the house...and the top is the hot(in) from the boiler?
And what is the pipe at the very top that is cut of by the picture?

 

[JohnDolz]

Nice set up guys... huffdawg , your pic easily show the pipes.. so the bottom is the (out )as In to the house...and the top is the hot(in) from the boiler?
And what is the pipe at the very top that is cut of by the picture?

Take a look at the link below and it will give you a TON of info. But the top comes from the boiler and also supplies the house. Bottom is return to the tank and supply to the boiler.

http://www.nyserda.ny.gov/-/media/Files/EERP/Renewables/Biomass/biomass-hydronics-training.pdf

 

[huffdawg]

The pipe at the top is an air vent .

 

[Bj1234]

Wow , different then what I thought.. thanks for the link....checking it out now..

 

[JohnDolz]

Here's a pic of my tank mods. View attachment 172140

I notice that you are going up with your return pipe (mine is also plumbed this way). I did a lot of reading this year and learned that the recommended setup for my loading pump is to have the return pipe be at the same low level as where it enters my loading pump. The idea is that if power ever goes out the system will then just have a gravity fed loop to keep the boiler from overheating. My thoughts are to redo it this way in the spring (I have some other plumbing that needs to be done), wondering what you think about this and why you chose to go up with that pipe?

 

[huffdawg]

The storage tank supply and return attach to a buffer tank . Primary secondary set up..

 

[JohnDolz]

The storage tank supply and return attach to a buffer tank . Primary secondary set up..

OK thanks. I am going straight to/from my boiler.

 

[Bob Rohr]

Here is a link to some additional info.
If at all possible mount the tank vertically, side ports, and consider the Two Pipe method for connecting.

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

 

[maple1]

Wow , different then what I thought.. thanks for the link....checking it out now..

More info & pics of my setup are in my install thread linked in my sig. My first piece of advice would be to get any tank welding done by a pro.

 

[huffdawg]

Here is a link to some additional info.
If at all possible mount the tank vertically, side ports, and consider the Two Pipe method for connecting.

http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

Does the two pipe method have to have the pipe connections for the heat loads close to the storage tank?

Edit: Found the answer in the link:

When using a 2-pipe confi guration, it is important to
keep the tees connecting to the load piping as close to
the tank as possible. The header piping between these
tees and the tank should also be generously sized to
reduce head loss to almost zero. Thus, the piping that
the heat source circuit and the load circuit share in
common has very low head loss, as illustrated in Figure
3-5. This ensures excellent hydraulic separation

It doesn't really say why Bob , how far would be too far from the storage tank?

 

[huffdawg]

I notice that you are going up with your return pipe (mine is also plumbed this way). I did a lot of reading this year and learned that the recommended setup for my loading pump is to have the return pipe be at the same low level as where it enters my loading pump. The idea is that if power ever goes out the system will then just have a gravity fed loop to keep the boiler from overheating. My thoughts are to redo it this way in the spring (I have some other plumbing that needs to be done), wondering what you think about this and why you chose to go up with that pipe?

I have a stby generator ready for just that reason.My Storage tanks are about 30ft away from the boiler in a separate room, to keep the return pipe low I would have had to run the pipe in front of the boiler room door

 

[Kristen]

My boiler has a connection to the mains water. Not quite sure how it is plumbed, but in the event of overheat the valve to the (cold) mains water opens and hot water / steam! is flushed to a tundish, and from there to the drain. We had a power cut last week in mid-Burn so I know that it is working

 

[woodsmaster]

I notice that you are going up with your return pipe (mine is also plumbed this way). I did a lot of reading this year and learned that the recommended setup for my loading pump is to have the return pipe be at the same low level as where it enters my loading pump. The idea is that if power ever goes out the system will then just have a gravity fed loop to keep the boiler from overheating. My thoughts are to redo it this way in the spring (I have some other plumbing that needs to be done), wondering what you think about this and why you chose to go up with that pipe?

I have mine plumbed similar to huffdawgs, but my return is at about the same level as the pump and it does thermosiphen enough to keep boiler from overheating in a no power situation.

 

[Bob Rohr]

Does the two pipe method have to have the pipe connections for the heat loads close to the storage tank?

Edit: Found the answer in the link:

When using a 2-pipe confi guration, it is important to
keep the tees connecting to the load piping as close to
the tank as possible. The header piping between these
tees and the tank should also be generously sized to
reduce head loss to almost zero. Thus, the piping that
the heat source circuit and the load circuit share in
common has very low head loss, as illustrated in Figure
3-5. This ensures excellent hydraulic separation

It doesn't really say why Bob , how far would be too far from the storage tank?

That short, fat section of piping becomes your hydraulic separator. Keeping it close and sized large assures the pumps do not interfere with one another, just as a hydraulic separator does. You don't want any of the pumps causing un-wanted flow in the others.

 

[huffdawg]

That short, fat section of piping becomes your hydraulic separator. Keeping it close and sized large assures the pumps do not interfere with one another, just as a hydraulic separator does. You don't want any of the pumps causing un-wanted flow in the others.

. I was thinking of replumbing to the 2 pipe system so if the the storage tanks are already plumbed 1-1/4" and the boiler loop is 1-1/4 it wouldn't work without that pipe reduction? I was going to t in on the horizontal copper just before the vertcal run of black iron pipe on my tanks with 1-1/4 for the primary loop feeding the heat loads.
.

 

[Bob Rohr]

what are the combined flowrates in that section? ideally that section is sized so flow velocity with all pumps running is below 2 fps.

 

[huffdawg]

I don't have flow meter inline. All I can tell you is , it is all 1-1/4 being fed by a 15/58 grundfos.

 

[Bj1234]

Can someone tell me ur thoughts...

If you guys had the space, what would be better, installing( 1 )1000gal storage tank horizontally OR installing (2)500gal tanks.side by side vertically?

 

[ewdudley]

Can someone tell me ur thoughts...

If you guys had the space, what would be better, installing( 1 )1000gal storage tank horizontally OR installing (2)500gal tanks.side by side vertically?

Vertical has certain advantages, but they are not overwhelming advantages.

Both vertical and horizontal will stratify effectively, especially if horizontal ports, internal riser and dip tubes, diffusers, or internal elbows are used to minimize vertical jetting.

Personally, if I had the space, I would place a 1000 tank horizontally up on some sort of superstructure so I could use all the space below it. The boiler, plumbing, expansion tank, and a cord or so of wood could all fit below nicely.

You would likely prefer some other arrangement, but my point is that what matters is how best to make use of the space available in your own particular situation, not the question of horizontal vs. vertical.

(If you do go vertical, note that if you use horizontal ports from the sides of the tank, all the volume above the upper port and all the volume below the lower port will be lost for heat storage. To avoid this design defect you need to use an internal riser tube to inject or draw hot water from the top of the tank, and likewise you need to use an internal dip tube for the bottom of the tank.

Or you can use ports at the top and bottom of the tank, perhaps with diffusers or internal elbows, which works very well, but takes just that much more vertical space and is difficult to plumb, in my experience.)