storage ques.

I have two five hundred gallon used propane tanks the I use. I flushed them and then filled them to within 3" of the tops with water. I used a cutting torch and cut holes in each tanks. I install 1-1/2" pipe that stops about 3" off the floor of each tank. This is the cold water return line. I also welde on short 3" long, 1-1/2 pipes that serve as the hot or supply line to the tanks. The tanks are side by side and connected with each other with 1-1/2" pipe for both the supply and return. Then I run one 1-1/2" pipe to the end of the tank and this is the return line and the other line is the supply line. I did this with tees and regular pipe fittings. When I test fired the boiler, I ran it for about 6 hours about 2/3 full of wood and it heated both tanks up to about 150 degrees. The stratification was amazing, there would be hot water on top and at the line there would be cold water just underneath, no mixing. It would be so hot you can't touch it and a few inches away, so cold that dew was forming on the outside of the tanks. Eventually I ran a full wood load test and it heated the tanks completely. The room the tanks are in is so hot, you can't breath so I am now insulating the tanks with blue foam.
I also welded a flange 1-1/4" fitting in the bottom of each tank so I could drain them if necessary.

Frozenasset, Do you have special welding certs ? What rod and how many passes did you lay on the joints ? I was thinking of a hole saw for cutting, but torch would be faster plus you could get a bevel going prior to grinding.
Will

I'm not a certified welder, however I have been welding for over 40 years. I made 3 passes with 3/16" 6013 rod, D.C.

Then I filled the tanks with water and pressurized to 100 psi and it held fine. The steel in my propane tanks is 3/8" thick. I am pretty sure the propane company wanted to get rid of the tanks for two reasons.
(1) they had some rust pits and propane tanks can run 250psi.

(2) the new fill valves will not fit, or so I am told.

Anyway, my tanks are in a seperate building and both have pressure reliefs valves set at 30psi.

Use a certified welder if you can find one.

frozenasset
Any chance of some pictures or a drawing of your setup?

Right now the tanks are all cover up with blankets and bedrolls to hold the heat in as I build an insulated box over them. When I uncover them, I'll get some pictures.

Here is a drawing of how I plumbed the boiler and tanks. I used 1-1/2" pipe as much as possible and 1-1/4" from the tanks to the heat exchanger.

I removed the danfoss as it restricted the flow too much and the boiler would eventually overheat and bypass too much hot water back to the boiler. I could have replumbed it all with a balancing valve but the ports are too small in the danfoss and it works much better without it in the system. Maybe if I wasn't using storage, the dan foss would be OK.

I am getting ready to plumb my system, What size pumps did you use? If you got yours from Cozy I asume it is a 007 and a 010 So you removed your ball valves and danfoss? Do you have your tanks end to end or stacked on top of each other?


Any pictures of your tanks plumbed?


Thank you,

Rob

the two 500 gallon tanks are side by side and I connect the supply pipes , tank to tank and they meet at a tee in the middle. Same with the return pipes. The cool water is returned to the bottom of each tank. The supply from the tanks, (hot) are teed together in the middle, so what I end up with is a single line from the wood boiler that supplys hot water to the tanks and a single line that is the to the return side of both tanks. They stratify just fine and the temps are even. I used 1-1/2" steel pipe with regular pipe fittings, elbos, tees, 90's, etc. The EKO-60 has a single Grundfoss 26-99FC pump but I removed the check valve for better flow. I think this is not necessary as this pump runs on lowest speed and still charges the tanks fine.
The tanks are all coverd up with sleeping bags, blankets and a box I built over both with 2" blue board foam installed. If I ever dismantle it to add more insulation, I'll try to take some pics.
I took the danfoss out as I found out it was too restrictive, causing the boiler to overheat and throttle back on it own.A bypass ball valve may have helped but since I run the boiler wide open it only takes a few minutes to get the return water to go over 130(f) anyway. I guess if you ran and EKO without storage tanks, then the danfoss or similar might be helpful.

Here is a picture of my EKO-60 with the danfoss insalled.

Here is a picture of my EKO-60 after I removed the danfoss valve...