Eko 40 - 1,400 gallons of storage - piping and schematics questions

Hi everyone,


After a few postings and tons of reading, here is the setup I am currently installing :


Eko 40 into about 1,200-1,400 gallons of storage in an open vented unpressurized system. The system is connected from the garage to the house (underground piping of 127 feet), to a hydronic air handler to provide to the basement and the main floor, a sidearm HX connected to the DHW, and to 1 radiator for our entrance.

This is the first time my plumber will be installing multiple storage tanks, and I just want the opinion of people with more experience in this area, hence the current post. Please bear in mind that, although my installation is fairly common for this site, I will most likely be the only one to have such a system in a 200-500 km radius, which explains why my plumber, not anyone else in my community has direct experience with such an installation.

Attached you will find my plumber’s plans. The open vent will be installed on the last tank on the left, at the very top. The water will be filled up to the line on the diagram, with the remaining space kept for water expansion, he will also add a U-shaped piping above the water line in/out the tank for the air vent and possible water overflow, should the water overheat/over expand.

Also, the first smaller tank is connected separately from the 2x500 gallon in a manner to bypass the storage, should I need to prioritize the heating of the house, instead of storing the heat in the tanks.

My questions regarding the current suggested schematics are:

1. My installer proposed the attached series connection, since the tanks are of different sizes, he is “afraid” there might be thermosyphoning issues that could impact the actual water available to heat... is this a legitimate concern? Or would a parallel connection be more appropriate for my situation and benefit more of the stratification?

2. My second question is : does anyone see a problem with the way the open vent might have a negative effect on the overall performance of the system? (Please do not suggest me to install the system in a closed pressurized environment, since laws and regulations prohibit such an installation concerning my system)

3. Do you see any other problems that I should consider before moving forward with the final installation?

My plumber is coming back Wednesday morning, any input before then would be greatly appreciated.

NE WOOD BURNER said:

Good Morning,

Looking at your concrete blocks under your tanks. I would rethink the blocks. the blocks are not structural lying on the side. lots of horror stories with people using them that way.


Much discussion on vented systems on this forum. usually requires a tank at a higher elevation. search through the forum and you should find info on an open unpressurized system.

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I was put aware of the block situation yesterday... problem is that I don’t have the machinery to move the tanks around... I have a total of about 50 blocks underneath the platforms, with about ½ inch to 1 inch of space under the welded frame for the 2x500 gallons. At that quantity, do you still think it could be an issue..?

maple1 said:

I'm not understanding how the heat will get from the big tanks to your house when drawing from storage?


I think I would put all my tanks in parallel, with the tops at the same height. (i.e. raise the small one up). Then just run the loads from the top of one of them. Thermosiphoning is usually something to be encouraged, not stopped. Especially when talking overheat protection or the power suddenly going out when burning.


Hard to tell exactly from the pic - but how much headroom do you have above your big tanks? And/or what is above the ceiling? (I think I see a ceiling). Reason I ask is that if I was going to try running the tanks open, I would not do the airspace thing in the big tanks but rather put another smaller tank up higher than everything else for expansion room, connected by a small pipe. My boiler manual has a rough diagram for that, it specs the expansion should be 8' above the highest point in the system to help prevent oxygen infiltration into the rest of the system. I could see the insides of your tanks rusting quite quickly with vented air at the top.


Also think this is the first I've read of laws preventing a closed system. Are you sure? Especially in a garage. What does your boiler manual say about running in an open system?

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The big tanks are recirculating to the smaller tank, that way, if storage is cold, I can bypass them. I’m no expert on the matter and simply stating what my installer plans on doing, which is why I’m asking you guys opinion

I don’t have much headroom, 2 feet max from the top of the tanks to the ceiling, then I have the attic, which could potentially add a few more feet, but there is no way I can reach 8 feet above the tanks.

Boilers and pressure vessels are regulated in Ontario, again, I’m no expert on the matter and could be misinterpreting it, but from what I read, the boiler and the vessels should be ASME rated. http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_010220_e.htm

I would also prefer a closed system and just add and expansion tank for the simplicity, but both my research and a few installers have warned me about the ASME regulations.

The manual also shows me that the tanks have an open vented (all the setups are shown with open vents and no closed systems, btw) tank above the system (no reference to 8 feet, although I have read it somewhere else also).

maple1 said:

I think I would put all my tanks in parallel, with the tops at the same height. (i.e. raise the small one up). Then just run the loads from the top of one of them. Thermosiphoning is usually something to be encouraged, not stopped. Especially when talking overheat protection or the power suddenly going out when burning.

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What about if I were to leave the tanks at the same height, parallel them and use the last big tank on the left to heat the house. That way, the first tank, being lower, would thermosiphon the cold out of the big tanks; that way i get the hottest water into the tanks closest to the house... does that make sense?

NE WOOD BURNER said:

a gallon of water is 8.34 pounds. so 1000 gallons = 8340 pounds plus your tanks

So I wouldn't do it. I would use solid blocks if you need to raise them of the floor.

I have seen many cars with crushed concrete blocks under them. And they weigh much less then your tanks when filled. IMHO

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Hmm, then I guess I'll try to get a hold of steel H or I beams and slide them under there to held with the structural support.

NE WOOD BURNER said:

or extend legs on tank.
or drop them down to concrete slab

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What do you mean by extended legs on the tanks? They are on a 6.5 feet by 3.33 feet steel frame.

I put them on a sheet of plywood to create a thermal break from the steel to concrete, but I had to raise the since my slab has a tendency to sweat, I did not want to create rot by having the wood exposed to slab condensation and no air to dry it out.

maple1 said:

I would think that if the steel frame was resting right on the concrete, and you insulate under the tanks, there shouldn't be much sweating? Or you could add a layer of foam board between the concrete & the plywood. You'd have to figure out a way to get the blocks out though - some time and careful use of jacks & prys might do that though?

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Should the foam have any compressive strength requirements or 1' poly board should be fine?

maple1 said:

I'd just use whatever the building supply place sells to put under concrete slabs before they're poured. I'm no expert on that though.

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Thanks!

And since you mentioned that you would parallel and level the top of all 3 tanks, what do you think of this :

What about if I were to leave the tanks at their current height, parallel them and use put the the out flow towards the house from the last big tank on the left. That way, the first tank, being lower, would thermosiphon the cold out of the big tanks and I would get the hottest water into the tanks closest to the house... does that make sense?

No one else feels like chiming in on the design

NE WOOD BURNER said:

I would think that the blue tanks would be your storage and use the smaller tank for your expansion higher than your system for your eurodesign open system

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Even if I can only go 2 feet above the highest point of my system (highest point being the blue tanks)

maple1 said:

If you can get the blue tanks set down on the slab, that should give you enough room to put a smaller tank above them for an expansion tank - or multiple smaller ones. Picture electric water heaters on their sides up there. If you can find some decent used ones, some have used those. Or ordinary old-school bladderless expansion tanks - you might find some on kijiji. I have a line on one here I hope to get next weekend, coincidentally. But electric water heaters with elements removed might be more corrosion resistant. A couple of 40's might be enough - 3 should be for sure. I would go in that direction, and still would get that smaller tank (400 gal?) higher so that the top of it is the same height as the top of the others. That would get you max convection from the boiler to the top of tanks for power outage situation, and maximum stratification I think. Plumb them parallel reverse return (boiler into tanks top left, tanks out to boiler bottom right), and run your zone supply out of the top of the right one (farthest from the boiler), and zone return into bottom of left one (could T into the bottom of the line that would connect the bottom of the left tank to bottom of middle tank). There might be a small delay when firing from cold, before you get hot water to your zones, but it shouldn't be too much of a delay if you can get your tank connections as high as possible - the hot water coming out of the boiler should run right across the tops of the them.

Also, can't tell from the pics - but now is the time to start your tank insulating, with a good layer of insulation behind & beside the tanks against the wall. Try to max that - not really such thing as too much insulation especially if that's an exterior wall. Like, at least 6", but a foot would be even better.

EDIT: You said attic above the tanks - I might even put expansion up there, would give you more headroom for tank insulation. Not sure what it's like up there, but if you insulate the expansion tanks, and the pipe going to them, you should be OK. The extra few feet of separation will surely help.

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Thanks for the input, I'm supposed to have a discussion with my installer in the next couple of days. I'll try to sort that out, but I'm not really convinced on keeping the 400 gal one anymore - seems to be too much trouble for what it's worth!

As for insulation, I was thinking about spray foaming the whole thing once it's been piped and leak-proofed.

Is this what you mean by the parallel reverse return?

huffdawg said:

closed cell foam work

s excellent

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That's what I'm aiming for; thinking of spraying about 6 inches