Separator tank as primary loop

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in hot water

New Member
Jul 31, 2008
895
SW Missouri
Here is the latest change to my system. This 50 gallon prototype tank has six 2" FIP ports on the sides and three 3/4' on top. It acts as a hydro-separator tank, instead of a primary loop with closely spaced tees. It also serves as an air eliminator, and a bit of buffer tank.

On the left side it is piped to the EKO boiler. Out the back it pipes to a 500 gallon LP tank storage. Facing out are the connections to my heat and DHW located across the shop.

For a nice boiler fitting I use a Duplex bushing with an air vent and a sensor well. This 2" tee on top of the EKO is the high point in the boiler room piping. An additional vent will go on top of the separator tank. The separator tank has a well I built to allow 3 sensors to go into the tank.

Control work in progress as we speak. A dual differential (solar) control runs the boiler pump and the pump from the separator to the 500 gallon. Both pumps run on a variable speed function, as the temperature rises in the boiler the pump speeds up. The pump kicks on when the boiler reaches 150F at that top sensor, off at 140F.

hr
 

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When you do stuff like that everyone will want a tank like that ! Great idea... Happy Holidays.
Question, if you had back a up boiler would you plumb that into tank also ?
 
RobC said:
When you do stuff like that everyone will want a tank like that ! Great idea... Happy Holidays.
Question, if you had back a up boiler would you plumb that into tank also ?
Click to expand...

That's how I set mine up, both the backup boiler and a transfer pump from storage are plumbed to feed the 'nexus tank'. That way I can get tankless DHW and hot tub heat with whatever heat source is in use.

Tank has two zones, priority to DHW and hot tub coils on top. Radiant loads draw from lower portion of tank and return to the bottom. Heat sources draw from bottom of tank and feed to top.

--ewd
 

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RobC said:
When you do stuff like that everyone will want a tank like that ! Great idea... Happy Holidays.
Question, if you had back a up boiler would you plumb that into tank also ?
Click to expand...

That tank will be available in a 50, 80, and 120 sometime next year.

I would tie a backup boiler in parallel with the wood boiler. I'd have it feed the separator tank, but lock out the 500 gallon tank from the gas fired boiler. That could be done with a control function.

A small modulating condensing boiler with it's own DHW tank or HX would be ideal. That way the boiler, and sep tank could run at the lowest possible temperature to hand the heat emitters. My shop and office are all in slab radiant so I could run down tom 90F when the boiler is running.
 
ewdudley said:
RobC said:
When you do stuff like that everyone will want a tank like that ! Great idea... Happy Holidays.
Question, if you had back a up boiler would you plumb that into tank also ?
Click to expand...

That's how I set mine up, both the backup boiler and a transfer pump from storage are plumbed to feed the 'nexus tank'. That way I can get tankless DHW and hot tub heat with whatever heat source is in use.

Tank has two zones, priority to DHW and hot tub coils on top. Radiant loads draw from lower portion of tank and return to the bottom. Heat sources draw from bottom of tank and feed to top.

Nice tank, I like the tankless coil options. Custom made? Is it a galvanized tank?

hr

--ewd
Click to expand...
 
in hot water said:
I like the tankless coil options. Custom made? Is it a galvanized tank?
Click to expand...

The Caleffi tank in the 'Primary/Secondary Stickie' looked like the right answer to me, so I went with that plus borrowing a lot from what appears to be the Siegenthaler/European way of doing things.

It's just a 30 gallon propane tank with 3/4" half couplings for sensor wells and 1 1/4" half couplings for circuit connections. The necks and collars are from a boiler manufacturer (Keystoker) that was kind enough to retail the parts. I prepped the surfaces and contoured the fittings and took it to a local shop for welding. Cut the holes after welding, seemed to work pretty nice. Filled with water and then pumped in 80 weight axle oil with a grease gun to get it up to 100 psi for testing.

Not galvanized, just painted silver.

--ewd
 
Would you guys go into more detail on the benefits of this "hydro-separator" tank?
 
chuck172 said:
Would you guys go into more detail on the benefits of this "hydro-separator" tank?
Click to expand...

Basically it's like the benefits of a primary/secondary configuration with one less pump.

For my situation the main benefit it offers is to make it easy to minimize the temperature of water returning to storage. I only pump water into the separator when the water at the bottom of the separator is as cool as possible so that water from storage only ever makes one trip per firing cycle out to the system and back.

Also, as the name suggests, I can separate out and capture intermittent flows of very cool water at the bottom of the tank and send them to the storage tank before they can temper the heating water.

Type the following into google and stand back:


siegenthaler (hydraulic | hydronic) separator


Also:

http://www.pmmag.com/Articles/Column/38b99783250d7010VgnVCM100000f932a8c0____

http://www.caleffi.us/caleffi/en_US...gazine_detail_0000054/type/magazine/index.sdo


--ewd
 
ewdudley said:
in hot water said:
I like the tankless coil options. Custom made? Is it a galvanized tank?
Click to expand...

The Caleffi tank in the 'Primary/Secondary Stickie' looked like the right answer to me, so I went with that plus borrowing a lot from what appears to be the Siegenthaler/European way of doing things.

It's just a 30 gallon propane tank with 3/4" half couplings for sensor wells and 1 1/4" half couplings for circuit connections. The necks and collars are from a boiler manufacturer (Keystoker) that was kind enough to retail the parts. I prepped the surfaces and contoured the fittings and took it to a local shop for welding. Cut the holes after welding, seemed to work pretty nice. Filled with water and then pumped in 80 weight axle oil with a grease gun to get it up to 100 psi for testing.

Not galvanized, just painted silver.

--ewd
Click to expand...

With your coils hanging out the top, it looks like a prop from a science fiction movie! ... EWD builds cosmic raygun in back yard...
 
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