I'm in the process of installing a vigas 40 with 1000 gallons of storage and I am starting to run out of space and I am trying to find a spot to put my two extrol 110 expansion tanks.... I was planning on running a 1/2" copper line off of my air separator which is mounted directly above the boiler itself. Is there a limit to how far away from the boiler the expansion tanks can be? I would like to place them about 20 feet away if possible...
expansion tank location
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Put your air scoop or air separator just ahead of the main pump in the system and pipe from that to anywhere you need for the tanks.
Not sure if I agree with you heaterman, it is in good practice to always pump away from your air separator/expansion tanks. The suction side of the pump is where the lowest pressure is in your piping system which helps in air elimination (provided you are pumping away from your expansion tanks, also coined the point of no pressure change) Piped in this manner it allows the full pressure differential created by your circ pump to be added to your system fill pressure. Piped with the pump pumping towards the expansion tank subtracts the pumps differential from the system fill pressure, which could cause problems. The above should also be on the supply side of your boiler and not like the old timers did by having your pump on the return
Back to the OP's question, expansion could be 100'+ away, it won't really matter, the flow of water from the system to the tanks is minimal, 1/2" will be fine. If you valve your expansion tanks (which you should) it is a good idea to either lock open the valve or remove the handle, it is one valve in your system you do not want to have in the off position unless you are doing maintenance on you tank(s)
Back to the OP's question, expansion could be 100'+ away, it won't really matter, the flow of water from the system to the tanks is minimal, 1/2" will be fine. If you valve your expansion tanks (which you should) it is a good idea to either lock open the valve or remove the handle, it is one valve in your system you do not want to have in the off position unless you are doing maintenance on you tank(s)
/agree with Morgan. If you can pump away from the expansion tank / air separator, that is best. Lower pressure means air will come out easier, and the expansion tank is working with the pump instead of against it.
I believe Heaterman is saying the same thing. By "just ahead" I took him to mean 'upstream', so that the circulator is pumping away from the point where the expansion tank connected to the system.
That could be taken two ways - 'ahead' = before in the flow (upstream of), or 'ahead' = up ahead in the flow (downstream of). I'm thinking he meant the former also.
It matters more where they will fit. I hate the space those suckers take up. Floor space is a premium. Mine are 20' from my storage, furthest thing away in the whole system.
JP
JP
I'm using a loading unit which is loacted on return side of boiler , planning on spirovent just after hot supply leaves boiler and was going to hook expansion into spiro vent botttom. Anybody see problem with that. It is not the suction side as I understand it.
Piping diagrams, get the "best accurate" answers.
It will work, just not as efficiently. Water will be hot, but it will be at it's highest pressure, so you will get less air venting action, and your pump will be working against the expansion tank. Also according to many, pumping away increases expansion tank bladder life (System working together instead of against)
If you tie in the expansion tank before the pump, it has the same affect on the lines following it. Doesn't matter where the expansion tank really is.
Also if your pump is located on the return side of the boiler, you are putting the highest point of pressure in the boiler. More work for the pump / higher pressure in boiler when you want it in system.
![[Hearth.com] expansion tank location](https://www.hearth.com/talk/data/attachments/76/76066-e91c604eb36cd321a05998f6b9d23866.jpg?hash=G2HDXCRt-h "[Hearth.com] expansion tank location")
It will work, just not as efficiently. Water will be hot, but it will be at it's highest pressure, so you will get less air venting action, and your pump will be working against the expansion tank. Also according to many, pumping away increases expansion tank bladder life (System working together instead of against)
If you tie in the expansion tank before the pump, it has the same affect on the lines following it. Doesn't matter where the expansion tank really is.
Also if your pump is located on the return side of the boiler, you are putting the highest point of pressure in the boiler. More work for the pump / higher pressure in boiler when you want it in system.
I think this is what you are describing? It's fine to locate the Spiro and expansion at the top. Air removal is best at the hottest point in the system. Really you are still "pumping away" from the PONPC. In theory if the circ is half way, or less from the expansion tank connection in the loop it is pumping away.
The wood boilers are fairly wide open vessels, little if any pressure drop thru them. The circ doesn't know if it is a boiler or 6 feet of pipe. Probably the circ on that loading unit is a low head pump, developing 3- 4 psi difference.
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I think this is why so many design-it-yourself systems discussed on this forum work fairly well despite being a little unorthodox.
Let me rephrase it then.....The point at which the expansion tank ties into the piping should be located at or near the inlet side of the main circulator in the system. This applies to any sealed boiler system or any piping on the sealed side of a heat exchanger. For the open systems it really doesn't make a lot of difference as you can't eliminate the air in the first place and you don't need an expansion tank.
HR, your diagram is not exactly how I planned my plumbing. The spiro vent with expansion connection at bottom will be after the 90 going to return protection on load side. Using a loading unit, is there a way to have the circulator not on return side? I can't see how?
Not saying mine is right or in any way the most correct way but here is an example. The lower the top pump is main circulator. The bottom is used for additional flow at end of charge, and or battery back up water flow.
gg
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gg
See my diagram. Changes I have made are: Return protection line will "T" off after spirotherm, Expansion attached at bottom of spiro therm, Zone Valve eliminated, No 45 offset in return line. I'm using a loading unit, so no way I can see to have circ after expansion location on hot supply. The lines to/from storage run close to ceiling for space. Storage is about 26 ft from boiler. Load "T" is close to boiler. Any suggestions appreciated
Maybe you have it already but fossil boiler may need return temperature protection, first to prevent condensation, and second to avoid heating up all of storage before you get much hot water. Or you could valve off storage when fossil backup is in use.
Good point. I have not had fossil fuel heat for many years, and I'm leaving a future for it as I'm not getting younger. Do not have backup unit as of now. Yes, thought I could valve off from storage also. Storage will have aquastat on top of tank to cut off back up boiler when storage tank temp reaches set point so I don't heat much more of storage than needed to supply load.
I think I would put my storage between the boiler & the loads - although it might not matter much. How will things flow when the fire is out & your system is drawing from storage? Also, you could T your expansion in before the loading unit, like perhaps in the area where the drain valve is - that would put your circ after expansion.
No way move storage unless I run lots more pipe. I'm already in too deep $ on pipe! Boiler and loads are close to each other, storage is across garage. I could T in just ahead of loading unit, but it would be at cooler water temp and require more pipe in my application. Those expansion tanks eat up room. When drawing from storage, Supply and returns will reverse flow. Loading unit will prevent flow thru boiler.
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