Air and expansion tanks

[NCPABill]

I have begun installing a 500 gallon pressurized storage tank to my biomass 40 system. I have an air scoop, expansion tank and "coin" vent on the already installed portion. I would like to install a separate expansion tank for the storage. Can I tee from a spare tank fitting over to a new, floor mounted expansion tank, plumbed to the top, with a "coin" vent just before the tank? The expansion tank would be shelf mounted above the storage tank.

I don't have a good way to install another air scoop setup on the storage tank plumbing, and wouldn't mind saving the money if this was not necessary!

Thanks in advance for your time.

Bill

 

[woodsmaster]

I believe you need the expanshion tank plumbed at the bottom so you dont get air in the systm when it cools. I dont think you need the coin vent becouse your expansion tank should have a fitting to add or let out air. If Im not mistaken the expanshion tank should be plumbed in just before your main circulator. I'm not an expert so take my advise with a grain of salt. Are you trying not to get into the existing plumbing ? You could probably t off of the inlet of your esisting exp. tank.

 

[in hot water]

If the storage tank is in the same piping circuit as the current tank, not separated by a heat exchanger for example, then connect the new tank at the same location as the current one. Install a tee below the scoop for example and use pex or copper tube to run over to the new tank.

The location of the expansion tank in the piping establishes the PONPC the point of no pressure change. You should only have one PONPC in the system and this is also the ideal place to tie in an autofill valve. The expansion tank is best piped in at the inlet side of the circulator in the boiler loop, the air scoop should be at the hottest point in the system for best air removal. If you have a scoop type air eliminator it is best to have 18" or so of straight pipe before the scoop.

Adjust the pre-charge in the new tank before you connect it. The pressure should be adjusted to the fill pressure of your system, maybe a psi or two below to allow a small amount of fluid into the tank.

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