Expansion tanks options?

[goosegunner]

basically instead of having a tank with air on top and water in the bottom, i am using the 80 gal tank for water acceptance and the air in the drop tank, only because I could not find a single tank big enough for both water acceptance and air. We will see how it works.... top of the 80 gal water tank connects to the bottom of the drop tank, schrader valve on top of the drop tank to charge with air...

How much water are you going to put in the 80 gallon tank?

One thing I think would make an improvement on my Expansion tank is one of the Bell & Gosset valves that goes in the bottom to return air from the separator to the expansion tank.
Not sure where to get on with a long stem though.

gg

 

[maple1]

I'm guessing whatever amount of water that ends up in the 80 gallon tank will just be whatever enters it as the cold storage pressure equalizes with the pre- charged water pressure in the drop tank. Kind of just a two piece expansion tank.

 

[cjdave]

I'm guessing whatever amount of water that ends up in the 80 gallon tank will just be whatever enters it as the cold storage pressure equalizes with the pre- charged water pressure in the drop tank. Kind of just a two piece expansion tank.

Yes that is what i am planning on happening. That brings me to a new question, how much air pressure should I pre charge with?

 

[RobC]

As I recall when doing mine I just let it equalize with system pressure. My propane tank has a level gauge on it and it reads about 40%. After filling you may want to add some air but I wouldn't go overboard.

 

[maple1]

Assuming your system pressure when system is cold is to be around 12psi (a standard number), I would shut off both your 'extra' tanks from system with system at low system temp & 'extra' tanks empty, fill system (boiler, storage & distribution) with water to 12psi at low system temp, charge the two 'extra' tanks to 12psi of air, then open them to storage & start heating. If you start with less than 12psi in the 'extra' tanks at low system temp, then when you open them to the system water will flow in until pressure equalizes. That will reduce room left for expansion as system heats.

 

[Donl]

Assuming your system pressure when system is cold is to be around 12psi (a standard number), I would shut off both your 'extra' tanks from system with system at low system temp & 'extra' tanks empty, fill system (boiler, storage & distribution) with water to 12psi at low system temp, charge the two 'extra' tanks to 12psi of air, then open them to storage & start heating. If you start with less than 12psi in the 'extra' tanks at low system temp, then when you open them to the system water will flow in until pressure equalizes. That will reduce room left for expansion as system heats.

Yes!