Expansion tank position

Vince_4

Do-it-yourselfer here looking for info. on the correct placement of a Spirovent and expansion tank in relation to a buffer tank system. I've seen some systems plumbed with the expansion tank on the heat source side of the buffer tank and others connected on the zone side for a radiant floor heat system. What are the pros/cons of each method? Does it depend on the run time and temperature of the circulating water?

CHARLES_4

Expansion tank or diaphragm tank? Spirovents and conventional expansion tanks don't get along with each other. Kinda like my kids...

Vince_4

Expansion tank position

I should have said thermal expansion tank in a closed-loop system. What do you mean by "spirovents and conventional expansion tanks don't get along"? Are you refering to well expansion tanks?

Weezbo

captive air .

an extrol tank and an expansion tank are similar buh....arent found in the same company*~/:)

thats the distinction that is being made so that there is no confusion as whats what.

Brad White_30

Spirovents and E-Tanks

To me the best placement of the Spirovent is on the leaving side of the boiler where the water is hottest and the air release is greatest. The expansion tank (a closed bladder or diaphragm type as we all seem to agree) attaches to the bottom tapping on the Spirovent. (Mine is a little remote using a flexible braided hose but that is just a detail.)

Then downstream from the Spirovent is the circulator. Pumping away from the expansion tank is the key principle here.

In general I keep this on the near-boiler piping for the best air removal due to hottest water. But the Spirovent makes it almost academic. It will still work on return but take longer to get all the air out.

An advantage of putting the assembly on the secondary side is that those tend to have smaller tubing hence higher velocity potential for self-purging. But no matter where you put it, you will eventually get all the air out.