samf526
New Member
I am replacing my thermal expansion tank on my Navien combo-boiler system. I've heard two different things about the 'correct' pressure for the expansion tank:
1. The main water line pressure (from an external hose spigot this is 45psi)
2. The pressure within the closed heat system (much lower...I've heard this is ~13psi).
Right now I have my new tank charged to 45psi, and I'm finding that the pressure relief is getting activated, as the boiler is reaching 30-35psi while active. This is leading me to think that #2 is correct. But, the alternative is that I did not set the pressure correctly inside the boiler when I purged the air out.
Thanks!
1. The main water line pressure (from an external hose spigot this is 45psi)
2. The pressure within the closed heat system (much lower...I've heard this is ~13psi).
Right now I have my new tank charged to 45psi, and I'm finding that the pressure relief is getting activated, as the boiler is reaching 30-35psi while active. This is leading me to think that #2 is correct. But, the alternative is that I did not set the pressure correctly inside the boiler when I purged the air out.
Thanks!
