In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Take a look at the drawing... While the boiler is running at +- 18psi, all on a sudden within 2-4 seconds the pressure raises to 30psi and blows the pressure relief. Temperature doesn't appear to have any bearing.... Not sure what does.... The system acts as if expansion tank " isn't there.... I temporarily installed Expansion tank "B" and all is well... Even if I turn expansion tank "A" off so it acts as if "A" weren't there.. . I have switched tanks with Expansion tank "A" and it doesn't matter.... So I believe that Ex tank "A" is good...
I have the indirect shut off both the coil & the domestic.
This happens when the temp is 180degF or 120degF... doesn't matter.
It seems that installing the expansion tank "B" solves the problem.. which is great but I wanna know why... :)
1. Why am I getting pressure spikes? in the first place...
2. Why doesn't expansion tank "A" seem to be seen by the system?
3. How come installing expansion tank "B" solves the problem even with "A" off?
I've rounded the system off to be +- 18 gallons...
Expansion tank "A" = Extrol #30
Expansion tank "B" = Extrol #30
Oh... one other thing... I didn't install the system... I'm just there to fix it.. :)
Thanks for all your help!! I really appreciate it...