Batch heater tank psi question

[isisbob]

I am replacing the tank on my 20 yr. old Cornell batch solar heater. Original tank is galvanized. I can get a galvanized tank to fit with a rating of 150psi. Is this sufficient or do I need greater psi? I used a std. hot water relief valve on it (150psi/210 degrees). Would I be better going for a stainless tank even though cost is much greater? Thanks for any help.  Bill

[Spelljammer]

Isisbob,

I thought that the batch heater systems typically ran about 7 - 10 psi.  I would think that a galvanized tank would work well especially considering the fact that you have a relief valve on it.  I would worry that the tank and relief are both 150 psi.  I would prefer to use a relief valve set to a lower value, like 100 psi or so.  You could even use 2 relief valves right next to each other.  Since valves can fail to open at the set pressure sometimes, having two would increase your odds and help you sleep a little better.