David: have a little experience from a previous life, T and P's are designed for one time only on the
temperature side, to force the user to investigate the cause. The pressure side can be used a few times.
I believe almost all domestic stuff is this way.
Bryan's cure would be elegant, but if you don't have a lathe, try commercial air system PSV's. Some of
the better ones have discharge connections, (not just holes) but the discharge cannot be restricted in
any way or function will be compromised. This however will not take into account any temperature issues,
but rapid release of pressure at above boiling will quickly cool things down.
Most are brass, and are suitable for Water/Oil/Gas.
Hope that isn't just a hindrance.