> Not a problem however since I installed
> the small ball valve. I can reach in
> behind the passenger side center panel
> and open/close it seasonally to cut flow
> completely off to the core.

Not a bad idea, if you need to reduce flow to absolute zero.

You might want to open that valve once every week or two, in order to get some circulation through the core. Without periodic flushing, the core can rot. I've never figured out why it matters, since the liquid in there will still be ethylene glycol whether it gets flushed through the system or not, but I do know that the major troubles I've seen with old heaters are due to lack of use.

- Erik