Moodog, I have a similar config. 2 years of use made me conclude that I needed to lift pans 2-3" to offset tendency for sap to overflow on rolling boil and to keep from burning on inside of pan above sap line. Would like to exchange thouights on operation with you, if possible. I have a 5-full pan configuration. Also I use perlite and firebrick to line/protect concrete blocks from heat damage.
