I have a HB Smith gas boiler model # GB100W. It is a two zone heating system. When both thermostats are shut off the boiler will continue to run. I have changed out the Honeywell relay control center R8285D-1026 and the problem still exist. Yesterday I changed the Honeywell L4080b-1253 Aquastat controller and I am still having the problem:confused. Any suggestions would be appreciated. Thanks in advance.